"Long Rod" 351-W tech/info needed

[lovehamr]

David, it could turn out to be a very cool motor. What cam are ya'll planning on?

Steve

[DAVID GAGNARD]

Originally Posted by lovehamr

David, it could turn out to be a very cool motor. What cam are ya'll planning on?

Steve

Right now it's got an old grind from Crane in it,hydraulic flat tappet, 484 lift, 272 duration, advertised as a 4x4/towing camshaft, very good bottom end torque, good from 1500 to 5000 rpms.

I'd like to see him go up to a cam in the low 500 lift, with no more than around 280 duration, but for now, plans are to re-use the same cam unless some $$$ gets freed up for another cam....

David

[vector1]

david

i have a comp cams xe284h cam and hydraulic flat tappet lifter setup brand new in the box i can put to your door for $125. came with some other parts i bought and i don't foresee a need for it until after i sell it.

[jdean]

Yeah Mark, if you are like me, the odds of you needing it go way down if you keep it.

[DAVID GAGNARD]

Originally Posted by vector1

david

i have a comp cams xe284h cam and hydraulic flat tappet lifter setup brand new in the box i can put to your door for $125. came with some other parts i bought and i don't foresee a need for it until after i sell it.

Is it part # 31-250-4???????? if not, what is the parts number????

I like the lift on this cam, but duration is a little long for his needs, doesn't need a "lopy",rough idling cam,needs one with about 15" of vacum for power brakes,etc...the one in there now pulls 17" of vacum at 850 rpm, idles great and has real good off-idle acceleration....but, I'll mention it to him and see what he says, price is great........

David

[vector1]

Originally Posted by DAVID GAGNARD

Is it part # 31-250-4???????? if not, what is the parts number????

I like the lift on this cam, but duration is a little long for his needs, doesn't need a "lopy",rough idling cam,needs one with about 15" of vacum for power brakes,etc...the one in there now pulls 17" of vacum at 850 rpm, idles great and has real good off-idle acceleration....but, I'll mention it to him and see what he says, price is great........

David

that's the part number. i have a solid roller cam a little wilder then that and it pulls pretty good vacuum with a dual plane intake. with a single plane it pulled a little less then 8" at 1200rpm, with the dual plane it would be almost double.

[DAVID GAGNARD]

Originally Posted by vector1

that's the part number. i have a solid roller cam a little wilder then that and it pulls pretty good vacuum with a dual plane intake. with a single plane it pulled a little less then 8" at 1200rpm, with the dual plane it would be almost double.

He's running an aluminum dual plane manifold right now, so your cam may work, vacum wise.........

David

[Jac Mac]

6.58 rod is wider at big end & must be narrowed to fit 351w crank, tunnel dia is same & clevo 351 brgs fit straight in. Rod bolts for 6.58 rod are approx 0.200" longer than 351c.
Built a couple of 400 cu in strokers in 351w blocks using these rods & 400m crank plus a 0.900" pin height pistons & reduced base circle cams---- lot of work.

351w crank with 6.58 rod & 1.165 pin height piston from 331 stroker would be a nice unit... piston pin bushes from 272/292/312 'Y' block press straight into 6.58 rod small end & suit std 351 wrist pin.

[Woodz428]

David have you checked Speed-o-motive? I know they offer a long rod kit and you may be able to get which piston is used from there. They typically list what components are being used. I have on of their catalogs somewhere and now that the weekend is here I'll try an locate it.

[DAVID GAGNARD]

Originally Posted by Jac Mac

6.58 rod is wider at big end & must be narrowed to fit 351w crank, tunnel dia is same & clevo 351 brgs fit straight in. Rod bolts for 6.58 rod are approx 0.200" longer than 351c.
Built a couple of 400 cu in strokers in 351w blocks using these rods & 400m crank plus a 0.900" pin height pistons & reduced base circle cams---- lot of work.

351w crank with 6.58 rod & 1.165 pin height piston from 331 stroker would be a nice unit... piston pin bushes from 272/292/312 'Y' block press straight into 6.58 rod small end & suit std 351 wrist pin.

