Lets talk Small Block

[BrianG]

Originally Posted by storm9c1

I still think you might be able to gain 1-2" using full manifold vacuum on the distributor and retuning the carb for that. But every engine is different. It'd be more of an experiment than a promise. Keep in mind a few things if you switch this. 1) You have to make the switch with the engine warmed up to see correct results. 2) You will have to lower the idle at the carb with the stop screw. 3) You should retune the carb with a vacuum gauge after making these changes. Otherwise it will seem like you have no gain and perhaps even develop a stumble without that type of retune. It does change the vacuum profile of the engine. Screw the debates about which is better (ported or vacuum), the engine profile tells you this. Stock profiles might like one type. Radical profiles might like another. It's a trial and error process. Nobody can tell you which is right or wrong (which is why this is so heavily debated). But your engine can tell you if you listen.

I'd also be tempted to try a vacuum canister next. Not uncommon to need one with a radical cam. Or last resort, as discussed, change the cam.

I have tried the vacuum advance each of three ways (ported, full vac, and disconnected). I've re-tuned using a vacuum gauge after each change. It seems to like ported best. None have really helped though. I could try a vacuum canister and that would maybe net me a few extra brake pedal pushes. But in the end, it would only solve some of my issues. I still would have a rough idling 350 that just seems to be underpowered until it starts to really wind up.

I've had at least one person respond saying that they had a 350 in a 4x4 that made decent enough power. A few suggestions for putting on Vortec heads and a new cam, but less than I expected responses about feeling that I'd be best off going for the 383.

Honestly, I'm leaning toward pulling the motor and changing the heads, cam and intake to something that have been proven to work well together. I'm not quite sure what that will be though. I've got to figure out if my block is set up for a roller cam. It does have the one piece rear main seal, but I'm not sure if the machine work was done for the roller cam.

I don't think my current stock replacement heads are bad, I'm just not sure what their potential is. Also, I'm on the fence about spending a couple thousand for a top end kit, or maybe 4 thousand for a 383 crate engine. One thing goes wrong if I go with the top end kit and I've got to pull it and start over, and I'd been maybe better off to go with a crate engine. I tend to have bad luck with such things.