Wondering if anyone is using one. I have one and cant seem to get rid of it, so I wanna see about putting money into it, and if it worth it.

 

I believe all small blocks installed in cars and light duty trucks were 2 bolt mains. If I'm not mistaken only the heavy duty trucks got 4 bolt main blocks (2500s and 3500s)

 

From what I understand you can always splay a 2-bolt which would be stronger than a 4-bolt as well.

 

2 bolt here-engine originally was installed in an '84 'vette-vette engine had windage tray and forged TRW pistons,but standard 2 bolt mains.As noted above,4 bolt used on H/D truck apps and certain H/P car apps back in the muscle car era.4 bolt really only a benefit with forced induction or high torque /heavy load trucks

 

ok what would be testing the limits on a 2 bolt and im going to google what "splaying the block" means

 

I've run quite a few of em over the years. Never had a single failure of any kind at any time in any motor that could be attributed to lacking more main bolts.

Splayed: http://www.milodon.com/main-caps/main-caps.asp for example.

If the block won't sell, maybe you're asking too much? What sort of a block is it exactly, what condition is it in, and what are you trying to get for it?

 

its a block from the 70s to the 80s from what I read, had 882 heads on it and its a long block, the guy said it was rebuilt 50k ago. but since looking at the splayed mains I may just keep it now. I want to get rid of the heads for sure

 

You'll spend a lot of money on splayed main caps and the needed machine wok to install them.

Unless you plan on fogging this engine with a ton of N2O, you'll just be wasting money.

2bolt main and some good arp bolts or studs will hold up fine for most builds.

The cast crank and stock rods/rod bolts will fail before the mains.

 

The only thing most people get out of a 4 bolt block is the ability to say that they have a 4 bolt block.

I have one but that was just luck IMHO for 90% of the 350 builds out there you only need a 2 bolt block. Keep the revs below 6000 and HP at 400 and below and it should last forever.

 

I've got a 454 block thats a studded 2 bolt main, and have heard of alot of other people running them. It depends on what your usage is with the motor but if its nothing extreme more than 7000 rpms just stud the mains and be on your way. When i worked at Cummins every motor i saw was a two bolt main but they also don't turn high rpms BUT they run really high cylinder pressures to meet emission requirements set by the epa which puts alot of stress on everything

 

Yea ditch the heads and go with a good set of dart aluminum heads for right under a thousand bucks $. My buddy had a set of those heads and his car smoked like a freight train and somehow ran 13.3s. We swapped those heads and put a Comp XE274H in it and it made all the difference.

 

yea I heard some people have said its just for the ability to say they have a 4 bolt, but what I want to do is dd it and occasionally go to the drag strip but most of all be reliable like my 305 lol.
So midias said keep it under 400 hp but with a 4 bolt you can go well past that?

 

It is not all about HP I was just speaking generally.

The balance of the rotating assembly contributes a lot and so does max RPM.

if you are not going forced induction or spinning above 6k RPM you are probably not going to be making much above 400 anyway so the 2 bolt should work fine.

 

Afaik all L98's were two bolt main.

You'll be fine. Buy some good arp bolts or studs like I said, if you're worried.

 

Don't use the 2 bolt main 350, they like blowing up when you pass someone on the highway.

 

NOT!!!.I'll stake 50 yrs of building engines on that.

 

I was joking on the last post. Its funny how people convince themselves they need to have the best parts when the "lesser" parts will do the same job just fine. In this situation, I guess the 4 bolt main gives people an added sense of security when the 2 bolt main was good enough.

 

that was anther thing I was going to say, weren't the L98s 2 bolts.

 

Yes, they were. The motor I built was a 2 bolt L98 that came with the car. I have an estimated 400 hp, and I've had no problems with the block. I was even going to put a supercharger with 4-5 psi of boost through that motor.

 

did you? so with boost you can run just a small amount but that's with arp studs

 

You'll be fine.
Are you rebuilding this?

Most recommend line boring if you are going to studs.

 

If there is no evidence of prior main bearing damage,studs might be the extreme too.They don't do a thing for the main bear saddles or clamping of the bearing.Where ARP bolts are more than enough insurance.Main thing is to have a trusted machine shop check parallel of the crank center to the deck.Thing to remember is when you line hone,your somewhat moving the crank up into the block which could effect timing.So if you don't need it,don't do the line hone.There have been tons of hp high 300's,lower 400's that have been run without any mods to the mains.You find the most main bearings spun as a result of poor cleaning during the build and some junk got between the crank/crank bearing causing heat which caused wear and the clearance opened up and the bearing spun.A good practice is even after the block has been machined and hot tanked(really the other way around)to rife brush clean the oil passages is appropriate.

 

The 2 bolt is just fine. I've only had one 4 bolt in the engines
I've built, not that I've built hundreds of them probably closer to a dozen. I agree most people like saying they have a 4 bolt main. I have had a machinist actually tell me not ever bother with it, He said if your really making crazy power then a 2 bolt splayed or better yet an aftermarket block is the way to go.


Mark.

 

thanks guys!
im going to put my lt1 back together and go to the machine shop after and talk numbers

 

How much money do you plan on spending on this LT1? Could make more power on a cam only ls junkyard build

 

A cam only LT build is going to be a lot cheaper to put into the car than a cam only LS swap, especially if he has ANYTHING invested in the Gen I platform.

That said... I see he has a T5. He needs to decide if he wants to replace T5's forever or spend on a T56. If you're spending the $800-$1500 on an LT1 T56... you need to take a long hard look at whether or not you want to do an LS swap. I'm probably going to do an LT swap at some point just because of what I've got invested in my T56. Cam only LT1 can do 350-400hp.

Also, for what it's worth, I'm running a 2 bolt block myself. Nothing extreme, though.

 

No the lt1 is in my other Camaro, it was my fathers car. I just had to replace the seals on the intake cause it was leaking oil in the back, and I didn't get a chance to go to the machine shop.
My trans will be rebuilt stronger later on for the 350 I want to put in it, its a good trans lasted this long with 200k on it so its good for me.
An ls swap would be nice and all but im not making boku money so that'll have to wait.

 

You're getting a lot of conservatism in the replies above concerning power and rpm limits for a factory 2-bolt main block. BUT......they're steering you right

Just to give you MORE assurance, I've been spinning my 2-bolt main rebuilt LT1 to 7000 rpm for 3 years, a couple hundred dragstrip passes and some roadcourse duty, about 540 crank hp, and a few times up to 660 hp on the spray. Stock main bolts - no issues.
I HAVE seen evidence of cap walk on a 7000 rpm 383 assembled with stock caps and ARP bolts. It's rpm that stresses the bolts more than hp output does.

 

thanks 86, once I get time ill go talk to some people bout the engine. thanks again to all of you!