4-bolt cap question - Chevelle Tech
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post #1 of 11 (permalink) Old Oct 8th, 19, 11:32 AM Thread Starter
 
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4-bolt cap question

Hello all, I'm looking at purchasing a '70 854 block. It has been decked, so those numbers are gone, but still a desirable block. I just don't want to overpay for a converted 2-bolt. Suppose to be all original L-78 and everything I see points to that. My question is, what # were the 4-bolt caps that originally came on the L-78. Cast date January of '70. Thanks in advance. Dave.
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post #2 of 11 (permalink) Old Oct 8th, 19, 3:26 PM
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Re: 4-bolt cap question

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Originally Posted by BBdave View Post
Hello all, I'm looking at purchasing a '70 854 block. It has been decked, so those numbers are gone, but still a desirable block. I just don't want to overpay for a converted 2-bolt. Suppose to be all original L-78 and everything I see points to that. My question is, what # were the 4-bolt caps that originally came on the L-78. Cast date January of '70. Thanks in advance. Dave.
Hi Dave, it would help if you were a bit more specific??

Is it now a 4 B.M. casting and you want to know if it started life as an original 2 B.M.?

If so one way to tell is by the sizes of the oil plugs over the oil filter hsg area. An original will be one very large hole (approx 1.125") directly above the filter and a slightly smaller one (approx .875") a bit more forward.

Thanks, Gary in N.Y.

P.S. On a side note we've done a large number of 2 B.M. to 4 B.M. conversions for many Vette owners with the L-88's and the LS-6's. One recent one was a "351" block, another was a "512", but when they need to have the "look" we drill the needed oil passages all the way through and to size so they are actually functional! Labor-intensive, but these guy's just don't care about costs, they want them "OEM" looking! Here's a shot of a 2 B.M., one "medium" hole, one small!
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Last edited by GOSFAST; Oct 8th, 19 at 3:33 PM. Reason: C
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post #3 of 11 (permalink) Old Oct 8th, 19, 4:30 PM
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Re: 4-bolt cap question

If it was an original wouldnt it already be a 4 bolt main?

I wouldnt pay #match unless they had proof of some kind, thats reaching on the sellers end. Everyone had a #match very rare part.
If they did a nice job on the splayed mains it certainly would be appealing .

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post #4 of 11 (permalink) Old Oct 8th, 19, 6:29 PM
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Re: 4-bolt cap question

Quote:
Originally Posted by GOSFAST View Post
Hi Dave, it would help if you were a bit more specific??

Is it now a 4 B.M. casting and you want to know if it started life as an original 2 B.M.?

If so one way to tell is by the sizes of the oil plugs over the oil filter hsg area. An original will be one very large hole (approx 1.125") directly above the filter and a slightly smaller one (approx .875") a bit more forward.

Thanks, Gary in N.Y.

P.S. On a side note we've done a large number of 2 B.M. to 4 B.M. conversions for many Vette owners with the L-88's and the LS-6's. One recent one was a "351" block, another was a "512", but when they need to have the "look" we drill the needed oil passages all the way through and to size so they are actually functional! Labor-intensive, but these guy's just don't care about costs, they want them "OEM" looking! Here's a shot of a 2 B.M., one "medium" hole, one small!

Gary, did my 402 caps a few months ago and I'm very happy with how they turned out. Got everything I needed, very reasonably priced.
I'll be getting the rest of my internals from him as funds come available.

Chris
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post #5 of 11 (permalink) Old Oct 9th, 19, 9:39 AM Thread Starter
 
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It is a 4 bolt and has 964 caps. I was thinking the 70's blocks came with 334 caps?? The maching of the large holes above the oil filter, and the internal holes going through, compare nicely with my 512 and 962 blocks that I know were factory 4-bolts.
Dave.
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post #6 of 11 (permalink) Old Oct 9th, 19, 8:25 PM
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Re: 4-bolt cap question

if your block has the large hole above the oil filter I'd go with it a factory 4-bolt main. if that hole was machined afterward it would still be in somebodies rare high value Corvette.
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post #7 of 11 (permalink) Old Oct 10th, 19, 12:37 PM
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Re: 4-bolt cap question

Here are 2 photos taken of one of my '69 272 4-bolt blocks. This block is dated January '69 and has 964 main caps. The other is dated June '69, and it also has 964 caps. Both blocks retain their original stampings, verifying them as original L78 blocks.
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post #8 of 11 (permalink) Old Oct 10th, 19, 12:45 PM
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Re: 4-bolt cap question

Here is a look at the two pipe-threaded bosses at the rear of this '69 L78 block. The forward of the two ports is used for the oil pressure gauge sending unit. The rearward hole (between the sending unit and clutch linkage pivot ball) sports a square headed pipe plug, just as it did from the factory.
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post #9 of 11 (permalink) Old Oct 11th, 19, 10:13 AM Thread Starter
 
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Quote:
Originally Posted by Tom Mobley View Post
if your block has the large hole above the oil filter I'd go with it a factory 4-bolt main. if that hole was machined afterward it would still be in somebodies rare high value Corvette.
😂 lmao!!

All good info..the reason for my question is "IF" these caps are incorrect, and it started life as a true l-78, why the wrong caps?? I suppose it's ammunition for me to get the price down..plus I'd like to know. I have to pull the trigger or pass this weekend.
Thanks again, and thanks to saltherring for the chevy porn..I'm into the "stock" rebuilds using period correct components.
Dave.
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post #10 of 11 (permalink) Old Oct 11th, 19, 12:25 PM
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Re: 4-bolt cap question

Sounds like it's an original 4 bolt but without the deck stamping it can't really be verified as an L78. Whether it was an original L78 or not is a moot point because it can't be proven and in my opinion the price should reflect. It's just another 396 now.

Since the stamp is gone it can't be a "perfect" restoration. In such case I would buy a cheap 454 and use an internally balanced 4.25 crank and dress it like an L78. Apart from the casting number on the back it will be just as correct as this block without the deck stamp but probably cost less. More power for less money? That's the reason I'm a Chevy guy.

But that wouldn't make it a "correct" restoration either if that's the ultimate goal. I guess that's why I'll never do a "perfect" restoration. The expense of trying to get all the right parts and the pearl-clutching over every little detail is exactly why I love my base model junk.

Sorry about the tangent. I can't help with the caps. I just don't think you should pay L78 money without hard proof that it actually is one.

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post #11 of 11 (permalink) Old Oct 11th, 19, 5:29 PM Thread Starter
 
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Thanks TtC, but I'm not doing a restoration. I build engines for myself, but still want them as correct as possible. Lol, if the numbers were still there, and it is a true l-78, my tight a$$ probably wouldn't cough up the cabbage anyway. I agree, it's just another 402 4-bolt now.
I did search the site for an answer but came up empty.
I appreciate the info guys. Seemed like an easy question, but I guess not. Hope I can help answer some of your questions in the future. Team Chevelle rocks!!
Dave.
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