Should I port my heads?

[hardline_42]

I've got a 509 block 400 sbc with stock 493 (the heavier casting) heads, an Edelbrock Performer 2101 intake and 4 bbl carb (600 cfm I think). I'm running out of money for this engine swap so I'm considering porting and polishing the heads myself instead of buying a new set of aluminum heads. I've never done it before but this site has some pretty good instructions and a decent kit for a DIY port job:

http://www.sa-motorsports.com/diyport.shtm

Of course I'll practice on some junk heads first, but, my real question is what kind of improvements can I see after porting and having a 3 angle valve job done? Will the lowering of my already low compression ratio (8.3 with 76cc chambers plus whatever volume is gained by polishing) overshadow any gains in flow? What camshaft specs should I consider? Any suggestions would be appreciated.

 

[hhott71]

Leave the chambers alone. But clean up any all casting flash.
Clean up the bowl and guide boss area.
Make it streamlined and radius'd
gasket match the port opening.

That will give you as much benefit on the cheap as you can get.

 

[MyBoTy]

By the time you get bigger valves, springs, etc., you're not too far from some of the entry level heads - Iron Eagles, etc. You can often pick 'em up cheap from folks that feel the need to upgrade to the newest fastest. I got a set a couple of years ago for $500 complete and they already had the valve springs I needed. If it were a big block, I'd work the heads you already have but small block heads need a LOT of work before they're even close to the performance and flow of aftermarket heads. My .02

 

[rustbucket79]

porting the bowls is an easy afternoon job and as long as you stay 1/8" away from the valve seats and blend the short turn radius in a nice flowing fashion you should be able to make an extra 15 or 20 HP for your efforts. If you have been dealing with a machine shop already they may port one intake and one exhaust bowl as a sample for you to copy for a nominal fee. We do that quite often and the people who are careful and take their time produce some nice work. Something to consider....
Don't forget a dust mask and a face shield!

 

[hhott71]

Don't forget a dust mask and a face shield!

A shop Vac is a great asset. use it on the other end of the port while bowl grinding or port matching.
Keeps it all clean and easy to work on.

 

[slimlynn1]

A shop Vac is a great asset. use it on the other end of the port while bowl grinding or port matching.
Keeps it all clean and easy to work on.

That's an awesome tip!

 

[1978LT]

A 400 SBC deserves aftermarket heads, IMO. They really can use larger ports/valves. Having a shop do larger valve installation isn't cheap, so unless you're happy with ported 1.94/1.50 valve heads, look elsewhere. There is a HUGE difference between stock and aftermarket....or even 1.94 Vortecs!!

 

[pdq67]

Some of the stock 400 SB heads came with 1.94"/1.60" valves in them.

I guess I would really consider a set of the cheap cast-iron or aluminum heads that Hot Rods USA;

http://www.hotrodsusa.com/

and Texas Performance Products

http://texasperformanceproducts.com

are selling...............

Try this thread over at Team Camaro..

http://www.camaros.net/forums/showthread.php?t=72832

And I am sure others too..................


pdq67

 

[HULKZ28]

hardline, I ported the stock heads #624 in my 80z with a 355 and she runs damn nice. stock ccs on the intake side was 150 its now 170.I cleaned up just below the seat and into the bowl put 3 cuts on the short side radius and rounded it off matched the port openings to the intake also has 2.02 1.60ss valves and 3 angle valve job done. unshroud the valves a little also. you can use a .015 felpro head gasket #1094 to get the comp. up a bit.I would like to try a set of AFRs or something comparable to see the difference (when the kids stop eatin).It screams all the way to 6500 rpms with a XE274 cam. Im happy for now..If you have the time its worth doing. good luck.