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Old 12-04-2021, 02:19 PM   #1
Slammo
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SBC starting issue

Hey Guys,

I finished a restomod a few months ago on my’57 pickup. I’m running a mid 80’s 350 SBC, which was running perfectly fine for a few months, then the engine cut out. I was able to restart it. Then it happened a few more times within a mile or so, then nothing. It cranks but does not fire up. I replaced the HEI distributor, but still no go. I ran a hot wire from the battery to the distributor lead, sounds like miss firing when I crank it.
The truck engine was running perfectly fine up until this happened. Plugs look good, timing is good as well.

Any suggestions would be greatly appreciated!
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Old 12-04-2021, 03:07 PM   #2
Getter-Done
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Re: SBC starting issue

Have you run a Compression check?
Timing chain jumped?

Does it have any Computer stuff on it?
Carb or EFI ?
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Old 12-04-2021, 03:49 PM   #3
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Re: SBC starting issue

Quote:
Originally Posted by Getter-Done View Post
Have you run a Compression check?
Timing chain jumped?

Does it have any Computer stuff on it?
Carb or EFI ?
Compression checks out ok. I did not get around to checking the timing chain, the engines restarted and ran good for a while a few times, before shutting off completely. Definitely getting fuel to the carb. No computer or crank sensor on this engine.
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Old 12-04-2021, 06:47 PM   #4
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Re: SBC starting issue

Quote:
Originally Posted by Slammo View Post
Compression checks out ok. I did not get around to checking the timing chain, the engines restarted and ran good for a while a few times, before shutting off completely. Definitely getting fuel to the carb. No computer or crank sensor on this engine.
Getting fuel to the carb, but is it getting through the carb? Had a piece of plastic cover the needle seat, sounds similar..
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Old 12-04-2021, 08:37 PM   #5
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Re: SBC starting issue

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Originally Posted by skip99 View Post
Getting fuel to the carb, but is it getting through the carb? Had a piece of plastic cover the needle seat, sounds similar..
Gas is definitely getting through the carb. I pulled the fairly new plugs and double checked the gaps, all were .035. I also replaced the HEI distributor with a new one, same issue.
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Old 12-04-2021, 09:02 PM   #6
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Re: SBC starting issue

Quote:
Originally Posted by Slammo View Post
Compression checks out ok. I did not get around to checking the timing chain, the engines restarted and ran good for a while a few times, before shutting off completely. Definitely getting fuel to the carb. No computer or crank sensor on this engine.
So, occasionally it runs good, ? For how long? Then just dies?when it dies, are you losing spark or gas? Theres not much else if its running…
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Old 12-04-2021, 09:22 PM   #7
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Re: SBC starting issue

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Originally Posted by skip99 View Post
So, occasionally it runs good, ? For how long? Then just dies?when it dies, are you losing spark or gas? Theres not much else if its running…
Last Sunday I was heading to a local car show, the truck shut off 3 times on the way there. I was able to start it each time and made it to the show. When I left the show, it shut off a few miles down the road and would not start. I installed a Painless Wiring harness when I was rebuilding the truck. I was expecting a loose wire or a bad connector, but everything looks good. I’m getting 11.6 volts at the distributor and spark at the plugs. Tomorrow I’ll check the timing chain if time allows.
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Old 12-04-2021, 11:45 PM   #8
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Re: SBC starting issue

Have you checked to see if you actually have spark? If it does, great, if not, maybe the HEI module failed or failing...but you were able to restart it...they usually fail and die once. Also, you mentioned that your gap is set at .035...I believe HEI gap is .045....but it should still start at .035.....
Maybe the wiring...are you getting spark when the key is in the cranking position?
Unlikely the module because you have tried 2 different dizzys....timing chain broke or jumped a tooth throwing timing off maybe. How many miles on the engine??
Just reread that you have spark....nevermind...
timing chain maybe....
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Old 12-05-2021, 12:42 AM   #9
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Re: SBC starting issue

even if you are getting fuel to the carb when it starts and runs, do you have fuel when it dies? do you have an electric fuel pump? If so it could be an intermitant problem with the pump. I would run it at home untill it dies, then disconnect the fuel line and see if there is fuel flow. just another idea.
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Old 12-05-2021, 02:18 AM   #10
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Re: SBC starting issue

Have you got an actual Delco distributor plug on the end of the wire or just a female slide terminal? Personal experience with the Hei that I put on my 71 with a 350 is that a female slide will get just loose enough to not keep contact with the male pin in the cap. Mine usually chose 3 am on the way to work in the rain to do it.

