PORTING 906 HEADS AROUND THE VALVES-SHROUDING

PORTING 906 HEADS AROUND THE VALVES-SHROUDING - 10/30/12 04:14 PM

DOES ANYONE HAVE FLOW BENCH NUMBERS FOR PORTING AROUND THE INTAKE AND EXHAUST VALVES ON A 906 HEAD OR THE LIKE, TO ELEVIATE SHROUDING? I AM REFERRING TO THOSE WITH 2.14, 2.18, 2.20 INTAKES AND 1.81 OR 1.88 EXHAUST VALVES.

I AM THINKING THE NUMBERS COME IN AROUND 5 CFM OR SO?

Posted By: 451Mopar

Re: PORTING 906 HEADS AROUND THE VALVES-SHROUDING - 10/31/12 03:07 AM

Do you mean chamber shrouding?
I don't have any info on that, sorry.

Posted By: 4406bbl

Re: PORTING 906 HEADS AROUND THE VALVES-SHROUDING - 10/31/12 07:01 PM

Quote:

DOES ANYONE HAVE FLOW BENCH NUMBERS FOR PORTING AROUND THE INTAKE AND EXHAUST VALVES ON A 906 HEAD OR THE LIKE, TO ELEVIATE SHROUDING? I AM REFERRING TO THOSE WITH 2.14, 2.18, 2.20 INTAKES AND 1.81 OR 1.88 EXHAUST VALVES.

I AM THINKING THE NUMBERS COME IN AROUND 5 CFM OR SO?

I do not know the exact figure, BUT if you do it do not unshroud all the way out to the head gasket. The smart way is to put the heads on a finish bored block, mark them left and right, then scratch a circle from the crank side on the head, unshroud and polish out to that line. If you use 1.88 and unshroud too much you may need to notch the bore, not a big deal but you need to check it, less is more sometimes, most like the 1.81, the whole block and head package fit is more important than a few cfm on a bench.

Posted By: minnesota guy

Re: PORTING 906 HEADS AROUND THE VALVES-SHROUDING - 11/01/12 04:02 PM

I had to install 2.20 and 1.88 valves due to the seats and the heads prior useage. 20.00 swpa meet heads that had been running 2.18 and 1.81...I did some valve unshrouding clean up. Not excessive as I need to keep chambers as small as possible. I agree that you can outflow 2.20 1.88 valves with 2.14 and 1.81...the size becomes a factor and gets in the way of flow. Thanks.