1967, L89 Aluminum heads: painted or natural finish?

[Michael H.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

There's an easy way to see how much the removal of 70 pounds off the engine will affect the ride height.

Use a bathroom scale with a low profile Corvette jack under the rear of the front cross member. Jack it up until you see 70 lbs on the scale. That should be roughly the same as removing 70 lbs with aluminum heads.

[Wayne M.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

....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 -- here's a pic of original owner of my 1965 L76 C60 N03, taken in Flagstaff AZ in '66. Front end sag, obviously not 36 gallons in the tank . Also, believe he had already replaced the rear tires, what with the 4.11 gearing.

[Joe L.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

I see what you mean (same figures listed in Corvette Black Book). The 1965 AIM page L78-A2 Revision Record shows that F40 was added on 1-25-65, did it "become" part of the L78 option package at that point, but possibly not implemented on the assembly line until several months later, resulting in the mismatched F40 suspension vs. L78 (and L84) numbers totals?

Scott------


I highly doubt that F-40 was ever part of the L-78 package. Plus, I have no SERVICE parts information which indicates it was.

[Wayne M.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

..... The 1965 AIM page L78-A2 Revision Record shows that F40 was added on 1-25-65, did it "become" part of the L78 option package at that point, but possibly not implemented on the assembly line until several months later, resulting in the mismatched F40 suspension vs. L78 (and L84) numbers totals?

No, Scott; --- F40 really was a separate suspension option for the new BB. I can say that the last 396, #23564 has the "other" markers for the standard suspension; ie. front sway bar 7/8" dia. and rear spring 9-leaves. Original shocks long gone, but some previous owner replaced front springs with the F40 (which really causes front end sag) and is on my list for replacement with 3888250 BB springs this winter, even though I agree with others that the small block spring 3851100 was used for base suspension L78 [contradicts the 5th ed. of '65 TIM&JG].

[Scott S.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

Scott--- You are right about the air conditioned small blocks using the same front springs as the non-air cars. I had a low mileage extremely original 67 327/350 with A/C and I remember tearing off one of the spring tags and it was definitely 3851100.

Patrick,

Thank you for the reply, it's always good to get confirmation about an original car with the same options as the car I'm working on.

[Scott S.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

Wayne and Joe,

I see that both the 1966 AIM (L72-A2) and 1967 AIM (L36-A2) follow the '65 AIM's description, saying "Assembled same as RPO F-40" ('66) and "F-41" ('67) regarding the front and rear suspension. I understand that they didn't all have H.D. suspensions, so what are they meaning to say by "assembled same as RPO F-40/F-41"?

[Joe L.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

Wayne and Joe,

I see that both the 1966 AIM (L72-A2) and 1967 AIM (L36-A2) follow the '65 AIM's description, saying "Assembled same as RPO F-40" ('66) and "F-41" ('67) regarding the front and rear suspension. I understand that they didn't all have H.D. suspensions, so what are they meaning to say by "assembled same as RPO F-40/F41"?

Scott------


I don't know why they used that phraseology. However, the fact that it says "assembles the same as RPO F-40/F-41" is a sure sign that it was NOT the F-40/F-41 suspension. Actually, though, F-40/F-41 assembles the same as standard suspension. However, the phraseology implies that there was some difference in the L-78 suspension than that used for base engine small blocks and there was. L-78 did use a different front sway bar than standard suspension so that may be why they chose to relate it to F-40/F-41 rather than standard suspension. Just a guess, though.

[John H.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

I see that both the 1966 AIM (L72-A2) and 1967 AIM (L36-A2) follow the '65 AIM's description, saying "Assembled same as RPO F-40" ('66) and "F-41" ('67) regarding the front and rear suspension. I understand that they didn't all have H.D. suspensions, so what are they meaning to say by "assembled same as RPO F-40/F-41"?

Scott -

That statement means that the physical assembly process (and fasteners, if involved) is the same, but the part number is different; that's why it says to refer to the Engineering Bill of Material or Parts List for the part number.

