I have a 1986 351 HO motor that I am going to refresh and drop into a 1983 Bronco. I would like to keep the truck as a daily driver and didn't want to go crazy on re-inventing the wheel as far as the power plant goes. Does anyone have experience with the power these engines are making with a simple addition of headers and smog free carb setup?

Also, if I wanted to break in the 300's with HP and torque where should I begin? Cam timing?

Thanks for any advice you can lend....

 

I could have sworn I answered this question a couple days ago.. did you post the same question anywhere else?

In case I'm losing it.. here it is again.

This motor needs more compression and better airflow to break 300hp so swap on a set of GT40 heads and you'll bet both at the same time, then add longtube headers and you'll get anywhere from 374-400 torque.

 

You are starting with 210/305 hp/tq. This is the result of a 4bbl carb and a decent cam on top of the 139/278 standard offering. So the "easy" part was already done. I think you are going to need pistons to gain some compression, and maybe a different cam on top of the headers to get to 300 hp.

Try the headers and a decent large single or dual exhaust to start. Watch your de-smog effort as you may have to fiddle with ignition curves and timing if you dump EGR. Leave your evap set up. Toss the air injection. No real power to be gained there, it just makes things simpler.

Make sure you are not going to be getting law changes requireing inspections before you jump.

(on edit: while I dither looking for cylinder head info and 351w HO vs. GT40 comparo's, Conanski comes in and whacks it)

 

Thanks guys. I swear it wasn't me who posted that question already and if I did, it was a while back and I don't remember.

Initially I was scared to shop for GT40 heads and get too involved with a custom motor for fear of dumping a ton of money into it and having one part of the recipe wrong and wasting both time and money. I kind of wish there was a go to guide.... you have this block and heads, add this intake and exhaust and you'll generate this power....

All that being said, a pair of GT40 heads popped up locally on CL today so I think I'm going to look into picking them up and going in that direction. I guess the next question would be to swap the cam or keep the "RV" cam that's in the block.

The next question after that is what to do about a tongue converter.....

 

Stock HO cam is pretty good, it came from the marine division. There are bigger more radical cams of course but don't bother unless you get both the heads and a full exhaust system on it.


Nothing.. unless you can retrofit one that has a locking clutch in it, the last thing you want is one that slips more. You think your fuel milage sucks now...

 

Question, I started out with a '78 351W engine, I bored engine block out .60 over, running Kieth Black Dome top racing pistons with moly custom cut rings cut to fit & work with nitrous, std. crank & rods other than ARP rod bolts installed, crankshaft scrapper & windage tray, dual sump oil pan, Melling High Volume oil pump, all brand name bearings that everything has been checked for tolerances/clearances, Rattler Harmonic balancer, block has been decked, original heads which was originally (if I recall correctly was 74-76cc) but heads have been cut/shaved a little.

Running a Lunati Hyd. 292 duration .512 lift cam, Crane 1.6 roller rockers, Pete Jackson gear to gear timing, running rebuilder valves in it which is just a size bigger than stock, 3 angle valve job on heads, All ARP bolts throughout engine, Edelbrock torker II intake with torque plus gaskets, Holley 750 1 to 1 Racing Carb., Holley High volume & pressure electric fuel pump, Total MSD ignition, 6AL box, Pro-billet distributor with 8.8mm wires, shorty headers off a mustang, along with custom built & set up power under-drive pulleys w/serpentine belt.

I have a C-4 w/3000 stall B&M converter with adjustable modulator and reverse valve body, B&M Pro Ratchet Shifter. I was planning on hooking up a 2 stage nitrous system with about a 250HP shot, launch with 100HP and have the final kick in when shift into 3rd. What's y'alls opinion on this set-up? Good or bad, what ya think? Now, I do have a set of 289 HIPO heads that are 62CC but I'm already around 12-13 to 1 compression ratio, if I'm not wrong with this set up so you can imagine what it would jump to with them HIPO heads. But, I'm open for suggestions? I haven't ran this thing yet other than just cranking it to do break-in and I'll crank it to keep it fresh.

I like the old school way with cast iron heads but yes, I know the restrictions they have from the factory and yes, I'm aware of gasket matching & porting them to flow better.
But still, what do y'all think about this set up? Good or bad, I can take it.

 

You won't break 300hp with stock heads on that motor, they don't flow enough to make power past 4000rpm on this displacement and you got a 3k stall so you'll have a wopping 1000rpm powerband before it runs into a wall. You need some serious heads like AFR185 or better to make power up where that cam works, what you have now is a totally mismatched disaster. This is why everywhere on this site you will see people advising not to put a red cent into any stock small block head, they only flow half what is needed just to make 1hp per cubic inch naturally aspirated and I'd guess you'd like to make quite a bit more than that.

 

My two cents, forget about those, and save for aluminum.


Make sure your compression is at least in the 9.5:1 range.


Any major cam company will offer you a cam recommendation.


Weiand dual plane gets my vote.


Run a carb you feel comfortable with.


Duraspark II distributor, gm module, and tfi coil, really does perform better than the stock duraspark module/coil. Its my opinion, search for the how to, if interested.

 

Conanski, Thanks for the insight. I'm trying to avoid dumping a ton of money into something that I won't take advantage of so I think I'll invest in the GT40 heads and keep the cam as stock and see what kind of numbers I get. In the end I don't think I can go wrong with along the stock configuration to breath a lot better with heads, intake and exhaust.