Hawghead

I don't know much about the diesel blocks and building engines based on them, but I was wondering, can the diesel blocks be fitted with 4 bolt mains or is that only possible with the NASCAR blocks?

Thanks,
Scott

cutlassefi

Yes there are a few guys offering 4 bolt caps for the diesel blocks, both in standard mains (3.00") or 2.500".
What hp level are you headed to? The stock stuff is good to at least 600 or more.

Smitty275

I have for bolt caps for the D/DX just as others do. It's a very common upgrade. As to which journal to go with all depends on your end goal and budget.

Hawghead

Thanks for the info guys. I've always tried to build motors with the best bottom end I could (within reason and within my budget). I was just wondering if (assuming you could find a good block at a decent price) if converting it to four bolt mains was possible without being cost prohibitive for a really good street motor.

Scott

BlackGold

Just remember that if you lighten the rotating assembly the importance of beefing up the bottom end diminishes. I'm not saying you shouldn't add 4-bolt mains, but you should first use lighter pistons and rods.

Hawghead

Not saying I'm going to do it, I was just kind of thinking out loud. Although the thought of a killer small block that wasn't a belly button bowtie is kind of intriguing. You make a good point, sometimes I think it's forgotten, that one of the easiest ways to effectively strengthen the bottom end, is to reduce the load on it.

Thanks,
Scott

Smitty275

Ya, but who's gonna spend a bunch of money to lighten everything and stay at the same power level to have reduced stresses. No one I have ever dealt with. They're gonna spend money on quality parts to lighten the assembly so that they can increase power which has the end result of putting more stress on everything.

Hawghead

True,

I guess I should have said that one of the ways to "in effect" strengthen the lower end, when building for high performance, is to lighten the reciprocating assembly. This is not to say, this is the only thing that needs to be done, but just one of the things that can help.

Scott

Hawghead

Smitty, et al

While I have your attention and we're waxing philosophical anyway, how about some Oldsmobile clearances 101.

On performance Olds motors it's accepted that the main and rod bearing clearances are increased correct? How much depends on how much horsepower you intend to make, the rpm range and the rigidity of the components used.

My understanding is that this is done to provide a bigger oil cushion between the main/rod journal and the main/rod bearing correct?

My question is why is the connecting rod side clearances increased also? It seems to me that increasing the rod side clearances would increase the "oil leak" from the rod journals and make it harder to maintain that thicker "oil cushion" that the increased rod bearing clearance was there to provide in the first place. Or have I completely misunderstood the purpose of increasing the bearing clearance in the first place? (actually I guess that would be in the second place)

Thanks,
Scott

cutlassefi

A couple things to consider.
First of all the larger main won't have as much of an adverse effect on rotating weight because its close to the center, unlike the rod journals.
Secondly you can get off the shelf pieces that will drastically reduce reciprocating weight, far more important than reducing rotating weight, as in the smaller mains. A stock 455 normally has a bobweight of 2450 or so. An aftermarket setup will be around 2250-2300. The pieces I mentioned for a 4.155-4.185 bore, 4.00" stroke DX would be down around 1800. A huge improvement on its own.
And I wouldn't worry about bearing speed on even a moderate street build. It won't amount to much of a difference.
When it comes to clearances I only open them up if using inferior parts. If you're using good pieces that'll have minimal deflection the larger clearances aren't necessary. Stick with the old rule of thumb, .001 clearance for every 1" of journal diameter and you'll be fine.
And there are many good running builds using .100 side clearance with piston guided rods. I believe that's really more of an excess oil on the walls issue as anything else.

Hope this helps.

Hawghead

cutlassefi,

Thanks for the info, but my understanding was that the main and rod journals weren't reduced in size to save weight but to increase journal to bearing clearance and therefor provide a thicker oil cushion as the force against those components increases causing distortion in high performance engines (the more distortion the more clearance is needed to prevent bearing to journal contact) is that correct?

While we're at it, I'd like your opinion on the crankshaft in my hypothetical DX based 350. Assuming you weren't going to increase displacement, with the exception of over-bored pistons ie +.030-.060 would you recommend the stock, large journal cast crankshaft, or a smaller journal forged steel crank like out of a 330?

