GM small block mechanic help

[churchmouse]

You should still need an ecm for several sensors on the motor and cooling system. I dont know how in depth the ecm was for an 87 and what it all controlled as vehicle computers were only starting to become more prevalent, but todays ecms are much more powerful and control pretty much everything.

Nope. It does not come into play on an aftermarket carb set up like this. Those sensors set Fuel/air and timing on a TBI set up.
Even the ECM controlled carb engines have no need after the ECM controlled components are stripped away. 85 Monti Carlo SS had the ECM quadrajet on it. When we pulled that turd out and inserted a very nice 355 in its place all of the ECM and wiring harnesses were removed. Same thing on our 88 Chev. truck when the engine went south in it. Re-built a 350 with a carb and out with the turd and in with the new. No ECM. WE had to do the trans as well to eliminate that issue. All analog all the time. That truck is still rolling last I heard...

 

[Biggredchev]

You should still need an ecm for several sensors on the motor and cooling system. I dont know how in depth the ecm was for an 87 and what it all controlled as vehicle computers were only starting to become more prevalent, but todays ecms are much more powerful and control pretty much everything.

Actually the 2 sensors a carb/hei engine should have are oil psi and coolant temp, are mechanical sensors on a k5. The hei distributor will control the spark and timing and the carb will control the fuel and air. If it has the th350 it literally doesnt need a computer for anything either as that is also mechanically controlled.

Edit: churchmouse beat me to it

That said its not getting any spark if you put fuel in the carb and it didnt even sputter. Even an out of time carburated engine will sputter with fuel and spark. As said before, Check to see if the coil is getting 12v, if so and its not putting out 12v then replace it. You could even check it with a test light if you dont have a meter. If its putting out power then the distributor/ cap/ rotor is the culprit.

 

[halfmileharry]

I'm GUESSING that you're not getting spark from your ignition switch/wiring. You'll get juice to crank the starter but not ignite the ignition voltage.
Drop all the Computerized crap you can. Transmission might be an issue. You can always run a seperate feed to to the ignition to bypass that harness that feeds computerized demons.

 

[Jaybird1980]

Would check 12v source to HEI, also check to make sure grounds are good. 12v for ignition and fuel pump originally came from same distribution block near HVAC blower motor. Find out where they pulled 12v source from, and make sure fuel pump has 12v, and a pressure regulator that is working. I believe the ecm powered up the fuel pump relay.

 

[Leadeye]

With no sputter at all when you put gas down the carb, either the coil is dead, not connected correctly, or it's not getting power. A friend reminded me once when I was chasing a voltage regulation problem that new was not always good. Sure enough I checked the new voltage regulator and it was bad.

 

[JeepHammer]

Everything I checked said yes. It is a brand new Mallory hei ignition and distributor. I’m probably just missing something and just out of time down here.

Your #1 cylinder needs to be at Top Dead Center (TDC) of COMPRESSION stroke.
This is a 4 cycle engine, the Piston will reach TDC TWICE, top of compression, top of exhaust strokes.

Pull #1 spark plugs, roll engine over until compression starts, the rotate crank BY HAND until the Piston reaches TDC,
Use something soft, chop sticks or wood dowel rod to feel for Piston, crank engine email BY HAND when sneaking up on TDC,
Use something soft to feel for Piston top to find TDC.

DO NOT rely on 'Hash' mark on balancer!
The outside ring on harmonic balancer often slip on the hub, and timing cover scale & balancer is often mismatched.
Find TDC of #1 cylinder, and THEN check the balancer against the timing cover... This will verify both the balancer & timing tab.

Malory Unilite has a quirk, if you leave the power turned 'On' without the engine running, the module will burn out.
(Ford DuraSpark modules has the same issue)
Try and start the vehicle and forget key is in 'Run' position for a long time, and the module can burn itself.

Mallory will NOT fire if line voltage drops below 10 volts.
The starter often drops a weaker (but not dead) battery below 10 volts when cranking.
Inline ignition resistors can drop voltage to the unit, Mallory NOT being designed to work with a resistor on the main power line.