Thanks for the info. I have a 69, 351-W torn down in the shop and the 351M egines should be here in a week or two, once I get one apart, I can get the big widths of the rods and get to work on the 351M rods and get them to size, machine work is basically free if I do it, have access to a shop on weekends for my personal use...
"Back when", using the 400 crank in the 351-W block was the only game in town for strokers and a lot of machine work to the crank was needed, now with all the after market stuff, the 351M/400 engines are pretty much worthless to the average Joe.

David have you checked Speed-o-motive? I know they offer a long rod kit and you may be able to get which piston is used from there. They typically list what components are being used. I have on of their catalogs somewhere and now that the weekend is here I'll try an locate it.

I checked on their kit on-line, they don't give the "specs" or piston part number, just the rotating assy. If you have a catalog with the piston type/part number, that would be a great help, that's the only thing "missing" right now, I'd be forever grateful and in your debt....

David

[concobra]

Hello David

Thank you for responding to my inquiry regarding the motivation for using the longer rod.

Allow me to respectfully submit the followng observations and paraphrased comments.

1. There are no rules in engine building that hold true for every engine that is built. In other words as it pertains to this verbal exchange a longer rod does not always equate to more torque. The old thinking that a long rod helps an engine produce more torque has been challanged by some of the best engine builders and designers over the last twenty years. To support this statement, Reyer and Morrison tested serveral different rod lengths in a big block chevy and found no to very insignificant variations in torque produced. Their ending comment was, and I paraphrase, don't worry about rod length. just pick your piston pin height and crank through then define the length of rod you need.

Please keep in mind that Reyer and Morrison had no dog in the fight. They were testing purely for the sake of determining rod length advantages or disadvantages. I would submit that most magazine articles are written with a high degree of bias towards embellishing the results. So I don't trust them. Also, how accurate is the test in the magazine? If any other variables were added to the increased rod perspective such as a cam change, head change, manifold or whatever then the results are misleading at best.


If you give in to the concept that additional rod length is a benefit then the question arrises, how much benefit. I would challenge that the piston dwell time and initial decending speed of the piston as the crank rotates pulling the piston down between the original rod length of 5.9545 and the 400m rod length of 6.58 would be insignificant. So why spend the extra money and even more important, the extra time and engineering resources to end up with very little if any gain?

I would submit that power, either defined as torque for HP is created in general in three areas. (Given engine size as a constant.) Air flow, compression, and cam timing. Focus on these three. Understand the intended uasge for the engine and create the correct combination of parts that address this intended usage.

a. Flow your heads. Even if they are stock any engine build and cam selection requires this information to pick the other two catagories.
b. Define the RPM range the engine will need to make power in and pick a cam that meets these needs. Keep in mind the cam must work with your head flow, exhaust type, vacuum requirements and intended usage.
c. Pick your compression ratio based on dynamic compression and not static compression. (Pump fuel octane is a given here.)

I wish you the best on your build.

Humble Submitted
Concobra

PS. Stay away from fast ramp cams such as Comp Cams' Extreme Energy grinds. These were developed for low ration rocker arms and have a tendency to produce excess valve train noise and wear when used with 1.6 ratio and above rocker arms. (This comment is based on my personal experiences and no quantifiable evidence.)

[DAVID GAGNARD]

Concobra:

I've been doing a lot of research on this project in the last week or two and have read many articles, including the one you posted,both pro and con on this combo. I'm no engineer, but I enjoy doing the research and fairly well understand the principles involved.

I understand the points made in your post and do not disagree with them, but I've seen many posts/articles from other sites, mostly 4x4/Mustang related sites where this engine combo was used and have not seen one bad report yet. The 4x4 guys like it for the low end torque and the Mustang guys like it for the same reason and simple,inexpensive build using inexpensive factory parts. The Mustang guys are using this engine for eveything from a daily driver to dedicated drag racing with good results...

I've spoken at length to an old friend who has been a mechanic for the last 46 years (jet engine/piston engine,gas/piston engine,diesel) and he has his thoughts on this combo, he thinks it can't hurt, but also thinks the "long rod" theory may be somewhat exagerated as your article suggest, but he did say "go for it, it can't hurt to try"...