Thanks,
Scott

Smitty275

This topic alone, "bearing clearances on Oldsmobile engines", has made my blood boil more than any other when on internet forums. There is absolutely NO REASON to open up the bearing clearances for any reason other than "lack of quality machine work" or because of "shoddy machine work". ANY engine builder that is truly worth his salt can build a high rpm high horse power Oldsmobile that is with in factory spec and even to the tight side at that. "Those who can't" use large clearances to cover their inability to get the basic machine work correct in the first place. I'm going to only consider the building of an Oldsmobile engine and rod and main bearing "vertical" clearance from here on out because that is what this thread & this site is all about.
Is .001 / inch of diameter acceptable? Yes.
Is it needed? NO, it is not.

OVER THE YEARS:
You need to glean over many years to get the full range of what was recommended for the BBO from Oldsmobile but the jist of it is they recommended from a low of .0005" to a high of .0031" on the mains and .0004" to .0035" on the rods. Heck of a range isn't it. Now the question is where did they actually build them in that range? You'll find that while over a span of time they had that above range inclusive the majority of that time the range was actually much more controlled at the factory with .0005" to .0021" for the mains on both B & SBO. Though they never really tightened up the rod journals until the D/DX (BBO size) engines which were spec'd to .0005" to .0026".
In the 30+yrs I've been working with these engines I have dissected many many engines that were in excellent condition as they were being readied for high performance. What I have found is that the factory stuck to the middle of the road for the most part on clearances. Naturally there are exceptions in either direction but the over whelming majority have had mains and rods both in the .0018-.0022 range. (This includes the SBO engines I have dissected also.)

WHAT IS REALLY NEEDED:
I just put it right in front of you. If you build your engine with rod and main clearance in the .0018-.0022 range you can have an engine that is high performance, high horsepower, and live a long, long, long, life on the street or the track.
HOW IS IT DONE:
Well, that it the secret that those who can't do it won't tell you. Because they are not enough of a machinist or even engine builder/assembler to know what to tell you. In their defense I'll offer this other tidbit; Most of them have no idea how to measure. They might have all the tools but not the knowledge to use them propely which often times leads them to thinking the're getting clearances well on the high side of what they really have. I've been through some of their engines that have failed. Amazing what insights you can get on the others when your the one asked to fix their follies.

PRECISION MACHINE WORK:
... is how you do it. That's the only way you do it. Not a single high performance engine leaves my shop with out the main saddle being line honed for size, straightness, and location. Many get much more than that depending on what else is being done to it. Every crank is ground by a shop with top notch crank grinding equipment. Not old worn out crap that a large majority of the "local crank guy" has. BUT, some of those guys are really good. Don't immediately discount them. Just know that it's OK to be leary. Especially when your first doing business with them. Check , check, and double check. Everyone has a friend or friend of a friend that is a machinist. Offer him dinner if he'll be so nice as to come over and measure your engine components some evening. No beer until after he's done measuring though.

WHY KEEP CLEARANCES AT A REASONABLE MINIMUM?
It's all about maintaining a proper hydrodynamic wedge that is built up by the pressurized oil system that feeds the oil to the bearings to keep parts from touching. Keep the clearances correct, and the oil weight correct, and you have the outstanding ability to control the crankshaft in the bores. By controlling the crankshaft you minimize it's ability to move around, flex, get out of alignment, and cause other issues. The larger the clearances the harder it is for the oil to form the wedge and maintain the wedge. It also takes more oil to maintain the wedge just from the fact that it can run right out the side of the bearings easier.
Remember back where I mentioned they tightened up the rod clearances on the D/DX engines. It had nothing to do with their lower PRM range or anything like that. It was because when the rod journals had clearance much above .002" they would beat the rod bearings out resulting in a lot of warranty claims. When the clearance was re-set on the tight side they lasted forever.

