351W Questions

Kurt2002 · Oct 30, 2005

ok I have a non-roller 351W motor that came out of a 1991 F150. I'm going to rebuild it but have a few questions.

1) is it worth having the block machined for roller cam & lifters since it is not a roller block?

2) How much can I bore the block out before it becomes to dangerous? I have heard of .060 over being the limit.

3) While the machine shop has the block is there anything I should have done to the block?

Thanks
Kurt

giddyup306 · Oct 30, 2005

Kurt2002 said:
ok I have a non-roller 351W motor that came out of a 1991 F150. I'm going to rebuild it but have a few questions.

1) is it worth having the block machined for roller cam & lifters since it is not a roller block?

2) How much can I bore the block out before it becomes to dangerous? I have heard of .060 over being the limit.

3) While the machine shop has the block is there anything I should have done to the block?

Thanks
Kurt

Ummm you don't have to have a block "machined" to become a roller block. Just run vertical locking lifters.

Bore as little as you can and still retain a square bore. I've only seen .060" on mariene motors. .040" is the absolute max I would. Closer to .030" or less is my liking. You can make power in much better ways....

A COMPETENT machinest will look at all... But if you have to ask look at your main bores... Deck straightnes etc........

vristang · Oct 30, 2005

As mentioned above there is no machining needed to convert to roller lifters. The aftermarket does supply lifters that are linked, but the stock 302 lifters/dogbones/spider can be converted to a non roller 351w. A good machine shop will be able to do this, or you can do it yourself with a drill/tap and grinder.

Also, a good machine shop will want to have the pistons you plan on using when you drop off the block. This way they know exactly how much honing to do.

Personally, I would look into stroker combos when doing any rebuild. Depends on the budget I guess.

good luck
jason

Mavrick · Oct 31, 2005

There is no machining required to run a roller setup in a non roller block? Can anyone elaborate on this, or give me a link to what is needed?

So in the end, what ALL is needed to take a non roller 351w motor, and make it a roller motor?

65ShelbyClone · Oct 31, 2005

Mavrick said:
So in the end, what ALL is needed to take a non roller 351w motor, and make it a roller motor?

The linked lifters and a small base circle roller cam. Thats all, unless you want to count pushrods.

Mavrick · Oct 31, 2005

Are these special lifters? For some reason, i thought there was machining needed to convert to a roller motor?

Either way, good to hear!

vristang · Oct 31, 2005

In order to use the less espensive stock lifter, you will need to clearance the block to allow the dogbones to sit properly, and drill 2 holes to mount the spider down. The 2 spider holes are directly above the cam bearings so take the time to do this before dropping the block off at the machine shop. None of it is difficult, just time comsuming. I'll see if I can find a pic of the clearancing that I did for this conversion. If I don't get back with them pm me to remind me.

jason

Kurt2002 · Oct 31, 2005

so the cam bearings are the same for a roller cam and non roller cam?
I'm just building a mild 351W motor, compression around 10.5, a good cam, and a carb setup. It is going into a convertible so no racing for it lol.

65ShelbyClone · Oct 31, 2005

Mavrick said:
Are these special lifters? For some reason, i thought there was machining needed to convert to a roller motor?

Either way, good to hear!

You bet they are. They cost alot more than factory roller lifters(usually ~$400) and the cam is expensive too, but its a drop-in affair unlike using factory parts as vristang outlined.

Kurt-cam bearings are all the same for all Windsor smallblocks(260, 289, 302, 351W).

tjm73 · Oct 31, 2005

For the cost involved I'd just run a custom ground for your application flat tappet cam. It'll still make great power.

FORCED2DV8 · Oct 31, 2005

Or just buy a rolloer 351 block, I just saw one for sale ebay or somewhere for 400 buck, the whole short block. Otherwise I would just stay with the solid lifter cam

bluevenom867 · Oct 31, 2005

Actualy,from test I have seen,unless the cam is fairly large and for higher rpm's a flat tappet cam will make more power than a roller.

Kurt2002 · Oct 31, 2005

will solid lifters be to much for a street car? Even with solid lifter I still could use roller rockers correct?

