Looking for info on rare '68 L-88 option

[Finn]

I may possibly have stumbled across a very rare '68 and want to know how I can verify the info. For obvious confidentiality reasons, I won't disclose the VIN on-line, but we have verified the numbers to show the engine is original to this car.

I'm pretty well versed in muscle cars, but I'm in no way a Corvette expert.

Here's what I have:
'68 Coupe (t-tops)
L-88 427 Rat
Muncie M-22 4-speed Crusher.
Engine has cast heads and intake, NOT aluminum.
Engine has single large Holley (850?), NOT 6-pack.
Original owner had car until 2002 (actually mother of 'Nam Vet killed in early '70s)

This car is said to have a rare GM optional 427/ 570HP option, but I cannot find any info that supports this was ever an option.

If this is true, why not the aluminum heads, intake and tri-power?

How do I verify this? What more do I need to find out about the car before I purchase it?

Car is very, very solid runner (makes your heart pound), body is fair.

How do I determine a fair value?

Your expertise will be greatly appreciated. Finn

 

[67HEAVEN]

Indeed, the L-88 came with a single 4-bbl, not the tri-power. Tri-power was the L-71/L-89, L-71, and L-68 engines only.

You did come to the right place, however.

Start here........... http://www.corvetteactioncenter.com/specs/l88/index.html

Welcome aboard and check back for other contributions.

 

[67HEAVEN]

Note: The L-88 was factory-rated at 430hp, just under the L-71 (435hp). We all know that to be somewhat misleading however. They simply rated it well down the rpm range.

Realistic Gross HP ratings for the engine were 560hp through headers, not factory cast iron manifolds.

 

[67HEAVEN]

The car should have a special tag on the lower centre console indicating a requirement for high-octane fuel.

There are many other items to check, which others will be happy to contribute to...........such as the extra hi-rise, rear induction hood, J-56 Special Heavy-Duty brakes, etc.

 

[67HEAVEN]

One more thing. Those ol' 12.5:1 compression engines made enough power to seriously hurt themselves, so very few originals are left. We beat hard on those old cars in the late '60s.

The absence of aluminum heads and intake indicate either a non-L-88, or a serious de-tuning effort.

Looking for block numbers is required.

 

[Finn]

67Heaven, thanks for the quick response. I only looked at the car for about an hour. It does have the rear induction hood and the headers (below the rockers), but that could obviously been done after the fact.

I will be taking a longer look at it over the weekend and will post any additional info I find.

Appreciate your feedback, I'm hoping even if it's a 390HP it might have some good value, yet.

 

[Vettehead Mikey]

I'd be very leary of anyone claming that it's a real L88 and telling the son-killed-in-Vietnam story.

There's tons of fakes out there, many are detected only after the purchaser has put his money down. Simple 'numbers' checking is not enough- those are dead easy to falsify.

 

[Finn]

Thanks Mikey. I, too, am all to familiar with the son-killed-in-Nam story.

 

[67HEAVEN]

It does have the rear induction hood and the headers (below the rockers), but that could obviously been done after the fact.

They all came from the factory with cast iron exhaust manifolds.

They needed headers to wake them up, however.

 

[jonstr]

Here are a few things you can look for that might help.

The motor number should have an IT suffix if it is an L88 block.

As 67Heaven said the car should have a few other options that were mandatory with the L88: power brakes, HD brakes, transistor ignition, F41 HD suspension, and radio delete were all required with an L88 order.

Block casting should be either 3916321 (early 68) or 3935439 (late 68). The same casting number was used for all 427 motors, not just L88s, but it would be good to check it as well as the VIN stamping. Check the casting date also to ensure that it lines up with the build date of the car. It isn't unusual to have several months between the engine casting and the build date on an L88.

Tach redline should be 6500 RPM.

Intake and heads should be aluminum, but I suppose they could have been changed easily. Carburetor should be a Holley 850 CFM number 4150, but that may have been changed with the intake.

