Ford Muscle Cars Tech Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
182 Posts
Discussion Starter · #1 ·
Hello!

I have always hear and read that Ford engines has way to big main crankshaft bearings and this is a problem.

It seams that it writes and talks alot of this but in reality I never see any of it.

Is it really a big deal that Ford choose a bigger main bearing than Mopar and Chevy?

I mean what do you loose on it? Is it 5,10,20Hp? warmer eninge? Bad oilcontrol? Friction problems? or what?

Ford engines in racing seams to work alright so why do I hear this from time to time?

Would be very intresting to get an professional answer since I am very tired to listen to my chevy/Mopar fans about it.
 

·
Registered
Joined
·
5,551 Posts
well supposedly the big 3" mains can cause bearing problems due to the higher surface speed vs. a small block Chevy, for example. I've never SEEN (I have read about it before though) proof of it actually being a problem.

Ever seen the mains on a KB nitro hemi (top fuel and top alcohol)? They aren't small...and they last just fine.

I think the issue gets beat to death due to circle track racers trying to run a stock crankshaft 351w or stroker (3" mains) to 9000 RPM for extended periods of time. On a mild drag car engine, I think the 3" mains are just fine. Makes for a heavier crankshaft, but hey...I said MILD engine. Most aftermarket blocks are designed for the smaller mains, though, for what it's worth.
 

·
Registered
Joined
·
991 Posts
351cleveland mains 2.75 work just fine for me to 9000rpm
 

·
Registered
Joined
·
182 Posts
Discussion Starter · #4 ·
Same rumour that Clevland has the badest oiling system of any eninge?

I have run my 440Hp 351W for 10 years and it works just fine.

Never ever had any problems.

Is there anyone here that can really give a proof of the problems of "meaty" bearing`s?
 

·
Registered
Joined
·
991 Posts
lol the cleveland oiling is the same as the 429-460. What proof are you looing for? 3 inch mains at sustained high rpm is not ideal. But for 95% of people, the 3 inch mains on a very healthy 500hp or so street car is fine. Look at anyone that is turning high rpm and they all start atleast with a 2.75 cleveland main.
 

·
Registered
Joined
·
182 Posts
Discussion Starter · #6 ·
I'm sorry i didn't want to start a new thread about oiling system.


Proof?
Just why and if anyone here have IRL experiance and hard facts about problems with 3''

I have already read to many "I think", "supposed" and "heard about" in this issue.


For a street guy like me is it really any issue?

Talk to a Dragrace engine builder about an 428 he was builing and he claimed it was alot of gain, but how much and what he gained he could not answer.

I like facts and figures!
 

·
Registered
Joined
·
991 Posts
for a street guy like you , its no issue whatsoever. If you feel it is an issue buy a 351w crank with cleveland mains
 

·
Registered
Joined
·
182 Posts
Discussion Starter · #8 ·
No I will not change.
I am just curious and like to think and debate it.

Learning new things is always an issue for me.
 

·
Registered
Joined
·
1,892 Posts
I've seen JustJim on this site run his 351w powered '62 falcon at the track. The 3" mains don't seem to bother him as he makes the equivalent of high 11 second sea-level passes one after the other. He also drives this car over half an hour to the track on the highway with 3.70 (I think) gears and no overdrive. Seems to be doing just fine.

I think Woody knows what he's talking about.

<font size=-1>[ This Message was edited by: 289nate on 9/26/06 4:26am ]</font>
 

·
Registered
Joined
·
1,287 Posts
In my opinion, it's no issue at all. If the engine is setup properly with correct clearances etc, a 3" main works almost no differently than a 2.75" main. Where the Windsor mains get a bad rep is in racing such as NASCAR and the 'Minor Leagues' of NASCAR...the Saturday night circle track crowd. NASCAR will spend sick amounts of money to gain .05hp and ANY reliability is better than winning the lottery...so 2.75" mains are a logical step. The Saturday night circle trackers...seeing what NASCAR is doing...have grabbed hold of it with both hands and turned it into something nearing an urban legend. I personally know guys spinning 3" main 5000$ windsor motors to 9000rpm, every Saturday night, for 25-50 lap main events. Rpm's NEVER drop below 5000, except on yellows. They're usually passing a guy with a 15000$ 2.75" Windsor cranked motor when doing it too. Will a 3" main bearing spin before a 2.75" one? Probably...or more likely, maybe. Physics have a great deal to do with internal combustion engines...but in this instance, I just don't think at any level below NASCAR it's really an issue.

If it really bothers you, buy a sportsman or dart block, or a spacer kit...and go get yourself a 2.75" Windsor crank. As for me I'm not worried about it...I see the proof that it's irrelevant every week =).

