Specs

Equipment Specifications — Grove MZ66B Manlift

Quick-reference spec sheet. See Research for sourcing, diagnosis, and full provenance on every figure below.

Machine

Engine — Nissan A15

All figures in this section are transcribed directly from the actual Nissan factory manual, Service Data and Specifications, p.MA-9 (see the engine service manual) — this is real factory data, not an aggregator estimate.

Compression as actually measured, 09 Sep 2026. First real readings on this engine, taken on the starter with the plugs out. Seven gauge photos, read off the dial faces rather than written down at the machine, give roughly 120, 120, 250, 250, 250, 90 and 185 psi (±10 psi), with no record of which cylinder or which pass each belongs to. An eighth photo, of the tester lying on the frame rail after it came off, holds 180 and is almost certainly the last of the seven read again. Numbers written down at the machine supersede all of these.

• The three near 250 psi are not compression. At roughly 9:1, cranking against atmosphere, this engine cannot make 250. Liquid left in the bore does not compress and drives the indicated pressure far above normal, which fits an engine that had penetrant poured down the plug holes on 07 Sep and was ejecting material while being cranked. A gauge not bled between cylinders produces the same signature, so watch the needle return to zero on the next pass
• 185 and 180 psi sit at the 181 psi factory standard, so at least one cylinder makes full factory compression cold, on a tired battery. Nothing is worn out
• 120 psi is under the 142 psi minimum but normal for a bore still carboned, rusted or damp
• 90 psi is the one to chase with the wet-versus-dry test below
• Cranking speed, throttle position and battery condition all pull low readings lower still

See 09 Sep 2026 for how the needle was read, which is easy to get backwards on this gauge.

The manual’s own follow-up test, when a cylinder reads low (p.MA-4). Pour a small amount of engine oil into that cylinder through the plug hole and repeat the test.

• If adding oil raises the reading, the piston rings are worn or damaged
• If the reading stays low, a valve is sticking or not seating
• If two adjacent cylinders are low and adding oil does not help either, there is leakage past the head gasket surface

Given this engine’s history, a third possibility sits alongside the first two. A ring stuck in its groove with rust and carbon rather than worn, which can free up with running time.

Torque specs (complete factory table, p.MA-9)

The bolded rows are the ones that matter most for a rebuild (head, mains, rods). The head bolt figure is 51–54 ft-lb from the actual factory table. Main bearing and rod bearing torques match Grindstaff’s general figures exactly (36–43 and 23–27 ft-lb).

Wrench sizes measured on the machine

Not in any manual — recorded off the actual fasteners so they don’t have to be guessed at again. This table grows as more get measured.

The crank bolt size matters for freeing the engine — that’s the socket you need on a breaker bar.

Valve clearance

Both figures are factory, from the Engine Assembly section (p.EM-16, step 32 and its Note). An earlier pass through this project stated the manual gives no cold clearance; it does — the point is that the cold number is a build-time placeholder, not a spec you can leave the engine on. Final adjustment is always hot at 0.35 mm.

The order of work matters: with No. 1 at TDC compression adjust valves 1, 2, 3 and 5; with No. 4 at TDC compression adjust valves 4, 6, 7 and 8, counting the valves 1–8 from the front of the engine (p.MA-3, Fig. SMA099). That figure’s “Front” arrow is also the factory confirmation that cylinder No. 1 is the front one.

Ignition — confirmed factory data

Settled, this engine is electronic and not points. Cap and rotor off on 22 Aug 2026, the distributor shows a four-lobe reluctor and a crescent magnetic pickup with a two-wire pigtail. No contact set, no condenser, no breaker plate. Grove’s own engine harness drawing (parts catalog, catalog pp.152-154 / PDF p.169, harness assembly 6512002038) had this right all along, labelling a tap point for an electronic distributor alongside the anti-diesel solenoid. And on 09 Sep 2026 the body casting gave up its own numbers, T4T56371 / 22100-G5110, a T4T family unit rather than either T3T points unit in the manual. Three independent sources.

Consequences to carry.

