Flat tappet vs. Roller 351

[DanM]

What are your thoughts on converting a 351W block to use roller cams? Suppose my goal is roughly 350hp street-driven and at least decently reliable from a 351W. (1) Can that level of performance (350hp) be achieved with a flat tappet setup? (2) If so, will the flat tappet be constantly requiring adjustment, or will it be decently reliable?

Trying to get a feel for whether the added expense of a roller conversion is worth it.

Edit: oh and while I'm at it, I'm told that for moderate power levels (like 350hp), the 2-bolt mains on the 351W block are just fine, no need for a 4-bolt conversion. This true? Thx

[MidOHasp]

I can't answer the first question very well - I can say that you CAN get that power easily w/ flat tappets. As far as adjustment, I don't think it's ever "constant" - but more than the hydro roller...

I can answer the second one. 2 bolt mains are fine for 350HP. They say the 2-bolt mains are good to 550.

If it breaks, don't come looking for me. I have 2 bolt mains and am running fairly significant horsepower. So far, so good.

[DanM]

Thanks...2 bolt mains it is.

So from what I'm able to read, sounds like hydraulic flat tappets are capable of producing 350hp levels pretty easily, and are just as reliable as hydraulic rollers? Thx.

[Tony Radford]

I had a hydraulic flat tappet cam/lifter set up in my previous 351. My builder put a solid flat tappet in my new Windsor stroker. I have my valves adjusted every 2,000-2,500 miles. I like the solid way better. If you're happy with 350 HP, you can get that with most any cam set up.

[DAVID GAGNARD]

Dan;

A number of years ago Ford had a 351-W crate motor rated at 350 hp at the flywheel,they used a camshaft that had approx. .490 lift,do not remember the duration........When I built my engine in 1995,I used their specs,well, most of them anyway.....My enigne uses a 1972 or 1974 (can't remember which) junkyard block I bought for 50 bucks,with the heads (still using the same block/heads/crank),484 lift cam, Crane hydraulic flat tappet,have "set" the valves once in 22,000 miles and they really did not need it,10.4 to 1 compression and some headwork including 1.90/1.60 valves,it has never been dynoed,but looking at my specs and the Ford 350 hp crate motor,I would guess my motor should be at 350 hp.....Been in the car since 1995,about 22,000 miles now,40 or so 1/4 drag stip passes,probably 500 miles of open track running,idles at 800 rpms all day runs 180 degrees of water temp on or off the track,uses NO oil and fires right up every time I hit the key......Stock crank and rods,ARP rod bolts,flat top pistons,would not change a thing,very streetable and very reliable....

I'd say a stock 351-W block is good for 500+ hp any day,when you get towards 600 hp,then I'd be looking at aftermarket crank/rods and forged everything else........

David

[DanM]

Thanks for the replies. I really do not want to have to be adjusting things every 2500 miles, so I think I'd best stick with hydraulic flat tappets. Either that or go hydraulic roller.

I guess then the question is - will a hydro flat tappet setup allow me to use a cam profile agressive enough to hit 350hp?? From what you guys are saying, the answer seems to be yes...?

I have no intention of going anywhere near 600hp with this. 350, maybe 400 is what I want. So if I can do that with hydro flat tappets, and not have to worry about adjustment every 3k, great.

[DAVID GAGNARD]

Dan;

For a motor that you want to get somewhere between 350/400 hp,I do not think the extra expense of a hydraulic roller cam is worth it with so many hydraulic flat tappet cams on the market.....Take the extra money you would have spent on the roller set-up and put into some good cylinder heads/manifold/carb...... Then get a set of poly-locks for your rocker arms and set them as per the cam manufacter's instructions,they should never need re-adjusting....Just set it and forget it.............

Solid cams roller or flat tappet need adjusting and are for mainly higher hp engines..........

David

[DanM]

So from what I'm hearing, I can pretty much just find something from a junkyard, "freshen" the bottom end, and just stick with the stock crank & rods, and that should easily handle my 350-400hp?? I'll want to concentrate mostly on a good set of heads, intake and a good cam??

This thing doesn't have to last 200k miles. It's not like it'd be a daily driver. But I would like it to make it more than 2000 miles before blowing up. Pragmatically speaking, it'll probably never see 30k miles before I get tired and move on to something else...

[DAVID GAGNARD]

Dan;

I went to a local junk yard and bought my engine out of a 72 or 74 Ford LTD.... That was the only 351-W the owner had at the time and he said it would run but had a bad "rattle" in it,for 50 bucks,I figured I had that much in parts I could use even if the block was not useable....

Took it home,took it apart,then to the machine shop.... They bored the block .040 over,turned the crank 10/10,installed ARP rod bolts and resized my rods...... Had a friend port/polish/gasket match the heads,machine shop intalled 1.90/1.60 valves,put an Edelbrock Performer RPM intake and Holley 600 carb,484 lift Crane cam,roller rockers,assembled the motor and been running it ever since....

If I was to do it over,the only thing I'd change is the heads,I would not mess with the old iron heads,but put a good set of aluminum heads on it......For the money I spent on the iron heads (valves/port/polish/screw-in studs/machine work) I could have bought a set of AFR or any other aluminum head new and have a better set of heads and more hp......

My motor with a set of AFR heads should easily be 400 to 425 hp......

The rest of the motor I would leave the same.........

It does not take that much to get 350 hp out of a 351-W and you will be suprised at what 350 hp can and will do.......

