[rubadub]

I just read this guy had a 512 block and it was a 427.

Anybody tell me anything on the 1969 427 in a chevelle, anything that can explain how it came about etc. What constitutes a 427, thanks Rob

[Stikman33]

A 427 is essentially a 454 block with a 396 crank. The parts are just balanced differently to compensate for the weight. That is at least what constitutes a 427.

Daniel

[1966_L78]

Originally Posted by rubadub

I just read this guy had a 512 block and it was a 427.

Anybody tell me anything on the 1969 427 in a chevelle, anything that can explain how it came about etc. What constitutes a 427, thanks Rob

1969 427 in a Chevelle... If its stock (from the factory), then that would be a COPO car...

Chevrolet came out with the 427 for the 66 model year (production car 427 that is, they have had other "427" engines for racing and trucks)

GM had an internal ban on engines greater than 400 cubic inches in the mid-size cars. This is why the early GTOs had the 389 and 400 engines (usually), the Chevelle had the 396, the Buick GS had the 401 (close to 400, so I guess GM let it slide), etc... The 427 was available in the full-size and Corvette lines, and the external dimiensions are identical to the 396, so it was/is an easy swap... But the GM ban didn't let it happen (there were a few that slipped out, but not really "official" authorized builds...

There were some dealers that did alot of high Performance work, including swapping new 396 engines for crate 427s (usually shortblocks, as the heads were the same)... These dealers went through a lot of work and expense to swap the engines, and so they (mostly Don Yenko) came up with an idea to "legally" bypass the GM Corporate ban on the engine size (I think this also related to the Camaros as well)... With the help of GM personnel (Vince Piggins?), they actually create a Fleet order for 427 powered cars, much like the Highway Patrol, or County Mainenance crews or big companies could order cars with special options not typically available to the public.

This not only allowed these dealers to still offer their customers the 427 cars, but it was easier and cheaper for the dealers. I think any dealer could order one of these cars, but they would have to be "in the know"...

These 427 Chevelles were NOT SuperSports (although they did have the SS hoods and HD items like the 12-bolt rear, etc), but most people interested in these machines didn't care what the emblems were, they just wanted the performance of these cars...

This program was for 1969 Chevelles, Camaros and Novas (slightly different for each, and the Camaros actually had 3 different COPO numbers)... These are (generally) the only "factory" 427 powered mid-sized or smaller Chevrolets... For the 1970 model year, GM lifted the ban, and Chevy installed the 454 in the Chevelle... The rest is history...


IMO, the "mythical" 427 was a great motor at the time, but its legendary status seems to have been made not by the special size, but rather the parts and pieces as well as the competition...

Chevy discontinued the 427 and replaced it with the 454 for 1970. There were many "pedestrian" versions of the 427, but the top dogs are the ones remembered: L71, L72, L88 and the ZL1... Two of these, the L88 and ZL1 were very radical engines, the L88 meant for Road racing (all Corvettes) and the ZL1 mainly used in drag racing (mostly Camaros). These two "RACE" engines really are legendary...

I wonder how a comparison of a 427 and an identically equipped 454 would go...

The 427 has the same bore as the later 454 and the same stroke as the 396/402. Anyone can built a 427 by installing a 396 crank into a 454 block, and it would be pretty much as Chevy intended (specifically balanced for the different pistons)...

[pdq67]

Comparing an L-88 to an LS-7 is like 530 to maybe 550hp to 600+hp!!

That is WITH a good set of four tube, long headers open on both motors from what I read..

ANyway, GM thought that the Dr. Daddy's boys couldn't handle 600+ hp so canned it, imho!! That AND smog and insurance stuff too!!

pdq67

[kfriel]

When my son and I bought our Malibu, it came with an "extra" engine. The seller told us it was a tall deck 427. After running the numbers, it turned out to be a 512 block (427). We built it to 10.5:1 CR with 215 heads, Crane-284 cam, Performer RPM intake and Holley 3310. We installed it a few months ago and boy is it fun. I have rebuilt many diesel engines, but this is the first gas motor we have done so we were very nervous. Desk Top Dyno had it about 480 HP.

[rubadub]

That was interesting information, Thanks a lot, have a good one.

Rob