Cris
 

·
Registered
Joined
·
3,658 Posts
Yeah, you'll see a little more friction because of the increased bearing speeds.

It might account for a handful of failures that have no other cause, which, in cases like NASCAR, are worth paying thousands to keep that "maybe" from happening. In the money-limited world, the 3" main is fine. Like everyone has said, it only makes a difference in extreme situations.
 

·
Premium Member
Joined
·
1,950 Posts
I was getting approximately 100-150 laps from my 3" main 351 W in my IMCA modified before the main bearings were toast. I was turning it 6500-7200 RPM's. It got better with .0035-.0040" clearance, but it was still a pain in the but to put bearings in it every couple of weeks. I finally installed a 2.75" spacer kit in it and the problem was solved. I have seen a few folks try to turn a 3" mained 351 W at the RPM's I was turning for more than 100-150 laps, and the results are usually disastrous.
 

·
Registered
Joined
·
1,287 Posts
Odd...what bearings?

I don't know the specifics on the motors I've seen running these speeds, meaning what kind of bearings etc. My dad runs a small block chevy so my experience is admittedly second hand in that area, but I do know that some of these motors are stock block, small displacement strokers (some are even 358's!), and they HAVE to spin them to higher rpm's to keep up with the big 430's etc. This is an unlimited late model class btw. I'll have to look into it next race =).

Cris

Oh btw F15Falcon....we've been down to New Mexico to race on occasion, and if I recall correctly, even to El Paso once. My Dad actually grew up there. We owned a feed lot and he went to...I believe...Eastwood High School? Pretty sure that's the name.

Anyhow, small world =).

C
 

·
Registered
Joined
·
310 Posts
I tore down the 398 from the old maverick tonight. It is probably 525 HP and has had 3 years of 7000 rpm shift points drag racing 1/8 mile.
The mains were still in good condition, but the main caps show mild cap walk.
 

·
Registered
Joined
·
3,692 Posts
In drag racing engines you'll notice little if any wear problems due to the short cycle times involved in in their operation. Circle track engines however will see more wear due to their longer cylce times of several minutes to even several hours of sustained rpm.
 

·
Premium Member
Joined
·
34,855 Posts
How can it be an issue of friction or heat if the oiling system is working? With proper clearances the only thing touching the bearing is the oil... Can the speed of a 2.5 inch bearing be that much slower than a 3" and enough of a diffrence to heat the oil past boiling or to a burning point, or where the oil would fail and melt the bearing... (400 or so degrees right?...)

If there is NO combustion in an engine and you pump up the oil pressure and turn the crank 10,000 rpm's will the oil get hot?

Does hydraulic friction create so much heat?


FE
 

·
Registered
Joined
·
182 Posts
Discussion Starter · #17 ·
Intresting reading from you all!
Thanks!


Well circle track engines are short lived and often design to barely hold together.
Ofcourse smaller is better if you want to win there.

For avarage guys like most of us it is almost crazy to invest the money for it.
 

·
Registered
Joined
·
7,499 Posts
It's the constant high rpm and abuse a circle track engine sees that kills it's bearings. These NEED extra clearance and benefit from those 3/4 groove race bearings... especially in oval track applications... and it's still not optimal.

For short duration bursts, such as drag racing, they seem to do ok.

Circle tracks are HELL on engines and oiling systems.

Good Luck!
 

·
Registered
Joined
·
4,003 Posts
The three inch mains on the Windsor 351's is a problem of bearings peeling under high loads at high RPM's. It was enough of a problem that Ford used the Cleveland mains on the SVO blocks.
On the street there is no problem. Well, that is unless you are running a blower or nitrous and turning your windsor above 8000 RPM. At low RPM the larger diameter is a plus because you get a better cushion of oil at very low RPMs. Of course most of us don't run our engins at 450 RPMs so that is a moot point as well. The 351 Windsor is one of the best street engines you can run. They are strong on the bottom end and use one of the most reliable (though low tech) valve trains ever produced. The oiling systems need only a high volume pump as improvement for performance and in spite of the fact that too few parts interchange between the other "small blocks" and the big Windsor there are ample parts available to make the Windsor a good engine on the street with todays gas. At the RPMs of a street motor the windsor holds volumetric efficiency above that of the Cleveland engines - especially the 4v heads. Once you get above 6500-7000 RPM the Cleveland engines do better but that is well above the RPMs for what I call a street engine.
 

·
Premium Member
Joined
·
34,855 Posts
OK you bunch of smart guy's answer me this....

If a Cleveland 3" main peels the bearings at loads under the duress of 6,500+ rpm's, then why do RICER's, (albeit only HALF an engine), turn some of theirs upwards of 10,000 rpm's and not have bearing peeling issues....

I just can't see it... Maybe I'm stubborn....
 
1 - 20 of 23 Posts
Top