2 bolt main block
 

So i got this 350 out of a 93 yukon...the engine was still running when it was pulled out but i wanted to start a summer project so i proceeded to tear it down.

after stripping the block down of literally everything i noticed that its only a 2 bolt main:-x now i had a goal of 550 to 600 horses so i dont think 2 would cut it....i'd need at least 4..

so my question is...can you stregnthin the block or convert it to 4 bolt to handle the power or is it just too much work and not worth it?

and im just wondering how much do you think a 2 bolt main would hold up to roughly?

summit makes 4 bolt main conversion i did it to my 350 block the 2 outer bolts are on an angle and they claim its stronger than a factory 4 bolt main setup the kit wasnt much but i had to get it line bored, but i did a bunch of machine work to the block. i think the line bore was 200 or 400 bucks

i can take some pics if you would like

A machine shop can set you up for splayed caps. JohnJZ and/or Josh will kick their $0.18 in here soon, I'm sure.

2-bolts can handle a lot of hp - is 550-600 really what you are planning? I might thinki you are beginning to lean into aftermarket block territory at 600+. But I'm no expert. I just try to listen to them.

thanks bonzo and your correct = today with the cost of a new casting and the kind of HP you want, a late 2 bolt one piece seal block is not the way i would do it, the first thing if its what you are going to use, is to do is have it sonic tested and that will tell how thick it is in the areas needed for such power, Line honing in my opinion is a last resort to a block that has passed all checks and has much invested in it like alloy rod clearencing, tapped vent valley holes with 3 inch standoffs, epoxy magnets with a screen kits installed ect ect kind of thing -- now splaying can be done on a bridgeport using a blank cap from another motor, and shoot the holes on angle 3/8 X 16 -X 2 1/4 G9 12 point socket head screws, is what we have used and yes the crank is then held in place better BUT it ALSO saves having to have a high end timing chain with a .005 smaller chain on the cam to make up the difference the line honing takes away -- good luck with that -- jz

For a decent street car.... 2 bolt is FINE!

I love it when johnjz posts, it saves me typing....

There are other things to consider than hp - cubic inch, stroke, type of induction and use are all factors that will help you in selecting what type of block you want to start with..

i was actually thinking that a stock block might have been a waste of time but the price was right....and ive seen people get that much power out of the 70s 350s

if i keep it im gonna send it out to get sonic checked and boiled...i have not been lucky in finding the parts to strengthen the block so if any of u guys got any part numbers or URLS to share i would greatly appreciate it.

i also heard of a thing called a girdle that bolts into the pushrod valley to add more durability so im tryin to find that 2

http://www.jegs.com/i/Eagle/356/C4102S/10002/-1 different brand but same exact design

I would go for the Milodon over the Eagle ones.

Even then- for the price of doing this right, you could find a 4 bolt block. I bought and sold a few of them for around $150-200.

milodon is the brand i got i just couldnt remember lol i posted that link just to show what they look like thx!!

i also heard of a thing called a girdle that bolts into the pushrod valley to add more durability so im tryin to find that 2


its called a stud girdle -- and you only need it with a big solid lift roller cam that requires a lot of spring pressure 200 on the seat 500 open type of thing -- jz

i saw that on horsepower tv last weekend

looks cool but i dont know if its worth the effort...if i went with that i may just have a machine shop install it..

i guess my pipe dream may just have to go on hold just a little bit longer

i did it myself other than machining its not hard just mark the drill bit with tape so you dont go to far...comes with everything you need.

you do know its 600 bucks to install them and have the block than line honed and the special timing chain is 155 bucks < plus boiling and sonic testing 125 / boiling 85 bucks and you still have a weak one piece seal 2 bolt block that is prone to cracking when the power out put goes over 475 HP i dont get it -- jz

DITTO!!

now now John, as I have stated earlier, the engine in my IROC is the original 2 bolt block from 88 with a billet splayed main cap set on it. It consistently makes power over the 800 range and works just fine.. Not to say it doesnt have some trick machine work done but the point is that the late model stuff is capable of holding some decent power..

hahahahha you did not say anything about the week you might have spent on the block removing every sharp edge, or the fact you might have had it cryoed or shot peened as well -- as a professional builder you know how to treat a real motor, and can in fact keep it at that high HP range use it and race it , that a young guy street driving a home built toy wont get the power or the life from it compared to someone like you << not fair <<<< hahahhahahahah -- i could be wrong but we do the same things, its because we can -- jz

where is my cat??!! dammit, you let it out of the bag again!!

needless to say there is quite a bit of info for me to ponder here hmm

thanks for the input fellas

I have a 4 bolt main short block for sale.

There is a guy on LS1LT1.com that runs a two bolt main LT block with over 800hp and he races it. So food for thought. Also, I have heard that it is better to add the 4 bolt mains going straight versus slanted if that makes any sense.

If you are going to convert a 2 bolt block to a 4, the splayed caps are a better choice than just running another set of bolts in straight.

- Justin

Well at least for the LT block, there is more "meat" to be tapped into running another bolt parallel to the original versus splayed. It was in an article somewhere, I forget.

what do u want for it?