Put the distributor cap on the distributor and Mark the #1 plug wire ON THE DISTRIBUTOR BODY.
This way you will know where #1 is without the cap on the distributor.
The rotor needs to be on the distributor shaft, and that rotor needs to be backed up in rotation *about* one spark plugs wire terminal BEFORE you drop the distributor on the camshaft.

The angle cut off the gears will rotate the rotor/shaft FORWARD while the distributor falls into place.
If you don't compensate, the distributor will seat one plug wire too far around the rotation.

The oil pump drive will *Probably* not line up, and your distributor will NOT seat on the intake.
This is common.
To seat the distributor you will need to HAND CRANK the engine 2 full turns.
I said 2 full turns to come back to TDC of COMPRESSION.
One turn will bring you to TDC of EXHAUST stroke, not compression.

You hand crank because the gears aren't seated and you CAN chip/break gears & bend the distributor shaft if you use the starter motor, just too much torque.

Once balancer/timing tab is VERIFIED, you can use it to determine when you reach TDC, but you MUST verify TDC by hand before you can trust the hash mark/timing tab. There are several versions of each, mix & match happens, and balancer rings slip...

If you don't know the rotation direction of the distributor, the vacuum advance always pulls AWAY from rotation.
The vacuum advance nipple will point AWAY (opposite) the rotation of the distributor.

It sometimes takes a few tries to get the distributor to drop in, fully seated on the intake AND have the rotor come up pointing at the #1 plug wire mark you made.
This is because you don't get the counter rotation of the shaft, just shy of one plug wire distance on the cap, in the correct place before you turn the crank.
Don't get frustrated, it happens to all of us, just compensate and try again, two full turns off the crank each time.

Make sure your plug wires are correct!
Check, recheck, and check again. The firing order MUST be correct, and it's commonly screwed up.
I've seen VERY experienced builders & mechanics screw up the firing order.

 

[El Conquistador]

What he said. Jeep hammer gave you great advice.

 

[JeepHammer]

My very first 'Business' was distributors and I've seen a lot of screw-ups (a bunch were mine).
At 12 years old I was building/rebuilding and curving distributors, and I did that on and off until distributor-less ignitions killed the market.
I still do retro distributors/magnets on occasion, and refit breaker point distributors for hidden magnetic triggers (electronic ignition) for guys wanting a stock look in a restored vehicle.

I don't use a Mallory unless the customer just insists on it, Mallory Unilite in particular has issues, I learned that the hard way.

Most times when it's not a trained mechanic dropping the distributor, it's seating on the oil pump shaft, reversing the shaft to compensate for angle cut of the gears, or forgetting/not knowing the piston hits TDC twice on a 4 cycle engine.

Once in a while, the balancer outer ring slipping, or being mismatched to the timing tab show up.

It's just way too simple to VERIFY TDC of compression stroke,
Simply crank until compression first starts (just 'Bump' starter) and once compression starts, crank by hand until your wood dowel rod/chop stick (NO METAL IN THE CYLINDER!)
The wooden dowel rod will tell you when you reach TDC.

Check balancer 'Hash' mark against the timing tab to verify the balancer/tab to verify the tab/balancer.
Then you can trust the balancer/tab.

By turning the crank BY HAND (with a socket on crank bolt) you don't over-run TDC, or break parts.
Over-running Compression TDC is really easy since the spark plug is out, and it's QUITE common.

If you deal with enough distributors you will see broken teeth on distributor or camshaft, bent shafts, broken housings and/or the wrong gear on the distributor.
Nothing like a 351C gear getting on a 351W distributor shaft and wedging into the timing cover so solidly you have to use a hydraulic press to get it back out,
Which is why you turn the engine by hand, the starter will wedge the shaft/gear in so tight you can't get it back out with an engine crane, ask me how I know that...

GM used both clockwise & counter-clockwise distributors & gears, and they will interchange on the common distributor shaft.
Since they interchange without issues, you CAN get the wrong direction gear on a distributor shaft from manufacturer/remanufacturer/rebuilder.
It's not common, but it will drive you insane and/or break parts until you figure it out.

