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Old 06-02-2012, 11:00 PM
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Porting 396 chev oval port heads to rectangular port

Hello. Fellow Hot Rodders. I have a 1969 Chev BBC with original Oval Port heads. Can I port-grind out enlarge the oval ports to match a rectangular port tunnel ram Intake, with two 650cfm carbs. I also want to install a Comp Cam 11-213-3 Magnum Hydraulic flat tappet camshaft with .550 " int./ .550 exh. lift, & 292 duration. Will this set up dramatically increase my HP & torgue. THX, Marty.
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Old 06-02-2012, 11:22 PM
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Quote:
Originally Posted by martin7844
Hello. Fellow Hot Rodders. I have a 1969 Chev BBC with original Oval Port heads. Can I port-grind out enlarge the oval ports to match a rectangular port tunnel ram Intake, with two 650cfm carbs. I also want to install a Comp Cam 11-213-3 Magnum Hydraulic flat tappet camshaft with .550 " int./ .550 exh. lift, & 292 duration. Will this set up dramatically increase my HP & torgue. THX, Marty.
No need to try to turn the oval ports into rectangular ports- you can't anyway. Just run the intake on the heads, as-is- if you can't get the correct intake to match the heads. There have been reports that this combo works better than you would expect. Use rectangle port gaskets.
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Old 06-03-2012, 07:21 AM
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Originally Posted by cobalt327
No need to try to turn the oval ports into rectangular ports- you can't anyway. Just run the intake on the heads, as-is- if you can't get the correct intake to match the heads. There have been reports that this combo works better than you would expect. Use rectangle port gaskets.
I have a pair of these rect-oval ported heads in my "Do not do" archives. Whenever a customer asks about "converting" a set of oval port heads. I show them. A lot of work for nothing. Th only "port match" is at the gasket surface. There isn't enuff material in the upper port to even come close to a rectangle port match.

The Super Stock drag racers in the seventies used rectangle port intakes on oval port heats on a regular basis. I've built a few street/strip BBC's this way and have seen no ill effects. As stated, Just use the rectangle port gasket.
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Old 06-03-2012, 07:30 AM
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Hello Fellow hot Rodders. Thanks for your valuable Information. If there is not enough spare metal in the oval port head to "Port out", and If the super stock drag Racers in the 70's ran rect port intakes to their Oval port Heads. Well NO WORRIES!!! I'll but the rect port tunnel ram Intake for my 69 BBC oval port heads. THX again for your help. I'll keep you posted as to how this engine RUNS.Cheers, Marty.
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Old 06-27-2012, 11:41 AM
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Originally Posted by BOBCRMAN@aol.com
I have a pair of these rect-oval ported heads in my "Do not do" archives. Whenever a customer asks about "converting" a set of oval port heads. I show them. A lot of work for nothing. Th only "port match" is at the gasket surface. There isn't enuff material in the upper port to even come close to a rectangle port match.

The Super Stock drag racers in the seventies used rectangle port intakes on oval port heats on a regular basis. I've built a few street/strip BBC's this way and have seen no ill effects. As stated, Just use the rectangle port gasket.

I beg to differ, I have done a set of Squirvel ports on my dads 496....although you are right not much material on the roof BUT enough to make the top of the port Square and the bottom I left Oval...and it works really to good, as he already damaged the TH400 whitch had all new clutches re-built, and has recently switch to a bulletproof TH350 with a brake...it will be running soon and i will take pics/vid of the car so all might see what the "sqirvel ports" can do with port work
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Old 07-02-2012, 12:12 AM
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Much better cam for your tunnel ramed big block would be the comp 294s solid lifter version magnum cam.
The solid cams work a lot better than hyds in this rpm level, in BBC's
the valvetrain is much heaveier than a SBC.
If you want max performance from your BBC use a street strip solid lifter cam
over a hyd.
The 294s cam or something in that ball park is just right.

EG Lunati street strip mechanical UD harold design cam
#402A4LUN

or #402A9LUN

Be sure to use the right valvesprings, reguardless

These cams are street strip friendly powerfull cams just right for your
street tunnel ram BBC.

The 292H cam is good but these Lunati/UDHarold solids will outperform it.
These cams are easy to maintain.

www.lunaticams.com
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