WHAT ABOUT INCREASED RPM:
It really doesn't matter for the RPM that your going to spin 99.9% of any Oldsmobile V8 engine if you have the clearances right and the machine work right. Just as long as you have the oil supply sufficient and proper oil weight you'll be fine. Don't forget the proper components for the kind of power your going to be making is important too.
I have a multitude of customers out there that run the clearances as described above, oil wieghts from 0W20 to 10W30 for the most part and have been together for better than 10 years of street/strip/ and dedicated strip use. The hotter ones run 7000rpm through the traps every pass. Some higher than that. For a guy running at 6000 RPM through the traps the above clearances are more than plentiful if the machine work is performed properly and the engine is assembled with proper components and is clean.
Conversely, there is a shop in a local town with quite an attitude about how good they are. One of their faithful Oldsmobile customers has his engine back in there every fall because of bearing failure. I'm talking every fall for probably 20yrs. in a rush to get it back so he can finish the season. Why? Because they put .0035-.004 on the mains and .003-.0035 on the rods. My question to him is why he keeps going back? I just get a "deer in the headlights" look from him. I gaurentee they take his money and never say their sorry for his inconvenience. If that happened with something I built he would get it back ASAP and wouldn't put a dime towards it being fixed.

THE ABOVE IS MY OPINION BASED ON 30+ YEARS OF EXPERIENCE. I did not learn it all on my own. I've been fortunate to have some of the best in the industry willing to teach me better ways over the years. From GM insiders to having access to engineering staff of The Timken Co. for the 22yrs I worked there. The Timken Co. apprenticeship I went through is equivalent to a BS in Engineering. While there I machined tooling and machine components to tolerances that would boggle the mind of most individuals, built machines from scratch for the purpose of making even better bearings, worked in engineering, etc. It was a great job until they decided to close it down in favor of going over seas with all our hard work and research. I put that same care into how I build engines, be it Olds or otherwise.

OTHERS OPINIONS WILL VARY.....Choose your engine builder carefully

captjim

There is a "famous" Olds builder who recommends .004 rod clearances, which is ridiculous, especially on a street engine, IMHO.

That said, Smitty, what is the "harm" for lack of a better work, in running the mains at .003 and the rods at .0025? Just as you have had good success keeping things snug (which in principal, I agree with completely, same goes for piston/cylinder clearance) so have many following the ".001 per inch" rule. I don't consider .0022 "tight" on the rods, that is right at .001 per inch. .002 is a bit snug on a 3" main, but certainly presents no problem if done correctly.

Lastly, does this philosophy also apply to 403s? TIA

Bernhard

Hi Smitty
I'm not taking anything away from your builds or skill set as a engine builder.
Factory big blocks as they come from the factory spin bearings this has been debated may
times.
I have first hand experience in factory big block spinning bearings.
ROP had many examples of spun rod bearings before the crash.
There are race and street strip cars running specs like Jim posted with good results.
If the famous engine builder builds engines that fail how come the boards have no negative feedback?
Does not the center thrust bearing control fore and aft and rod side clearance control fore and aft as well?
If parts are not being hurt how can .001 to .0015 extra clearance cause engine failure or shorten engine life ?
What is the point of 70 psi oil pressure if one is not hurting parts with 45 psi?

captjim

I did NOT say it "failed", but oil pressure was/is VERY low at idle with .004 on the rods. IMHO, and you guys have a lot more experience than I do, .004 is too much, just no need on a 2.125 journal.

Bernhard

Hi Jim

I know that you never said that it failed.
Smitty has success running tighter clearance but what is the issue running more clearance if you are not hurting parts?
I'm not being negative just want to know what the down side is of a little extra clearance?
I just have not read any negative posts by anyone that is running this builders engines.
Would like to see these posts so that I could be better informed.
If the engine does not hurt itself with 45 lbs of oil pressure why would one need 75 lbs ?

Hawghead

Smitty,

Thanks for all the information. Am I correct in understanding what you are saying if I surmised that, provided the machine work is done properly on good equipment, factory clearance values will work fine in all but perhaps the most radical builds?

So with a world full of guys with a lathe and a website, how is the best way to determine if a particular machine shop is capable of doing the work correctly?

Thanks,
Scott

Smitty275

As usual people read something, and well, don't really read it. It starts to hit against the guy they worship because he "wrote a book" and immediately their looking for ways to sink the opinion. That was all about vertical bearing clearance and what is "needed". No where did it say that that it was the only way and that no other way would work.

Case in point.
"Is .001 / inch of diameter acceptable? Yes." I just added in that it isn't needed. No where did I say it won't work.

Another response has posed the question as to what is the down fall of using even larger main bearing clearances. That answer is dependent on the application. In a dedicated race engine it is less of a factor than it is an engine that sees real street and high way miles, not just putt to the local cruise and putt back home.