• Don’t buy a contact set or condenser, and ignore any dwell reading. There is nothing to gap
• Firing order, rotation and ignition timing are unaffected. 1-3-4-2, counter-clockwise, 10° BTDC. See Firing Order & Plug Wires
• Order cap, rotor and leads against T4T56371 / 22100-G5110, not against a vehicle application. A cap bought on an application lookup did not match this distributor
• Inspected at the same time, the cap is serviceable, clean inside face, no tracking, carbon button well above the 3 mm (0.12 in) wear limit

The same harness drawing also shows an LP vacuum switch on the engine, which is independent support for the dual-fuel reading in Research §4.2.

This engine’s rebuild spec (as ordered/measured)

Common replacement parts — plugs and filters

Service consumables, in one place. The single most important thing to know before ordering: two different suppliers own two different halves of this list.

• Machine parts — Grove numbers, buy from MinnPar (1-800-889-3382, sales@minnpar.com), the current rights holder. Air cleaner, fuel filter, hydraulic filters.
• Engine parts — Nissan numbers, buy from Grindstaff (816-796-7676) or a Nissan forklift parts dealer. Plugs, engine oil filter, ignition parts, drive belt. Quote engine serial 85029.

The reason for the split is structural, not an oversight in this research: the Grove parts catalog lists the engine as a single line item — power unit assembly 2154800742 — and never breaks it down. There is no engine oil filter, spark plug or fan belt anywhere in its 400 pages, and the Nissan document is a service manual with no part numbers in it. So for the engine consumables below, the catalogue-grade part number genuinely does not exist in the documents this project holds, and the honest answer is the specification plus who to phone.

Ignition

Routing the leads onto the cap: Firing Order & Plug Wires.

Filters

Four of those — fuel 7437000104, oil-return element 9304100081, air cleaner element 9304100091, pressure element 9437100642 — are exactly the set Grove itself designates as periodic-service items. They are the entire contents of the catalog’s “Belt and Filter Maintenance List” (Appendix D), which is Grove’s own answer to “what do I re-order routinely.” Despite the name, that appendix lists no belt at all, which is consistent with the engine being carried as one assembly.

On the fuel filter, two Grove numbers exist and they are not interchangeable guesses. The Grove parts catalog — which is cut to this machine’s serial — gives 7437000104. The MinnPar catalog lists two more against the MZ66B model generally: 7437000205 (“filter, fuel”) and 7437000183 (“filter, fuel, with head”). MinnPar also lists spin-on secondary and water-separator fuel filters (9414100804, 9414101067) for the MZ66B. Those are most likely later supersessions or other-build variants. Order 7437000104 first, since it comes from the catalog built for this machine; keep the others as fallbacks to quote if MinnPar says the first is dead.

On the engine oil filter. No document in Manuals contains a part number for it. Do not buy on a guess from a cross-reference site — the widely-circulated Nissan forklift filter numbers found in general web listings are not tied to the A15 by any source with real provenance, and this project does not treat that as good enough. Two ways to close it properly, in order of preference:

1. Call Grindstaff with engine serial 85029. They supply this engine family and can give the correct current number in one call.
2. Measure the filter that’s on it. It’s a spin-on; thread size and gasket OD are all a counter-person needs to cross it. The machine is right there — faster than any amount of catalog archaeology.

Numbers taken off the machine itself

The manuals can’t supply these, so they were recorded from the hardware and the parts counter. They take precedence over any catalog cross-reference, because they describe what is actually bolted on.

Note on the hydraulic filter. Grove’s catalog describes hydraulic filtration as cartridge elements in housings (pressure element 9437100642, oil-return element 9304100081); the machine has a spin-on. Either it was converted or this build shipped that way. HF728 fits what’s on it.

Note on the oil filter. 51516 and 51361 are different filters, and on a spin-on the differences that matter are thread size, gasket diameter, bypass setting and anti-drainback valve. The 51361 came from an A15 lookup, so it’s the one to trust.

After a flooded crankcase, the first oil fill is a flush, not a service. Plan on running oil in, turning the engine, and dumping it at least twice before treating a fill as real.

Note on the ignition coil. This engine’s ignition circuit carries a dropping resistor in series with the coil feed, bypassed during cranking so the coil sees full battery voltage while the starter turns (engine service manual, Ignition System description, p.EL-15). That is why the coil on the machine is stamped “external resistor required”. Two consequences when replacing it.