That will save me some cash in machining and buying $400 roller lifters lol

What pistons should I go with using the stock rods?

Kurt

65ShelbyClone · Oct 31, 2005

bluevenom867 said:
Actualy,from test I have seen,unless the cam is fairly large and for higher rpm's a flat tappet cam will make more power than a roller.

Quite the contrary. Rollers are able to make more power in just about any situation through less friction and more freedom with lobe profiles. If they were worse for low performance applications, then every 302 and 351W built since about '93 would have had flat cams.

Kurt- a solid cam would not be too much for a street car, but it will require occasional adjustment. Also, using solid flat lifters will not compensate for omitting the roller conversion. If yoo're not going with rollers, then a hydraulic flat cam will be fine and wont need any adjusting. Also, you can use roller rockers with ANY type of cam and lifters. The pistons you should get depend on what you will do with the engine. Forged SpeedPros or TRWs shouldnt cost too much more than hypereutectic and can take alot of abuse.

bluevenom867 · Nov 1, 2005

65ShelbyClone said:
Quite the contrary. Rollers are able to make more power in just about any situation through less friction and more freedom with lobe profiles. If they were worse for low performance applications, then every 302 and 351W built since about '93 would have had flat cams.

Eh,wrong.

They do reduced friction,but not by as much as most would like to think.They are also acceleration limited,there for the flat tappet will open the valve faster and get to peak lift faster,making more power and torque.

I posted an article I found from a magazine (I think it was PHR),that stats exactly what Im saying and has dyno proof.Its a very logical article and I can see there points quite easly.

If you would like,I can post it again.

kn7671 · Nov 1, 2005

OK, why buy all the special equipment for a 351W to turn it into a Hyd Roller when you could make your 302 into a stroker 347, appearing all stock, using the same intake, and same headers.

Seems like a lot of extra work when you can easily drop a 347 from a number of reliable sources for about the same or less money.

vristang · Nov 1, 2005

kn7671 said:
OK, why buy all the special equipment for a 351W to turn it into a Hyd Roller when you could make your 302 into a stroker 347, appearing all stock, using the same intake, and same headers.

Seems like a lot of extra work when you can easily drop a 347 from a number of reliable sources for about the same or less money.

Strokers are great, but at 347 you are maxing out the 302 capability. Not only is this the peak displacement, but if built for higher power levels the 302 block itself can be pushed past its limit, and snap in half. The 351w block (even the later roller blocks) can handle well over 500hp very reliably, while the 302 is pretty much at the limits at 500hp. A conversion to a 351w will cost about the same as a reasonable 347 stroker.

Short answer is that the 351w has more potential.

vristang · Nov 1, 2005

bluevenom867 said:
Eh,wrong.

They do reduced friction,but not by as much as most would like to think.They are also acceleration limited,there for the flat tappet will open the valve faster and get to peak lift faster,making more power and torque.

I posted an article I found from a magazine (I think it was PHR),that stats exactly what Im saying and has dyno proof.Its a very logical article and I can see there points quite easly.

If you would like,I can post it again.

I want to see some of these dyno test results, and see the cam profiles that were used.

If a flat tappet cam did make more power than a roller, I would suspect that cam profiles were not maximized for the roller lifter. For example sticking a roller lifter on a flat tappet cam will not produce very good results.

Kurt2002 · Nov 1, 2005

I'm just trying to weight out the two to see if it would be worth converting to roller or staying hyd lifters.

The convertible mainly for summer cruises and car shows, my 02 GT is for the track lol. I just what a solid running motor with some NA power. Yes I could stroke it but I don't what that kind of power or money in my street car, rather put that money in my track car.

vristang · Nov 1, 2005

Kurt2002 said:
I'm just trying to weight out the two to see if it would be worth converting to roller or staying hyd lifters.

The convertible mainly for summer cruises and car shows, my 02 GT is for the track lol. I just what a solid running motor with some NA power. Yes I could stroke it but I don't what that kind of power or money in my street car, rather put that money in my track car.

Maybe you just worded that wrong, but...
Lifters can be Hyd Roller, Solid Roller, Hyd Flat, or Solid Flat.

For a street car, I personally would go with a hyd roller.

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