[Patrick B.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

There's an easy way to see how much the removal of 70 pounds off the engine will affect the ride height.

Use a bathroom scale with a low profile Corvette jack under the rear of the front cross member. Jack it up until you see 70 lbs on the scale. That should be roughly the same as removing 70 lbs with aluminum heads.

Michael --- That is a nice simple direct way of evaluating the difference. However, I'm working on a bare chassis at this point and your solution is not available to me. I just found GM data on a 67 gave the wheel rate of a 67 small block as 80 lb/in (195 lb/in spring) but omitted the information on the big block spring. Estimating the big block spring rate at 90 lb/in at the wheel, a reduction of 68 lb on the front axle versus an L71 would cause a higher ride height of about 3/8"
(68/(2X90)). Maybe that is not so bad.

[Kit D.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

For what it's worth, an article by Thomas Glatch (unk date) mentions that the L89 used the small block front springs:
http://www.c2registry.org/index.php?...3&supersized=2
kit

[Kit D.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

And, additionally for what it's worth, Car & Driver's 1967 road test article on the L89 discusses the weight savings issue of the BB w' alum heads versus the SB with iron heads and states that when they weighed the L89 car it indeed weighed 43lbs LESS than the last L79 they weighed. The L89 tipped their scales at 3,137lbs. True, C&D didn't mention whether or not that L79 had A/C, but it's a pretty impressive fact nonetheless. This info supports equipping the L89 with the small block front springs IMHO.

See the article here:
http://www.c2registry.org/index.php?job=ShowArticle&art_id=72&ap_page=3&supe rsized=2

[Michael H.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

And, additionally for what it's worth, Car & Driver's 1967 road test article on the L89 discusses the weight savings issue of the BB w' alum heads versus the SB with iron heads and states that when they weighed the L89 car it indeed weighed 43lbs LESS than the last L79 they weighed. The L89 tipped their scales at 3,137lbs. True, C&D didn't mention whether or not that L79 had A/C, but it's a pretty impressive fact nonetheless. This info supports equipping the L89 with the small block front springs IMHO.

See the article here:
http://www.c2registry.org/index.php?job=ShowArticle&art_id=72&ap_page=3&supe rsized=2

Kit,

I'll bet the difference in weight is a lot less than the articles claim. I doubt any L89's had small block springs.

[Wayne M.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

And, additionally for what it's worth, Car & Driver's 1967 road test article on the L89 discusses the weight savings issue of the BB w' alum heads versus the SB with iron heads and states that when they weighed the L89 car it indeed weighed 43lbs LESS than the last L79 they weighed. The L89 tipped their scales at 3,137lbs. True, C&D didn't mention whether or not that L79 had A/C, but it's a pretty impressive fact nonetheless. .......

Found the previous Car & Driver 327 article; was the January 1965 issue, on an L79 coupe, with air conditioning and knock off wheels, and I see a radio antenna (if you can trust the article photos as belonging to same car -- these options not mentioned in text).

Dry weight 2975 lb, Curb weight 3180 lbs (test weight 3500); weight distribution 47 front / 53% rear. Price as tested: $5276.30 F.O.B St. Louis.
-------------------------------------
The L89 article (as shown in the C2 registry link) was from Car & Driver May 1967 and options listed: L89, A01, A31, G81 (3.55), A85, J50, K66, M21, N40, U69, QB1 (so you guys can do all the +/- math to check weight). Price as tested $ 5900.15

L89 article doesn't quote dry weight, but gives curb weight as 3137 lb (43 lb less than the '65 L79) and test weight as 3563 lb. (46 front / 54% rear distribution)

[Joe L.]

Re: 1967, L89 Aluminum heads: painted or natural finish?

Kit,

I'll bet the difference in weight is a lot less than the articles claim. I doubt any L89's had small block springs.

Michael------


I totally agree. I would say that the chances that 1967 L-89 (or 1968-69 L-89, for that matter) were equipped with small block springs is just about as close to ZERO as one could get.