• Fit another external-resistor coil. An internally-resisted coil dropped in behind the original resistor gives a weak spark that gets worse as things warm up
• Find the resistor and its cranking bypass and check both. Nothing labelled as an ignition ballast resistor appears on Grove’s engine harness drawing (parts catalog pp.152-154), which shows the coil, an ignition relay, the electronic distributor and the anti-diesel and choke solenoids, so it is most likely on the Nissan side of the harness, either as a block near the coil or as a resistance wire. The part itself is identified, Nissan 22460-14615 / Hanshin RA-16, 1.6 Ω (→ now SMP RU13), see “The ballast resistor, identified” below. What has not been found is the one on this machine

Coil measurements taken 09 Sep 2026, for comparison against a replacement. Secondary open circuit (OL between the HT tower and either low-tension terminal, both terminals tried), primary about 4 ohms. An open secondary cannot make a spark under any condition. A ballast-type coil’s primary normally reads nearer 1.5 ohms, so the primary is suspect too.

Superseded parts, at a glance

Read this before ordering anything from an older section of this document. Several parts named in the factory manuals are discontinued or out of production. Wherever an original appears elsewhere in these docs it should carry a "→ now" callout pointing here. If you find one that does not, this table wins.

Two part numbers in these docs are historical only and must not be ordered.

• Distributor Mitsubishi T3T03581. That is the points unit the Nissan manual documents. This engine has an electronic distributor, T4T56371 / Nissan 22100-G5110. There is no contact set or condenser to buy
• Starter Mitsubishi M2T20181 is the factory number. The machine carries a reman M2T42981, which is a different unit

One number is not a supersession and is easy to misread. AC Delco R44T and ACDelco 19542401 are the same plug; 19542401 is just the four-pack number. R44T is a taper-seat, 0.431 in reach plug and is not a replacement for B4ES or BR4ES. Which of the two this engine needs is still open, see the plug seat warning below.

STOP. The plug in this engine and the plug in the manual are not the same plug

Established 2026-09-10, and it supersedes the “gasket seat, buy NGK 4129” guidance that was written here earlier the same day. That guidance came from the factory manual alone. The machine disagrees with the manual, and the head is the arbiter, not the book.

These do not cross-reference to each other in either direction. The reach differs by roughly 0.32 in, which is most of a centimetre of thread.

So one of two things is true, and they need opposite parts.

• The head is the factory A15 head, flat seat and 0.750 in reach. Then the R44T plugs that have been in it are badly wrong. The tip sits about 0.32 in up inside the threads, the exposed threads carbon up and run hot, and the taper cone is sealing on a flat counterbore at best
• The head is not factory, or was re-machined. This engine is a Grindstaff reman, bored .030 over, so a different head is entirely possible. Then R44T is right, “no compression ring” is right, and 1/16 turn past snug was the correct way to torque them

Do not order B4ES on the manual’s word. If the head is taper seat, a 0.750 in reach plug protrudes about 0.3 in into the chamber and can hit the piston. Getting it wrong in that direction is the one that breaks something.

Settling it at the machine, with a plug and a light

1. Look into a plug hole. A flat machined face at the top of the threads is a gasket seat. A cone partway down is a taper seat
2. Thread an old R44T in by hand. If it comes up solid on a cone with the hex still clear of the head, that is a taper seat and the plug belongs there. If it winds in and the hex lands on the head with no distinct seating feel, the head is a gasket seat and the plug is wrong
3. Look for a carbon step in the threads. A short plug in a long hole leaves a carbonised ring partway down the bore of the hole. That is the giveaway that the wrong plug has been run
4. Measure the threaded depth with a wire or a zip tie against the plug’s own threaded length. About 0.75 in is the long-reach head, about 0.43 in is the short one

Then buy accordingly.

• Flat seat, 0.750 in reach, gasket → NGK BR4ES, stock no. 1097 (B4ES is discontinued), torque 11 to 14 ft-lb
• Taper seat, 0.431 in reach → AC Delco R44T (ACDelco P/N 19542401) or NGK YR5, torque by the taper method, 1/16 turn past snug, which is what was already done

The ballast resistor, identified

Nissan 22460-14615, “Resistor, Ignition Coil” (→ now SMP RU13). Also sold as Hanshin RA-16, with alternate Nissan numbers 22460-U2200, 22460-U2210 and 22460-U2211. Nissan’s part group for it is 22460.

