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Porting of heads, Winter project.


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Almost time to put the car in storage. I am thinking of porting my heads as a winter project.

Porting info here.

This will be my first head project and am a bit afraid of messing it up. Any one have a set of heads that are in good condition that will fit an 89? What would a fair price be for these heads?

Any tips or cautions etc?

Thanks in advance, Robert

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I did this a few years ago to prepare for my new engine. I couldn't do mine in a weekend, even after doing a couple of sets, but, it is certainly a DIY project. The only suggestions I can make are these: disassmble the heads and have them hot tanked and checked for cracks. They will come back reasonably clean and will reduce the amount of really dirty carbon you will need to remove, although I have never seen them come completely clean. I also used 6" long carbide double cut "burrs" in various shapes to get the basic shape I wanted and then used the cartrige roll sandpaper to finish and semi polish. I found it easiest to see what you are doing if you shine a powerful light into the opposite end of the valve tract you are working on. I used one of those bench lights with a long articulated arm for this. It enhances contrast as well. As long as you just try to enhance the basic shape and not radically change it, you shouldn't damage the heads. I polished the combustion chambers and the ports as a last step with Cratex abrasive embedded rubber tips which fit a Dremel. They do not really remove much material but do a marvelous job of polishing. I didn't open up the combustion chambers as I was after maximum compression ratio but I did remove sharp edges which can cause a hot spot. Install the plugs you are using and check to see if there are any exposed threads, either in the head or the plug itself. Smooth the sharpe edges of the threads, they aren't doing anything anyway. Since I was doing a complete engine, I did cc the heads and piston recesses to match the volumes as close as possible but you could skip this step. The last thing was take the heads back for a three angle valve job and a fresh flush for any left behind shavings. You could try one of those radius valve jobs also which is even smoother. The only other caution is to use the stock GM headgaskets when you reinstall. I found the Fel-Pro's have too large an opening for the cylinder and you will lose compression ratio, a lot in fact. The Fel-Pro was almost 4" in diameter and the maximum overbore for the 3800 is .040" or 3.840". By contrast, the stock gaskets are 3.85". G'Luck and enjoy.

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Personally I do not like to shave the heads unless they are warped. The chambers are pretty small already and you would also need to shave the intake manifold half of the amount to correct for the closer spacing of the ports, depending on how much is shaved of course. Reduces the deck thickness and stiffness of the head. If you shave .050"-.060" from the block, you would approx. duplicate the taller pistons I installed. That said, a few thousandths shouldn't matter and I would doubt any change in fuel would be required, but I would only do it if it is needed. if you could find a thinner headgasket you could obtain the same.

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