I'm doing some fine tuning after pulling my 305 and putting in my 350.

The car doesn't want to idle right. Unless I turn the idle way up. With the idle that high, it is hard to stop and it wants to take off with my foot mashed on the brakes.

It revs real good in park, but in drive it has a noticable stumble at first, and then it builds speed. I say builds speed because one can feel the acceleration but there is no initial launch. I assumed it was my power valve because I had recently had a good backfire, but after replacing this, I noticed no difference.

I'm leaning towards timing being off, or perhaps a vac leak. I'll end up checking both come saturday, I'm just wondering if you got some more advice for me to test?

Also, in a carbed 87-92 motor with 193 heads; in which valve cover does one put the PCV, and what goes in the other valve cover?


Quick stats, more details on my webpage
78-280z 2+2 Stats and Mods
Block: 5.7L Short Block 87-92 GM Truck
Heads: Mildly Ported 193s; I:1.94, E: 1.5, Pocket Ported and Valve deShrouded
Intake: Eddy Performer, Dual plane 0-5500RPM with egr
Cam: SUMMIT budget cam, In:262(204) / Ex:272(214), LCA:12, Overlap:43
Tranny: '89 700r4 with B&M Street/Strip Shift Kit
Air/Fuel: Holley 600cfm Vac2nd, Stock Jets and springs, recently replaiced Power Valve (thought it might be my problem)
Ignition: HEI Dizzy with fully adjustable advance and 50kV Coil & Module. Accel Super Stock wires, Bosch Platinum plugs

 

I thought you had a q-jet on that...?

whats your base timing at? cam duration?
err, summit 204/214 cam eh? (writing before reading here...)

one valve cover should have your pcv, going to your carb, the other valve cover should have a breather, or be connected to your air cleaner.

The air goes into the breather (or air cleaner element), into the valve covers, in the crank case, out the other valve cover, through the pcv valve, and into the carb to be burned. (IIRC)

if you can get to your plugs easily, (SBC, you should be able to), i'd recommend leaving the platinum plugs out, and sticking with coppers.

 

Very observant... I'm using the Holley right now, because I know it works. The Quadrajet was rebuilt, but hasn't been installed yet. Once I get the rest of the motor tuned and running right, I'll put the Quadra on. You know, one less variable.

 

hmm, well I think the main part in tuning is the carb. Timing is pretty easy, and unless you're degreeing the cam or something, there really isn't anything left.

Might as well drop on the carb you want to use, and tune that to suit. It'd suck to tune the holley right, then put on the q-jet and start from square 1 again.

Anyway, I would guess you're using too much idle speed, and not enough timing, but I don't know squat about holleys, only a bit about q-jets.

I gave you that link in your other thread, i've got a few other articles on tuning q-jets in that same directory, feel free to download them.