MYRON Posted March 5, 2003 Share Posted March 5, 2003 Hey guys, I am working on a BBC project. I looked up the casting #'s on this motor and the book says that it is 74-76 BBC "2 OR 4 bolt main caps". It is currently in a vehicle and I cant drop the pan yet. I also noticed on the bottom of the block near the oil filter the words "HI PERF PASS" does this mean that it was from a hi performance passenger car and that it has 4 bolt main caps...... From what I know about GM cars there was NOTHING noteworthy performance wise from 74-76.. They were all pretty much dogs. Any insight would be great..... BTW: if this motor is salvageable it may go in my 78Z project. Myron Quote Link to comment Share on other sites More sharing options...
fl327 Posted March 5, 2003 Share Posted March 5, 2003 i dont think any of the 74-76 have four bolt mains Quote Link to comment Share on other sites More sharing options...
jt1 Posted March 6, 2003 Share Posted March 6, 2003 All the 4 bolt BBC's I've seen have the two bosses cast above the oil filter where oil lines can be attached. Now, one thing for sure, I haven't seen them all. Unless it's out of a vette, camaro, or ton truck, it's PROBABLY a two bolt, but you can never be sure with GM until you drop the pan and look. If you're going with a real strong buildup, a two bolt with aftermarket caps is desirable anyway. If you're looking for 600 hp or less, a two bolt with studs is fine anyway. I wouldn't worry about the 4 bolt too much. John Quote Link to comment Share on other sites More sharing options...
MYRON Posted March 6, 2003 Author Share Posted March 6, 2003 The block does have the 2 extra bosses for oil pressure guages. Any referance to what the "HI-PERF" is supposed to mean?. Did GM ever use forged parts in their BBC's back in the day. The casting on the heads indicates that it is nothing special but they may be off a different motor. they are of the "peanut port" variety. Myron Quote Link to comment Share on other sites More sharing options...
jt1 Posted March 6, 2003 Share Posted March 6, 2003 High perf has no special meaning I know of. A lot of 2 bolts and oval port heads have that on them. It defintely could have a forged crank, but you know, the only way to tell for sure......... John Quote Link to comment Share on other sites More sharing options...
Michael Posted March 7, 2003 Share Posted March 7, 2003 I have a '78 454 from a Suburban. Sure enough, it has the "hi perf pass" casting. My impression is that ALL standard-deck 454 blocks from the 70's had that casting. It also has the oil-line bosses above the oil filter mount, but it's a 2-bolt block with cast crank. I don't know of any post-1973 454 with had a factory forged crank. Forged-crank 454's basically died with the LS5. Heads are 346236 - yours are probably the same. 113 cc oval port heads, but they're not "peanut port"; those are even smaller. Some people claim that with pocket porting and upgrade to 2.25"/1.88" valves, these heads can support 450 hp. That got me confused over the choice to get aftermarket heads, since 450 hp is exactly my goal for the Z. If you do put a BBC in your Z, keep us informed! Man do I have some information on that topic (the hard way....). Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.