1967, L89 Aluminum heads: painted or natural finish?
Collapse
X
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
Joe-- Thanks for the confirmation. Was that also true of 1968 when there were a considerable number L89's?- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
Yes, it was the same for 1968-69 L-89, although different front springs were used for all Corvette applications except F-41 for C3 Corvettes. As far as I can tell, it was also the same for 1971 LS-6 for those cars not equipped with F-41.In Appreciation of John Hinckley- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
Wayne-----
Yes, I expect that the 60 pound difference was not enough to trigger the need for a spring change. Actually, the overall difference in weight between a 1967 L-36 and a 1967 L-89 would have been a little greater due to the difference in intake manifold material.
I have mused about this issue before. However, the focus of my speculation centered on what springs a 1969 ZL-1 would have used IF ZL-1 had been available with standard suspension? A fully dressed out ZL-1 engine weighs slightly less than a base engine small block. So, if the ZL-1 had been available with standard suspension, would it also have used small block springs? My guess is that it would have. Of course, it can only be a matter of conjecture since what never was can only remain what never was.In Appreciation of John Hinckley- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
Wayne-----
Yes, I expect that the 60 pound difference was not enough to trigger the need for a spring change. Actually, the overall difference in weight between a 1967 L-36 and a 1967 L-89 would have been a little greater due to the difference in intake manifold material.
It also shows a spring rate of 250lb/in for small blocks and 284lb/in for big blocks, with the same compressed length of 9.99 inches for 1968. It does not translate it into wheel rates.- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
A 1977 NCCC publication called "Corvettes Technically Speaking" which seems to be a compilation of MVMA specification sheets lists the weight reduction of the aluminum heads alone as an option on the L71 in 1968 as 73 lb (68 front, 5 rear). This is easy to believe if you have ever lifted L71 and L89 heads side by side. For context, it shows an increase in front weight of 76 lb for A/C, 151 lb for 427/390, 126 lb for 427/435.
It also shows a spring rate of 250lb/in for small blocks and 284lb/in for big blocks, with the same compressed length of 9.99 inches for 1968. It does not translate it into wheel rates.
Want to have some fun: run the weights for 1969 L89/M40 loaded with PW/PS/PB. I was amazed at how heavy, in spite of the aluminum heads. Maybe I am just easily impressed.Terry- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
A 1977 NCCC publication called "Corvettes Technically Speaking" which seems to be a compilation of MVMA specification sheets lists the weight reduction of the aluminum heads alone as an option on the L71 in 1968 as 73 lb (68 front, 5 rear). This is easy to believe if you have ever lifted L71 and L89 heads side by side. For context, it shows an increase in front weight of 76 lb for A/C, 151 lb for 427/390, 126 lb for 427/435.
It also shows a spring rate of 250lb/in for small blocks and 284lb/in for big blocks, with the same compressed length of 9.99 inches for 1968. It does not translate it into wheel rates.
Although it would seem that the AMA specifications, the bulk of the contents of the "Corvettes Technically Speaking" tome ought to be authoritative, there are a number of errors I have found there. I don't know exactly why this occurred by I postulate that these specs were put together sometime well before actual final production decisions/configurations were established. One glaring error that I do recall is that these AMA specifications say that 1968-69 Corvettes with THM transmission were equipped with CCS exhaust emission controls and not AIR. NO 1968-69 Corvettes were built with CCS and without AIR, although most other Chevrolet cars were equipped this way for 68-69. There were other errors in the specs that I have found but I do not recall now what they were. But, I've found enough of them that I do not consider these specs to be reliable enough to take as "gospel".
However, the weight specs that you're referring to seem about right. The 76 pounds is the amount that C-60 adds over standard engine configuration. These additional 76 pounds result in a different front spring for small blocks with C-60 versus those without. The 76 pounds would also be ADDED to the weight of the L-36 or L-68 (C-60 was not available with L-71). The big blocks without C-60 used a spring different than small block OR small block with C-60. Big blocks with C-60 used a different spring than big blocks without C-60. So, everything "fits" with respect to the weights you've pointed out and the springs that were used.
