I have an 85 F150 with a 351W in it. I am going to need to rebuild the motor probably because I had it rebuilt by a friends dad who used to do it for a living. Problem is instead of putting new pistons in it when he redid it (only needed to be honed and not bored) he reused the old ones. Drove it around for a year and then when I was on my way to college (800 miles away give or take) the truck died on me. Started blowing smoke like it was a fog machine. Had to trailer it back home. The truck idles great but it smokes like a fog machine. Not really sure what excately is wrong with it because I didnt have the time/money to get into it over the summer but what I want to do next summer is redo the truck with GT-40P heads that I found on an explorer in the junkyard. I want to use this truck primarily for pulling pretty heavy loads. I plan on changing out the springs in the back to one ton springs and changing trans to the ZF transmission. Whats the best way to go about redoin the motor? How much do you think I should bore it? Will the cam that I have in it right now work? Less than a year on it. What kind of rebuild kit should I get? I appreciate all your help.

 

i would be pissed, who rebuilds a motor and reuses the old pistons. If you are building the motor for pulling i would get the bottem end rebuilt or even punched out to a 393 or 408. Get some GT40 heads not the P version and run about 9-1compression. it wont have much past 4000rpms but that should be fine. Even doing a basic rebuild with some later E7heads would be better in my oppinion. the gt40p heads take special headers and the plug angle sucks.

 

an old 'trick' used on the solid engines like olds, amc and pontiac where the blocks were so hard, after 100K there was like .006 or less taper - just knurl the slugs and away you go.

The headers to clear the angled plugs on the P-heads aint that expensive - only marginally more so - and these are FMS prices.

only $270 from here

and the 409 stainless, while not as pretty as nickel or polished, wont rust away (my last set of JBA headers - who makes headers for FMS - were polished and eventually rusted at the collector - since I always tow I produced more heat over the lifetime that what the headers are designed for)

 

those headers are for a car and fit like crap in a truck. custom exhaust work would be required to get the pipes run. and the fms headers arnt all that great.

 

what car were they used in?

 

Yeah I know that they require a different set of manifolds/headers but I got the heads for $10 so I am not going to throw them out and go with a different set. Believe me I was not happy at all about him reusing the old pistons. I plan on rebuilding the entire thing because its a really special truck to me and I plan on keeping it basically forever.

 

Bore it as little as necessary to clean up the bores. The machine shop can tell you what that is. Then get a stroker kit with that size pistons. You coulde probably re-use the cam if you keep the lifters in the order they were removed in, but I seriously doubt it would match up well to the motor you will be building even if you don't stroke it and just use the new heads. If you just want a master rebuild kit you can get one from Northern Auto Parts online.

 

Instead of rebuilding those gt40p heads that will choke your motor, look at this company from alabama called Patriot. You can get aluminum bare heads for 500 bucks and put your own valvetrain in them or you can buy them complete for 800 bucks. I personally got mine bare cause i heard the hardware they put in them are junk. The heads are 185cc runners with 2.02in and 1.60ex. Perfect for a streeable windsor

 

Yeah thats way more money than what I have to put into the heads. And everyone I have talked to have told me that the GT-40P heads are quite a bit better than the stock ones that I have. After all I am a poor college kid.

 

Everyone wants to spend your money, don't they? I'm going to list a build tommorow with those heads that might change some minds.

 

Buy a budget rebuild kit, slap on those gt40p's, and put a mild comp cam in it and have fun

 

oooh i want to see

 

It's easy to engage your mouth, (or fingers) without really thinking about what you are saying, and I'm as guilty of this as anyone. What I mean is, we tend to spout off advice based on what we would like to build sometimes, instead of really looking at what the wants and needs of the poster REALLY is. I still think stroking is a great way to get more power for cheap, but it is not the cheapest thing for some builds. Now, let's start with what you have: the '85 351W sported 8.2:1 CR made somewhere around 240HP and 310lbs. of torque. We may get some disagreement on the exact figures, but this is going to be close to what anyone says. Now for the promised build: Standard JY block, stock crank turned .010 under, stock rods reconditioned w/ARP bolts, Federal Mogul forged .030 oversized flattops, (10:1 CR), Melling HV oil pump, Comp Cams Extreme Energy 282 hydraulic flat tappet cam, hydraulic flat tappet lifters, Comp Cams roller rockers,MSD ignition, an Edelbrock RPM manifold w/ a Demon 750 CFM carb, 1 5/8" long tube headers, and finally- Ford Explorer GT-40P heads w/ 1.94/1.62 valves unported- "straight out of the box". This motor made 398.9 HP @ 6000 rpm and 393.6 ft/lbs of torque @ 4500 rpm. It made 352.5 ft./lbs of torque @ 3000 rpm, and made "brute torque right off idle" So what does this mean? It means you can build a motor with "brute torque right off idle" for "primarily pulling heavy loads". Bigger better flowing heads just move the powerband up higher in the rpm range at the expense of low end power and torque. In other words, those high dollar aluminum heads are a worse choice for what you want out of a motor. To make bigger heads work, you need bigger induction, which again is out of the ideal power band for a heavy load pulling motor. If you can afford to build the motor exactly as listed, that would be a great motor for you IMO. But even it is way more motor than you really need- somewhere around 2/3 more of what you have now! So here's a few things you can do to reduce the cost and still have a pretty good motor: Cast flattop pistons, stock rods, stock rocker arms, a used Edelbrock Performer manifold or a Proffesional Products 54023 Power Plus Typhoon (@$150 new), a 650 CFM carb and a Summit K440 cam and lifter kit. Stock ignition. As far as the plug problem goes- there has to be a bunch of stock manifolds off these trucks laying around..... Will you have the numbers like the above motor? NO. You'll lose some #'s with each step down, but at the end of the day, even a motor like I just outlined is probably more than capable of pulling heavy loads comfortably.

 

Gearing is also a big help when towing. looks to be a great build Doug, what headers do you plan on running? and just so you know i think 10-1 is to much compression for an iron head build like this. you will have detonation issues even running premium fuel. if you bring that down you will better utilize the power of the motor and not have to retard the timing to compensate.

 

I'm not building this motor, it's a suggestion for the OP. I thought about the CR, apparently it's not an issue in the textbook build, but stepping down on the cam like I suggested could very well cause issues. How to get a higher CR without spending a lot of money is the question though. I suppose if he went with the stock dished pistons and milled the heads a bit and/or decked the block and went to .030 on the pistons, he would have a CR in line with the second build. I must confess ignorance on the cc of the GT-40P heads, (are they smaller than the '85 heads?) If so, then he definately wouldn't need flattops.