Shelby GT350 R heads done by Valley head service

[cjperformance]

We put a proper Ignition on this, MSD pro billet & 6AL.
It woke right up, big time!

It was fouling plugs on light throttle cruise & getting atrocious fuel economy, that's why he admitted defeat on the old twin point, new ignition literally halved the fuel consumption, never fouls plugs any more & owner says seat of pants it's picked up a fairly decent amount of grunt.

Good to hear of the improvement, at least he can store the original dissy and not wear it out!
I have stripped a pro billet before , had it sand blasted(the visible area) then wet rubbed it lightly with 400 then 600 then a bit of autosol polish, just smoothes off the top of the blasting and it makes it look pretty similar to an old cast dissy that has had a 60's backyard polish job, looks very old fashioned, quite a cool look.
P.s. Did you find out the wet blaster name mate?

[blown265]

If original appearance is important, then the twin point distributor could be used to trigger the (hidden) 6AL.
MSD white wire switching isn't quite as stable as magnetic/electronic, but as long as the original dizzy is mechanically sound, it'll function well up to moderate rpm.
Further, depending on the style of twin point, the leading set of points could be switched 'off' , temporarily utilising the second set only, thus retarding the timing a few degrees under boost. (a manifold vacuum NC switch used as the trigger)
Regards
Paulie

[Mummert]

We have built a few of the Paxton blower equipped gt350 289's in recent years. That carb hat is not engineered very well and causes huge fuel and air distribution issues. We have used o2 sensors in each individual header tube , egt probes in each tube, and spark plug readings to diagnose issues, and hand made air deflectors fitted into hat to fix problem.

Putting a small stainless mesh air filter inside the bonnet can be worth sizable power gains. Helps straighten out the tornado in the air hat.

[BILL-C]

We have built a few of the Paxton blower equipped gt350 289's in recent years. That carb hat is not engineered very well and causes huge fuel and air distribution issues. We have used o2 sensors in each individual header tube , egt probes in each tube, and spark plug readings to diagnose issues, and hand made air deflectors fitted into hat to fix problem.

Putting a small stainless mesh air filter inside the bonnet can be worth sizable power gains. Helps straighten out the tornado in the air hat.

Good idea Geoff! We made a couple of fins to stop the toilet bowl swirl.

[Mummert]

We've dynoed a few motors recently with 8 O2's. A lot of the problems that I thought were manifold distribution problems were actually starting above the carburetor and continuing off the bottom of the carburetor.
I know its not nostalgic but a better bonnet would help.

[Mummert]

I'm not really familiar with the C6FE head. Looking at pictures its appears to have a big exhaust port. What other changes does it have compared to traditional 289 heads?

[BILL-C]

C6FE casting has chambers very similar to 69-70 351w heads and Intake ports slightly bigger and better than 351w. Those big square exit exh ports not ideal, but good enough. 1.94 / 1.60 valves will fit. 240 cfm no problem, 250 possible but casting will need to be like an eggshell in spots at ssr and in bowl. We have made 504 hp on 12.5 cr 289 before with these heads.

[Mummert]

How does that compare to a fully worked set of production 289 heads.

[Carnut1]

How does that compare to a fully worked set of production 289 heads.

viewtopic.php?f=1&t=48919&p=778243&hili ... 89#p77824I I think I squeezed 244 cfm out of a 289 head. DV will be dynoing these soon, I hope! Thanks, Charlie

[BILL-C]

C6FE heads have more potential than 289 head. Charlie can probably get 260 out of one of these castings, but I get scared easy! If anything I build develops a leak , then I have big problems. My stuff has to withstand big time abuse and live for a long time without cracking or seeping, so I keep the castings a little thicker at the expense of that last little bit of flow. If I have to do stuff over again free, I can’t pay the bills.

[Mummert]

Yeah I here it. I've a got the head in the low 230's at this point with a 1.88" and may just leave it.
There is always air flow to find without a grinder. So I will probably just work the details into the ground.

After playing around on the seat guide machine, is #3 the big chamber?

[BILL-C]

On 289 or C6FE?

[Mummert]

289

[BILL-C]

I haven't consistently noticed any terrible chamber problems on production 289 heads. We have however noted the trend of a center cyl being 4-5 cc bigger than rest on C6FE castings. PITA!

[In-Tech]

Hello,
Do you think the variance in cc was designed into the casting or just a flaw?