[BlueBronco]

I'm planning to build a 351w for my 86 Bronco. Would the World Sr cast iron heads have too large of intake runners for a 393 or 408W propane engine? I'll be running a Weiand Stealth dual plane high rise intake. I'm considering one of the Voodoo cams or a custom cam for propane.

The heads I'm looking at are new and have 2.02/1.6 valves and dual springs for .600 max lift. 64cc or 58cc intake chamber. 200 cc intake runners.

I haven't been able to find much on this particular head.

Edit: No one seemed to notice the propane cam.

 

[RLKBOB]

If you want your power band up high in the rpm range then 200-210cc intake runner is what you want. If you want your power down low then you want to keep the intake runner around 180cc.

 

[BlueBronco]

If you want your power band up high in the rpm range then 200-210cc intake runner is what you want. If you want your power down low then you want to keep the intake runner around 180cc.

I get that with a 302 or 351 ci but what about larger displacement?

 

[bmc69]

For whatever this is worth, the heads on my 408C are 64cc chambers, 2.045/1.65 valves and 190cc runner volume. With a 270H Comp cam, dual-plane intake and TBI injection, the low-end to mid-range torque and throttle response is outrageous..
..and it runs out of 'steam' at around 4500 RPM.

At least you get a 'data point' for comparison. I'm sure that if I changed the cam timing I'm running and went with a larger-runner intake, the heads I'm using would still be just fine for another 1000 RPM or so of useful power band..I just don't want the powr band 'up there' for my rig.

 

[BigWheelz]

Look into some of the other heads available, I hear that World heads are good, but by far are not the best bang for the buck. Ford Racing GT40P's are CHEAP, and when drilled for 1/2" head bolts will work very well. The edelbrock performer 5.8's are very high quality for only a few $$ more than the world products. The TFS twisted wedges are one of the best on the market, but expect some valvetrain noise. I guess what I am saying is that you have a wealth of choices with a SBF, so look into it before you decide.

 

[81Bronk36]

Ford Racing GT40P's are CHEAP, and when drilled for 1/2" head bolts will work very well.

If you take that advice I got some headers I can sell ya. Save ya lots of $$ (they were actually only 229.00 brand new)

 

[RLKBOB]

I get that with a 302 or 351 ci but what about larger displacement?

Same thing. Larger intake runner will move your power band up. I would look at AFR or TFS heads if I were you.

 

[SigEpBlue]

If you go AFR, get the bare heads and use Ferrea valves with your choice of springs. The valvetrain AFRs come with is pathetic and has a reputation for failure.

 

[RLKBOB]

That's news to me. AFR is one of the best heads out there.

 

[SigEpBlue]

I thought they were, too! That's the messed-up part; I was going to get a set for my Mustang. They look so great with the CNC-profiled ports and chambers. :thumbup However, I've had quite a few people (reliable ones that are in the know) report to me their valve guides being totally messed up, valves losing their heads in the cylinders, keepers mysteriously flying out of place...

The other way I look at it is this: I don't see too many people in NMRA running them. Racers typically run only the most-reliable parts available, 'cuz having your motor puke on the track isn't cool. Brodix/Neal/Ford, Edelbrock, and Trick Flow are on that short list.

 

[RLKBOB]

I have Trick Flow Twisted Wedge. :thumbup

 

[MileHighTurbo]

I have know 12 different people to own AFR heads, they are Great

two of them orderd bare and chose there own valvetrain the other 10 as they come from AFR. the only set that failed was one of the custom sets

you have to remember your not gonna drag race or twist the motor to 7000rpm's
the GT-40's and Twisted wedge ARE TOO SMALL for 393 or 408 cubic inch
if you look at AFR there was a test done on a Ford racing 392 long block it made 461hp 455lbs w/GT-40X heads out of the box by switching to AFR 185's they gained 75HP!! 537HP 505lbs tq and ive seen tests done w/AFR 205's making 586hp. the big inch motors need bigger intake cc runner heads

Go to www.airflowresearch.com and look at the top of home page under "articles" and you will find this test "75 HP GAIN 392 Nov-00"

The world sr's are a good budget head!! and will work well with 393 or 408 cubic inch with the heart shaped chamber they have good swirl and quench.
go with the 64cc and keep the compresion between 9:5 to 10:1.