The FMX will hold up for sure, but I don't think you'll get 400 hp with stock W heads, even ported. Go aluminum and stroke that sucker!

 

i wish i had a dyno pull under my belt but desktop dyno shows my 302 with ported W heads at a tad over 400 without accounting for the msd 6al ignition, windage tray, roller rockers, and balancing. so i guess 425 at the flywheel and its prolly pretty close.

that being said i dont think its out of the question to achieve 400 hp from a 351 with the ported heads. although i will not argure that a set of aftermarket heads arent better - obviously they are. im just old school, i like to make as much power possible using fomoco castings - like people would have done when these cars were new

 

Stroke the Windsor to 408 if you want reliability... I just drove my 67 coupe with a 408W from Texas to Cali...

 

rebuild your tranny and stick a stall in there

its auto right?

 

Thanks, Yes it's an Auto 3spd

 

FMX stronger than a C6? Not hardly. C6 cheaper to manufacture? Not really easiereither. Think about all the trucks that have C6s behind 460s, 390s, 428s, and 429s.. the C6 is the heavy duty auto 3 speed. A C6 will take more abuse then a TH400 will, and trust me a TH400 will take a huge beating before it dies provided its not the 4 friction disc wimpy chevy ones. All the large engines have to use a beefy trans that will live with the torque. The OEMs wanted transmissions that would last 100,000 miles, and in the 60s/70s that was a long time. A small trans isnt going to live as long as a heavy one with plenty of friction area in the clutches.

The FMX is an intermediate trans, supposed to fit between the C4 and C6 and provide some longevity behind the more powerful 351s of the early 70s. When they designed it they didnt know the gas crisis was coming, and that the EPA would make them neuter all the engines so it was overbuilt for most engines it was bolted to.

Get it to stop leaking, a quality rebuild on it, you dont need exotic parts like billet anything, and install a cooler. A shift kit will just make it shift harder, most Fords shift pretty hard as it is. A mild stall converter will help move the car, something with around 1900-2400 stall works good in a small cammed combination.

Really nice Stangs... the only thing I would change about them is who's name is on the title.

 

Just what does your desktop dyno account for? Did you input flow numbers for your heads? If not, it is quite possible to get about any number you want. Ported W heads would be hard pressed to flow more than 200 cfm on the intake.

 

trying to remember cause its been awhile but heres some of what you can put in...

bore x stroke
compression distance - taking into account how far the pistons are in the hole, head gasket thickness when crushed, cc of the heads, and cc added or subtracted from any dome or piston reliefs you may have
cam type - hyd, mech, roller
cam specs - you can enter in your exact duration at either .050 or advertised, lift, and centerline
manifolds, ported manifolds, short tube, or long tube headers - also you can choose large tube or small tube
single exhaust, dual exhaust, with or without mufflers (cant remember if they had X / H pipe option)
dual plane, single plane, high rise intake - i think there was ported or unported options
stock heads, mildly ported stock heads, fully ported stock heads, and then several options for aftermarket heads - you can also inport flow bench numbers as well as specify valve sizes
carb size, you can also choose a few different fuel injection options like tbi or multiport
supercharger / blower / turbo and you can adjust the boost variables on those too if i remember.

it gives you estimated torque and hp curves, and will do volumetric efficiency calculations.

for the record, the extent of my porting is egr bumps removed, any casting flash crap smoothed down, i ground 30 deg angles above the 45's on the valves to smooth them out (n.o.s. manley valves from cirka 1980) and some very nice machine porting under the valve seats. i entered my heads into the software as 1.84 /1.54 valves with mild porting. if i remember it came up with numbers between 390 and 410 depending on little changes i would make, like changing cam info from advertised to .050, etc. etc.
add full roller rockers, the msd 6al, balancing, windage tray, port matching from the intake to the heads, knocking down the center web (or whatever the term is) on the intake (made it look more like a rpm airgap instead of a rpm where it divides the two sides) im guessing 425 is a reasonable number. i certainly dont want to toot the "my chevy 350 makes 10 kajillion hp" horn, but i believe its pretty accurate. keep in mind this isnt a pump gas motor either.... .440 dome popups and it pings on anything less than 100 av gas blended with 93 pump..... but it would rather drink the 110 sonoco / 93 blend i usually feed it.

at one of the shops i worked at we used the OLD desktop dyno which was like dos based anceint software for some race motor cam selections and even with the crap software it was very good at telling weather a perticular cam would be better or worse - believe me we played with umpteen different SBC combinations. i used the new dyno 2000 software for my stuff. its actually a really handy program and is pretty cheap to get.

on a side note: i also have prosis software for engine specs which you can only get by owning a machine shop and being a aera member (big money for that program) it lists everything from installed valve stem heights to bolt torque specs, engine TSB's, casting number id's for all components and so much more - VERY handy little program.

anyways, what do YOU GUYS think? i;d honestly like to know if im a wishfull thinker or did i just build a nasty 302?

 

My guess is that either the cam is so lumpy you have no vacuum to run power brakes and it is not streetable, or you forgot to mention your blower to push air through those tiny W ports. I don't see 425hp through those heads with that small a displacement at reasonable rpms. I am very familiar with DD and have seen high output numbers based on optimistic input. Maybe with 12:1 cr, a .650 lift and 7500 rpm, but you would need 300 cfm heads to make use of it. I don't think 25 hp comes out of the items you have that are not accounted for in DD, maybe 5-10? And those items are just smart things to do anyway. What is your altitude where you live?
Quarter mile times and real dyno numbers would support any high hp claim out there.

 

Heyuwti,
Love the Shelby, isthat a factory color? On the trannys, have 2 fmxs, don't lik'em. C4 probly the best.