My motor (1980 302 emissions motor - factory spec'ed at 130hp in 1980) has finally thrown in the towel. I have so much blow-by that the breather is actually leaking enough oil down over the valve covers and onto the exhaust manifold that noticeable amounts of smoke start to billow out of the engine bay at idle.

I would like to turn the truck into more of a daily driver than it has been, especially if I am going to start dumping money into it. The engine options that I am considering are as follows:

1 - Rebuild current 302 with an Edelbrock top end kit, cylinder hone and re-ring bottom end.

2 - Rebuild 95 351 roller sitting in my garage with Edelbrock top-end, cylinder hone and re-ring bottom end

3 - Ford Racing M-6007-X302 Crate - 340 horsepower @ 5500 RPM & 350 lb.ft. torque @ 4200 RPM*

4 - ATK HP-11 351W Crate - 385 HP & 377 TQ*

*Im sure both of these motors are rated under "best case" circumstances and expect 10% less at the crank and another 15-20% at the wheels

Both of the crate motors are priced at $3,800 from Summit, and while at first I thought a rebuild would be cheaper, they even out pretty fast if I need to have any machine work done.

The simplicity and limited "what-ifs" of a crate motor are making me lean pretty hard in that direction.

That said, what Im struggling with is how much is too much. The highest HP vehicle Ive ever (sadly) driven is my wife's Grand Cherokee (rated at 235), so I have no idea how 340 or 385 will feel in the truck, and how either will be for fuel economy.

How much hp can a F150 take and still be reasonably street-drivable? Is there going to be a noticeable difference in mpg between them, or can the extra torque of the 351 take lower ring & pinion to even things out? Am I crazy to think I can get 15 mpg's out of either if put through an NP435 with the proper rear end gearing?

 

Option 2 would be my vote because you know what you got and can build it the way you want. These crate motors are built targeting use in a relatively lightweight car so the cams selected sacrifice low rpm torque for more impressive topend horsepower, and as a result they won't deliver the best fuel milage in a truck. If instead you focus on building maximum low rpm torque the motor will still make more HP that you have experienced and it'll deliver significantly better milage when geared correctly.

 

I called ATK this afternoon and got a real live person the first try. He didnt have the complete specs on the motor right there, but said he would send me a full component list to look over. In the mean time he pointed me to a PDF on their site that outlined the basics - http://high-performance-engines.com/pdf/HP11.pdf

It looks like this motor might actually be a truck build. The dyno sheet they show has TQ over 350 by 2,500, and Summit's write up confirms that it comes with a "truck" style rear sump pan, and while the cam specs are not 100% consistent it looks to get .498 or .512 of lift on both the intake and exhaust with .50" duration in the range of 220* on both as well. Lobe separation is not listed.

He also said that in the event I wanted to change anything from the standard build, the up-charge would limited to the difference in price from their cost of one part versus another.

Comp Cams now has their own cam reccomend-er (CamQuest) which tells me that the 35-510-8 cam is ideal for what Im looking for, and their desktop dyno is giving me TQ of 378 by 2,000 RPM peaking at 465 @ 4,000 RPM with peak hp of 440@5500 (very top of usable range). Those numbers seem insanely optimistic, but even 80% of that is good enough for me.

 

Option 4 and the truck can handle the power and it should get at least 15 mpg the only problem would be keepin the seg off your face when you drive it because youll have too much fun

 

I like ATK's 24 month/unlimited mileage warranty, and they do have a decent reputation.

For a daily driver, go smaller on the cam, rather than larger, always. I didn't see if you have an auto or a stick, which will play into the equation, as well - for sure go easy on the cam with an auto. A stick gives you some more leeway. The Comp number you mentioned, which is actually designed for a 302, would give a ton of torque at low RPM's in that 351, and would work great for either stick or auto.

The 770 Holley they're showing in that .pdf might be a tad much - something in the 600 cfm range would probably better suited to your needs.

Back in the dark ages, I had an '83 F150 4x4 351 4-speed shortbed that was built along the same lines as the ATK (except for iron heads I re-worked; not too many aluminum heads available back then ), and I was able to get around 16-18 MPG as long as I kept my foot out of it.

 

if you are capable of doing the engine building yourself i would recommend option 2 that way you can build it the way you want it. a solid 300-350 hp motor will feel great in your truck, it will be night and day compared to your old 302 and dialed in properly there will be no downside. for a rough comparison, my parents have a '90 chevy half ton short bed and my dad replaced the stock 350 with a 383 high torque crate engine rated around 340 hp if i recall correctly and with a properly set up carb it is obviously far stronger than the anemic 350 that came out and gets 30-50% better fuel economy both in town and on the highway as well as better drive ability.

 

Option one isn't even an option. Those blocks are weak as pea soup, the real lightweights among 302 blocks. Thin decks, thin bores, thin everywhere. They're scrap fodder in my opinion. I'm basing all this on it being an E0 casting, if by chance it's a D8VE block, then disregard this, the D8VE's are keepers, especially if it's an A3A suffix. I would go with #2 also. I have a roller 351 sitting on the stand now from a 97 F250. No idea on the miles on it, but the bores still look fresh.

 

That's exactly what I'm talking about, the graph doesn't even start until 3000rpm so this is not a truck motor


Yes now you're talkin.. that's a truck cam and yes those output specs are a bit optimistic but it'll make in the vicinity of 400tq/350hp no problem at all.

 

 

#2 but with TFS Twisted Wedge 185's, matching TFS camshaft and a pair of shorty hedders..

 

Tore down the engine as far as I could with it sitting in the cradle. Bores look good, cross-hatching is still very evident so Im much more confident I can do a hone and re-ring.

Few questions that I have thought of -

1 - With the stock pistons and deck height what sort of static compression ratios can I expect with 58 and 60 cc chambers in the heads? Is one more ideal than the other?

2 - What is the ideal intake runner? I was thinking 170 to keep the velocity up, but also saw 185 mentioned above.

3 - The stock pistons have a decent dish to them. What is the chance I will have any valve clearance issues with the Twisted Wedge 2.020 intake valves?

4 - The instructions for the TW heads say I need "longer than stock hardened pushrods" and suggest 8.050" for a roller cam. Where can I find these?

5 - Ive lapped the barrels and bolts on my long-range (1,000m) rifles, and I know you can lap valve seats, what about lapping the mains and the connecting rods on the crank? Aside from an align bore, what other ways can I reduce some internal friction myself?

 

Follow-up question -

I see plenty of rebuild kits for the 351 up through 1993 years on Summit Racing. Why is there nothing for 94-96?

 

94-97 (97 was the last year for the 351) may have had a slightly different piston (I think). Plus the hyd roller cam and block. That combined with the fact that few people who are responsible for parts listings understand Fords (or any other brands too) is likely why the 94-97's aren't listed. Summit is famous for not understanding Fords, they're all Chevy people. Roller 351 pushrods are 7.5" long. 8.05" are flat tappet p'rods. The stock heads (E7's) have a 64 cc chamber, so replacing them with 58-60's will give you a half point bump in the ratio, I think the stock ratio is 9 to 1, making the switch will yeild 9.5. Flat tops will give it about 10.5 to 1.

 

9.5:1 is about where I was hoping to end up. From what Ive read so far I should still be able to burn 87 octane.

As far as the pushrods, those are the Trick Flow specs. For the TW heads they recommend 8.050" for hyd rollers and 8.600" for flat tappet cams.

 

OK, if you believe that. Seems strange that TW heads would use pushrods a half inch longer than the stock ones.