Is it possible that L-89 could have appropriately used the small block with C-60 springs? Yes, it's possible but I have absolutely no information that would support that other than my conjecture. As far as I can ascertain there were no other springs available in the "parts bin" for Corvettes at the time. Every indication that I have supports the position that the same standard suspension springs used for other big blocks were used for L-89.In Appreciation of John Hinckley- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
I also found errors in the 1967 AMA package from GM.
The 1963 AIM calls out a special spring by part number for Z06 and for C60 on the front shock & spring page (Section 3, Sheet 4), but the 1964-1967 AIMs show a Spring Chart. According to the Chart, all 1964-67 standard production small blocks use 3851100 front spring, only L36 (and presumably L68) use a unique front spring when C60 is added. The C60 section Contents page only references the Spring Chart on the standard production front shock & spring page.
If correct, it seems this might result in a '67 small block with C60 sitting a little low in the right front, due to the extra weight and location of the A6 compressor.- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
Joe,
I also found errors in the 1967 AMA package from GM.
This was one of the first apparent errors I discovered in the 1967 AMA specs. It shows different front springs being used for a '67 small block with C60. But if I understand correctly, ALL midyear small blocks from 1964-1967 (not counting F40 or F41) used the same GM 3851100 front spring, with OR without air conditioning.
The 1963 AIM calls out a special spring by part number for Z06 and for C60 on the front shock & spring page (Section 3, Sheet 4), but the 1964-1967 AIMs show a Spring Chart. According to the Chart, all 1964-67 standard production small blocks use 3851100 front spring, only L36 (and presumably L68) use a unique front spring when C60 is added. The C60 section Contents page only references the Spring Chart on the standard production front shock & spring page.
If correct, it seems this might result in a '67 small block with C60 sitting a little low in the right front, due to the extra weight and location of the A6 compressor.
Scott------
1965 L-78 also used the 3851100 spring.In Appreciation of John Hinckley- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
Joe,
It shows different front springs being used for a '67 small block with C60. But if I understand correctly, ALL midyear small blocks from 1964-1967 (not counting F40 or F41) used the same GM 3851100 front spring, with OR without air conditioning.
The 1963 AIM calls out a special spring by part number for Z06 and for C60 on the front shock & spring page (Section 3, Sheet 4), but the 1964-1967 AIMs show a Spring Chart. According to the Chart, all 1964-67 standard production small blocks use 3851100 front spring, only L36 (and presumably L68) use a unique front spring when C60 is added. The C60 section Contents page only references the Spring Chart on the standard production front shock & spring page.
If correct, it seems this might result in a '67 small block with C60 sitting a little low in the right front, due to the extra weight and location of the A6 compressor.
You are correct. I think the 3851100 spring was used for all 64-67 (except early 64) small block applications, even if equipped with A/C.- Top
Comment
-
- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
Scott------
Well, the F-40 was not part of the L-78 option. According to GM 975 1965 Corvettes were built with F-40 suspension and 2,157 were built with L-78. So, there had to be quite a few L-78's that didn't get F-40, especially considering that some of the 975 cars with F-40 were L-84's.In Appreciation of John Hinckley- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
I also forgot that any imbalance due to the A6 compressor would probably be mostly offset by the relocation of the battery to the driver's side with C60.- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
Scott------
Well, the F-40 was not part of the L-78 option. According to GM 975 1965 Corvettes were built with F-40 suspension and 2,157 were built with L-78. So, there had to be quite a few L-78's that didn't get F-40, especially considering that some of the 975 cars with F-40 were L-84's.- Top
Comment
-
Re: 1967, L89 Aluminum heads: painted or natural finish?
Joe,
I also found errors in the 1967 AMA package from GM.
This was one of the first apparent errors I discovered in the 1967 AMA specs. It shows different front springs being used for a '67 small block with C60. But if I understand correctly, ALL midyear small blocks from 1964-1967 (not counting F40 or F41) used the same GM 3851100 front spring, with OR without air conditioning.- Top
Comment
Comment