Thread: 383 head change ??

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I built a 383 a couple years ago, Put it in My 54 GMC Panel and really like it I used a good set of 71 350 heads (75cc) that I had to save some $. It is now time to change them. I have to run 93-94 octane to keep it for detonating. Am I going to have problems going to Vortec Heads with the smaller cambers or is the chamber design enuff better that the comp increase won,t detonate Thanks in Advance

What type piston do you have in it?

The vortecs are 64cc but have a much better design and quench. I run mine on 87 goat piss with no problem(@ 9.1:1). Be forewarned that you cannot run more than .475" lift without modifications and you'll need a new intake. Like Camaro said, what is your static CR now?

Pistons are flat tops w/valve reliefs. The Vortecs have been modified for more lift.

You may run into a problem with piston to valve clearance depends on lift and with the flat tops and 64cc chambers it will put you over 10.1 and more than likely lead to detonation. I used Dart Pro1 alu. heads 200cc runners ,72cc chambers on my 383 and my lift is .544/.520 270/276 dur. advertised. I do run premium and no problem runs hard and strong.

Dave

"I have to run 93-94 octane to keep it for detonating."

I'm guessing this is because you paid little or no attention to the squish. With a good tight squish of 0.035"-0.040", you could probably run a lesser grade of fuel without detonation. I'm further guessing that with Vortecs, this motor will rattle like a can of rocks if you don't adjust the squish. Just my opinion.

At the time that it was put together and because of the heads used Squish was not taken into enuff consideration. The heads are still going to be changed. I'm just tyring to figure out what direction with a tight bugdet

Why not wait, save up a bit more money, and get the heads that will work right with the rest of the engine???? In the long run, getting the correct parts the first time usually ends up being the most cost effective way to go.....

What heads should I get? At the time it was buildt The idea was that the heads would last untill there was more cash. It almost worked seems like there is never the cash part. So try to keep me on the less expensive side.

Just saw a set of Dutweiller aluminum heads advertised at Sumitt for about $1,000.00, didn't look to see what all the specs were. Might want to check them out.

If you want stump pulling torque for a heavy vehicle, go with a head in the 170-185cc intake runners. If you're looking for upper rpm hp, some 190-200cc runner heads are the choice. Vortecs do make a super torquey 383 but they are pretty much done at 5500-6k rpm which is good for a street car. The difference will be like night and day over the heads you have. Go with 64cc chambers and adjust the quish as Tech advised and you won't have problems.