"Long Rod" 351-W tech/info needed

[DAVID GAGNARD]

Here's the story:
My niece's husband has a mid 80's big Bronco, hunting/knock around truck, 351-W in it.I did a "standard" rebuild on it last year, basically rings/bearing. It was tired then and even more so now, had a fair amount of wear in the cylinders, but since he only puts a couple of thousand miles a year on it, he didn't want to spend a bunch of money on it.....

The engine is very "tired" now and he wants "us" to rebuild it. He's read a few articles about buiding a "long rod" 351-W using the 351M/400 rods.....I did some research and found some info, but not all I need.... We have 2 complete 351-W engines to work with and a couple of 351-M engines for parts.

According to what I've found, you use the 351-M/400 rods (they are the same) roughly 6.5 inch rods and what we're looking for is the piston type/number.... The rod journal are the same size, but I don't have the 351-M/400 rods with me yet, to measure the width...

Are the rod width's the same or do I have to do some work on the rod???? The plan is to bore the block .030 over and use the 351-W crank with the long rods and whatever piston is needed, mild camshaft in the 490 to 500 lift range with mild duration for a low rpm/high torque engine which is what he needs in the real heavy Bronco.....

Anyone done this or have any info??????

I see a few places have the "kit" for sale for about a thousand bucks, but he's got a baby on the way and fixin to build a new house and we have the 351-M/400 rods for free, all we'll need to do is bore the block and get the correct pistons, machine work if any is needed will be almost free, trading the machine shop some old blocks for the machine work...

Thanks for any help........

David

[blykins]

For a long term engine, I'd rather have the shorter rod and a taller piston for stability. That piston is going to have a compression height of about 1.250".

The big end widths are the same for a Cleveland/Windsor.

You can get Scat Windsor replacement rods at a very low price.....probably cheaper than having to buy custom pistons.

[Rick Parker]

Are the mains the same in a Windsor and 351m-400?

[blykins]

Yes, main journal diameter is the same.

[Jerry Clayton]

The main sizes are the same and on the rods the crank is the same size but there is .010 difference in the rod big end bore size. Use the correct bearing

[Woodz428]

It is the pin end that needs to be considered. I'm pretty certain that the M/400 have larger diameter pins than the Cleveland/Windsor. If you plan on busing them, that would take care of the diameter variation but the pistons would need be compatible with pin locks.
Rod journal sizes are the same, as are mains but pistons configuration is where you may have problems. Of course these type of problems are easily corrected with $$. It may be cheaper to have the pistons opened to the M/400 pin size and retain pressfit rods.

[DAVID GAGNARD]

Originally Posted by Woodz428

It is the pin end that needs to be considered. I'm pretty certain that the M/400 have larger diameter pins than the Cleveland/Windsor. If you plan on busing them, that would take care of the diameter variation but the pistons would need be compatible with pin locks.
Rod journal sizes are the same, as are mains but pistons configuration is where you may have problems. Of course these type of problems are easily corrected with $$. It may be cheaper to have the pistons opened to the M/400 pin size and retain pressfit rods.

Thanks guys, so far I've found that the rod journal size is the same for the 351-W and the 351M/400, read were you use the same piston as used for a 331 stroker for the pin height, trying to confirm this. KB makes a flat top piston for this application, which one is the question......According to what I've read so far, you use the 351-W crank, just change the rods and pistons........the rod and crank journals are the same size in the 351-W and the 351M/400 engines....351M/400 rods are about 1/2 inch longer and beefier........hence the need for a shorter piston.

This is a super budget rebuild, so far, he'll have to bore the block (has about .020 wear in the cylinders), we have two running 351M's at our disposal, all we have to do is go get them.So the rods are free,main thing is to find out exactly which piston we need and we should be good to go....
Woodz,from what I can gather, there is a flat top piston out there for this combo that is pressed-pin fit, just trying to find out which one...

Reports on other sites were very good on this combo, especially for heavy trucks/4x4's like his, where low rpm, good torque is needed...

Even had a few Mustang drag racers using this combo with very good results....It seems like an easy and inexpensive way to build a stump puller engine, which is what he's looking far, and with a new baby on the way as well as a new house fixin to start up, his budget for this is non-existant.......

Sure wish I could find someone had done this so I could pick his brain for the little details to do......

We're gonna re-use pretty much erveything else, heads/intake etc.,etc., about the only other thing is a new hydraulic cam......

Thanks again;

David

[Bonos]

I had a machine shop do my 408 machine work ,which had 351 m rods and they also machined a notch in the bottom of each cylinder skirt for the rod bolt on each to clear due to the long rod.

bonos

[DAVID GAGNARD]

Originally Posted by Bonos

I had a machine shop do my 408 machine work ,which had 351 m rods and they also machined a notch in the bottom of each cylinder skirt for the rod bolt on each to clear due to the long rod.

bonos

The 351-W bock can only handle a 3.5 inch stroke in "standard/factory" form, anything more, one has to notch the bottom of the cylinders for rod clearance, much the same with a factory 302 block.
Your 408 should have a 4 inch stroke, so notching the cylinders is a must, regardless of what type or brand of connecting rod used....

David

[olddog]

Is the 351M the same deck hieght as the 400M?

I heard the 351M is the same deck as the 351C -- believe little that you hear.

[DAVID GAGNARD]

Originally Posted by olddog

Is the 351M the same deck hieght as the 400M?

I heard the 351M is the same deck as the 351C -- believe little that you hear.

