Corrected…I meant bigger
Edelbrock AVS fuel pressure / Carter M6866 7.5 psi pump
- Thread starter 1MeanA
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What are you trying to accomplish? Leaner idle? Leaner part throttle? WOT?
leaner part throttle...I got pretty close making the small rod diameter bigger which didn't make sense to me
What's the idle vacuum?
Lower than I expected 10-12 Inches with a stock '68 4 speed 340 cam...15 inches max cruise. I tested for vacuum leaks, etc. Just for fun I'm going to check when the intake valve opens and compare to the cam card but I checked centerline and it installed it at 110.5 deg. which is 1.5 degrees advanced. I don't recall why I did that. It will give me a chance to pull the covers and have a look now that its broke in and has some miles on it.
That's a little lower than I would have expected as well. Have you verified your vacuum gauge is correct?
harrisonm
Well-Known Member
FWIW, Edelbrock makes a fuel pump that puts out the required pressure for their carbs. I needed a fuel pump several years ago and got one.
WHERE and HOW is your fuel filter mounted?
Well that's clear as mud. Can you post a picture?
Have you checked cruise vacuum as well?
Off on a tangent here....I was having another look at this hot start issue and put my plug tester on and saw that there is no spark when cranking (at least with the engine warm). I have already tested to see that there is power to the ballast in start and run positions. Dumping a little fuel in the carb doesn't help. I was looking into other posts about hard starting when hot / starts when key is released type issues and read where somebody said that the coil will fire one time when you let go of the key. It made me wonder if that is what was starting the engine at least when hot....perhaps the pickup was weak. I pulled my new Mopar distributor today and see the pickup gap is about 0.025". I checked this before but I think the magnetism fooled me into thinking the gap was ok. I can see the large gap now the distributor out. I'll adjust, reassemble and test later today if the Ativan from the dentist trip lets me.
Should be about .008.
Johnny Dart
Well-Known Member
Not sure if are just using a base gasket under your carb, but if you are this heat insulator from Edelbrock cures a lot of hot start issues.
Edelbrock #9266
Edelbrock #9266
I put one on earlier this week. I'm thinking my hard starting issue is due to the distributor pickup....tba
Johnny Dart
Well-Known Member
Cool. That gap is crucial for proper operation.
I bought some brass feeler gauges as my set only has a brass 0.010" gauge which I am sure would have been fine. I checked the gaps and a few were tighter than the rest so I set them at 0.008". The engine starts quickly cold and hot. I wonder if this would have affected engine performance. Oh well now I will go and check the tuning and see if there are any changes.
No need to buy anything. Just fold a piece of paper twice and there you go. I do hope that fixes it.
I doubt the large gap would have affected spark production past idle. As rpm increases, the p/up generates higher voltages. The worst case scenario for p/ups is generating enough voltage signal at cranking rpm. What the large gap would cause is retarded timing; but doubt the butt meter would feel it.
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