Intake manifold question

[garycrist]

Try to be easy w/ the gaskets as you will be inspecting them closely!

[91GriggsGT]

Just a suggestion, but before you tear it all down again, start going thru everything systematically looking for any vacuum ports that are open, wires not connected, etc.

Also, try starting from scratch on your timing. Is it possible you are 180 degrees out on the timing? I wold make sure you have #1 at TDC, end of compression, then pull the cap and see where your rotor is.

Also check all your vacuum fittings on the carb and make sure you dont have one leaking. You also said you have new MSD everything. Run thru all the wires and see if there is any adjustments that need to be made.

From what you are describing, it sounds like it could be any number of things, but timing and vacuum leaks would be two of the things I wold focus on.

Just my .02

[Baba Ganoush]

Just a suggestion, but before you tear it all down again, start going thru everything systematically looking for any vacuum ports that are open, wires not connected, etc.

Also, try starting from scratch on your timing. Is it possible you are 180 degrees out on the timing? I wold make sure you have #1 at TDC, end of compression, then pull the cap and see where your rotor is.

Also check all your vacuum fittings on the carb and make sure you dont have one leaking. You also said you have new MSD everything. Run thru all the wires and see if there is any adjustments that need to be made.

From what you are describing, it sounds like it could be any number of things, but timing and vacuum leaks would be two of the things I wold focus on.

Just my .02

I'm sure my timing is correct. I meticulously checked it since the symptoms seem to me to point to ignition. The entire car was rewired, especially the underhood wiring, there is nothing stock about it. I've gone through my wiring and everything seems to be correct. The only possible error is the heavy red 12v constant to my MSD box is not hooked straight to the battery, like MSD wants. It instead hooks to a post where all other power is distributed, so I might run it straight to the battery and see if anything changes. I've got to try anything at this point.

It starts right up when the key is turned, but tries to die, idles up real high, drops and repeats until it dies. It also sounds like it's missing so I'm still suspect of my ignition, but it may just be my initial timing since I can't set it until I get a steady idle. I'm just not sure how to diagnose it's symptoms, as I'm sure a trained ear could narrow it down in a few minutes.

[green1995gt]

Did you set the msd to 8 cyl?

I'm sure my timing is correct. I meticulously checked it since the symptoms seem to me to point to ignition. The entire car was rewired, especially the underhood wiring, there is nothing stock about it. I've gone through my wiring and everything seems to be correct. The only possible error is the heavy red 12v constant to my MSD box is not hooked straight to the battery, like MSD wants. It instead hooks to a post where all other power is distributed, so I might run it straight to the battery and see if anything changes. I've got to try anything at this point.

It starts right up when the key is turned, but tries to die, idles up real high, drops and repeats until it dies. It also sounds like it's missing so I'm still suspect of my ignition, but it may just be my initial timing since I can't set it until I get a steady idle. I'm just not sure how to diagnose it's symptoms, as I'm sure a trained ear could narrow it down in a few minutes.

[Baba Ganoush]

Did you set the msd to 8 cyl?

Isn't the default for a 6al 8cyl? I think you have to cut a couple of wire loops to use it on anything else, but I will double check that.

[91GriggsGT]

Not sure the red 12v constant MSD box wire would be the issue. I dont run one, but I do know guys that run a battery cut off switch and the box is hooked to the solenoid, and not directly to the battery.

Have you checked for vacuum leaks? Will the car run if you give it gas when you start it?

[green1995gt]

Isn't the default for a 6al 8cyl? I think you have to cut a couple of wire loops to use it on anything else, but I will double check that.

I dont know mine has a dial for 8cyl 6cyl 4cyl, but its the msd with the two step option dont remember which one but I got it three months ago.

I had a crane before

[Baba Ganoush]

Not sure the red 12v constant MSD box wire would be the issue. I dont run one, but I do know guys that run a battery cut off switch and the box is hooked to the solenoid, and not directly to the battery.

Have you checked for vacuum leaks? Will the car run if you give it gas when you start it?

Yes it will run with gas, and almost idle but not without surging. It sounds like it's missing though, that may just be the dizzy a little off, not sure. I am using a battery cuttoff and the MSD is bundled with everything else on the switched post. I've made sure to stab it right, and I've even checked every spark plug and wire to make sure they're firing. I may move the heavy 12v from my MSD box to the battery side of my cutoff and see what happens.

I'm thinking it is my intake, but I can't get back to it until Friday night. I may just trailer it to my mechanic so I'll have some more help. I've built the entire car on my own, and I'm exhausted!

[Baba Ganoush]

Solved it.


Fixed with a port matched Edelbrock Performer RPM intake. It runs like a champ now. To my surprise, not all 302 4barrel intakes are created equal, and mine was leaking due to incorrect port size/matching. It wasn't a significant difference, and required minimal porting, but I had to use the beefier Edelbrock and it worked nicely.

[shumpertdavid]

Good deal, always a good feeling knowing you fixed it