Currently have my TPI base, runners, and plenum out being ported [by Darrin, of course!] When they return, I am going to pull the heads and match the ports. My question is, while the heads are off, I am thinking of having them machined to bump up the compression a little. Is this going to be worthwhile, or should I just do the porting and end it there? This is a 5.7 with 52mm throttle body, Hooker 2155's, no cat, and Dynomax exhaust. Thanks for any help!!!

 

Complete utter total waste of time and abrasive to do that but nothing else.

All that is, is eye candy to fool the inexperienced.

That's not where the gains in head porting live. About 60% of the improvement in stock heads lies in the bowl area; about 15% in the valve guides; about 10% in treatment of the valves themselves; and the remaining 5% in everything else, of which "port matching" is not even the largest factor.

The change in compression you can get from milling the heads won't be very large at all, but can't really hurt, as long as the sharp edges that are created where the deck meets the chambers, are rounded off.

I'd also suggest a better cam; one SPECIFICALLY OPTIMIZED for the constraints that TPI saddles a motor with. Above all, NOT one picked for "sound" or "lope", either of which will make the car go slower than the stock one. My suggestion would be the Comp "502" grind http://www.summitracing.com/parts/cca-08-502-8 with suitable upgrades to the springs... the stock ones ABSOLUTELY CANNOT AND MUST NOT be used with a cam like that.

 

Thanks for the input, looks like the heads are staying on.

 

He didn't say leave the heads on, he just said don't focus on port matching. that's small fries compared to the other port work that can be done for more effect. Unless your head port is smaller than the port on the intake, then it might be worth it. Still, the gains are smaller than the other porting mods that can be done.

 

Pretty sure the head port will be smaller than the intake port, as I am getting stage 4 porting. I am just trying to decide if I want to pull the heads, because once I do, I will probably go the whole route [have them ported, cam, rockers] Thanks again.

 

Doesn't matter.

Go ahead and do it. Just, learn what actually ACCOMPLISHES SOMETHING, and what's just eye candy to fool the n00bs into wasting their time and/or money.

The bowl, behind the valve, is where it's at. "Port matching" is a total waste until AFTER every other ACTUALLY EFFECTIVE mod has already been made, in a way that ACTUALLY IMPROVES flow. Which is not at all the same as a Cletus and BillyBob "hog em out" hack job. Unless you have a database of templates for stock ports, and a flow bench to test your results, you should stick with the "big four": clean up the throat of the bowls behind the valves by getting rid of all the angles and ridges where they just sorta jammed a cutter into a raw casting, and make them about 85% of the valve diameter; make the guides into an "airfoil" or "teardrop" shape; back-cut and radius the valves; and smooth the short-side radius, esp exhaust, WITHOUT lowering the floor. Those 4 things can be done by eye, and are where 75 - 80% of the potential gains in head porting are, anyway.

 

If your looking at having the heads modified I would look at getting a set of aftermarket heads. Would be a good idea to get a larger cam too if you have opened up the intake a lot. I would not bother with port matching unless there is a huge difference in port size. If its just a slight over lap don't bother with it.