I'm at a decision point. I can assemble & put my freshly machined 351W (from a 69 Mustang) into my 75 Bronco in place of its old 302. Or I can spend a few $ and stroke it. Seems like 393, 408, 418 & 427 are the popular choices. I know the reasons for going all the way to 427 but would it be a mistake somehow? The kit prices don't differ that much. I'll be using the original iron heads with a Carter 625 cfm & Edelbrock Performer RPM. My use will be street & occasional off road. I don't expect to rev past 5,000. I just want lots of torque. Why would someone choose a 393 if the larger sizes are nearly the same price?

 

stay the way you are unless you upgrade the heads. stroking the motor and leaving stock heads is pointless and a waste. also a 625 carb would be to small for a motor like that.

 

Hmm - I failed to mention that I have the 69 heads with 1.84 intakes & 1.54 exhausts. I know thats not big but I've heard the later heads are smaller. I do have a 750 Holley but I'm saving that for my 428CJ. What is a good but inexpensive head for a stroker? Also, original question still stands - if cost is not a significant factor - 393, 408, 418 or 427?

 

If your not going to rev it over 5000 Rpm then tricky heads would be irrelevent. You will be adding Torque because you are adding stroke. That means your 75 Bronco is going to accelerate into traffic very well, and much better than a non stroker. I'd stroke it for all it's worth.

IMHO of course.

Ken

 

i would go 408 max for your application. and heads will make a difference regardless of rpm range. there is a guy on here with a 393 running gt40Y heads and his dyno numbers are pour. when stroking the motor needs to breath well period .

 

I believe the 392 is the largest you can go without clearancing the block. Really, it depends on some other variables, sometimes the 383 is as big as you can go.

If you've already machined and cleaned the block then you'll have the added expense.
Joe

 

Damnit, I'm that guy!

The more cubes, the more air that needs to go through it. You'll make the torque either way, but the horsepower will be low. Do you want a 400+ci motor with 300 hp? lol

 

sorry about that justin, i had a brain fart on what your forum name was and giving your first name wouldnt help here.

also figured it might rub ya wrong if i posted it.

 

Aw hell, I ain't that soft

My motor stinks but it'll be good eventually

 

eehh....a few keystrokes and a chip would probably wake that thing up a bit. Too bad ya don't live near me.

 

It's SCT tuned if that's what you meant...my problems are further then just tuning...wrong headgasket, wrong intake, small lift cam, small heads.

.030 or .040 gasket, TFS-R intake, 600+ lift cam, AFR185s would fix-r' right up.

 

Now I understand. I thought you mentioed going with Edle intakes and heads at one time (not the GT-40 heads though). But a 600+ lift on a heavy-azz truck?

 

I don't have my lift figures off the top of my head right now, but something around 520-530ish, many say to me it's not enough. The actual figures of my current cam are 480/501 I think, add to that the 1.7 rockers. I havn't spent any time figuring out what cam would be right for me because I havn't finalized my setup yet. I'm guessing near 600 instead of under 550. Not like 650+ or anything...

Whatever I run will be aimed at keeping the powerband acceptable for a truck, mine weighs in at 5400+ lbs. But it's not going to be a total low RPM torque monster. I want it to have good low end but still kick butt.

I do have an edy intake, but ford heads. The edy intake is killin' my power quite a bit.

I'm only making 220rwhp/330rwtq...believed to be because of simple mismatching of parts. The heads are good for over 300rwhp, and trick flow said I could see anywhere from 30-70+hp after switching intakes, so that makes sense. Also, since I don't have the right head gasket on it, my quench area isn't right, and possibly hurting power and seemingly causing it to run a little funny.

I think I'm going to end up pulling the 393 out, putting a 351 I have in it til I get the 393 the way I want it. I can't do it with the 393 in the truck all at once.

I'm going back on the dyno for the 3rd time wed morning.


- back to thread -

When building a larger displacement motor, it's crutial to make sure you're still getting enough air through it. There are a bunch of different head combinations, cast or aluminum. Most aluminums are $1100+...

The key is matching components, having heads that flow the right amount so that it sets the general power range, a matching intake, and a cam to finalize the deal. First step is deciding what displacement. All of them have the same bore, just longer strokes. The rod ratio is important if longevity is big concern for you, so pick accordingly if that's the case. Otherwise, pick a displacement that works well with the other parts you can afford to purchase. Each CI increment basically just adds a little more torque. You'll see over 500tq with a 427...make sure the rest of the vehicle can handle that or can be made to handle that within your budget.

 

Appreciate all the input. At this point, I'm thinking World Products Windsor JR or SR heads would be a good idea (maybe even better that stroking). I had a chance to compare my "good" factory heads to some World Products SR Torquers for a Chevy I'm building and I was really surprised at how small the Ford exhaust ports are. The intake runners compared somewhat to the Chevy heads but overall the heads look weak. On a stroker, they would be even weaker. Yeah the low end torque would be good but it would be like kicking a turd (kinda like a stock 82 Corvette - nuther story). Anyone have anything bad to say about the World Prod. heads? I found a complete new set of SR's for $820.

It now looks like heads and maybe a stroker. Any early Bronco folks out there who did this? I don't want to go breaking transfer cases & CV joints but I need to keep up with bling-bling Escalades & Durangos <g>.</g>

 

Find out their head flow data and compair it to other heads, pick the head that will set the general powerband you want from the motor. Then pick an intake that follows the same characteristics as the head, and then pick a cam to seal the deal.