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I have a 69 L68 427 400 hp tri power that has a hot start issue. I'm no stranger to Holley's and have tuned many of them over the years, but not sure if this issue is inherent to Tri Powers.
The car will not start without excessive cranking when warm, literally if I shut the car off and restart immediately or if I let it sit for a while. The fact that it won't start within seconds after I shut it off seems like it would not be vapor lock.
The carbs used to boil, then I blocked the heat riser and installed a 160 stat - that helped. I have a Dewitts rad and it runs at 180 all the time. Timing is 6 initial and 38 total. Air Fuels are dialed in to highest vacuum reading, about 1.5 turns out. Ignition is Pertronix.
Once the car is running, it everything is fine - in traffic or otherwise. Why would it not restart immediately after shutting it off?
Thanks
Mike
I've been chasing that rabbit on my1970 350cu.in. w/Holley 600.
The engine runs at 180 degrees constantly/never overheats.
The resistor ignition wire has been completely replaced and Dist. is rebuilt.
When I remove the present cable-drive HEI Dist. and install a 1982 GM HEI Dist.(No tach drive) the problem vanishes.
Sorry I couldn't help.
6 initial, 38 total? At what RPM? Do you have 32 degrees of mechanical advance in your distributor, or are you counting the vacuum advance, too?
Just checking the obvious and the easy to fix. Manifold vacuum advance made my 79 much easier to start in all conditions. I have had exactly one instance of vapor lock, and that was after being parked for an hour, and before the timing was correctly adjusted.
If it is heat related, I'd suspect the Pertronix (just as I'd suspect an HEI module). Can you swap back to points easily, to see if the problem goes away?
6 initial, 38 total? At what RPM? Do you have 32 degrees of mechanical advance in your distributor, or are you counting the vacuum advance, too?
Just checking the obvious and the easy to fix. Manifold vacuum advance made my 79 much easier to start in all conditions. I have had exactly one instance of vapor lock, and that was after being parked for an hour, and before the timing was correctly adjusted.
If it is heat related, I'd suspect the Pertronix (just as I'd suspect an HEI module). Can you swap back to points easily, to see if the problem goes away?
Yes, 32 degrees of mechanical advance in the distributer. Idles at 750 with 6 degrees advance and 38 total at 3000. I took the readings with the vacuum disconnected.
I got the car with the Pertronix and the new starter does not have the R terminal, so going back to points would not be easy.
The accelerator pump is working fine and so is the choke. It's baffling to me.
Last edited by Monaco400HP; Sep 20, 2021 at 08:47 AM.
Maybe it is a fuel issue but your looking in the wrong direction.
Maybe its not fuel starvation.
Maybe its flooding at shut-down.
If just one of the three floats is sinking, and there is still some pressure in the fuel supply line it can overfill a bowl. But which one?
I think I would hold the throttle wide open and take a real close inspection of the plenum. Use a flashlight if needed.
Is one area of the Intake wet while the other is dry?
Last edited by HeadsU.P.; Sep 20, 2021 at 10:38 AM.
most Holleys boil fuel out of the accelerator pump nozzles after shutdown causing a flooding issue.
Blown or leaky power valves are also a problem.
Cranking while holding half throttle or more usually does the trick. Just be ready to let off the throttle when it cranks lol.
The old bowls had a check ball that required some action from the accelerator pump to seat the ball, were not prone to this problem.
The newer orange umbrella style check valve is always seated so when the fuel in the pump cavity gets hot, it boils out through the discharge nozzle.
Factory ford bowls have a tiny hole drilled outside the umbrella to allow fuel to boil back into the bowl. Even the new bowls have a dimple where the hole goes.
You do lose a tiny amount of shot from this, but from my experience if the transfer slot it set correctly, you dont need a ton of accelerator pump.
BTW I am not advising you drill a hole in your fuel bowl, just sharing my experience with hot start issues and holleys.
I appreciate all the advice - I've actually seen the fuel squirt out the nozzles on my 502 after sitting extended periods of time when hot.
I just want to reiterate that the car can be idling perfectly, I can shut the car off and IMMEDIATELY try to start it, it takes excessive cranking. Same if it sits 30 seconds or an hour.
is the coil getting hot and failing do you think?
have a similar problem...had to lower the floats some and will be putting a heat shield in addition to the plastic spacer. That ethanol fuel just doesnt seem to like heat
under 180 deg restarts no problem. 190 or more forget it.
Yes, 32 degrees of mechanical advance in the distributer. Idles at 750 with 6 degrees advance and 38 total at 3000. I took the readings with the vacuum disconnected.
I got the car with the Pertronix and the new starter does not have the R terminal, so going back to points would not be easy.
The accelerator pump is working fine and so is the choke. It's baffling to me.
Depending on your starter if it has a stock gm type starter you can buy a solenoid for a pre 75. I did that when I did a carb conversion on my 84 C4 and went to a points distributor. Easy fix!
Two quick things from me.
1. If you don't have one install a return fuel line.
You can do it at the pressure regulator at the carbs.
If you don't have a pressure regulator install one as well and adjust the fuel pressure to the proper pressure, 5-5.5 psi max.
2. look into a high torque mini starter and get rid of the big GM starter that functions like a big heat soak and put a heat shield between the starter and the exhaust manifold.
Last edited by OldCarBum; Sep 20, 2021 at 07:35 PM.
Wondering if the ignition module in the HEI unit is becoming heat sensitive. Do you have a spare module to swap out and see if the problem persists? (tTose modules MUST have dielectric grease under them to help transfer heat out of the module. That also could be the problem.)
It appears I had 2 separate issues going on causing the hot start excessive cranking.
1. Leaky needle and seat on the primary carb. I could see gas dripping into the carb and into the manifold after shut off. Replaced the needle and seat and reset the float.
2. Ignition. The points were replaced in 2000 with Pertronix, and I suspected maybe something was not working right. Replaced with Ignitor III and now the car starts fine...like normal car! Turns out the old Pertronix can't handle a newer Blaster 2 coil, they recommend a resistance of 1.5 ohms or higher and I had .7 with the Blaster. Ignitor III has a built in rev limiter, multiple spark, and you can leave the key on RUN without the engine running (which you can't do in the original Ignitor).
Excessive cranking on a hot start