• 1.6 Ω, which is exactly the value the vendors selling the OE coil state that coil must run with
• Two-post ceramic block
• Listed for the Datsun and Nissan points-ignition family including A12, A13 and A14, the same ignition architecture as this A15, alongside 510, 610, 710, 240Z, 1200, B110, B210, 520, 521, 620 and the L60 Patrol
• Currently listed in stock at Amayama, unlike the coil and the OE leads

It is the correct partner for the factory coil this manual names, HP5-13E10 / Nissan 22433-U3110 (→ now SMP UC12).

It is not visible anywhere on this machine

Every photograph of the coil from 2026-09-09 shows the same thing. The coil sits in a band clamp on a plain rusty steel bracket, with two spade-terminated wires at its low-tension posts, a blue and a yellow, and nothing else. There is no ceramic block on the bracket, beside it, or anywhere in frame. So on this machine the drop is one of three things.

1. A resistance wire buried in the Grove harness, which is what those photos would look like
2. Mounted remotely, somewhere not photographed
3. Absent, because a previous owner fitted a ballast-type coil without one

Option 3 matters, because running a 1.5 Ω external-resistor coil on a full 12 V feed cooks it. The coil that came off has a dead secondary and a primary reading 4 Ω against a 1.5 Ω spec, which is what an overworked coil looks like. That is a plausible reason it died, and a reason not to fit the new one until the feed is measured.

Settle it with the meter before fitting the new coil

The classic arrangement puts two feeds on the coil’s + terminal, one through the resistor for running and one direct from the starter for cranking. That is what the “bypasses the resistor during cranking” line in the engine manual (p.EL-15) describes.

1. Key ON, not cranking, measure at the coil +. Around 6 to 9 V means a resistor or resistance wire is in circuit and working. Full battery voltage means there is nothing dropping it, and the new coil needs a 1.6 Ω resistor added before it runs
2. Measure the same terminal while cranking. It should rise to near full battery voltage, which proves the bypass
3. To find it, disconnect the coil + wire and measure from that wire back toward the ignition switch. 1.6 Ω or thereabouts means it is in that path, as a block or a resistance wire. Near 0 Ω means it is not there at all

Dual fuel. What the manuals actually contain

This machine is factory dual-fuel (RESEARCH.md §4.2). The dual-fuel material is spread across four documents in this set, and it is easy to miss because the engine manual has none of it.

Switching fuels, from the handbook p.4-4

The switch has a neutral position and the procedure uses it deliberately, to run the other fuel system out before changing over.

• Gasoline to LP. Run the gasoline carburettor dry with FUEL SELECT in neutral. When the engine stops, move to L.P. and restart
• LP to gasoline. Running on LP, put FUEL SELECT to neutral. When the engine stops, move to GAS and restart. It may take extended cranking to fill the float bowl, but not more than 10 seconds continuously
• The handbook’s own note. Put the switch in neutral until the engine begins to miss, then throw it to the selected fuel

LPG ignition service intervals, from IMPCO p.7

These are LPG-system intervals and they are more frequent than the gasoline schedule in places.

• Clean the ignition coil at each major interval
• Replace spark plugs, replace distributor cap and rotor, replace plug leads on their own intervals
• Check plug leads for cuts, abrasions or hardening
• Note that propane engines are designed for HD-5 or HD-10 specification fuel. Other fuel can damage the emission control system

What is genuinely not in any of them

LP ignition specifications for the A15. No heat range, no gap, no timing figure for running on propane. The Nissan A12/A15 industrial service manual is gasoline-only, confirmed four ways.

1. A loose search for LP, LPG, propane, butane, gaseous, vaporiser and dual-fuel across all 91 pages of a fresh 250 dpi OCR
2. The Quick Reference Index, whose sections are GI, MA, EM, LC, EF and EL
3. The EF (Engine Fuel) section’s own contents, which are fuel pump, carburettor, governor, service data and trouble diagnoses. No vaporiser, converter or mixer
4. The maintenance schedule read as a page image rather than OCR. Gasoline plugs, points, cap, rotor and timing only, with no LP column

So B4ES, the 0.8 to 0.9 mm gap and 10° BTDC are gasoline figures. For the current plan that is correct, because the first start is on gasoline from a separate can with the LP side disconnected.

