"Sooo what is the strongest combo you ask??? a two bolt main converted to a four bolt with outer splayed bolts is the answer."

I had never heard this before. I have heard of drilling a 2 bolt to make a 4 bolt, but I had no idea of the effectiveness.
I was always told it was a "Bubba" thing.
Makes dang good sence to me, thanks for the great info.

So,....does this apply to BB's too?

 

No it does not apply to CBB only CSB.
You can find these engine set-ups among the professionals quite often in 'under financed teams' but they will run like a scaulded ape with no drawbacks or problems, other than a dent in the wallet.

 

[align=left]You are absolutely right about the 2 bolt conversion... it would be stronger. And Dave is right... 4 is a better platform for building high hp motors. If doublewasp's is an original 4 bolt like mine... it will be an extremely rare one like mine seems to be. I have been looking for 7 years now for others. I have been in touch with the NCRS judge for '73-74 Vettes, and he has been looking also. This was news to him when we first talked, and now after 5 years, he has not found another like mine. Doublewasp's sounded like a likely candidate because of the lack of options. His sounded like it was a COPO car ordered for drag racing. I sure hope he comes back to the forum... I would like to hear what he finds. And no matter what... I don't think I'll be posting this question on that 'other' site...




[/align][align=left] [/align]

 

Hey Wedge, Theblock for my '73is a '73 4 bolt LS4 corvette block. It is not the original although the caris an originalLS4 454 4speed, I don't know if it had a 4 bolt or 2 bolt from the factory. The webbing is Identical to a 2 bolt block just with the bolts drilled at the factory. The blocks are the same with the exception of the mains and the oil cooler holes. It would be really easy to convert one and no one would be the wiser. So whats real and whats not?....go figure. The two bolts are pretty meaty in their own right. Take alot of abuse to granade it.

 

Yeah... good point. The castings were virtually the same. I have been told by one of the racing program directors (now retired) that because of the nature of the oil galleys cast in 4 bolts, they could not just be re-drilled or duped in a 2 bolt block. Even if it was done it would be a whole lot of work, and money for bragging rights that really don't matter... The 4 bolt galley configuration was for external sumps or oil coolers. Pro Team sez 2 or 4 bolt don't mean diddly, that Chevy did all sorts of strange stuff back then. At this point, I'm just looking to see if anyone else has one! Keep in mind that this isn't the only- after LS6 4 bolt block. Others were made for truck applications in those years, but they weren't LS4's, and the replacement LS4 3999389 that Chevy did offer had a suffix code of CE instead of CWM,CWR,CWT or CWS.
Oh, and BTW... I already voted for yours this month... good luck and hope you win!
[align=left] [/align]

 

So the internal oil passageways are bigger through out the block or just at the hole? If so that would mean completely different tooling. They didn't have lost foam back then. So one would have to look deeper internally at the three oil cooler holes to see if a block has been converted? I'll have to check fora suffix code on mine and see if it is an original or replacement if not converted. I checked mine against the numbers on a site(Don't remember the name) and according to them it was an LS4 block. In your search I'm sure you have come across a definitive list of numbers. Can you post them? I wonder how rare a replacement LS4 4 bolt block would be....any figures on that? I know the story that they only used the 4 bolts from the racing program because they ran out of production blocks, but if they were out of production 2 bolt blocks, where did the '73 replacement 2 or 4 bolt blocks come from?....Racing or the truck line I would imagine. Be kinda neat to find that out. Run across any info on that in you quest?

Thanks for the info. I love learning.

And thanks for voting. I never thought my C3would get more than one or two votes considering the competition. Cheers

 

[align=left]The 4 bolt block LS4 was based on the 39633512 LS6 block. It was re-cast with the 3999389 LS4 casting number, but for all intents was a LS6 block. The 2 bolt block did indeed have different galley routing internally, and could be mimicked by re-tapping larger holes and drilling into the crank space, but it would not be the same as the original 4 bolt cast. As far as a definative list, the only LS4 is casting # 3999289. The suffix codes on the stamp pad used to match the vin number is what seperated them by option. CWS was California LS4/auto; CWT Cal. LS4/4spd; CWM 49 state LS4/4spd; CWR 49 state LS4/auto. I am not too sure about the castings of the CE block. I found out about them through Mortec (mortec.com) and the guy there wasn't in a giving mood... and I believe the date codes are later, cast in '73 and '74. My block was actually cast in '72 for the '73 production run. I posted the locations previously in this thread, along with how to decode a date stamp. Let me know what you find...
As far as numbers of replacemant CE code blocks... NFI (no ****** idea...) I don't think Chevy even knows that now. Their record keeping skills were and are for crap. The actual number of 4 bolts were somewhere around 250 (I heard) and they went into drag racing, the NASCAR program and even boats. Supposedly 12-16 were transferred to fill late production orders when they ran out of their stock of standard blocks. I was in contact with a guy who worked with some of the Baldwin Motion Vettes, and he was a treasure trove of info. I tried to reach him last year, but he passed away. He said "some" of the BM Vettes and Chevelles had 4 bolt blocks... but not all of them, and all were all COPO cars not off the lots. I wish I could get some info from the Yenko owners, but I think that program ended somewhere around '72. Any ideas on that?
Later... time for bed!
Wedge
[/align][align=left] [/align]

 

What about the "low deck" VS "high deck"?
What exactly, are they?

 

Mortec, That's the site. according to them some casting numbers could be 2 or 4 bolts, if I remember right. I'll have to go out and take a look real close at mine. you've got me curious now. Cheers

Ps to the OP...Sorry if we hijacked the thread. It's just interesting stuff.

 

Finally got my pan yanked, and it most certainly is a 4-bolt. Pretty interesting. I like this car just a little more now.

One more question. What's the handling like between a big block Corvette and a small block? Does the extra heft really make things that much worse off?

Thanks