engine cranks, no spark (SBC 350)

[Dustin07]

Just did an engine swap last week, the motor ran great a few weeks ago. its in the '61 now and wants to crank hard, but gets no spark (checked a plug for spark, there is none).

I'm wondering if its a miswire or something. Any troubleshooting suggestions on where i should start before I just start replacing stuff?

thanks guys

[fastwillie 696969]

check for voltage at the coil ? check for grounds ?

[Dustin07]

I honestly don't know how exactly. I have a multimeter, but I have not played with a coil before. should I turn they key to the on position then check volts? from where to where?

I'm somewhat naive on motors, this is my first swap.

[68gmsee]

Need more info like what engine did you swap for, HEI or points.

Check the wiring first to make sure it's wired correctly at the starter and to the coil. If you have points, check to make sure they're adjusted properly.

Check for pin hole in the rotor and any cracks or for arcing on the cap.

Coils don't generally go bad but it is possible. First just make sure everything else is correct. If you have another coil laying around you can try that since they're very easy to swap out.

[Dustin07]

thanks, the truck had a 350 in it, previous owner pulled it out before selling the truck, so I put mine in. It is points system. The wiring in the new truck appears to basically match the wiring in the old truck. only difference being the type of oil pressure sensor, but that seems to be wired correctly.

reading this, I think my coil is wired right:
http://www.hotrodders.com/forum/igni...p-u-11236.html

the motor does try to turn, but no spark to the plugs.

where would the pinhole be, just anywhere in the rotor? we had pulled it when we pulled the motor, but were careful to mark it. we also disconnected from the old th350 first, then pulled, then dropped the motor in the new truck, put rotor back in, and then reconnected to tranny. Still, I'm wondering if it could be bad or damaged somehow.

[litew8]

Originally Posted by Dustin07

the motor does try to turn, but no spark to the plugs.

What does "motor does try to turn" mean? It simply turns over, without wanting to fire?
Check/clean your points/rotor/cap first. If they look worn excessively, replace.

http://auto.howstuffworks.com/ignition-system4.htm

[Dustin07]

Originally Posted by litew8

What does "motor does try to turn" mean? It simply turns over, without wanting to fire?
Check/clean your points/rotor/cap first. If they look worn excessively, replace.

http://auto.howstuffworks.com/ignition-system4.htm

yeah it cranks over no problem, just zero spark. the motor started smooth as butter before the did the motor swap I should mention too.

[Dustin07]

maybe timing chain?

[Gumby]

ground straps in place?

[litew8]

like others have said, ground strap. Check that you have one going from the cab to the block or head at least. Then engine you pulled should have had one.
Rotor/points, cap can go bad just as easily fast. Try taking some fine grit sandpaper and very gently (lightly) clean the contacts shown in the animated picture on that link above.
Otherwise, by process of elimination, just replace them first.

[Dustin07]

thanks I'll try that. I know there is at least one ground strap attached, but not sure about to the cab. I'll double check tomorrow (truck isn't home yet unfortunately, working on it at my folks house).

[litew8]

There should be one somewhere. The frame maybe. One is prob. good enough (make sure it's rust free). The coil would be the next in line to check.

[Dustin07]

my main ground goes from the battery to the block using the same bolt as the alternator.

today I found a wire that was disconnected... the POWER from the ignition to the distributor. DOH! so now I have spark!! even put off a little smoke, but no real starting sound, just spark when I held a plug against the block and cranked.


however new symptom. Hooked up a new battery, truck tried to turn over a little bit, but acted like the battery was dead. I was told my timing is probably off now.... so back to that I guess.

[litew8]

At least you were looking in all the right places. Good to hear you're making progress.
If you can, try hooking up/running a battery charger while running diagnostics, might help some.

[Dustin07]

yeah its definitely progress. had no spark, now I do! lol.

but timing, I've never done before. so I'll have some research to do to troubleshoot.

[oldblue1968chevy]

if you think its timing, just retard it (turn it clockwise just a hair), if it was timing motor should spin over easier

[Dustin07]

I haven't had a chance to work on the patient since Sunday, getting really sick, looking pneumonia... bummer...

so what else would cause a brand new battery to act like a dead battery, the first time you try to crank it, if not the timing?

[Dustin07]

any other thoughts on why it would act like a dead battery, on a brand new battery? I"m going to work on it again tomorrow.

[cableguy0]

Your timing is likely advanced far too much. DO you have a timing light? Do you have a friend with a timing light? You need to retard the timing by turning the distributor. Im assuming you pulled the distributor out when you did the swap.

[Dustin07]

we did pull it, we were careful to mark it, but anything is possible. I can pick up a timing light probably or I think my dad may have one. not sure how to use it, but I will start doing some googling! lol

[Dustin07]

well I just thought i'd update... timing was off, moved all plugs ahead one cylinder and truck runs pretty darn good. just a little miss and cap is old, so going to replace it soon

[Gumby]

insted of adjusting the timing, you just move the plug wires around???

[Dustin07]

lol pretty much it was off by exactly one cylinder. I took it to local mechanic and he ran piston 1 to TDC, and instead of pulling rotor, just advanced plugs by one cyl each for short term fix lol

[cableguy0]

You can leave it that way. Its not an issue. Just so long as you know which terminal on the cap is #1. The actually positioning doesnt matter at all. Now get a timing light and set the timing if that wasnt already done.

[ironman3452]

ok 19 years ago, the 350 in my panel ran, so said the person I got it from, he is no longer with us, so I cannot ask any more questions about the motor, I have rebuilt the 350 and it is all back together in the panel, set TDC on #1 and dropped the distributer back in, wired the plugs, installed new points, rotor, cap, coil, it turns over, but no spark, checked wiring to coil, all is good, any thoughts on why there is no spark