The 351 W in the 4x4 right now has served it purpose well and with the cam in it right now has very good low end torque to get the heavy truck going, we don't need a high rpm screamer for this application. In fact, I have the very same camshaft in my 65 fastback with a 351 W, been in the car since the mid 90's and I love the way it idles and the power band is great from off idle to 5,000 rpms.....that's why we put the same cam in the 4x4.....the old 351 W in the 4x4 is "tired" and has been abused somewhat and is due for a rebuild......
The 351 W in the 4x4 right now has the stock pistons/rods, the 484/272 crane cam, aluminum dual plane intake and a Edlebrock 600 carb, topped off with an early set of 289 head, the heads have been polished/ported and have had larger than stock valves installed... I'm not sure these are the best heads for this 351 W and we may have found an older used set of Edlebrock alum. heads for the rebuild. The 289 heads do work well with the present combo as his rpm range is from off idle to about 4,500 , compression ratio is 9.5 to 1......

Still doing research, and the plan is to build this engine combo later this summer, it'll be interesting to see the results compared to the present 351 W.....

Thanks for the info and insight.........

David

[concobra]

Hello David

Please let me know how it comes out. I am always interested in any combination.

Good luck and I hope all goes well.
Concobra

[lovehamr]

Of course, you could always offset grind the crank and................

[Keithc8]

This truck is a perfect candidate for a 408 Windsor. The kits are real reasonable for them with the cast crank, I-beam rod and cast pistons. I think we can get you a complete kit with bearings and all for about 1000.00 or less.
This would be a much torquer engine for the heavy truck you have. Do the 408 while you have it apart and it will work much better.

Good luck, Keith Craft

[DAVID GAGNARD]

Originally Posted by Keithc8

This truck is a perfect candidate for a 408 Windsor. The kits are real reasonable for them with the cast crank, I-beam rod and cast pistons. I think we can get you a complete kit with bearings and all for about 1000.00 or less.
This would be a much torquer engine for the heavy truck you have. Do the 408 while you have it apart and it will work much better.

Good luck, Keith Craft

Keith:

That sounds good and the 408 surely would provide the torque needed, we would need to find a better set of heads for the 408, the 289 heads would not be enough to make the 408 do it's job, if the deal on the used alum. Edlebrocks comes thru, the 408 would sound real good, I'll let you know.......

Thanks;

David

[Mark O'Neal]

This is just a bad idea. It's a lot of work and money for no gain.

I'd be more inclined to do a inexpensive version of the 393...or 408, 418, 427.

[DAVID GAGNARD]

Originally Posted by Mark O'Neal

This is just a bad idea. It's a lot of work and money for no gain.

I'd be more inclined to do a inexpensive version of the 393...or 408, 418, 427.

Respectfully, I don't understand your point....

We're gonna rebuild the engine regardless of what we do.
we have to bore the block....
we have to buy new .030 over pistons/rings either way we go.....
we have to buy new bearing either way we go....
new intake/head/pan/etc. gaskets either way we go...
the 351M/400 rods are free...
machine work is free......

basically the long rod 351W would be the least expensive option,whether or not there is any advantage to the long rod motor over a "standard" rod motor is still up in the air, for every vote for no appreciable gain, there is a vote for some gain, so I call that a "push"......

There is little to no $$$$$ for this rebuild, so inexpensive is # 1.....

If it was my motor/project, I'd go with a 393 stroker,that's my personal preference....I have been impressed with the ones I've seen and driven.....

After the long rod motor, probably the next most inexpensive motor would be something on the order of a 393 or 408 as Keith has eluded to.....
I've given the guy my thoughts/ preference, it's his money, or lack of money and untimately his call.....If not for a pregnant wife and new house going up in a month or two, he would spring for a nice 393/408 without hesitation,but the "Boss" has to approve of this and he has to live with her, not me........
the final decision hasn't been made yet, he has a bunch of spare 4x4 parts/carbs/etc. he's trying to sell and if it goes soon enough, he'll have a few dollars for a budget stroker kit, which is all he needs for a hunting/knock around,weekend truck......

David

[Mark O'Neal]

There is no advantage in running a long rod. He'd be better off just rebuilding the stock engine.

As far as rod length and performance, except in vary narrow circumstances, it is utterly irrelevant.

The narrow circumstances occur when cylinder head size is mismatched to the engine size.

[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.