David

[DanM]

Thanks a lot for the advice. I found a guy selling a complete 351W (including carb) for 550$ Canadian (400 US). He said it runs fine, from a late 80s Crown Vic. Or he said he'd sell just the bottom end for $350 ($200ish USD). I think I may go that route, or maybe hold out and look for an even cheaper bottom end to start with.

Guess I've got the bottom end plans figured out - now I just need to decide whether I want to go carb or FI. Thanks again for the help.

[Clois Harlan]

Dan,

Just finished reading all the post and I concur with David. I have seen and listened to his engine at two race tracks and he has a very fine running and sounding small block. My first engine in my Cobra was a small block and it Dyno'd at 335 hp at the rear wheels. Easy mods.

I too bought a late model from a salvage yard that was originally an Fuel Injected model. I took off the Plenium and injectors and threw them away. I took my block and heads to the machine shop and had everything checked and it turned out that all I needed to do to the block was to hone out the cylinders and replace the rings, mains, rod bearings and gaskets. Crank was turned .010 and my rods were resized. I had my heads cleaned up (New Crane springs and roller rocker arms (1.7 : 1 ratio)). Cam was a Crane roller I-476, E-496 lift and I-206-E-214 Duration. Edelbrock Performer RPM manifold and Edelbrock 650 cfm carb. MSD Ignition, Distributor and coil.

Good strong engine and would smoke the tires on demand. I understand it is still running strong.



Clois

[DanM]

Originally posted by Clois Harlan


Cam was a Crane roller I-476, E-496 lift and I-206-E-214 Duration.

So you did go with a roller cam?? Was it a roller block from a 94+, or did you do a conversion on it?

[Clois Harlan]

The 302 Engine block used a roller cam in 1986 and up. I used stock type roller lifters and a set of Crane roller rockers (<$200.00) from Ford Racing.

The nickle content is susposedly higher in the 1987 - 1989 Ford blocks and much stronger than the pre-1987 blocks. Also, if you intend to put a T-5 transmission behind your engine use a model year 1985 and up. Again, stronger insides. The 302 or 351 Windsor blocks have enough clearance that you won't need to mess with a hydraulic throw out bearing. Avoid these if you can because as good as some of them are they are all prone to leaks eventually. Go with a good clutch, pressure plate, flywheel, throw-out bearing and replace the pilot shaft bearing that goes in the end of your crank. A nice roller bearing can be had for less than $20.

Clois Harlan

[DAVID GAGNARD]

Dan;

Don't know much about Canadian prices,but down here the prices you quoted are about what you could expect to pay......recently at a local salvage yard and the going rate for a complete running 351-W was $500.00 on up......I would take the short block and rebuild it and put a set of aluminum heads on it and a camshaft in the high 400 lift to very low 500 lift and you should easily have 350 to 400 very streetable/realiable hp.....

From the late 70's on Ford used a "commom" head for the 302 and 351 and they are not that good to start with,they were designed for the 302 and do breath that well especially on a 351.....

About 6 or 8 years ago I drove a very early FFR with a bone stock 302 GT motor (225 hp),the owner had only put a K & N air filter on it and the T-5 had NO first gear,had to start off in secound.....After driving around a little to get used to it we were turning around to head home and the owner told me to "get on it",not wanting to flog someone else's car,I told him I would shift thru the gears at 4500 rpms which I did,was very impressed with the car,probably could outrun 75% of the cars on the road there with a stock 225hp motor.......350 or more hp will get you a really fast car that will probably outrun 95% of the cars on the road.........

I'd scrap the FI stuff,put an Edelbrock dual plane intake and a 600/650 Holley and go.......A carb set-up to me is simpler to install and work on,but I can rebuild a Holley in my sleep,been working on them since high school.....

For a street car,build a street motor,you'll be happier and enjoy driving it more than an overkill/tempermental race motor......

Not to brag,but at a couple of "open track" events I've had other drivers come up to me and ask what I had "under the hood",when I told them,they could not believe it.......In Nashville this past year I passed another 65 Fastback with a 393 stroker putting out around 500hp and in two laps could not even see him in the rear view mirror,hp is not everything,getting it to the ground will make you faster than just smoking the tires.....

David

[DanM]

Clois,

Ah, gotcha, didn't realize you were talking about a 302 block.

David,

I hear ya. I definitely want a streetable motor. At this point I don't really have a desire for 600hp. Just 350-400 in a solid motor that's not tempermental, and will last me a couple years of fun, that's all.

I agree that carb seems simpler. However I have access to most of the necessary computer equipment, so FI is probably 'less hard' for me than for some others (besides, I'm interested in it too, so I'd kind of like to). I guess I'll leave the FI/Carb decision for later. Doesn't need to be made right now while the bottom end is still my primary concern.

I'll contact that guy selling and see if I can take a look at the motor/shortblock. Anything I should be looking for before I buy it? I assume if it was pulled from a running vehicle with 120k miles (as he says), it's probably fine for my purposes....

Now the more pressing matter - where the hell am I gonna put a 300 pound chunk of iron?

Thanks again, you guys have been very helpful!!

[DAVID GAGNARD]

Dan;

When looking at the shortblock about the only thing to really check out since the motor is out of the vehicle is the cylinder bore wear,you do not want to bore it more than .040 and .030 is prefered..... had to bore mine .040 and at the time it was the only block I had,now, I have a couple of spares.........

When taking the motor apart,whether you do it or the present owner,save all the bolts and nuts and any related hardware you can,you will need it later on.......

As far as the 300 pound chunk of iron goes,anywhere but in the house,the misses will not like that!!!!!!!!!!!!!!!!!!!!!!!!!

David