4 Bolt Main Caps
Thread Starter
Instructor
Joined: Mar 2003
Posts: 176
Likes: 0
From: Holtsville NY
4 Bolt Main Caps
If I understand this correctly in LTx applications
Y-bodies came with 4 bolt mains, and F-bodies came with 2 bolt.
When Building an engine it is more desireable to get an F-body block so you can put 4 bolt splayed mains on?
Can you put 4 bolt splayed mains on a Y-body engine?
Also most crate engines seem to come with some type of upgraded main caps they seem to only do the three middle ones.
Why? I know it is harder and costlier to do the two end ones but what are the gains or losses of doing them or not?
It would seem that if you are building a hardcore engine it would be good insurance?
Thanks
Y-bodies came with 4 bolt mains, and F-bodies came with 2 bolt.
When Building an engine it is more desireable to get an F-body block so you can put 4 bolt splayed mains on?
Can you put 4 bolt splayed mains on a Y-body engine?
Also most crate engines seem to come with some type of upgraded main caps they seem to only do the three middle ones.
Why? I know it is harder and costlier to do the two end ones but what are the gains or losses of doing them or not?
It would seem that if you are building a hardcore engine it would be good insurance?
Thanks
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Re: 4 Bolt Main Caps (Epyon127)
Huum! back in the 60's I was always building 2 bolt mains-had them built to turn 10k RPM, never had a problem, I forget what year they switched to 4 bolt mains (by the way I'm referring to small blocks only). Later the general went to 4 bolt-I'm not sure what yr. without looking it up, but hey-4 bolts were definitely stronger :rolleyes: but you know-I never have launched a crank :hurray:
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: 4 Bolt Main Caps (Epyon127)
If I understand this correctly in LTx applications
Y-bodies came with 4 bolt mains, and F-bodies came with 2 bolt.
When Building an engine it is more desireable to get an F-body block so you can put 4 bolt splayed mains on?
Can you put 4 bolt splayed mains on a Y-body engine?
Also most crate engines seem to come with some type of upgraded main caps they seem to only do the three middle ones.
Why? I know it is harder and costlier to do the two end ones but what are the gains or losses of doing them or not?
It would seem that if you are building a hardcore engine it would be good insurance?
Thanks
Y-bodies came with 4 bolt mains, and F-bodies came with 2 bolt.
When Building an engine it is more desireable to get an F-body block so you can put 4 bolt splayed mains on?
Can you put 4 bolt splayed mains on a Y-body engine?
Also most crate engines seem to come with some type of upgraded main caps they seem to only do the three middle ones.
Why? I know it is harder and costlier to do the two end ones but what are the gains or losses of doing them or not?
It would seem that if you are building a hardcore engine it would be good insurance?
Thanks
Some of the newest Vette engines have 4 bolt caps, but not the earlier ones.
Yes, 4 bolt caps can be added; I'm using Oliver's on the center 3 and studs on all five.
The general consensus is that two bolt blocks are the most desirable, over 4 bolt blocks. A two bolt block is stronger (better casting) and after adding 4 bolt caps to the center three, it is much better than a four bolt block.
I suspect that the center three are the only ones that get the four bolt caps is due to chassis/oil pan clearance problems.
Jake
Melting Slicks
Joined: Jan 2002
Posts: 3,159
Likes: 0
Re: 4 Bolt Main Caps (rick lambert)
Huum! back in the 60's I was always building 2 bolt mains-had them built to turn 10k RPM, never had a problem, I forget what year they switched to 4 bolt mains (by the way I'm referring to small blocks only). Later the general went to 4 bolt-I'm not sure what yr. without looking it up, but hey-4 bolts were definitely stronger :rolleyes: but you know-I never have launched a crank :hurray:
its overkill for most motors. Its a lot like the wonderful idea that everyone needs forged internals on their 450hp rebuild :rolleyes:
I think Rick's answer begs the question, "what kind of power are we looking at here?"
Le Mans Master
Joined: Jun 2002
Posts: 6,097
Likes: 0
From: High Plains Drifter Fayetteville, AR
Re: 4 Bolt Main Caps (Epyon127)
Can you put 4 bolt splayed mains on a Y-body engine?
Thread Starter
Instructor
Joined: Mar 2003
Posts: 176
Likes: 0
From: Holtsville NY
Re: 4 Bolt Main Caps (TreyZ28)
The consideration was really towards reliability and durability at high RPM on a 396 LT1/4 buildup.
I would like 500 HP and maybe 7000 to 7500 RPM, but I know it all depends on components.
I was interested in the strength of the bottom end and its relationship to the main caps.
I have heard that a stock LT1 will not sustain more than 6300RPM.
Thanks for all the replies
I would like 500 HP and maybe 7000 to 7500 RPM, but I know it all depends on components.
I was interested in the strength of the bottom end and its relationship to the main caps.
I have heard that a stock LT1 will not sustain more than 6300RPM.
Thanks for all the replies
Safety Car
Joined: Mar 2000
Posts: 3,581
Likes: 1
From: Springfield VA
Re: 4 Bolt Main Caps (Epyon127)
Well this is opinion so take it for what its worth...
The limiting factor on a 350 over 6300rpm is the valve train, not the bottom end. I've seen 327s and 350 spun up to 7500rpms regularly with 2 bolt mains and good head / valve train combinations.
396s are different animals. The stroke of the 396 puts added stress on the crank, bearings, and connecting rods. Short duration blasts up to 5800 - 6000rpms (1/4 mile) and two bolt mains are probably okay. 20 - 30 minute stretches with the rpms running up to 6200 - 6800rpms (road course) require 4 bolt caps or you will see problems.
The limiting factor on a 350 over 6300rpm is the valve train, not the bottom end. I've seen 327s and 350 spun up to 7500rpms regularly with 2 bolt mains and good head / valve train combinations.
396s are different animals. The stroke of the 396 puts added stress on the crank, bearings, and connecting rods. Short duration blasts up to 5800 - 6000rpms (1/4 mile) and two bolt mains are probably okay. 20 - 30 minute stretches with the rpms running up to 6200 - 6800rpms (road course) require 4 bolt caps or you will see problems.
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