Lets take for example a dedicated racing engine that is towed to the lanes, fired up makes a pass, and then towed to the pit spot. The oil is never hot enough to thin out. So the oil maintains the viscosity to fill that .004 or .005 of clearance and the owner gets away with it. Of course the owner probably only makes a couple passes here and there. At best 6 or 7 passes in a three day weekend. Never enters a race that might round robin the car because he knows it can't do it and live. So it survives. Put that clearance in a bracket engine that might make 10 passes in a day, after a couple rounds goes round robin, straight back to lanes, and never gets that hour or two to cool off and the oil is going to thin and not maintain protection. It's fact, not fiction. It will start to eat itself.

Now lets put that same .004 on a true street engine. The owner gets out on the high way cranking along on a hot summers eve. Puts some serious miles on it and gets the oil nice and hot so it thins out which is normal. Pops off the high way after running at 65mph and hits the cruise scene. First light he pulls up to the hot rod next to him and they run 'em off. That engine with .004 clearance is going to start the process of eating itself alive. There is no way that the oiling system can keep that void filled with oil at those temps even with a 20w50 in it. It won't take long and it's gonna be pulled out to see a damaged crank and junk rod or two because of the heat associated with the circumstance.

Then there is omittance of:
"Don't forget the proper components for the kind of power your going to be making is important too."

This covers a good bit of the failures of engines with stock components. Factory rods are like spaghetti. (I think that statement might be in that book.) They are not intended for high performance applications. 400HP OR 5500- 6000rpm is honestly well beyond their intended design. It's not the bearing clearance that is responsible for the spun bearing. It's because the rod isn't strong enough to maintain it's round shape on the big end. AND we should always remember that anything can fail at any time. A friends wifes 3800 V6 Buick spun a rod bearing cruising along at 65mph. It wasn't a race engine. Was never driven like one. It just failed. Some times it truely is a case of "**it happens".

Lets talk about the factory engines that have had bearing problems develope. I'm willing to say that the overwhelming majority of the time the condition developed from nothing less than abuse in one way or another. Poor fuel leading to detonation, improper timing leading to detonation, excess RPM for stock components (see above), poor oil or oil change frequency or filtration (tiny oil filters), lack of oil or capacity, improper carburation causing lean conditions that lead to detonation, not enough fuel supply to maintain proper A/F ratios, running at elevated engine temps while out beating on it because of no gauges to know what is going on with the engine, two minute burnouts, etc. It's probably an endless list. And since most of these are engines have been through multiple owners no one really knows the life it lived before they got it and then had an issue. PLUS, as above in the rare occaision, some times it truely is a case of "**it happens". The factory wasn't perfect. It was a production line enviroment that paid incentive to get product out the door. So occasionally something slipped out that shouldn't have. AND they were never meant to be used the way hot rodders use them.

Here's a toughy:
"So with a world full of guys with a lathe and a website, how is the best way to determine if a particular machine shop is capable of doing the work correctly? "

I don't know if there is an absolute answer to this. I guess it's a gut call kind of thing. You have to ask lots of questions and see where he drops the ball. If you get a feeling that something is off, then it probably is. "Most" shops want to do a good job for their customers. If your going to a local machine shop flat out ask him if he's ever built what your wanting to build. If he says no, then ask him if he will build it to specs you supply. It's your money paying the bill. If they can't build within a particular tolerance range of a few tenths, well, go somewhere else. You do have to be careful not to step on their toes. It takes tact, especially if your dealing with a given shop owner for the first time.

When I build something it is with the intent of keeping the "**it happens" to the absolute minimum. I strive to control every aspect of the build of an engine so that will live as long as possible under the conditions that present themselves and hope the owner of the engine has enough common sense to not put their investment in a situation that will damage it. There is no way anyone can build a piece of equipment that will survive even the most hard headed of people. When a customer leaves the shop telling you he's not going to follow your advice it's a sinking feeling. You've already warned them that what they are about to do is going to cause a problem. Then they blame you for the problem when they do exactly what you told them not to. Sometimes you truly can't win. Fortunately that is a rare case. But it has happened.

