What was the original compression ratio of these engines? I've seen a number of '68-69 cars for sale with this motor (427/435) and was wondering if they will run on 93 octane unleaded? What kind of rpm did these things spin to?

Anything I need to know about these? I assume they have mechanical lifters.

 

11.0:1
6,800-7,000 rpm but the early ('67-68) L-71/L-89 cars had weak bottom
ends.
Yes, solid lifters.
These engines are IDENTICAL to the L-71 other than aluminum heads.

 

"weak bottom end"...doesn't sound too good.

Maybe my best bet is to find a clean roller convertible and build me a 4-bolt 502" and slap a 150hp shot of nitrous on it. :)

 

If you have access to a L-89, it's far more valuable as a very rare engine than it is as a racer. What's the story?

 

WA 2 FST, How dare you steal my liscense plate for your forum name! :reddevil LoL Just kiddin....I actually have QQ WA2FST now



[Modified by 74VETTE, 7:32 PM 9/2/2002]

 

74VETTE...cool plate, man! Take a look at the pic below. I've had these plates on my hot-rod since '94.

 

Well, I've seen a number of L-89 Vettes for sale, and I'm interested in buying a '68-69 BB Vette. Was just wondering what I should expect.

I would not be buying one as a collector's car, and I'm also not planning to race it. But I'm a hot-rodder, so it will get "bastardized" at some point.

 

"6,800-7,000 rpm but the early ('67-68) L-71/L-89 cars had weak bottom
ends."

I've never heard that one before. What would be the difference in the bottom end between 67, 68, and the 69's.

 

Rods and rod bolts.

 

Hmmm, interesting. Both my 67 435's have the original rods, as does my 69 L89. I don't recall any differences. I'd have to check and see if I've got pictures of the rods themselves. I know I photographed some of the engine stuff back when I was doing them. As far as the bolts, if my memory serves, all three of these engines have the small rod bolts. If you know any of this for sure I'd be interested in the specifics. My 69 L88 of course has the 7/16 rod bolts and I'm of the opinion that the L88's were the only pre 70 rods so equipped.

 

Hey man, does those rectangular tips effect the sound at all? I'm going to have exhaust welded on soon and I like the look of those tips, but I don't want to mellow my sound AT ALL....

 

Sweet stang WA 2 FST!

Aaron-74 It shouldnt change the volume of your exhaust at all. On mine it changed the tone just a tiny little bit at idle (no difference in RPMs), but didnt quite it down at all.
you can find the tips from http://www.rksport.com, but beware...they are around $120 and will take a good custom exhaust shop since the tips arent symetrical.
Good luck

 

You are quite correct sir.... There is no difference between the rods/bolts used in any of the special high performance engines of the late 1960s. They all used the small 3/8 connecting rod bolts as you noted, but these are entirely adequate for street applications. The problems arose in endurance racing where the 3/8 bolt proved to be a weak link in 1967 L-88s... One of the reasons that the 1968-69 versions went to the 7/16 connecting rod bolt.

As far as winding the engine to 6800-7000 rpm... Why? The factory "143" camshaft falls off sharply on power after 6000 rpm so it doesn't make a whole lot of sense to try and push much farther than this.

It sounds like you have one heck of a nice collection! All Corvettes, or have you "diversified?" :)

Regards,

 

Hmmmm, weak bottom ends.....I guess I was very fortunate not to granade the L-89 when I was beating the living tar out of it during weekend drags and club events at Mid-Ohio and Nelsons. In fact, the 68 served me more as a racer than as a daily driver. Of course I never ran the R's past 7K......6.5, yea......not a problem.

 

Correct guys. Brain fart on my part. After grenading my block the second time (first time paid for by GM), I went to the L-88 bottom end stuff and forgot that the later L-71 and L-89 did not.

I will, however, stand by my opinion that the SHP bottom ends are weak, at least for racing. I wouldn't race without the HD bottom end.

 

Rowdy, there're a few non Corvettes in the bunch, a 67 500 Shelby, a pair of original engined LS6's (one's an El Camino), 427 Biscayne, LS7 69 Camaro, (the car Chevy should've built) and a few projects not worth mentioning and probably never gettin' finished. Fact is, if I never buy another project I don't know if I've got enough years/patience left to put all this junk back together, but.....................THE GREEN 67 WILL ROLL UNDER IT'S OWN POWER THIS MONTH.

 

It sure sounds like you have some outstanding cars!

The Biscayne really intrigues me... I've been trying to locate a 1969 L-72 Biscayne for years now. Thought that I had one tracked down only to find the owner sold the car without calling me (as he said that he would do). The search continues...

Good luck with your '67! Sounds as though you're getting close to finishing that project.

Regards,

 

Nice car collection Solidlifters. What year is the Biscayne? I like the L72 Biscayne also. This was a great running engine that was only enjoyed by a small number of passenger and COPO cars in 1969. Same as the L71 but without the problems of the Tri carbs that many people ended up swapping out for a 4BB anyway. IMO

 

Rowdy, the Biscayne's a 68 and it's a clone. The only 2 cars that I have that aren't correct are it and the LS7 69 Camaro. I looked for an authentic Biscayne for several years and ran across several that were alledged to be, but nobody could prove it. The fact that it's not a real car freed me up to do some stuff I wouldn't have done to an original. It's got big tube Hooker Super Comps, a Hurst shifter and autometer guages. It does have a dead correct 68 L72 engine, that was actually the replacement in my 67 Corvette when I bought it. This was a CE block assembly and surprisingly it's dated pretty well for the car and I left the CE stamping on the pad. It's also got a correct from another 68 12 bolt that I stuck 4.56 gears in and poly bushings. I'm also putting the big 4 piston calipers on it that were on another 68. One other thing I did was bucket seats from a 68 SS Impala. I had Ciadello interiors (excellent stuff by the way) in Arizona do the seats and they even custom did a matching rear seat to go on the Biscayne's wider seat frame. The seats are mounted on stock brackets cut from a rusty SS and I found a 140 MPH speedo from a 68 police car (one year only dash). I've really enjoyed building it as a clone because there are no rules. I've probably got at least as much in it as I could've bought an original car for, but the fun factor's been worth it.

I found another one in a junkyard the other day that's real unusual for a Biscayne. It's a 2 door 68 also and was factory equipped with V8, 3 on the tree, factory air, power steering, and I think brakes also. Who'd ever order a Biscayne that way. I'm thinking about buying it and stickin' one of Chevy's new 572 crate motors in it when they come available later in the year.

The problem with 68 Biscaynes is there's very little available for them. There's a lot of stuff for 65, 6, 7, & 9, but the 68's are like a black hole in parts availability. Window hardware is keeping me from getting it finished, but it's been back from the paint shop for over a year and all the bumpers, grill, etc are done and back on. Just the windows and exhaust system and it's rollin'.

 

One more Biscayne tidbit: When I was looking for one to build I really wanted a 67. I like the tail end a lot better and the rest is similar. A guy from Ohio stiffed me on one at the Turkey Rod Run in Daytona 3 years ago and I was disappointed. Later on a trip to Floyd Garrett's Muscle Car Museum in Shelbyville, Tenn I saw a 67 Impala SS with a low horse 427 (385 I think) and it had a plaque saying that this was the highest horsepower engine placed in a full size Chevy in 67. I went up front and questioned Floyd about it and he said that for some reason in 67 there were no 427/425's installed in Biscaynes or Impalas. I've never known the reason, but it's safe to say that it worked out better in finding the 68 later even though it's not real. Anybody know anything about the 67's skipping the high horse motors? They were obviously available in 66, 68, & 69.