Need help tuning my 383

[TheSwede]

Hi guys, long time since I last visit here but I have been busy working on the house. Still got that Coronet in the garage and with some help from Spauldo I got myself a new Holley 750 DP Ultra and an Innovate MTX wideband lambda and the car really woke up and it feels like 50 more ponys.
The problem that I had with the Eddy 750 still remains, the engine stops for me now and then when I put in in D or R, when I drive and let of the gas it also stops, I have adjusted the airscrews so I have an AFR of 13.2-13.5 at idle, initial timing is at 15 degree, car runs very lean ( to lean?) at low speed, 15.0 15.5. Have not tried it at WOT yet with the Lambdameter but it runs great at WOT

I have a hughes 2200-2400 rpm converter, a Crane 288 cam so it is not a race car but it behaves like a crap car :angry fire:

I have new spark plugs , wires, fuel system the only thing left to change is the coil which is new but a no name.

Any ideas?
I will perform a compression test this afternoon but then I am out of ideas :sad9:

 

[TheSwede]

Just checked the compression, 160 psi for the lowest and 175 psi for the highest and the other 6 landed at 165-170 psi, 10 % differens, is that OK?
I also plugged the hose to the PCV valve, could a fault PCV valve cause this kind of problem?
Threw in a new set of plugs too and will take it for a ride today to see if it runs OK.

 

[Hemi Rebel]

Maybe want to richen it up a bit at idle and see how it does. Try 13.5 to 14 and see how it does

 

[SwedCharger67]

Your cylinder pressures seem to be ok, I had around 120 psi in a fairly hot-cammed, low compression 383, and it behaved like a pig! I had initial timing at 24 degrees, it wouldn't idle with less, due to low vaccum and low cylinder pressures.

If you have low vacuum, you should disconnect and plug the vacuum advance hose to the distributor, at least while fault finding.

I agree, you could set it leaner at idle, that might improve things a bit.
Otherwise I think your AFR looks fine, maybe a tad on the lean side for low speed, but if the engine runs well you can leave it as it is.

 

[eric383]

I like to use a vacuum gauge as an alternate method to tune engines or if I think they are having weird problems. Here is some interesting reading.
http://www.centuryperformance.com/f...ngine-Tuning-Using-a-Vacuum-Gauge?p=77#post77