Yes, the 351M acutally uses the same block as the 400, don't know about the 351C........
We have an older parts house here in town that still does things the old fashion way, by looking things up in the books, not on a computer, they let me go behind the counter and look thru the books doing research and they also have "inter-change" books for varouis manufacters.....

I went thru them the other day checking part numbers and such and the only difference in the 351M and 400 is the crankshaft and pistons...all other parts are common to both engines...also, in my research, it was stated that in 1971, Ford could not meet production needs with the 351W engines,so the 351M was built at another plant to fill the need for 351 cu in engines for cars and trucks...shortly afterwards when production met/exceeded demand for the 351 engines, they decided to up it to 400 cu in, easiest way was to stroke the 351M, so they did, all was needed was a 4 inch stroke crankshaft and new pistons, the block was beefed up enough from the begining to accomadate the 4 inch stroke without any modifications, whereas, the 351 W could not handle a 4 inch stroke without modifying the block, so the 400 was born, very inexpensively.....

In july of 1978, four months before I married my wifey, she ordered a new T-Bird and her dad talked her into getting the 400 cu in 2V motor instead of the standard 302, he liked big motors, so she did....

It was a good motor, nothing great, but a good motor, the only thing I found was it seemed "slow" to rev up and get up to speed" when you stood on the gas pedal, but then again, in 1978,it was a heavily smogged engine.....in November of that year we were married and went to Florida on our honeymoon and I remember the car getting 17 mpg on the interstate cruising at 75mph, not bad at the time comparing it to other big heavy cars.....

David

[sllib]

Try "High Performance Small Block Ford Engines" from the Hot Rod Magazine Technical Library. It's a collection of engine build articles, mostly budget builds.
Bill Stradtner

[blykins]

I think a 4" stroke in a 351W block with a regular 6" rod will clear without notching. A 4.100" stroke crank will fit with a 6.200" rod in a stock block without much grinding at all.

I would imagine that the combination of a 4" stroke with a extremely long rod would probably take some work.

[DAVID GAGNARD]

Originally Posted by sllib

Try "High Performance Small Block Ford Engines" from the Hot Rod Magazine Technical Library. It's a collection of engine build articles, mostly budget builds.
Bill Stradtner

One of the few places I have not looked at yet, will do so, thanks.

How much notching will be determined more by the shape/size of the big end profile---a rod for a Chev or Honda size crank pin will be much smaller profile than the stock ford size

From what I've read so far, no notching required on this set-up, not that it's a problem.....On my 331 stroker race motor (factory 302 block) with Eagle H-beam rods, it took a good notch on the bottom of each cylinder to give adequate clearance, probably spent 30 minutes on the whole job..

David

[speed220mph]

I just took delivery of my newly published book How to Build SB Ford Racing Engines where I discuss among many things rod length-to-stroke ratio. This ratio is best for racing engines at no less than 1.7:1.

[CobraEd]

The rod length subject is not a strong area for me, BUT, . . . I always underdstood that a SHORT rod produced a greater rod angle relative to the crank and produced way more torque due to the leverage. It is called "Mechanical Advantage" This is why the 347 stroker can easily produce 400 ftlbs of torque for such a small engine but should not be reved to high due to the associated piston speed. Therefore, . . . shorter rod length = more rod angle = more torque !!!! ????

This is 180 degrees off from what he wants to do. Am I missing something
.

[DAVID GAGNARD]

Originally Posted by CobraEd

The rod length subject is not a strong area for me, BUT, . . . I always underdstood that a SHORT rod produced a greater rod angle relative to the crank and produced way more torque due to the leverage. It is called "Mechanical Advantage" This is why the 347 stroker can easily produce 400 ftlbs of torque for such a small engine but should not be reved to high due to the associated piston speed. Therefore, . . . shorter rod length = more rod angle = more torque !!!! ????

This is 180 degrees off from what he wants to do. Am I missing something
.

I dunno, seems we are seeing/reading totally different things as what I've seen/read so far, points to just the opposite that you have stated....

the 347 stroker uses a 5.4 in long rod with a 3.4 in. long stroke giving a rod/ratio of 1.59......these motors are notorouis for side loading and wearing the sides of the cylinder bore....because of the extreme rod angle, as the piston is coming up in the bore, the rod is trying to force the piston out of the side of the block, causing faster than normal wear, generating more friction and heat,never heard/seen/read any hard data that this will make more torque,have you??? I'm familiar with the term "Mechanical Advantage", but you can also get to a point with it where you start losing advantage instead of gaining........"Diminishing Return" I think is what it is called......

for comparison, the folowing rod/ratios

331 stroker------1.66
347 stroker------1.59
351-W-----------1.71
351-W long rod--1.88
400--------------1.65

I just took delivery of my newly published book How to Build SB Ford Racing Engines where I discuss among many things rod length-to-stroke ratio. This ratio is best for racing engines at no less than 1.7:1.

and best I can figure for big blocks;

427----------1.72
460----------1.72

I'd love to see/read any published data you have come across about the short rod/extreme rod angle/more torque theory.....
I do enjoy the research almost as much as building and running engines...

David

[Jerry Clayton]

How much notching will be determined more by the shape/size of the big end profile---a rod for a Chev or Honda size crank pin will be much smaller profile than the stock ford size

[vector1]

are the rods 6.5 or 6.58?

[DAVID GAGNARD]

Originally Posted by vector1

are the rods 6.5 or 6.58?

351M/400 rod length is 6.58

351C rod length is 5.78

David