Before the LP side is ever commissioned, those three numbers need a source. A Nissan LPG supplement for the A-series industrial engine would be the right document and this project does not have one. That is a real gap, not a settled question.

Which resistor for which coil

The right resistor is set by the total primary circuit resistance, not by a part number. A 12 V ballast ignition wants coil primary plus ballast to land around 3.0 to 3.3 Ω. That is what sets the running current.

So the answer is the same 1.6 Ω for either coil, because the UC12’s primary sits in the same window as the factory coil’s. That is not a coincidence; the UC12 is sold as a replacement for exactly this class of coil.

Parts that meet it

Yes, it is a two-pole part, and that is verified rather than assumed. Searching RockAuto’s interchange for the OE number 22460-14615 returns exactly three ballast resistors, and all three are 2-terminal.

Four-pole ballasts do exist, and it is a fair thing to check. SMP’s RU12 is one, at 4.75 to 5.75 Ω. It has zero 22460 cross-references. No four-terminal resistor in that range crosses to this Nissan family at all, which is about as clean an answer as the catalogues can give.

RU13 or RU13T

They are physically the same part. Same terminal count, same terminal types, same gender, same mounting bracket. T-Series is Standard’s value line, described as “made from quality components, designed to meet the original”. The difference that matters is the warranty, 36 months against 12, for $3.41.

Buy the RU13. Three times the warranty, on a part whose failure mode is no spark and a dead machine in a field, for the price of a coffee. The wider cross-reference list on the T listing is not a real advantage either. Both carry 22460-14615, which is the only cross that matters here, and the extra U-numbers are catalogue data variance rather than a different part.

A correction

An earlier version of this page recommended SMP RU-10. That was wrong. RU10 is a 2-terminal ballast, but its interchange list is GM numbers only, with no Nissan 22460 cross-reference at all. It was picked up from a search result claiming it crossed to the Echlin ICR13, and never checked against the Nissan side. RU13 is the correct part.

Why two poles is enough here even with an electronic distributor

Worth spelling out, because the question is a fair one. A four-pole ballast exists to feed two separate things, classically one element dropping the coil and a second element supplying an ignition control module. This engine does not need that.

• The coil that came off is a plain two-terminal canister, and the UC12 replacing it is the same. There is no separate module supply to drop
• The crank bypass is a second wire, not a second element. It carries full battery voltage to the coil + during cranking, and it can land on the coil’s own + terminal. Some Nissan ballasts provide a spare post purely as a junction for it, which is where four-terminal confusion usually comes from
• The OE partner for the coil this manual names is a two-post part

The honest limit. There is no resistor on this machine to look at, so nothing here proves how many wires the Grove harness expects to land there. Count them when the coil feed is traced. If three wires want a home, put the bypass on the coil + rather than buying a different resistor.

Two things that would make it the wrong choice

• If the machine already has a resistance wire in the harness, adding any ballast in series roughly doubles the drop and gives a weak spark that gets worse hot. Measure the feed first
• If a previous owner has already fitted an internally-resisted coil elsewhere in the circuit, same problem. The coil that came off is stamped “external resistor required”, so that is unlikely here, but the meter settles it either way

A note on why the 310 catalog has no ballast resistor listing. RockAuto’s ignition categories for the 1982 Nissan 310 1.5 L run distributor, cap, pickup coil, reluctor, rotor, vacuum advance, coil, coil mounting bracket and ignition control module, with no ballast resistor category at all. Two things follow. That car ran an electronic distributor much like this machine’s, which is further support for the cap and lead choices above. And its voltage drop was almost certainly a resistance wire rather than a serviceable block, which is exactly the arrangement that would explain why no ceramic resistor is visible anywhere on this engine.

The verified buy list

Every line below was checked against the OE numbers taken off this machine’s own distributor casting. Confirmed 2026-09-10.

Buying the cap and the wire set together removes the fitment question I raised earlier. The worry was whether a set catalogued for a 1982 Nissan 310 would seat in this machine’s cap. It no longer matters, because the JH180 is this machine’s OE cap, and the NGK 8116 is listed for the same applications. They mate to each other by definition.

