Hard starts when warmed up...

[76LongBox]

It's been a while since I've been active on the forum, but I finally am getting around to doing a little work on my 1976 GMC.  Late last summer, I changed out the original engine/tranny with a GM 350 Crate Engine and a TCI StreetRodder TH350 transmission.  I also went with a new Edelbrock 2101 Intake and 1406 carb, new MSD distributor, new plug wires, etc.  I stayed with a mechanical fuel pump, but it is new as well.  I also run non-ethanol fuel in it.  The truck had factory air, but was converted to R134a a few years ago.  We were able to leave that system sealed when we did the engine swap, and the A/C still works just fine. 

After getting everything swapped out last year, I had some timing issues, but I believe those are now resolved for the most part.  However, I still have a couple of issues with the truck being hard to start up after it has warmed up to normal operating temperature. 

It will start up fine if you kill it, and then just bump the key...but if you wait a few minutes - like going into a store and coming back out to the parking lot - it is very hard to start.  I have to crank on it for a little while to get it going.  Also, it seems like the battery is going to give up just anytime when it's hot like that (but not when it's cold).  I did put a new starter on with a heat shield when I did the engine swap, but have no idea why it struggles so much to turn it over when it's hot, nor why it takes so much to crank it hot.  When it's cold it cranks up beautifully - especially if it's only been a day or two since it's been run.  Just set the choke by pressing the accelerator to the floor, and it'll generally start up faster than my 2010 Silverado.  It generally runs fine and idles great, even with the A/C running. It does, on occasion, bog down when accelerating heavily from a dead stop, but it doesn't do this all the time - which is also puzzling to me.

I'm not sure if I still have some timing issues, or fuel delivery, or what the problem(s) might be. If anyone can offer any suggestions, it would be greatly appreciated.

If you need any more details about the engine/tranny, let me know.

[rich weyand]

Try this when in that situation.  Push the pedal to the floor and hold for two seconds, then lift off; repeat four times in total.  Then hit the starter.  Report back.

[76LongBox]

Got a couple of errands to run this afternoon, so I will give it a try and report back.

Thanks...

Mike W.

[76LongBox]

Tried pressing the accelerator down 4 times as suggested, and it didn't change anything.  Still very difficult to start, and again it seemed like it was straining to turn over the engine more than when it's cold.

Also, when it does this, it usually runs really badly for a couple of minutes after it finally cranks up.  Once I get rolling, it's fine, but it idles very rough usually after the hard start.

Any help will be greatly appreciated.

[rich weyand]

Put an insulator between the 1406 and the 2101.  Edelbrocks are temperature sensitive, and the carb is normally cooled by the air flow and evaporative cooling due to the carburetion process.  When you park the truck, the heat in the engine will heat up the carb, and it will be cranky until you get air flow and evaporative cooling under way again, or until the engine and carb cool down.

My original thought was that the Edelbrock was slow getting gas flow started without the choke, and that's why I had you prime the manifold using the accelerator pump.  If that isn't it, it could be the heating of the carb once you turn the engine off.

For a dual-plane manifold, you want the one with the center divider.
http://www.summitracing.com/parts/edl-9266

[76LongBox]

Thanks Rich.  I will give that a try. 

[roger97338]

What exactly do you mean by difficult to start? Is the starter cranking the motor the same RPM hot and cold, but when it's hot, the motor doesn't actually start running? Or do you mean when it's hot, the starter is turning the motor much slower than normal?

If it's turning over slowly when it's hot, try taking some jumper cables and jumping ONLY the negative battery terminal to a different ground location. Try a different ground location on both the frame and the motor. It could just be a poor ground.

Also, make sure your battery terminals are clean and free of corrosion, and the battery cables are properly tightened.

[rich weyand]

And the cables could be bad.  After ten years, they start rotting internally.  No outward evidence.  Can be temp dependent.  If they are more than ten years old, replace them.

Still, if it is cranking, it should wick off no problem.

[76LongBox]

Thanks for the replies guys.....

There are 2 problems when it's hot:

1. It turns over very slowly, like the battery is almost dead.  It does not do this cold.
2. It has to turn over a bunch to crank when it's hot.

I hope I have #2 fixed now.  I was able to pick up one of the Edelbrock 9266 spacers that Rich recommended at my local O'Reilly today and installed it this afternoon.  I drove the truck this evening and went to dinner.  It cranked much better afterwards, but to be truthful, this wasn't the best test as we were in the restaurant long enough to let it cool down more than when I've noticed the problem.  I'll give this some more testing hopefully tomorrow.

Once I confirm that problem is fixed, I'll need to figure out the other one.  I don't know if the cables have ever been changed or not.  I've had the truck for over 10 years and I know I have never changed them, but never had this problem until after the engine swap either.  I did paint the all of the old brackets that I reused during the engine swap, including the alternator bracket, where I believe the ground wire is hooked up...so maybe it's just not getting good contact when it's hot?? 

Either way, I'll do some troubleshooting around that piece in the next day or two.

I really appreciate the guidance.  I'll report back as solutions are found (or not).

Thanks,
Mike W.

[Irish_Alley]

have you tried retarding the timing for this problem?

[rich weyand]

What's the base timing set at, and which distributor do you have?  That is, how much vac and centrifugal advance do you have?

The ground spot on the alternator bracket is an issue.  You need to make sure you have good ground there.  The other thing is that the cables could have been deteriorating, but didn't cause a problem until disturbed.  We have had, on the couple forums I frequent, a half a dozen bad sets of cables so far this year.  They're cheap, so replace them.

[76LongBox]

Thanks again guys for the additional comments.  I think I'll go ahead and replace the battery cables (and the rusted out battery tray while I'm at it).  I'll make sure the ground gets a good connection too.

As for the timing, I really don't know what it's set to right now.  I had a mechanic take care of that for me, as that is a little outside of my realm of expertise.

The distributor I have is this one:  http://www.jegs.com/i/MSD+Ignition/121/8362/10002/-1

[Irish_Alley]

got your attention yet? get a timing light and check your timing its easy and we're here to help you out

[76LongBox]

I actually do have a timing light that I bought last year, but just haven't learned how to use it yet.

I'll probably try to do that tomorrow if time allows...it's one of the digital ones by INNOVA - Equus Model 5568.  I think it's supposed to be a good one, and it should be easy enough to figure out, and I'll report back the timing. 

BTW, I did drive the truck a bit this evening, and the warm/hot starts were MUCH better with that insulator gasket in place.  The little bit that it did have to turn over to crank was pretty sluggish, but I do have new cables (and a new battery bracket) on the way.

[Irish_Alley]

dont get me wrong im not saying its not your cables. but if it was something simple as timing you could solve the problem for free plus you leaned something just encase you have a emergency with the distributor next time or you can teach someone else. but cmon did you like the flying donkey? makes me laugh each time i see it

Locate the mark on the harmonic balancer and the zero mark on the timing pointer first. Disconnect and plug the vacuum advance. With the engine warmed up set the timing by loosening the distributor hold down clamp and rotating the distributor to acheive 10-12° btdc for your initial setting.

its simple