ignition issues

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Jun 27, 2008 | 12:42 PM

clgreer

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ignition issues

Ive been having some issues with my timing. im currently running over 15 degrees timing and would like to get it back down to around 10, ive got a 302 with a 4 barrrel carb. i bought a rebuilt dizzy hoping that i could correct some sputtering issues at high rpms. ive got the problem under control, but like i said have to run 15 degrees to stop it and its not 100%. reason for wanting to back it down is to get the engine temp back down, at 15 im running a little hot. Ive checked the fuel filter, went as far as taking the carb apart and cleaning it out, new plugs, wires, cap, rotor, control module, etc.

so my questions are-

1974 f100(late year model, Black control module) 302 4 barrel eddy carb/intake

1. What total timing should i be seeing on a 74 302 with vacum advance hooked up
2. what plug gap should i be using? i believe ive got them at .044? my chiltons says to refer to the decal on the truck, well yeah its been gone for years.
3. what psi should i be seeing for fuel? ive got around 6 atm, but at high rpm it drops down to 5, should i look into a better fuel pump? ive got an electric one atm.

thnaks in advance

Jun 27, 2008 | 08:06 PM

OldMetal

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From: US/Baja border

Sounds to me like something is breaking down and your losing spark at hi revs. plugs,wires? Five degrees advance shouldn't do much for that.
Whats your fuel filter look like? Has the truck been sitting for any length of time?

Jun 30, 2008 | 01:40 PM

clgreer

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i drive the truck everyday, the plug wires are new as are the plugs, cap, rotor, coil, and distributor. the problem has actually gotten worse, its not at just high rpms anymore, now it happens at all rpms ranges randomly, im starting to think i might have water in my gas or maybe my fuel pump is getting clogged. so im going to get some water remover, and install a new filter before the pump, the filter that is at the carb looks good, no debris and is not dirty. i know for a fact it is not the carb, i put a friends on to test it out, and still had the same issues. if the filter dosent fix the problem, im going to get a new pump and change the plugs yet again, i pulled 4 of them on saturday and they looked good. im still not 100% sure im using the right plug gap, i used the one for 75 302, but i know that the 74 ignition system was different then 75. ill update after i try the tings listed above.
chris

Jun 30, 2008 | 01:56 PM

fmc400

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From: Austin, TX

6 psi is perfect for your fuel pressure. You might try a richer power valve; it sounds like it is leaning out at low vacuum. Don't waste your money on new spark plugs. Plug gap is a function of the coil secondary voltage. For a given voltage, there is a finite gap required to make the spark jump. You might want to dig a little deeper for that plug gap. 74\75 is around the time points disappeared in trucks.

Jun 30, 2008 | 04:50 PM

montana_highboy

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From: Big Sky Country

Pull the breaker plate on your distributor and see which advance slot you're using 10L 13L 15L 18L etc. with anything over 10L you're at risk for detonation at higher rpm's running 15 degrees of initial timing.

Jul 1, 2008 | 09:54 AM

clgreer

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im not sure what a breaker plate is. dizzys are one of those i just buy them and put them in. as for the power valve, is that something that i can purchase from edelbrock? im pretty sure that it is a fuel issue as all the electronics are new. and ive been using the plug gap from the 75 for that exact reason fmc400. chiltons calls for .044 for late 74/75 and up 302, and somehting like .035 for 73/early 74. thanks for the help

Jul 1, 2008 | 12:16 PM

fmc400

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From: Austin, TX

Sorry clgreer, for some reason when you said 4-barrel I assumed it was a Holley (not sure why). If you are running an Edelbrock carb then it will have metering rods instead of a power valve. Metering rod kits can be purchased from Edelbrock. You might want to look at your timing with a light that can measure advance, and see how steady the marker is because timing chain slop is another possible cause. Personally it sounds like a carburetion issue.