Dyno day, the good and the bad....

I think Jim just gave away one of his secrets.....

 

I'm glad you questioned Jim's numbers, I was thinking the same.

I had a good discussion with the machine shop about everything I wrote in the letter below:

"This is a do-over for this street/strip engine. Spun two rod bearings (#2 & #7) on engine dyno. Please record clearances and torque as I can not afford to do this a third time.

Machine, balance and assemble short block.

Block:
• Deck block. Passenger side (2,4,6,8) 0.012” and drivers side (1,3,5,7) 0.015”. Do not cut rails.
• Main caps - when installed, removed, and re-installed the do not sit in the same position. I know the #1 main cap does not self align squarely with the block, other caps suspected. Take measures insure consistent positioning when removed and re-installed. This slight movement contributed to uneven main bearing wear.
• Align hone mains once cap issue above is resolved. Use supplied Moly for thread lubrication during torque of mains. See attached sheet from ARP spec. or equiv.
• Do not hone bores unless it’s needed (call me).
• Do not hot tank block, clean thoroughly with warm soap and water preferred, brush all oil passages as they have been enlarged and contain metal shavings.
• Install main bearings (drop shipped), machined crank, and clean and oiled pistons.
• Install cam bearings (drop shipped). Installed depth important. Oil holes should be at 3 and 7 o’clock. After install use old cam provided to check cam bearing alignment.

Crank:
• 0.030” over Rod bearings to provide clearance of between 0.0024” to 0.0028”
• Machine crank for Rod side clearance of 0.014” to 0.018”, insure smooth radius
• 0.030” over Main bearings to provide clearance of between 0.0026” to 0.0030”
• Check straightness, had run-out of 0.002” as delivered.

Rods
• Six extra rods are supplied, remove them from pistons. Choose two good rods and use for #2 & #7
• Lighten and re-condition rods as needed. Use ARP bolts for re-conditioned rods after making sure both rod and nut sit flush onto rod and cap (may need machining for proper clearance).
Assembly:
• Neoprene main seal, see instructions for installation
• Moly on threads, bolt stretch method preferred.
•
• Recorded torque using Moly .. Rods = _________. Mains studs = _________ (95?)

• Rod Clearance = _________. Rod Side Clearance = _________

• Main Clearance #1 _________ #2 _________, #4_________, #5 _________
• Desired #1, #2, #3, & #4 clearance  0.0026” average. #5  0.0029”

Based on Jim's advice, maybe I should call the shop to advise slightly tighter on the mains. Specially since I'm using Federal Mogul instead of Clevite main bearings.

 

Bobby Warren doing the machine work?

 

Joey, Jeff's brother is doing it. Bobby is the father right? excellent 4-speed man from way back....so I've heard.

 

The grandfather (now 74 or 75) was NHRA national champ for a nunber of years. Back in the 1960s when he showed up at the old Sanford track we all new the jig was up --everybody else was just in a fight for second place. He never missed with his trademark black Camaro. He was so good that he could take another competitive car, switch and beat you with your own car. But you could not beat him with either one. He was a machine. He still runs a bit for fun.


Here he is a age 70 still whipping everybody just for fun. Oldest event winning NHRA driver I believe.

http://www.competitionplus.com/07_15_2004/bobby_warren.html

And he always is the same humble guy. He whips you and you cannot do anything but feel good about it. And he still does it with a manual trans and clutch.

 

You can run the mains that big, as long as you don't get freaked out by 10 psi of oil pressure at 700 rpm with the oil hot.

Good chance that is what you will have.

I like to see the mains a little tighter, there is no reason for it to be bigger than .0025. Not in any Buick engine, with good machine work. And that includes the race motors..

JW

 

I have 003 on my mains and I have 40 psi hot idle oil press. I do have a great T/A timing cover though.

 

Which is why any experts who aren't familiar with Buicks should stay away from the machine work, in my opinion, unless that's a "race" rule of thumb only, assuming lots of oiling system work. I sure wouldn't want to take delivery of a stocker with clearances like that.

Devon

 

Chris,

Experience is the simple answer to your question.

In the 50 some odd 455 and 455 based engines I have built in the last half dozen years, I have seen some interesting trends. I stress the word "trends" because every engine is just a little bit different. Observing these trends over the years leads me to the conclusions and to give the advice that I do. There are always exceptions. Engie has a motor with .003 on the mains, that idles at 40psi, with I assume 30wt motor oil. I have certainly seen that. Alan Wander's engine comes to mind.. that was a great one for maintaining oil pressure at low engine speeds, if I recall it would idle at 700 rpm with 40-50 psi, with the oil at 180*.. with a modified stock timing cover.

But you know what, those motors are the exception, not the norm.

Typically, they are going to be 25-30 psi at around 700 rpm, with 30wt and .002-.0025 on the mains. Run those mains out to .003 and your more likely to see 10 to 20 psi at that 700 rpm.

This last summer, I built an alumium head Electra motor, with a very mild cam, that would idle sooth as silk down at 600 rpm in gear. But with the more performance oriented main clerances (.0022 in that motor if I recall), the slow speed of the oil pump would only produce about 8-10 psi at idle. Not really a problem per se, but I have found that customers don't like to see an oil pressure gauge almost reading zero.. Kinda gives them the willies..

That taught me that the next time I build that motor, I will hold the mains down below .002.. probably stay nearer the factory high limit of .0018, thus mitigating the pontential lost pressure thru the lifter bores and cam jounals.

There is an X factor in low speed oil pressure with the 455 stock block- cam bearing clearance. While this is not a normally discussed or even often times measured clearance, it certainly does have a big influence on idle oil pressure. I tracked it for a while, even if there isn't really a damn thing I can do to tighten up a big clearance cam bearing motor, short of having a custom cam ground with bigger journals.

What I found is that there is a pretty decent variation in the bore sizes of the cam tunnel, and that in turn causes the cam bearing clearance to open up. It's not at all uncommon to see .0025+ on the cam bearings, although you will see them all they way down to .001.

Slightly worn lifter bores on the passenger side also will influence the low speed oil pressure.

And since both of these bleeds proceed the mains, if you have a block with larger cam bores, and slightly worn lifter bosses on the passenger side, and then you go and stick the mains in at .003, then your going to have a motor that simply can't pump enough oil at 700 rpm to keep the pressure up.

Keeping the mains tighter minimizes these losses, especially on the milder street motors, that don't idle at 800-900 rpm. They idle at 600-700 rpm. And 100-200 rpm really makes a difference here. It can be the difference between 10 psi and 25 psi at idle in a given engine.

Now, in relation to the big clearances some guys these days swear by, I offer only this.. Big clearances limit the damage possible, due to poor machine work, on the block and the crank. In this very thread, you see the issues that occur with out of round mains, and bent crankshafts. Had he run the clearance out to .003+ on the mains, it may very well have lived.

I have built about a dozen 650+ HP, stock type oiling system 455 based race motors now, excluding the exotic overhead oiled motor that was George Sweesy's. And non of those engines have over .0027 on the mains. And I have yet to ever have a main bearing failure, or a rod failure on those engines. So I take issue with anyone who says that you have to run that clearance out, to make the motor live. In my experience, that's just not true. IN fact I know a guy locally who ran a 494 STG 2 at 750+ HP, for years with .0015 on the mains.

And the .001 clearance per inch of journal rule is based on an engine with 2.25 -2.75 inch mains, not 3.25 inch ones. I'm no math wiz, but if you figure the square inches of bearing in a 2.75 vs. a 3.25 inch main, you will see why the buicks typically need to run tighter clearances, especially when you factor in our rather unique oiling system and oil pump placement.

So, these are the reasons that I told Craig what I did. I'm offering conclusions and advice based on the trends I have seen over the years, and on building probalby a couple dozen of the engines with the specs and HP level he is at now. Relaying to him, and everyone else, what worked for me, and with similar machine work, what will work for him.

BTW.. Good catch on the fact Mike moved the oil pickup passage on the new Alum block.. I was wondering how many folks were going to notice that. When I first saw it, my reaction was the same as yours.. but I walked out and looked at an old block, with the timing cover gasket impression very visible and thought to myself "Yup, it will work there..".

JW

 

Chris, this was not meant as an attack, only a warning that this so-called "kinda norm" must always be taken with a grain of salt, but again as I stated this is my opinion, and you know how the rest of that saying goes!

I have been building big block Buicks since 1985, and before/during college I worked full/part time doing resto and race work. Most of what I learned came the hard way as I broke a lot of stuff along the way. I have had many SBB and BBB friends/customers.

Twice in my youth I took delivery of my 430 engine from a company in Flint that thankfully is no more...Fletcher's Engine Service. Before assembly I measured main bearing clearances between 0.003" & 0.0033". At the time I wasn't alarmed and went forward. Both builds suffered low oil pressure on an otherwise stock engine; unfortunately the first died an early death due to losing the 7/8 rod bearings. I managed to crutch the 2nd build with a high volume pump, which resulted in a custom solid cam getting trashed due to gear wear. After a new cam and a bronze gear it stayed together a year before spinning a main bearing. I believe that if I'd known more about the other (now common) oiling system mods my luck might've been much better.

Since then I've learned a bit more about clearances as well as oiling system mods and I am a firm believer that to open the clearances up requires more volume than the stock cover/pump and 1/2" feed holes can deliver.

This is no rule, only my limited experience. I apologize if my previous post came across harshly, often I'm guilty of not taking the time to reread my comments or taking a moment to consider how my statements might be interpreted. I certainly did nor do not mean to offend you.

Devon

 

I just gave Chris a call and what a stand up guy.

Chris, thanks for accepting my apology and I'll buy when we get a chance to meet.

Devon

 

That goes both ways, Chris!

Devon

 

This thread is awesome! Loads of good information! Thanks to everyone that is contributing to Craigs build as it is good valuable info that any of us can benifit from when interfacing with our machinests.

It's also nice to see real, concrete, detailed reasons as to why BBBs are so sensitive to who is doing the machining rather than just saying: "make sure they know buicks..."

 

Chris,

I'm glad that you got together with Devon, knowing both of you, I was sure there was just a bit of internet influenced misunderstanding.

And you should know me well enough to know that there's no percentage in this for me to ever talk down another engine builder, so my comments about experience were related to my experience, not anyone's lack thereof..

Without being argumentative, but seeing a "teachable moment" for those looking in, your comments below are interesting.

So.. give me your input on the following questions, with your supposition in mind that both rods feeding off a main will be damaged, if there is a main bearing related oiling issue.

1. Why is it that High rpm race motors hurt number 3 rod bearing, but not number 2? This is a know common problem with race BBB's. I'm talking here about 6800+ rpm motors.

2. Why is it that 100K plus stock motors, almost always take out number 7 rod bearing, but not number six? Another really common problem.

In relation to the cam failure..

While the break in proceedure was unothodox for sure, and certainly camshaft ramp speed can really affect valve float, but I would be surprised if the valves were floating. I say this because the stock 455 had 180# of valve spring pressure on the nose, and Craig has basically stock weight valvetrain components. Craig said they ran a damper, and checked his open pressure at 255# without the inner spring. That should have been sufficent to keep the valvetrain in check.

I also doubt that his motor was held for any length of time at 4500 rpm.. more likely it was just cycled up to that speed briefly.

I beleive his cam failure is directly related to the rod bearing failure.

What's the direct link?

Please, keep in mind I'm not trying to pick on you, or be a wise-ass know it all, but Craig's failure here is a textbook example of why rebuilt BBB's fail the rods when they are rebuilt. I have seen this at least 10 times, in motors that have been give to me to "fix" after they have been rebuilt somewhere else. Every one of them has had either failed or badly stressed rod bearings, and wiped out or on the way out camshafts.


JW

 

Darnit Jim, I already have enough to think about this morning, now this! :idea2:

Sorry for the hijack, Craig...

Devon

 

Not trying to "get" anyone here Chris.. I'm not sure why you think the me trying to make you (or anyone) look bad, does anything but make me look bad. I learned that a long time ago on the internet, and I don't do it.

That's not my intent here..

Let's have an informed, friendly discussion here, that's all I am after.

I'm not saying:

• You cant't run .003 on the mains- you can, but idle oil pressure can be an issue.
• That your wrong, because in this case, you may be right..

But what I am saying is that just because you run .003 on race motors that you should be telling everyone to do that on their 400 HP street motor.

And I am also saying that a BBB is very different in a couple areas, because of engine design, than a BBC. Yes, Round is round, and straight is straight, regardless of engine make.. but there are some critical differences.

JW

 

I would like to take a moment here to thank each of the contributors to this thread. I am currently in the "prepping the block" phase of my +.030 455 project motor for my Riviera, and I have learned a great deal here and on other threads on the board. This is my first 455, having previously built a few chevy's and fords, along with one mopar small block, all street motors, all stock or mildly cammed engines.
I don't have all the fancy tools, and rely a great deal on machine shops that presumably know what they are doing to make sure the tolerances are where they need to be. I have been very lucky in the past, and never had a motor that died a young death.
That said, this motor is going to get alot more scrutiny as it goes together so that it will live a long and happy life in my 67 Riv. The advice and experience that you guys pass on to the members here on the board are making that possible. I just wanted to say thanks. Later, Randy

 

Isn't that a hoot -- I had a 455 done by them in about 1985 while attending GMI in Flint. I pounded the snot out of it for 50,000 miles before wearing the rings out. The same block and forged pistons (old 2362P's) are still in my car today.

 

Bob & Roy sure were a pair. A pair of what I cannot say in "print". My best 'vette customer swore by them until his "freshly rebuilt" numbers matching '67 427 started giving him fits. I'd never seen him so red in the face than the day I showed him the things they'd done to his original engine. What was worse is the denial card they played all the way to the courthouse.

Maybe they had their good days, but I never saw any of them.

Devon

 

They were the owners of Fletcher's. And you're right - the BBC is about as forgiving as any engine out there! I think they had to go out of their way to mess this one up. I convinced the 'vette owner to switch to a little known shop in a quiet little town called Montrose, MI who had always taken good care of me. That car ran like a Swiss watch after that.

Devon