As for checking an Hei Back in the early 80's one of the Napa Echlin ignition reps would drop by and put on some classes for my auto mechanics students and he gave me the Echlin check an HEI pamplets I have the eight pages saved to my photobucket album and suggest that anyone with an Hei save them to their computer and maybe even print them out. As long as you have a decent multi-meter you can test one.

https://app.photobucket.com/u/mr48ch...8-34b5e1631d08
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Old 12-05-2021, 03:38 PM   #11
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Re: SBC starting issue

Quote:
Originally Posted by nvrdone View Post
even if you are getting fuel to the carb when it starts and runs, do you have fuel when it dies? do you have an electric fuel pump? If so it could be an intermitant problem with the pump. I would run it at home untill it dies, then disconnect the fuel line and see if there is fuel flow. just another idea.
The engine has not started since last week. I’m getting fuel to the carb. I swapped in a new HEI distributor, still getting spark but does not start.
At this point I was thinking the timing chain jumped, but why would it restart and run the first few times last week? When it restarted, the engine sounded fine, no no idle issues, no knocking, no surging, etc. before it finally stopped about a few miles down the road. At no time did it sputter to a stop, it just shut off, which initially had me thinking it was electrical.
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Old 12-05-2021, 03:43 PM   #12
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Re: SBC starting issue

ok, just shooting in the dark here - how's the cable connections from the battery to the starter???
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Old 12-05-2021, 06:40 PM   #13
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Re: SBC starting issue

Quote:
Originally Posted by Slammo View Post
The engine has not started since last week. I’m getting fuel to the carb. I swapped in a new HEI distributor, still getting spark but does not start.
At this point I was thinking the timing chain jumped, but why would it restart and run the first few times last week? When it restarted, the engine sounded fine, no no idle issues, no knocking, no surging, etc. before it finally stopped about a few miles down the road. At no time did it sputter to a stop, it just shut off, which initially had me thinking it was electrical.
If you are getting spark at the right time, then fuel and air is all thats left..
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Old 12-05-2021, 10:27 PM   #14
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Re: SBC starting issue

A few thoughts.

Distributor timed right?

If you have the cap off the distributor and can turn the crank back and forth by hand how much does the crank turn backwards before the rotor moves? If you pull number one plug and bring it up on compression and line up the marks, is it in time?

One thing most guys do when they swap a V8 into an older truck is put a new timing chain and gears on it when they are checking it out but if it was pulled directly from a donor and especially a low mileage donor it may still have a plastic tooth timing gear in it. Even double roller chains wear out after a while.

One thing to think about is always review any and all changes you made recently before it started acting up. Quit often the littles change will end up messing with you. Also don't start swapping parts before you actually test the parts you think are suspect. A lot of times we change stuff because that was wrong with Uncle Bill's car when it acted up so it must be what is wrong with mine.

The pickup coil wires are famous for breaking or partially breaking and letting the rig run but loosing contact with the broken wire ends when the advance plate moves. I got burned and a lesson on that one a number of years back. That was before I was teaching and had the pamphlet that I posted the link to. The good was that a guy in the shop had been around that exact issue before and said that was most likely the problem and then showed me exactly where the problem was.
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My ongoing truck projects:
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Last edited by mr48chev; 12-05-2021 at 10:37 PM.
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Old 12-06-2021, 11:03 AM   #15
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Re: SBC starting issue

Just a guess here, but you say you have spark and fuel (I assume compression), but maybe not enough fuel?

Do you have a vented gas cap?

try removing the gas cap and starting it? maybe you have a vacuum in the gas tank restricting fuel flow?
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Old 12-06-2021, 09:11 PM   #16
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Re: SBC starting issue

It sounds like you have checked your fuel and spark.

What about your ignition switch? If there is a loose wire or worn switch, it may have a problem in the "run " position. Might explain why it doesn't sputter and just shuts off.
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Old 12-07-2021, 01:41 AM   #17
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Re: SBC starting issue

try gapping the plugs at .045, its what hei usually calls for. run it, if it will, and get it hot, then shut it down and check what the plugs look like. if it is running lean a bigger gap/hotter spark may be what you need, a lean mix is harder to ignite than a rich mixture. when it quits does it still squirt fuel into the carb bore when you pump the pedal? have you checked the carb float level? does it rattle prior to quitting, like lifter noise or preignition?
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Old 12-07-2021, 01:42 AM   #18
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Re: SBC starting issue

do you have a large power wire to supply the hei?
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Old 12-07-2021, 01:54 AM   #19
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Re: SBC starting issue

when in doubt start from scratch and check everything, compression dry and wet, cylinder leak down test, fuel pump pressure and output, timing chain slack-as described by mr48, vacuum leak possibilities, exhaust back pressure test, and In just thought of something-is there a heat passage under the carb in the intake manifold? some are blocked off but if not a lot of heat can pass through there and that makes the carb and fuel get pretty hot, does it quit once it has heated up but is ok when first started? is there a fiber type gasket under the carb?
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Old 12-07-2021, 01:57 AM   #20
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Re: SBC starting issue

is the engine actually from the '80's or was it rebuilt? what emmissions stuff does it have, if any? got a pic of underhood?
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Old 12-07-2021, 02:01 AM   #21
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Re: SBC starting issue

if using the same dizzy cap, look under the cap to ensure the carbon electrode is intact and the rotor is in good shape on the center contact
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Old 12-07-2021, 02:24 AM   #22
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Re: SBC starting issue

A few things to consider:

Good Spark to the end of the plug wire when you crank it, meaning when you hold the wire close. No need to mess with anything else in the ignition system, it is working as it should be. Don't get carried away imagining issues where there aren't any.

