Starting problem

[josh912]

I was laying in bed last night, trying to sleep, and trying to figure out what the heck is wrong with my car. It been a problem for a while. The car will not rev up at the start. I have to pump the thottle for up to minute before the car will rev up. During that minute it wont rev beyond 1K and if I quit pumping the trottle it will die. This only happens after sitting for a while, half a day or so, usually a day. I have webers, an 050, blue coil, and no other fancy dazy stuff. So any help or sugestions are GREATLY appriciated!!!

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Joshua Harrison
1968 912 Coupe
www.geocities.com/jkh912

[WFBowen]

Josh:
Does it seem like an over-rich condition or do you think it's fuel starvation during these times?
If you think it's starvation, I'd check fuel pump (actual delivery under this specific condition); float levels & accel. pump gaskets.
If you sense over-rich, plugs/heat range; float needle valves; proper jetting of Webers.Just guesses, but maybe it'll open some new doors.
Sleep easy - at least it starts up!
Bill.

[klmsouth]

I have the same problem on my 68. Whenb cold you have tu pump the daylights out of it to get it to idle or even start. Unfortunately I do not have the answer but a fuel pump is beginning to look like the possible culprit.

[josh912]

I have an elctric fuel pump so it has fuel, which means the floats are filled, which means the carbs should flow right off the bat, right?

I did forget to mention that the timing is at TDC when at idle, but I'm going to bring it back to normal soon (too hot in the summer).

As far as too rich or lean, I think its not getting gas, IF its a problem with the carbs. The needles are good, the carb is jetted 55 idle 135 main 200 airs. The plugs are W5AC. But, if any of those were wrong are bad, the car wouldn't run afterwards??? It runs great, once it gets going. So i dunno.

Still accepting help and sugestions.

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Joshua Harrison
1968 912 Coupe
www.geocities.com/jkh912

[This message has been edited by josh912 (edited 09-24-2001).]

[Duke]

Josh: I live in Redding,CA & the summer heat is very intense with many days well above 100. I have the 050 with the static setting at 5BTDC & have never had to change it. I think your timing is part of your problem. Have you checked the accelerator pump delivery? Should be .45cc in summer & .65 in cold winters (two strokes of the throttle linkage) Good luck. Duke, 69 912.

[josh912]

Duke, I have 10.5:1 compression!!!!! It pings like you won't believe. I'm not exactly sure right now what my accelerator pump discarge is but I'm prestty sure its .45cc. But that shouldn't be the problem as it should run well when started, no necessarly idle well but run.

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Joshua Harrison
1968 912 Coupe
www.geocities.com/jkh912

[Green 912]

I run 6BTDC at idle and this gives me about 35 at 3000+RPM with a 050. Even with air temps in the 90s I don’t have heat problems in the heads or pistons. EGTs run in the 12s to 13s at the end of the long straights and CHTs never pass 350 deg. Oil runs 180 to 200 deg but I installed an aux cooler that is too large. Put the timing back if you can but the 10.5 to 1 may continue to give problems.
The accel pump has no effect on the idle. Check, don’t just assume, that the accel pump is set and working correctly on both sides. You might have a partly restricted advancement system. Running way too lean until warm and then just too lean. 10.5 to 1 and too lean is a recipe for new pistons due to detonation.
It could also be as simple as your fuel line draining out from a bad check in the fuel pump. Will it start and idle well even if it will not rev?
I got a hunch about the timing system. You should check the advance in the distributor, If the lube gums up it might not advance until it warms up some. Don’t laugh, I have seen this one. It’s easy to check just twist the rotor and see if it moves smoothly and snaps back with some spring tension.
Higher comp and then retarding the timing is counter productive to power production. It is better to have less comp and better tune unless you can get high oct gas (100 or +) and mix it 25/75 with 93. I have built motors that run at 10.5 to 1 but it has to be tuned tightly and not pushed hard unless you use high oct.