The plugs are the one conditional line. BR4ES is the 19 mm flat-seat plug. The head’s seat and reach are still unconfirmed, and the engine currently has 10.92 mm taper plugs in it. Buying them is fine, they are cheap and returnable. Fitting them before the head is identified is the thing that can put 0.32 in of plug into the combustion chamber. Do the socket and depth check first.

Not on the list yet, and correctly so. The ballast resistor. Measure for the 1.6 Ω first, because the machine may already have one, or a resistance wire, and adding a second in series halves the spark.

Interference risk from the R44T plugs. There is none

Asked and answered 2026-09-10. The R44T cannot touch a piston or a valve, because it is too short, not too long. The risk runs entirely the other way.

The reach difference is 8 mm, about 0.32 in.

If the head is the factory flat-seat type, the R44T’s cone is wider than its own 14 mm thread, so it cannot enter the threaded hole at all. It stops on the head’s counterbore, and the electrode ends up sitting roughly 8 mm recessed up inside the threaded hole, short of the chamber. Nothing can reach the piston. It is therefore safe to turn the engine over with these plugs in.

What it does risk, which is not interference

• A pre-ignition hot spot. Eight millimetres of unfilled, carbon-packed thread between the plug tip and the chamber is exactly the kind of glowing edge that lights the mixture early. That is a damage path, just not a contact one
• Misfire and hard starting, because the spark is happening in a pocket rather than in the chamber
• A marginal seal. A cone bearing on a flat counterbore is line contact. It can leak combustion gas and gall the aluminium seat
• A hot-running plug regardless of heat range, because a plug sheds most of its heat through its seat and this one barely has one
• Carboned threads that may need chasing before a correct long-reach plug will go in cleanly

The actual interference case is the opposite one. Fitting a 19 mm reach plug (B4ES, BR4ES, or anything else on the manual’s spec) into a taper-seat head puts about 0.32 in of plug into the combustion chamber, where it can meet the piston or a valve. That is the direction that breaks something, and it is why the head has to be identified before ordering.

So the practical position. Cranking with the R44Ts in is fine. Running the engine on them is not, until the head is identified, because of the hot-spot and sealing points above.

The 8 mm difference makes the depth check unambiguous

Drop a thin rod or a zip tie down an empty plug hole until it stops on the piston, and mark it level with the head face. Then measure the old plug from its seat to the tip of its threads.

• Hole about 19 mm deeper than the plug’s reach means a flat-seat, long-reach head, and the R44Ts have been wrong all along
• Hole matching the plug’s 11 mm means a taper-seat head, and the R44T belongs there

The hex size is a second, instant tell. R44T takes a 5/8 in plug socket. B4ES and BR4ES take 13/16 in. Whichever socket fits the plugs that came out says which family the engine has been running.

B4ES is discontinued. The current plug is NGK BR4ES, stock no. 1097

Confirmed 2026-09-10 on NGK’s own site, which marks B4ES (stock 4129) discontinued and names BR4ES (stock 1097) as its replacement. BR4ES is a dimensional drop-in. The only difference is a built-in resistor.

The added resistor is fine here, and arguably an improvement. This engine has an electronic distributor, and resistor plugs exist to suppress the radio-frequency noise that can upset an electronic ignition module. Five kilohms at the plug is ordinary; the manual’s own limit is on the leads, at under 30,000 Ω each, and nothing in the system objects to a resistor plug on top of resistive leads.

Do not accept BPR4ES as a substitute. It turns up constantly next to BR4ES and the extra letter matters. BP = projected tip, which pushes the electrode further into the combustion chamber. B4ES and BR4ES are both non-projected. On an engine where the plug reach is not yet settled, a projected tip is the wrong direction to guess in.

Spark plugs, three designations exist and they are not interchangeable

Read the provenance column before picking one. An earlier revision of this page gave “L47PW or B4ES” and cited it to the Nissan manual p.EL-19. That citation was wrong. L47PW appears nowhere in the Nissan manual; it comes from a third-party aggregator, and it is the hot plug in a range, not the standard.

Two reasons the aggregator’s numbers are the wrong tree, both checkable in the factory manual.