If it starts and then acts up that is another story. Then you get that Napa pamphlet I posted out and get your multi meter out and start checking,

Fuel, If you can look down the carb and the pump gives a shot of gas when you work the throttle it should have enough gas to fire. Maybee not run at highways speeds but fire up and run.

Timing both ignition and cam. Engines with some miles on them jump time or loose the teeth off the plastic tooth cam gear on a regular basis.

Pop the cap off, put a socket on the crank bolt, and with a ratchet or breaker bar and work the crank back and forth to see how much the crank moves before the rotor moves. You can do that before or after you pull number one plug and crank the engine over with your finger over the hole to bring it up on compression and line up the marks. If the rotor is pointing right at where number 1 plug wire sits in the cap when it is latched down on the distributor life is good, if it is pointing somewhere else or if you can't seem to get it up on compression right life isn't so good.

One thing that I didn't think of is that on a 57 I am not positive you have power to the coil when you are cranking if you don't have a resistor bypass wire hooked up.
If you get a spark when you are cranking it, life is good, if you don't get a spark you may have to hook up the resistor bypass to get power to the coil when it is cranking. Meaning that the inside of the switch may be designed that way. I think that is one of the things I fought on my 57 panel when I bought it. It was an engine almost all ready to run but needs some work project when I bought it. Pre HEI though.

The main thing is check, test and eliminate before you throw parts or money at it.
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My ongoing truck projects:
48 Chev 3100 that will run a 292 Six.
71 GMC 2500 that is getting a Cad 500 transplant.
77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.
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Old 12-07-2021, 03:10 AM   #23
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Re: SBC starting issue

just thinking of your hei, not saying it's the issue since you are saying the thing has spark, when you changed the dizzy did you also change the cap, coil etc or re-use the old parts? if not check to ensure you have a ground wire inside the top where the coil is mounted. I have seen them where there is no ground wire and they have some of the same symptoms. when in there check the coil as well, sometimes they overheat and you will see the discoloured areas on the sides of the coil. like somebody else said, check for a good hot spark at the plug wire.
from another site talking about hei coil failure caused by incorrect assembly of coil-cap-contact etc
The correct sequence is: cap, carbon brush with spring positioned upwards, then silicone heat transfer grease on both sides of the insulator, installed onto the spring, then, coil. If this method isn't done correctly, the distance from the end of the carbon brush to the rotor connector bar becomes excessive, resistance on the secondary side and primary side of the coil rises, heat becomes too high, and the module fails.

a pic of the coil ground strap under the coil and also the coil ground wire that comes out of the coil, see post 10
https://www.chevelles.com/threads/he...ement.1112544/

a link to diagnosing hei ignition for anybody interested
https://www.gmcmi.com/wp-content/upl...stributors.pdf

after trying to start it have you pulled a plug to see if it is wet? does it chuggle at any time when trying to start it or it simply cranks and cranks with no attempt? I would lean towards a fuel problem then if the tune up stuff and timing chain slack seem ok.
just spit balling and info for a possible lurker with the same issue. when you get back at it let us know what you find out for test results. like mr48 says, don't throw parts at it until you know what it needs.
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Old 12-07-2021, 03:18 AM   #24
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Re: SBC starting issue

sometimes the brake booster can be a big vacuum leak. you could disconnect the the hose at the engine, plug the hole then try to start it. or pinch the vacuum line off and try to start.
exhaust systems also get plugged or a baffle breaks free inside the muffler and plugs the exhaust. giving the muffler a good bump with a dead blow hammer or your hand may reveal a rattle inside the muffler which indicates a problem. usually the engine will start though, just not rev and then stalls. rodents also like to pack stuff into the pipes if left for awhile and the mice are looking for a new home. I had a motorcycle repair for a guy who couldn't get it to start and when we got working on it it back-fired and a whole whack of popcorn kernels blew out like a shotgun. ran fine after. lol
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Old 12-11-2021, 08:03 PM   #25
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Re: SBC starting issue

Thanks for all of the reply’s and suggestions. Yanked the headers off and checked compression today, all cylinders are between 140-150. Timing seems to be dead on. #1 cylinder at TDC, timing marks are good and distributor is pointed at #1 plug. Cranking it over by hand, no slop at all at the distributor. Definitely getting fuel to the cylinders. As mentioned earlier, I tried a new distributor, cap and wires. Plugs have a few thousand miles on them at most.
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