If you think it might be a fake, sometimes it's better to look for what should not be there than what should be. For example, L88s, as radio delete cars, should not have the little capacitors under the dash that were put in to keep radio static down. They also should not have any ignition sheilding and there should be no antenna hole in the rear deck (you might need to look from underneath to see if the hole has been patched).

Hope this helps. Let us know what you find.

 

[Finn]

Jonstr (and others), I really appreciate all of your input and expertise. I don't know if you'd really care, but I'll post my findings after I go through this car, armed with all this expertise.

Thanks much and have a great weekend! Finn

One thing does keep luring me, though. Was there a rare 570HP/ 427 that was extremely limited, therefore not shown in production stats?

 

[67HEAVEN]

One thing does keep luring me, though. Was there a rare 570HP/ 427 that was extremely limited, therefore not shown in production stats?

No.

 

[kruzmisl]

Jonstr,
Great info! Your help and taking the time to inform are what makes CAC and the net so much fun. For the post'r, hope it's real!

 

[jonstr]

One thing does keep luring me, though. Was there a rare 570HP/ 427 that was extremely limited, therefore not shown in production stats?

As 67Heaven said, no there wasn't. Where this may have come from is that, while the L88 was officially advertised at 430 HP, many publications have rated its true HP peak at around 560 or more (although you won't get close to that without uncorking the exhaust a bit). I guess legend becomes fact as time passes.

Good luck, and please do let us know what you find.

 

[Finn]

I can see you're a great group. Thanks for all the insight. Finn

 

[Finn]

Kinda funny, I get wary of my teenagers doing the chat rooms all the time, now the ol' man is doing it!! Finn

 

[RedRagTop]

These two experts have given the info you need for sure. I am not as versed in these models like these guys, but my brother's '68 427 (soon to be mine) has cast high compression heads and a single big 4bbl making it a 390 hp. However, add that to the low gear ratio option and it makes for some tire-smoking power all right. It runs quite high RPM at the speed limit however, around 2500-2800 in 4th so thirsty and not the best for extended trips...

 

[Mako1969]

The only L88/ZL1 I have ever seen with cast iron heads was the ultra rare ZLX motor that was available through Baldwin Motion Performance. This of course was not a factory installed option, although like many tuner cars the bottom end motor (numbers) may be original.

Excerpt from "Corvette From Six to Stingray" By Martin L. Schorr, 1973, pg 59.

PHASE III 427 ZLX ENGINE
550 HP .............................$1,995.00
Special hand assembled 427 CID, HD 4-bolt main block, 12-to-1 forged "Open Chamber" style pistons, HD forged crank with radiused oil holes, Special Cast Iron "Open Chamber" cylinder heads 2.19 intake, 1.88 exhaust, special HD full float connecting rods with 7/16 rod bolts, high lift .560/.580- lift solid lifter camshaft, 8-qt. oil pan, aluminum high-rise intake manifold, Dyno-jetted 850 double pump carburetor, Motion/Mallory distributor, Ramcharger wires with boots, Phase III CD Unit and NHRA-approved clutch, flywheel and scatter-shield.

 

[zachh]

The 427 vettes with the 430/ 435hp option are known to dyno around 500 hp, I believe, I have a friend with a 100% original 68 with a 427/435, and his dynoed around 500 hp. The L88s, when they were tested for performance, had a few slight modifications, but the optional aluminum manifold and heads were on the car. There is a possibility that they can, on a good day, when they rolled off the line that they could produce 550- 560 gross hp.
zachh

 

[Finn]

I just want to say a quick "thanks" to all of you who have lended your input on this '68. I know this gentleman still has the car in his garage, but I've been too consumed in my daily life to get into the details of authenticating the man's claim. I personally believe this is probably a 427/390HP, but even that should be a pretty good investment these days.

It's really cool to see how passionate you all seem to be and how willing people are to help me (a total Corvette novice) make an educated decision.

I'll post what I find as soon as I get the time to go look it over.

Finn