• BPR is not B. In NGK’s code, BP is a projected tip and R is a resistor plug. B4ES is neither. Different plug, not a heat-range variant of the same one
• The -11 suffix means a 1.1 mm gap. This engine’s factory gap is 0.8 to 0.9 mm (p.EL-19), so a -11 plug is specified to the wrong gap out of the box. That mismatch is itself the tell that the aggregator is describing the car, not this industrial engine

Spark plug dimensions, from p.EL-19

19 mm is 3/4 in of reach, and NGK’s B-series “E” plugs are flat-seat plugs with a captive gasket. So this head is a gasket-seat head. Two consequences.

• A replacement plug that arrives without a gasket is the wrong plug for this engine
• A gasket-seat plug is torqued, not turn-counted. The “1/16 turn past snug” method is the taper-seat procedure. On this engine use the manual’s 11 to 14 ft-lb. A gasket-seat plug set to 1/16 past snug is badly under-torqued, and it will leak compression, run hot and can back out

Ignition coil, from p.GI-2 and p.EL-19

Measured on the machine 09 Sep 2026, the primary read about 4 Ω, which is roughly 2.4× the factory figure, and the secondary read open circuit. Both windings are out of spec, not just the secondary. There is no ambiguity left about whether this coil is dead.

Other Mitsubishi units on this engine, from p.GI-2

No Grove part number exists for the coil, the plugs or the leads. Closed three ways, 2026-09-10, so nobody needs to search the parts catalog for these again.

1. Full-text search of all 400 pages returns zero hits for “SPARK”.
2. The Alphabetical Index (Appendix A) has no entry where one would sort. The sequence runs SOLENOID, SOLENOID ASSY, SPACER, SPADE, SPINDLE, SPOOL, SPRING. SPARK would fall between SPADE and SPINDLE and there is no gap. That is a structural proof, not an absence-of-OCR argument. The only COIL entries in the index are hydraulic manifold coils (9926106062, 9926103487, 9926110847).
3. Grove’s own “Belt and Filter Maintenance List” (Appendix D) has exactly four line items, and none of them is an ignition part or even the engine oil filter. FILTER, FUEL 7437000104 (p.139); ELEMENT, AIR CLEANER 9304100091 (p.147); ELEMENT, OIL RETURN 9304100081 (p.265); ELEMENT, PRESSURE FILTER 9437100642 (p.267).

The MinnPar catalog carries none of them either. The reason is that Grove buys the engine in as a single assembly, 2154800742, and the “POWER UNIT INSTALLATION - NISSAN A-15 (GAS)” section (catalog pp.137-143) is mounting hardware, brackets and cap screws only. Every ignition and tune-up part for this machine is bought on the Nissan / Mitsubishi side.

Buying the plugs and the coil, resolved 2026-09-10

NGK indexes by stock number, so search the number, not the code. B4ES is stock 4129 and BR4ES is stock 1097. B4ES is discontinued; order NGK 1097 / BR4ES, which NGK itself names as the replacement. See the section above for why that swap is safe.

Cross-references for B4ES, if NGK is awkward to get.

• AC Delco R45XL, 47XL
• Champion N5C, N21, 504, 120
• Autolite 405, 398, 3666
• Denso W14E, 6009
• Bosch W9C, W8CC, W10C

Ignition coil, the buyable numbers

Published resistances for the OE coil, useful for testing a replacement.

• Primary 1.5 Ω ± 10% (factory manual p.EL-19), quoted by vendors as 1.5 - 1.7 Ω
• Secondary roughly 9.5 - 11.6 kΩ (vendor figure; the factory manual does not publish a secondary spec)

The coil that came off this machine reads about 4 Ω primary and open on the secondary. Against 1.5 Ω and ~10 kΩ, both windings are dead. There is nothing to debate.

The ballast resistor value is 1.6 ohms

Datsun/Nissan vendors selling the OE HP5-13E10 (→ now SMP UC12) state plainly that this coil must be used with a 1.6 Ω resistor. That is the number to look for when tracing the machine’s dropping resistor, and the number to buy to if it turns out to be missing or open.

Off-the-shelf ceramic ballast resistors that bracket it.

