6X-4 head porting

I have acquired a set of 6X-4 heads to replace the 6X-8 I have now. I am contemplating doing some porting in addition to milling the heads to get my 60 over 400 up to about 9.5:1 compression. Has anyone done the port work described by Jim Hand in his Pontiac engine book? If so how did it work out? I have a moderate cam 224/234 duration and 465/488 lift. Any comments appreciated.

Dave  

I haven't tried it myself, but if Jim Hand says it works, you can't go wrong folowing his advice.
Steve  
Trying to help... 'cause we don't all have to learn the hard way!

I found it easier to open up the chambers on my no.48's to 85cc to get 9.5:1 on my 406. I also ported the heads but followed H-O's head porting guide back in the 90's (most of the work is very similar to what is described in Jim Hand's Pontiac book). I noticed the power increase, especially with the Crane 284H (228 dur/ 480 lift)- also no problem ruuning 4 wheel disc brakes.

Geno  

I have #48 heads ported they flow 275 IN. 195 IN. EX on 474 pont.In a 67 bird,Jerico 4 speed,433 rear,2084lbs,All motor best time 10.00 at 137.00 mph.Const.10.10 135mph.  

onebadbird:
I have #48 heads ported they flow 275 IN. 195 IN. EX on 474 pont.In a 67 bird,Jerico 4 speed,433 rear,2084lbs,All motor best time 10.00 at 137.00 mph.Const.10.10 135mph.

Im brand new at this,dont know what HTML means  

Thanks for the feedback everybody. I have never thought opening up the closed chamber heads to lower compression. These heads are going to the machine shop for new guides and seats anyway. I will have them milled after I get my feet wet at cc'ing to find out where they are now. This is my first build and I'm going slow to gain experience but its good to know such performance is acquirable.  

I picked up a set of 6x-4's for my upcoming 455 build up. I haven't cc'd them but if they are 94cc as advertised I might open them up a little to 98cc to reduce my SCR to 9.2-9.4:1, since CA 91 octane is lousy gas. They'll also get ported, but I'm also going to open up the exhausts for 1.77's.

Geno  

6X is one of the best heads for porting that Pontiac mass produced. It has about the largest short turn radius available. The hand book is good, but if you are going to port them yourself buy the Jim Butlers Porting video. Any novice can get 235cfm out of them, and with the skills as described in the video, 250cfm. I have ported around 20 sets of 6X's for customers and 250cfm @ 28" is very safe.

My old 455 with 10:1 comp, 91oct, mild solid camshaft, TRW pistons, and headers made 530hp with 250cfm running mid 11's in a factory weight 3800lb TA and ran low 10's on NOS. After cutting up some 6X heads to see how extreme they can go, I have ported a couple of heads to 270cfm without failure and one set made 285cfm, but the chamber had to be opened to reduce valve shrouding.  

Just following up. I did port the heads successfully but man was that a job, not for the casual hobbyist. Im glad I did it, I understand flow better, but next time I will have it done. No flow numbers here, I just followed instructions carefully and hoped to match predicted results.  

onebadbird, check your messages, I'll try to help about the HTML thing.
Brazil