First of all, Hello everyone, this is my first time on this board. Seems like some knowledgable people around here.

Now, I got a 383 with Performer RPM heads, air-gap intake, and hydraulic 308/318, 234/244, 112LSA, 107ICL, RPM cam. It has 10.9:1CR.

I'm pulling the engine to paint the car and while it's out I want to get rid of the cam to go with the XE284 from Comp. (I didn't build the engine, I got it in the car with less than 5hrs runtime) I also want to clean the heads for better flow.

I need advice and so forth on porting these heads. I'm no stranger to porting heads and have done a few sets of Dart Iron Eagle. I normally clean the area behind the valve seats in the pocket, the contours of the turn into the chambers and the valve guide area. Anyone have any other suggestions or have some porting advice? Thanks, Ray

 

Probably nothing you dont already know, gasket match the intake ports and blend up into the runners. Do the same thing on your intake and also blend under where the carb sits as this will open up quite a bit of flow too.

Smooth out the chambers (smoother than they are already), depending on chamber design and valve size you could overlay a head gasket and clean up around the valve area to eliminate some shrouding issues.

To do the heads right you'll need a baret to match each chamber size, runner as well as a nice set of calipers to get each runner dimensionally the same. Typically in a shop they will flow 1 cylinder and keep working on it/reflowing it until they find optimum flow and then use the baret and calipers to match each port there after...that's why it cost so much to have heads ported correctly by a shop. Here for a complete porting of heads they start at $1K and go up if you want the intake done-typically another $200. This is a large reason when budgeting it's often easier/cheaper to see the heads you have and put them towards the purchase of a bigger set of heads.

If your just looking for a quick and easy home job, gasket matching and slight blending will net you good gains which is what it sounds like your after anyways.

 

I'm just basically trying to get a little bit better flow out of them as they max about 235cfm@.600 lift. That's hardly adequate for a Hi-Perf. 383cid. I'd love to get them to about the 255cfm area without having to spend a grand on them. I wouldn't have chosen these small runners as I like 190-200cc heads for a 383cid and 200-215cc for a 406. They are high velocity though and maybe I can get enough out of them to make some serious torque with some careful port work.

I think I might customize a cam with a 106 LSA to help it breath a little bit better.

 

I'm very happy with my 106LSA as it still allows the use of pwr braks with the addition of my vauum can, for street driving I can idle it down to 850rpm and it is very tame on the road.

IMHO I would take your runner sizes and actually lose the 190-200cfm runners for anything larger than a 355, meaning the 200-227 runners will really like sitting ontop of the 377/383, and then when you step up into the 400+cid then you should really start around 227-230 or even 215 race heads, the larger cubes need to breath alot of air so you need to provide the opportunity to do so, anything smaller and your choking it. And yes, that 235cfm is really holding you back, especially under the curve your losing out on alot of pwr, dont worry so much about peak numbers worry about the numbers in the .200-.400 area since the cam is seeing that opening more than peak

Picking up 20cfm on a out of box head is doable but it would definately help to have it flowed prior and post to see what your actual gains are. Typically shops are very affordable to check flow, I know locally if you just want one cyclinder flowed it's a $20bill so it's actually a no brainer IMO. but definately work the intake over as well. I did not have my intake flowed since I just took a few hrs to clean it up, but the car picked up a solid 1.5mph every pass just cleaning up and gasket matching the runners and a brief blending under the carb area...all of maybe an hrs work and I have'nt even maximized it yet.