Hey guys, i was looking into an engine swap and had a couple questions. I had a L03, but its just done. I have an LT1 from a 4th gen. Thats in its 2nd chassis though.

I want the most durable engine i can get. Haha Would LOVE to find an LT4, but i dont think its possible. Found some 4 bolt mains on craigslist from late 70s, research suggests L48. So i was wondering if the L48 would be more durable than the LT1? Or, besides LS, there any other F.I. 4 bolt mains out there? I didnt see any while looking but thought I should ask.

 

On a NA application where you're not revving way up 6500+ regularly....a 4 bolt isn't necessary. Personally, I'd stud a 2 bolt and feel secure through most situations given the reputations out there.


Post '95 3/4 and 1 ton vans and trucks often came with 4 bolt blocks. You could look for one of those. Oddly enough after my 2 bolt support statement, I use a 1 ton, 880, 4 bolt block in my '92.


And not that it matters but, LSx are 6 bolt not 4 bolt.

 

Depends on the application RPM, HP and stroke all play a factor on which block to use.

On those LT-1s I have installed alot of 4 bolt splayed caps on those blocks because guys were going to a 3.750 stroke.

I have seen what happens when guys use a 2 bolt where a 4 bolt should be used.

http://ls1tech.com/forums/advanced-e...ever-seen.html

 

Wow great info in there! I read that thread and the linked thread in there hahah So splaying the LT1, would that make it stronger than a 4 bolt? Also, I know a guy selling a 400sbc. It seems that is a different animal all on it owns. I heard some bad things about 400s though, but the chevelle forum said theyre stronger than 350's?


I should add; I want durability for sure, but on a 3000 budget TOTAL. I want F.I. even its its TBI. I was hoping to get 300hp without doing... Well the bottom lol but minimal top end work.

 

I'm going to go out on a limb here...
If your budget is 3 grand, I wouldn't be worried about a 4 bolt main. And the 350 vortec motors came 4 bolt in 3/4 ton trucks, even after 1995.

I'd be hunting for a late model roller block (as in an L31; short blocks can be identified by the 3 pedestals that are drilled and tapped in the lifter valley; directly under the intake manifold.) I wouldn't be crazy concerned about finding a 4 bolt main unless you can locate one close to price of a 2 bolt. On a 350 that isn't pushing close to 7,000 rpms (and is properly balanced) or a tremendous amount of power, I wouldn't worry about it! We've ran a L31 longblock deep into the 11s on a half ton 2 bolt block.


Edit: if you want to keep tbi, I'd probably do an L31 with a cam and the proper vortec to tbi manifold. 300 hp should be very easily attained.

 

 

400 blocks are a very frail block Big cylinder bores make for a weak deck that is cracked most of the time, Bores make for weak webbing, Big main line housing bores make for a weaker main webbing.


Very few 400 will pass a sonic test !!!


I would have to say the 350 block are a much strong block.

 

I ran a stock SBC bottom end at 500 hp plus a 125 shot with no issues. A good top end on a 400 will make a 350 look silly

 

3 grand now doesnt mean thats all forever. I was hoping to get 300HP on the initial install. I eventually want 500ish. I need to get my trans and rear end done first.

The only reason Im thinking about Gen1 blocks is the 4 bolt, not tbi.
(4bolt > 2) / (port > tbi)
(4bolt > port)
Is my thought processes here. Didnt know L31's came in 4 bolts! 255HP? I can get behind that. Is that the '880' Alice has? The infinite wisdom here phenomenal lol


Not to ignore the inquiries about the 400, its my least favorite option. 2 bolt with 66k miles. Unless i get lazy, id rather splay my LT1 and deal with the harness headache.

 

i wonder if you can get an assembled dart SHP shortblock for that price/budget? might be a smart move especially if you plan on adding much more power later.