EFI question

[Amsterdamned96]

I'm reverse engineering the EFI on a truck that had it's wire loom and other soft plastics ruined by excess heat/fire. I'm replacing the obsolete Accel EFI because it's no longer supported. I'm trying to reuse as much hardware as possible. The engine I'm working with is an early Gen V or IV that doesn't have a CPS, presumably the dizzy supplied both the cam and crank signal. It's the magnetic type with 8 teeth.
Having considered investing in coil-on-plug ignition and fitting an external missing-tooth wheel I had hoped that I get both of these signals from the distributor.
If not are there cheaper/ less laborious alternatives? I read somewhere that there are new distributors that both distribute power as well as provide cam and/or crank signals.

 

[Schurkey]

I'm reverse engineering the EFI on a truck that had it's wire loom and other soft plastics ruined by excess heat/fire. I'm replacing the obsolete Accel EFI because it's no longer supported.

Clearly, this is not an OEM EFI system. I assume you have no interest in going back to an OEM EFI system.

That leaves half-a-dozen manufacturers of on-board computers, injector systems, and accessories such as the various sensors, distributors, etc.

I'm trying to reuse as much hardware as possible.

Sensible, if the new system supports what you already have.

The engine I'm working with is an early Gen V or IV that doesn't have a CPS, presumably the dizzy supplied both the cam and crank signal. It's the magnetic type with 8 teeth.

TBI style. There is no crankshaft signal, just a pulse when the ignition needs to fire; and the distributor mechanically assures that the correct cylinder gets the spark. Could be either Mark IV or Gen 5 depending on the year. Is the timing cover metal (IV) or plastic (V)?

Some parts-swapping to a Gen VI timing cover and components would get you an OEM-type crank sensor. But that may not be what you want.

Having considered investing in coil-on-plug ignition and fitting an external missing-tooth wheel I had hoped that I get both of these signals from the distributor.
If not are there cheaper/ less laborious alternatives? I read somewhere that there are new distributors that both distribute power as well as provide cam and/or crank signals.

I can't help there. I don't know what might be available from Holley/MSD, FAST, or the lower-tier companies.

 

[LC2NLS6]

The Holley sniper doesn't have cam/crank sensor, it works like a carb setup would, you just mechanically bring engine to 0 tdc, then stab the dist in with a special cap and lock it down. Then use the handheld to turn off the advance and use a light to verify it.

You can install a msd crank trigger and ign box to run your ignition, if you go carb? Coil on plug would be holley hp or dominator/terminator type setups.

 

[Amsterdamned96]

Clearly, this is not an OEM EFI system. I assume you have no interest in going back to an OEM EFI system.

That leaves half-a-dozen manufacturers of on-board computers, injector systems, and accessories such as the various sensors, distributors, etc.


Sensible, if the new system supports what you already have.


TBI style. There is no crankshaft signal, just a pulse when the ignition needs to fire; and the distributor mechanically assures that the correct cylinder gets the spark. Could be either Mark IV or Gen 5 depending on the year. Is the timing cover metal (IV) or plastic (V)?

Some parts-swapping to a Gen VI timing cover and components would get you an OEM-type crank sensor. But that may not be what you want.


I can't help there. I don't know what might be available from Holley/MSD, FAST, or the lower-tier companies.

I have an old aftermarket intake manifold, So I won't be going back to TBI or an OEM throttle-body.
Choosing an ECU/EFI system isn't the problem, I've actually settled on a MegaSquirt after struggling with soldering together a DIY Speeduino although I may try that first if all the hardware is in place.

My main concern is the crankshaft signal, I'm reluctant to install a missing-tooth wheel because of potential fitment problems and whatnot. It is an early Gen V, it has a metal timing-chain cover. I didn't know that newer timing chain covers can be retrofitted or that they accomodate a CPS. I'll make a WTB post on the forum and scrounge online to see if I can find an affordable part. Is it just the housing/cover with a 'universal' threaded CPS/Hall effect sensor?

 

[Amsterdamned96]

Clearly, this is not an OEM EFI system. I assume you have no interest in going back to an OEM EFI system.

That leaves half-a-dozen manufacturers of on-board computers, injector systems, and accessories such as the various sensors, distributors, etc.


Sensible, if the new system supports what you already have.


TBI style. There is no crankshaft signal, just a pulse when the ignition needs to fire; and the distributor mechanically assures that the correct cylinder gets the spark. Could be either Mark IV or Gen 5 depending on the year. Is the timing cover metal (IV) or plastic (V)?

Some parts-swapping to a Gen VI timing cover and components would get you an OEM-type crank sensor. But that may not be what you want.


I can't help there. I don't know what might be available from Holley/MSD, FAST, or the lower-tier companies.

I was just looking over this old thread. Are the Gen VI timing sprockets and the reluctor wheel compatible with the old crank snout?

 

[Schurkey]

I was just looking over this old thread. Are the Gen VI timing sprockets and the reluctor wheel compatible with the old crank snout?

My GM timing set for Gen 6 step-nose camshaft went onto a Mark IV long-block.

Verify pulley alignment when you're able.

 

[Amsterdamned96]

My GM timing set for Gen 6 step-nose camshaft went onto a Mark IV long-block.

Verify pulley alignment when you're able.

Without the Gen 6 cam? I appreciate you clarifying this up for me. I understood additional holes need to be tapped for the cover as well.

 

[Schurkey]

Without the Gen 6 cam? I appreciate you clarifying this up for me. I understood additional holes need to be tapped for the cover as well.

WITH Gen 6 cam, using a marine timing cover so as to utilize a cam-driven neoprene-vane water pump.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

Note slack in timing chain.

Photo of previous engine, showing timing cover and bronze water pump.

You must be registered for see images attach

 

[Amsterdamned96]

WITH Gen 6 cam, using a marine timing cover so as to utilize a cam-driven neoprene-vane water pump.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

Note slack in timing chain.

Photo of previous engine, showing timing cover and bronze water pump.

You must be registered for see images attach

What kind of heads are those? Have you made any valvetrain modifications, lifters, pushrods?
Is the roller-cam thrust plate different from the stock flat tappet variant?

 

[Schurkey]

What kind of heads are those?

OEM iron. Those are either the heads that came with the engine (round-port, 2.08 valve) or they're L29 heads grafted onto a Mark IV block, depending on when the photo was taken. Current heads are Mark IV oval-ports with big valves and some port work.

Have you made any valvetrain modifications, lifters, pushrods?

You must be registered for see images attach

Yes. Roller cam, roller rockers, pushrods, beehive valve springs, retainers, and keepers to suit.

You must be registered for see images attach

I'm happy with the rocker sweep.

Is the roller-cam thrust plate different from the stock flat tappet variant?

Almost all Mark IV blocks have drilled 'n' tapped holes for the thrust plate. A few have the bosses, but are not drilled.

But the thrust plate isn't used on passenger-car engines. It was used on medium-duty (Tall-Deck) truck engines with a gear-drive and reverse-rotation cam.

The Gen 6 was the first "common" engine to actually use the thrust plate and step-nose cam. It's the same thrust plate as the second-design thrust plate for the small-block. Why GM screwed-up and created the First-design small-block thrust plate is a mystery to me, since the second-design had been in inventory since the dawn of the Mark IV.