• NAPA Echlin ICR34, 1.4 Ω
• NAPA Echlin ICR13, 1.8 Ω
• NAPA Echlin ICR11, 1.35 Ω

Do not fit a resistor without measuring first. If the machine already has a resistance wire in the harness, adding a ceramic resistor in series doubles the drop and gives a weak spark.

Plug leads. Buy NGK 8116

NGK 8116, NGK part RC-NX71. About $22 at RockAuto, regular inventory, lifetime warranty. A finished set. No crimping.

RockAuto catalogues it against 1982 Nissan 310, 1.5 L L4, which is the A15, and the rest of its application list is the same distributor-cap family this machine’s cap belongs to. 1982 to 1988 Sentra, 1983 to 1988 Pulsar and Pulsar NX, 1984 to 1991 Micra, all of which appear alongside A15S on cap 22162-G5711 (→ now SMP JH180).

The one thing to check before trusting it

The 1982 310 is the automotive A15 and its distributor is not this machine’s electronic Vanette unit. The cap family overlaps and both take 90° socket-type boots, but offer the cap-end terminals up to cap 22162-G5711 (→ now SMP JH180) before routing anything. If they seat, the set is right.

Other finished sets on the same page

All catalogued for the same 1982 Nissan 310 1.5 L, if the NGK is unavailable.

• Standard Motor Products 27414, Pro Series, silicone jacket
• Walker Products 9241094, Direct Fit, suppression core
• Standard Motor Products 7414, Standard Premium
• Denso 6714008, 7 mm
• Federal Parts 4605, about $5.33 as a closeout, published lengths 24 in coil and 20, 26, 30, 34 in plug leads. Cheap enough to keep as a spare

Why the first pass missed all of this

The searches were run against “Datsun” 210 and 310. RockAuto files this car as NISSAN 310. The 1982 model year is right on the Datsun-to-Nissan rebadge, and querying the wrong make returned bulk cable only, which led to the wrong conclusion that no finished set existed for the A-series. It does. There are more than a dozen. When an application looks empty, try the other badge before concluding the part does not exist.

Ignition parts, OE numbers

Sourced 2026-09-09 to 2026-09-10. The distributor’s own casting numbers were the key that unlocked these; searching on a machine application never would have. Amayama’s application data is explicitly “for reference only”, so verify against the physical part before buying.

The A12 and A15 have different distributors, and the manual’s own two pages disagree on the digits. p.GI-2 gives T3T03571 (A12) and T3T03581 (A15); the service data table on p.EL-19 OCRs the A12 column as T3T03671. Take p.GI-2 as the better read. Either way both are the points units, and neither is what is on this engine.

Where is the dropping resistor? Not yet found on this machine. No ceramic ballast block is visible at the coil or on its bracket in the 2026-09-09 photos, which show the coil clamped to a steel bracket with two spade wires and nothing else. On Nissan A-series installations it is normally either a small ceramic block near the coil or a resistance wire buried in the harness, and a resistance wire would look like exactly what those photos show. Grove’s harness drawing tags the coil with wires 205 and 298, and the archive.org schematic puts 205 and 208 in the “DIST, IGN” area, but that scan’s OCR is far too poor to trace. Read it off the drawing image.

Finding it with a meter takes two minutes and does not need the coil replaced first.

1. Key ON, engine not cranking. Measure at the coil’s + feed terminal. Battery voltage means there is no resistor in that path. Something around 6 to 9 V means there is one, and it works
2. Now measure the same terminal while cranking. It should jump to near full battery voltage. That is the cranking bypass doing its job. If it does not rise, the bypass is the fault
3. To find the resistor physically, disconnect the coil + wire and measure resistance from that wire back to the ignition switch feed. The target is 1.6 Ω, which is what the OE coil’s vendors specify. Anything in the 1.3 to 1.8 Ω band means a ballast or resistance wire is in the loop. Near 0 Ω means it is not in that path and the resistor is somewhere else

Do step 1 and 2 before fitting the new coil. If the resistor has failed open, the new coil will not fire either, and it is easy to blame the new part.

Not in any document held here

Flagged rather than guessed, so nobody re-searches these later thinking they were missed:

Key part numbers identified

Diagnosis-driven and rebuild part numbers. Routine service consumables are in the section above, not repeated here.