ALL distributors with a vacuum advance, the vacuum can will pull AGAINST normal rotation of the shaft.
The nipple will ALWAYS point AWAY from normal rotation, so it's easy to tell which way any distributor shaft is supposed to rotate.

One tip the professional racers use is to Mark the cap terminals with the firing order, and some mark the rotor/shaft rotation.
They almost always have #1 marked on the distributor housing.
This saves a crap load of time & mistakes when tearing down/rebuilding and solves a ton of mistakes when things get hectic.

#1 on an engine block will always be the furthest forward.
On a V-8, there are two connecting rods on each crankshaft 'Throw', one rod/cylinder will be the width of the connecting rod forward of the other because of this arrangement.
The furthest forward will be #1 and where you start.

 

[rem788]

JeepHammer gives some great information. Transmission control has been mentioned . I believe the only ECM control of the transmission was for the torque converter lock up on this vintage truck. This can be bypassed when the ECM is disconnected using a vacuum switch (if it is still available) that was used on some of the vans and trucks that had the feed back carburetors. There may have been a third gear switch in the transmission also which prevented lock up until the transmission was in third gear, working on memory here, don't have wiring diagrams in front of me. As others have mentioned, there is a host of issues to deal with when switching from ECM controlled to analog control or going the other way. There are solutions if you have enough time and money.

 

[Tactically Fat]

Everything in this thread is written in English. I can read all the words. An I even know what they mean as individual words.

But y'all go on about stringing them together in sentences and suddenly it's in Greek.

 

[1775usmarine]

Everything in this thread is written in English. I can read all the words. An I even know what they mean as individual words.

But y'all go on about stringing them together in sentences and suddenly it's in Greek.

Nshsus jcb dbjsisoo jsjaoaor jessuds qlxbaie mzOa diana ihb jsoa ndhqnnd kaodh qjqjdn?

 

[boogieman]

Finally got it back to Indy late last night. I appreciate all the info and will definately try checking the voltage for the distributor first. The trans isn't a TH350 but a 700r4 (not e model) It probably will be this weekend before I get to it though.

 

[PGRChaplain]

Run a small Jumper Wire to the + on the coil and the +Battery Post.

 

[bobzilla]

This. Ask me how I know....

+1.

 

[femurphy77]

I read some of the replies and scanned some so sorry if this has been mentioned but have you checked the rotation of the distributor to ensure you have your spark plug wires on the correct post? Sounds simple but I've done it. Granted it was a SBF but I assumed the distributor rotation was clockwise so I set up my spark plug firing order based on clockwise rotation when in reality the distributor rotates counter clockwise. When I discovered the error of my ways (diitributor rotation , not choice of blue oval products) I corrected the firing order and it fired immediately.

 

[churchmouse]

I read some of the replies and scanned some so sorry if this has been mentioned but have you checked the rotation of the distributor to ensure you have your spark plug wires on the correct post? Sounds simple but I've done it. Granted it was a SBF but I assumed the distributor rotation was clockwise so I set up my spark plug firing order based on clockwise rotation when in reality the distributor rotates counter clockwise. When I discovered the error of my ways (diitributor rotation , not choice of blue oval products) I corrected the firing order and it fired immediately.

Not ever had that syndrome but I have been 1 post off.

 

[femurphy77]

It was my first foray under the hood for anything besides an oil change. Swapped out a 200 6 for a 289, took me a month to figure that one out!

 

[Jaybird1980]

Any Luck? If not it occurred to me that nobody has mentioned to make sure that the 12v source for the distributor stays energized even when the key is turned to the start position and the starter is engaging. Some switched 12v sources go dead when the key is turned to start.

 

[HubertGummer]

I would check for 12V at the coil while cranking. I've heard of ignition switches going bad and preventing that. If it does then I would see if it will fire when putting starting fluid or gas directly into the carb.

Any Luck? If not it occurred to me that nobody has mentioned to make sure that the 12v source for the distributor stays energized even when the key is turned to the start position and the starter is engaging. Some switched 12v sources go dead when the key is turned to start.

I think somebody mentioned that

 

[Jaybird1980]

Must of missed that one, good work.