Bernhard

Hi Smitty.
First I don't worship any man or Woman, I only worship God J.C.
Yes I'm a fan of some engine builders but that does not mean that I don't appreciate others
efforts.
I would like proof that all his engines are hurting parts.
The book is a big deal because it debunks a lot of B.S put out by a famous Olds builder
I never was talking about engines running .004 clearance on the street but engines running larger than factory clearance.
.001 per inch of rod journal + .0005 for high performance engines.
If you run a aftermarket quality rod,light piston and rod,and bottom end support of course you can run tighter clearances.
There is lots of good information in the book
Factory rods don't stay round, BBO block and crank is not the strongest and can flex in hp applications
With factory rods you end up with no oil clearance when you rev them I found this out first hand.

,

captjim

OK, but you did imply (or out-right state) that guys who did build them loose were not competent machinists. Like many things in the performance world, there is no "right or wrong". Look at a guys track record and how satisfied his customers are, and choose your guy. In Smittys case, his cars at this years Olds race speak for themselves.

Hawghead

Smitty,

Thanks for taking the time to answer all my questions, both real and hypothetical. I've built a couple of street "performance" Oldsmobiles back in the day, and we always went with the factory clearances. (frankly never thought to question them and sure as hell didn't have anyone to ask.) But we took good care of them, even though we "exercised their authority" fairly often and they always held up just fine.

The reason I'm asking these questions is I'm currently building a 69' Cutlass and I don't know that I will ever be in a position to do another. I want an engine that I don't have to worry about whether it's going to hold up and one I won't have to take any **** off a 17 year old rich kid whose daddy just bought him a new Camero or Mustang.

Not having the experience you or others have, I'm forced to rely on my own research and that for the most part involves reading everything I can get my hands on. Yes I've read Bill Travato's book and for the most part I think he makes some good points. But if you build an engine and it runs 7.90 the first pass and grenades it self on the second (and I'm not saying any of his or anyone else's has, just a point I'm trying to make), would you call that a good engine build or a one hit wonder? In this country we've kind of accepted as fact, that if someone took the time to write it down, it must be true.

I want to build my own engine (I believe that if you don't have some blood in it, it's not yours) but obviously I'm going to have to rely on others to do the machine work and for the knowledge of how it should be done to meet my goals. Unfortunately, like I said, it seems that anyone with a lathe and a website thinks they can do performance work on anything and additionally aren't really concerned with the result. They have your money and if you don't like the product, tough. While I realize there are no guarantees in high performance cars, I'd at least like to minimize the chances for failure.

Thanks,
Scott

Smitty275

Hawghead, your more than welcome. I think it should be rather obvious that I am here to help any one I can get it right the first time and I don't require being a customer to offer sound advice.


Bernhard, since your very first posts you have preached that one must buy a specific book and follow it. Anytime anyone has had issue with what is in that book, or the guy who wrote it, you seem to take offence to it. Had you been around the last 15yrs you'd know a lot more of what has gone on. Umpteen crashes or ROP has deleted a lot of information that you'd like to see and will never find again.


Captjim, I also lay this at the end of my posts "OTHERS OPINIONS WILL VARY.....Choose your engine builder carefully" No matter what someone types or how carefully they present it, it can be misconstrued.

cutlassefi

A few other things to take into consideration. Remember Olds engines weren't originally built to run long miles, the warranty period back then was 12 months or 12,000 miles. Plus they didn't expect to run at high rpms for extended periods of time like todays performance builds are expected to do. At some point you need a good balance between oil volume and pressure. I did a 455 a few years ago to BTR's specs. I'll never do it again. I've since gone back to my .001 per inch of journal size with absolutely no issues. In fact this last build had serious oil pressure even at those "increased" clearances. And as Smitty said ask your machinist lots of questions. It's your money, you have that right.

Hawghead

Cutlassefi,

Mind if I ask why? What problems did you experience with the engine?

Thanks,
Scott

cutlassefi

Very low oil pressure, it didn't give me a warm fuzzy feeling.
I know that he says it can be done but I personally wouldn't do it again for a street high performance build with the expectation of a long life. Like my machinist says, "at some point Mark you'll need to build some oil pressure". I believe he's right. Plus I like the option of being able to run a lighter weight standard or synthetic oil, that means more hp/tq.

