About three weeks ago I bought a 69 427/390 hp coupe. Great car in great condition but I was somewhat disappointed when I jumped on it. It runs great, idles great, the clutch is in good condition, but it just doesn't do what I expected from 427 c.i. and 390 hp. It barely can pull second gear scratch and it seems to go "flat" when you drop the hammer. Almost feels like there's no secondaries cutting in. This is a completely stock, low mileage (69K) very original car. The engine has been rebuilt and it posted 195 lb. ft. of compression on all eight cylinders the day I bought it. It is an L36 engine with an M21 close ratio tranny and, I suspect, 3.08 gears. I acquired a 1969 Corvette fact book with the car and it shows that combination as posting a 15.02 e.t. with a trap speed of something like 92 mph back in the day. If that's the case, then I would guess the car is performing about like it should, but what a disappointment. It is actually slower than my mildly modified 69 Mustang 302 convertible (14.30 @ 99 mph) and is way slower than my 00 Camaro Z28 (13.44 @ 107.4 mph). I'm not willing to do anything to this car to corrupt it's stock condition just to improve performance, but I really feel that there should be a little more performance there then there presently is. Are the Rochesters really that poor a carb? I've used Holleys and Demons on my Mustangs but I've never been involved with a Rochester or and Edelbrock before. Any suggestions to improve performance? I'm not going to be racing this car but I would like to know it has some ***** off a stop light if needed. I got laughed at by a guy in a BMW Z4 the other day! HELP!

 

Sounds like it may just need a good looking over...carb, timing, etc. I'm thinking that vette is a mid 14 sec car, my stock L79, 3.08 with 4 speed did a 14.42. You have way more torque, even with the weight penalty, I think mid 14's is very easy number.

 

I would check the mechanical advance in the distributor first. It sounds like you are not getting any advance.

Mike

 

My stock low-compression 454/365 ran a 14.1 @102. Street tires, stock exhaust etc.

 

There ya go!

 

Don't stress dude...you haven't had it long......when I got my vette it couldn't even accelerate...I changed the spark plugs and put some new gas in and it went much better! it still needs some further tuning (vacuum leaks) but Im happy at the moment.

It will give you the power you want!! Do you have a mechanic or do the work yourself?

 

oh...and about the wan%er in the BMW....the jokes on him!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!


heres a joke for ya:

Whats the difference between a porqupine and a bmw??

highlight for answer:
the porqupine has ****** on the outside!

 

I live in the Silicon Valley so you see lots and lots of porqupines driving BMW's. I just don't have any idea how fast a Z4 is. Lately everything coming out of Germany or Japan is claiming mid 13's, though. I would have severely spoiled his day with the LS1 Z28.

Just got another wake up call. The bumpers on my car are original but they have very slight pitting on close inspection. I just got the Year One catalog so I looked up the cost of repro bumpers. CRAP! $375 for that puny thing in the front and $375 each for the two pieces in the rear. The repro bumpers for my Mustangs cost $89.95 each end. Of course there are a couple of million first generation Mustangs out there, but I am getting the impression that these guys are taking advantage of the "rich boys" driving Vettes. I'll check the Corvette Central catalog when I get home.

 

tune on that puppy!!
you got a small taste of how some of us later vette owner's feal (L48 with 195hp or L82 225hp)

 

That was what I was thinking initially but I got concerned when I saw that 15.02 number from an old mag. Of course, nobody ever said those magazine test drivers were worth a damn. You can lose .5 really easily if you can't shift or don't know how to hook em up. And I'm sure they were running on bias ply tires.

 

As mentioned check to make sure you're getting proper advance on your distributor. Also take a look at your initial timing & total timing- if your motor is the correct 10.25 to 1 compression ratio the timing may have been retarded so it can run on today's pump gas.

As for your Q-Jet, it may be jetted lean. They set those up on the lean side for smog. Also, when I bought my L36 the guy before me had bought a replacement carb but as it turned out it was for a smallblock & the jetting was way lean. You should be able to hear those big secondaries kicking in, so if you can't that could explain alot. Also check to make sure you're getting full throttle when you floor the pedal. I've seen a few dyno pulls fall way short due to this. Good luck- the power is there, you just have to find it!

 

If I chose just one thing I think its the secondaries. If they're not opening like they should then you are running on itty bitty primaries.
Since you didn't mention the roar of the secondaries opening???
In fact you even state it.

Just one more bit of advice. DON'T
Get those catalog bumpers. You don't know just too many things.

Get them rechromed or just live with the ones you got for awhile. Put some wax on them to stop the rust.

I got catalog bumpers. The front is OK but the left rear is rusting like it was built to rust and the right looks like crap. The originals look better and they aren't in very good shape!

 

them up good.

 

The 427 at 390hp is not something that is going to dust off many of todays performance cars. Had they rated it the way todays cars are rated for horsepower you could see why it's not the bear it sounds like. Many of the 383 strokers being installed now a days will put out that much horsepower or more. Before someone starts to blast me, I am in no way saying the 427 390hp is a dog. The thing should get up and go. It should have more than adequate power for daily driving and then some. It just won't compete with many of today's higher tech engines.