intake for my 401

[shawnsc25]

ok so right now here is what I have 401 .30 over built by a shop im not sure on the cam but im pritty sure it is to stock specs the intake I have on there now is an edellbrock performer with a edelbrock 650 carb and it has shorty headers on it.
now here is my problem it seems to run to rich and at low rpms (2000) the motor feels like it is draging now u get it over 3500 rpms and it feels alot better could this be the intake would a torker run better than a performer and what do u guys run.

[AMX69PHATTY]

Just a guess, but maybe try re-curving the distributor, what kind is it ?

[shawnsc25]

it has a full msd ignition and splitfire classic plugs put in yesterday

[fuzz401]

take the spitfire out and use autolite AR3932 plugs
5/8 hex gap to 45 to 50 with MSD

[AMX69PHATTY]

Think the MSD distributor is curved pretty conservatively out of the box.
Try installing the Silver 25 degree stop bushing and (2) Silver Advance springs, or (1) Silver and (1) Blue.
Then set total timing with a dial back light to 34-38 degrees by reving engine untill it is fully advanced.
Initial advance should be 9 to 13 degrees, but isn't top priority.
What matters is total advance, how quick, and at what rpm.
(2) Silver springs should be all in by 2700 rpm, (1) Blue & (1) Silver by 3000 rpm.
Vacuum Advance, if any, must be disconnected when setting the timing.

Slow advance curve might explain why it's a dog until hitting 3500 rpm.
Also plugs firing late may not be burning all the gas causing it to seem rich maybe.

[shawnsc25]

thanx ill try that this weekend and get back to u I think u are right about the plugs fireing late.

[AMX69PHATTY]

I also use AutoLite spark plugs. No experience with SplitFire's, too pricey for me I guess.

[theamxguy]

My experience also supports the idea you may have a timing issue, timing too retarded does act like your description. We will assume the carb is in good condition. Otherwise I would also check for sticky float, unusual calibration (pig rich idle circuit, unusually rich jetting, etc).

[ironman_gq]

check the powervalve.

[northplainsdrifter]

check the powervalve.

How do you determine if the powervalve is bad on a Holley without running it and watch the gas flow out the tailpipe?

[AMX69PHATTY]

If the idle mixture srews can be turned all the way in and lightly seated and it continues to idle, chances are the power valve diaphram is ruptured. Another way they can go bad is if they sit dry or get old sometimes the diaphram can get stiff and it will not suck closed at the specified vacuum rating. Got a Vacuum hand pump at Harbor Freight, their brand, it's metal rather than plastic, ~$20, and it comes with a suction cup type attachment that can be used to test power valve operation and at what vacuum level they close at.

[shawnsc25]

I dont have a holley it is an edellbrock I went with the autolight plugs and had great luck with them I did advance the timeing a little and that seemed to help to it was a little harder to start but ran great it still seems to run a little rich but I will be getting a different carb down the road anyway thanx for all the help :sa: