Billett mains or not?

T

turbobuickman

Member
Joined
Mar 8, 2002
Im building an engine for 99% street duty but hopefully capable of 11s reliably. Im probably gonna go with stock crank and rods with some good forged pistons. My question is do I need billett center mains for my goal? Im pretty sure a full girdle is not neccesary but still cant decide on the caps. What can I expect to pay for the two caps and machine work (align bore/hone) and would it be worth it? Any other possible complications I am overlooking besides an under timing set?

TIA
 
Thats good reading but I was wondering if I should get steel mains or use the stock ones. That discussion was mains vs girdle. Also, my block and stock caps are in near perfect condition and I wont be racing the car often if at all. The question I'm asking is...is it worth the extra $500+ and risk of a bad line bore/timing chain issues if it doesnt need a line bore now?
 
87we410877 said:
Alot of this is discussed in here. Ide do the caps if i were you. Take a job big or small do it right or not at all.

http://www.turbobuick.com/forums/ge...-tight-budget.html?highlight=gurdle+main+caps
Click to expand...

That thread looks familiar :biggrin:

FWIW ... due to my budget... I am going back with a stock bottom end.....all my reading suggest that low 11's... high 10's on a few track trips a year... it will live for awhile....just don't detonate it or run it lean. I am going to start to accumulate parts for a spare engine... with a girdle probably...and maybe a roller cam....

Of course.... if you fot the $$.... why do it twice....
 
Exactly the kind of input I was looking for Blazer, thanks. I am indeed on a budget and I certainly don't beat the piss out of my car like a lot of the guys here so I'm leaning towards stock bottom end for now. Anyone else been down this road before willing to share their wisdom?
 
Ide do the caps either way. I hate thinking about engine parts when im getting up into boost. But then again, if your on a budget, caps need align hone, that may lead to an undersized timing chain, crank cutting/polishing, searching for bearings and so on. Let us know how it turns out.
 
Insurance my friend. I wish i had taken some pics of my engine when i pulled it apart. completely stock motor with hooker down pipe with delta gate. street performance chip. blue top injectors. 25psi broke all but rear main cap:eek: .engine did have 130,000 and i did beat the crap out of it but that when i was much younger and much dumber. so i went with three caps and left rear main stock.I was even thinking of using a girdle to. but i heard the leak alot.it would be nice if the caps were a little cheaper. But then again nothing on these cars is cheap.lol
 
im doing two billet caps in my motor but im getn a steel crank also. i talked to Dan Strezo at DLS about this for awhile and he tells me the prob with the cast crank is they flex under load which is what kills the bottom end. if i were u id do the girdle if using a stock crank, and 2 billet centers if using a steel crank as it flexes much less. also he tells me since the 2 center caps carry 70% of the motor load they are all thats needed when using a steel crank. if youre only wanting to go 11s you would be fine leavin it just like it is, however, girdles are proven and will add a lot of reliability.
 
I'm not going to argue that caps or girdle isn't a good insurance policy.....

But I willsay this:

Razor told me the engine that was in his TTA last year at the nats... that won the pump gas/alky class.... that ran 132 mph in the quarter many passes that weekend..... had a stock bottom end... no caps or girdle... 10.50's @ 132 and change. I'm not suggesting it will last forever......just that treated properly... it will last awhile.....

He wasn't advocating that it wasn't a good idea to run caps or a girdle.... just that for occasional track visits.... you don't have to have it for low 11's ... high 10's.....properly tuned...
 
Here is how I look at it.

For your goals the stock bottom end will work just fine. If the engine is in and running fine then there is no need to pull it just to do caps. However if you have the engine out for a rebuild, I always have my customers put in the center caps. If looking for 10's, I will stck in the 1,2,3 just for safeties sake. Remmember these are not bolt in. They mus be fit to the block and then the mains have to be align honed and the align must be checked for accuracy. If going low 10's plus then a girdle is in order and I do not use the billets unless they are already installed. The girdle requires the caps to be machined.


hope this helps
 
turbobuickman said:
Exactly the kind of input I was looking for Blazer, thanks. I am indeed on a budget and I certainly don't beat the piss out of my car like a lot of the guys here so I'm leaning towards stock bottom end for now. Anyone else been down this road before willing to share their wisdom?
Click to expand...

ummm we beat the hell out of my new TTA for 5 years in the 11s with the stock bottom end :cool: sounds like your not goin to be pushing it like others have :biggrin:
 
Use the stock bottom end with some good bolts as suggested. Spend your money on a good tune and scan tool.
 
turbo buicks said:
im doing two billet caps in my motor but im getn a steel crank also. i talked to Dan Strezo at DLS about this for awhile and he tells me the prob with the cast crank is they flex under load which is what kills the bottom end. if i were u id do the girdle if using a stock crank, and 2 billet centers if using a steel crank as it flexes much less.
Click to expand...


The steel/forged crank flexes just as much cast. It can withstand much more abuse/power before breakage occurs. Key is to prevent main cap walking. When the caps walk or lifts off the block, that's when the weird stuff happens. After the walk, typically there is material transfer between the caps and the block. The caps will no longer be flat. It's like trying to torque down the main caps with bumps on the flat machined surfaces.
 
Being the caps (steel) are harder ,does it affect difficulty of align boring? guess i,m asking if it is easier to mis-align bore with steel caps?
 
Go with caps for sure.

It was told to me that the stock cranks will flex when being pushed real hard, which in turn will wipe out the bearings under repeated abuse. Since I already blew up a stock motor, it was easy to use two center steel caps (got mine from Weber Racing). Now I bought a steel crank to make double sure that the crank wont flex, but I would think since ur sticking with a stock crank, u might as well buy the front steel cap also, its real cheap. The rear cap is the costly one. A perfectly tuned car is not as hard on the parts and will last longer, but I dont think anyone out there can say they have a perfectly tuned car if they are tryin to go faster and faster, cuz its trial and mostly error when tuning for E.T. Call the guys at Weber Racing and ask them, they will give it to u straight with no B.S.
 
From an engineering point ...... (gotta use my engineering degree ... for an opinion sometimes)..... the caps only strengthen up that cap.... it is still bolted to the block which is somewhat weak.... If you were to model the block as some sort of beam... with loads placed where the caps are... going down toward the ground..... the deflection (the amount the block would move) would be almost the same with steel caps as with stock caps. The steel caps just won't deform (and therefore "cap walk") as easily..... The girdle however does increase the (engineering term) "section modulous". This helps keep the block from deflecting.... the more section modulous you can increase.... the less total stress the block "sees" and therefore doesn't deflect as much.

IMHO from an engineering point.... the girdle is superior in actually upping the overall strength as compared to caps only.

HTH
 
With billet caps and ARP main studs and a billet crank-how much can the block really deflect? it seems like it must be very minimal.at what power levels could deflection really play a part in cap failures?
 
I dont think a steel crank is part of his build.

49-blues said:
With billet caps and ARP main studs and a billet crank-how much can the block really deflect? it seems like it must be very minimal.at what power levels could deflection really play a part in cap failures?
Click to expand...

With the prices coming down soo far, I would think that all rebuilds would have a steel crank, its like stocking up on ammo, now that the Dems control congress! Better to be safe then sorry.:D Im just kidding!
 
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