Conversely I also believe the stock clearances are too tight for a "performance build". As mentioned the stock stuff wasn't expected to last forever and more importantly didn't have to live at higher sustained rpm's all the while making more power as well. On another note the new purple spring for Mellings' M-22FHV pump works great. Lots of pressure and much more consistent than shimming the green one.

Hawghead

Yeah, I know everyone says that Oldsmobiles neither have or need great oil pressure, but I'm like you, when I'm cruising down the highway at three grand, I like to see more than 30 psi on the gauge just for peace of mind.

But as has been discussed here, I would think that with the aftermarket parts that address the factory weakness, like H-beam rods and perhaps a halo girdle to reduce the distortion, along with good machine work, the factory clearances, at least on the high side should both provide enough protection and maintain good oil pressure.

Scott

pogo69

this was very well said, i have always been more concerned about stock rod failure than main bearing failure for performance applications mondello made changes in tolerences as new parts and materials were developed...but in the end if your part is machined properly your off to a good start

Bernhard

Hi Smitty
The book is a good read lots of good information for those that want to build a high performance Olds engine.

I never said follow it, I would never tell anyone to follow any book!!!!!!!
Any time you read a book one must not just read the book but understand what the book is saying.
Then with ones wise mind the person can make ones own decisions based on acquired information.
One must always question!

Bernhard

I have been around ROP for the last 8 years and have yet to read the negative posts that you speak of ?

I was on the board but had my name dropped do to lack of posts, I could not get back on the board no matter how many times I contacted the board.
Then after the last big crash I was able to rejoin.
There was lots of good info lost.

Cutlass EFI
Have you kept in touch with the 455 build with the big clearances?

When I build my engine I will be using bearing clearance on the high side of .001 per inch.

Like I said before were is the proof that these engines are hurting parts????

Bernhard

Hi Cutlass EFI

Since you have gone back to .001 and have good oil pressure have you thought about finding the point of perfect balance between oil pressure and max clearance?

When you built the engine to BTR spec's what clearances did you use?

How hard are the engines being run with the tighter specs ?

cutlassefi

And I have to agree with Smitty, you need to re-read some of your own posts. You absolutely recommend Bills book a lot and almost recite verbiage from it. It's very clear to a lot of us that you hold his book as bible. I bought it and read it myself. It's a great compilation of part numbers etc., but there are no revelations in it.

And there are a lot of good builders out there, not just Bill.

Bernhard

Thanks for the reply

There is only one Bible the Holly Bible

Yes I always recommend Bills Book because there is a lot of good information in it.
I seldom quote from the book because one must understand the martial them apply it based on parts used , hp level and end use strip or street strip.

Hawghead

I got that on an e-book. Lots of good information but when the author got into different venturis and emulsion tubes I got kinda lost.

Scott

cutlassefi

That would be the Holy Bible, not the Holly Bible.
And you don't typically quote but you paraphrase quite often. Again a good part of the info in his book is also available elsewhere. Just sayin.

chadman

And there is also some bad IMO.

chadman

Absolutely

Smitty275

I've a copy of the "Holley Bible". It has all the part numbers and assembly into for all Holley's up until about two years ago along with tuning info for different circumstances.

How hard are the engines ran built to tighter specs? Well into the 8s is since 2007 for one customer.
Others in heavy cars routinely in the low 10s and mid 9s and 6500-7000rpm through the traps every pass year after year. And not just one or two built that way.

Bernhard

Smitty has success running tighter clearance but what is the issue running more clearance if you are not hurting parts?
I'm not being negative just want to know what the down side is of a little extra clearance?
I just have not read any negative posts by anyone that is running this builders engines.
Would like to see these posts so that I could be better informed.
If the engine does not hurt itself with 45 lbs of oil pressure why would one need 75 lbs ?[/QUOTE]


Smitty
I know you have success running tighter clearances I posted that in one of my first posts

I know you have your fans/customers that are happy with your builds.

What I would like is negative feed back from those that run Bill's engines!
I would also like negative feed back from those that run more clearance!
What your implying with your post and negative view of large clearances is that you are the only good builder and that every one else is incompetent.


My Bad Holy Bible

Bernhard

Hi Chad
I would like to know what that is so that I won't follow it?

Bernhard

Bill is not the only good engine builder
x3