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I was just looking at camshaft specs and noticed that the 427 390hp camshaft for the 66 corvette has 214/218 duration and .461/.481 lift. That seems like a small camshaft for a 427 to me, but i really dont know anything about big blocks.
What is the output of the 427/390hp motors-rwhp?? Anybody know?
Do they actual have power?
I looked at a few at barrett jackson that looked appealing.
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What is the output of the 427/390hp motors-rwhp?? Anybody know?
Do they actual have power?
Thanks
Two 66' coupes...
The 427/390 is a fairly low RPM high torque stump puller... smaller ports in the heads two bolt mains. Engine pulls AC and power steering, great for driving everyday.
427/450 has 4 bolt mains, 2X2 inch ports in the Hi Performance heads and a solid lifter cam. High RPM engine a little harder to get off the line than the 427/390.
I've never had either one on a dyno, so I don't know how they compare otherwise.
I believe the 427/390 cam was the same as the 396/360 and 396/350 cam - a slightly more potent cam. I had one years ago and it was a pretty nice running car. It's power was rated 5400 rpm and I doubt this was an under-rating similar to where the 427/425 L72 was rated at HP below it's peak rpm. So this was probably a pretty honest rating for the time with a completely stripped engine on an engine dyno. It's a motor that will pull any rear ratio easily from a 3.08 to a 4.11. Mine had a 3.08 and was definately a a potent high speed cruiser on the highway. Lower gears would no doubt enhance acceleration considerably.
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I really like the 427/390. It makes alot of low end torque and you only have one carb to fiddle with. I have a 68 390 horse and it's plenty fast. I had a 67 400 horse which was about the same kind of power but didn't like playing with the 3 carbs. From what I have read a good running 390 horse puts about 290 to 300 hp to the rear wheels. Compared to the 435's the 390 horse is a bargain for a nice big block you can drive on the street without alot of hassle.
There was a time (in the late 70's) that I had both the '67 in my signature and a '67 convertible with the 427/390. The vert also had a 3:08 rear and a wide ratio 4 speed. Much easier to drive around town and do a 75% dig from a stop light!! Part of the problem with driving a 435 on the street was that the close ratio 4 speed was manditory with it. You really needed a 3:70 or higher rear end for good digs.
I had side exhausts on it and it sounded good----not as good as the 427/435, but good.
It took me a year or so to figure out the triples in the 435 and then they weren't much of a problem----other than gas leaks from the bowls. I finally solved that by machining the gasket surfaces flat on a milling machine.
The 390 is alive right from idle (well maybe 1500)---the 435 comes alive after 3500 rpm. The 390 is a great street engine and you could always change the cam if you wanted a little more rump-rump at idle.
The factory 390 HP cam is small. Too small. Too small even for the oval port heads on that motor. L72 cams have very reasonable street manners. Yes they make less torque at low RPM, but in a light car it's not that much of a disadvantage. From personal experience they work great with oval port heads. If you're set on a hydraulic cam, Comp Cams XE 274H is a close match to the L72.
It really irritates me to hear people bad mouthing 435's as fussy, hard to drive over heating beasts. Back in the late sixties/early seventies I had a 67 435 conv for a DD. It also did double duty towing my SCCA race car and trailer all over New England and New York. Never a problem engine wise or heat wise or starting up from a stop ( although I admit it had a 4.1 rear from the factory) . I expect a lot of the comments come from people who have never driven a 435 or possibly never even seen one.
I've owned a '66 427/425 convertible and now a '66 427/390 convertible. The L72 is a beast and gets tiring to drive, especially with a 4:11 rear and side exhaust. The L36 is very smooth and an easy drive, especially with a 3:36 rear and rear exhaust. But that myth of a '67 tri-power 435 being faster than a '66 425 (450 hp) with a single 780 Holley is just that. My L72 rebuilt with L36 10.25:1 pistons vs the factory 11:1's still walked away from a '67 427/435 by 6 car lengths. And that '67 was 1 of 16 rare L89's (aluminum heads).
The factory 390 HP cam is small. Too small. Too small even for the oval port heads on that motor. L72 cams have very reasonable street manners. Yes they make less torque at low RPM, but in a light car it's not that much of a disadvantage. From personal experience they work great with oval port heads. If you're set on a hydraulic cam, Comp Cams XE 274H is a close match to the L72.
Not really. The L-36/68 cam is a lot closer to the L-79 cam than the base small block cam. (214/218/115 LSA versus 222/222/114 LSA) One of the quickest accelerating cars I ever rode in back in the day was a '67 L-68 Coupe with a CR trans and 3.70 axle. From 25 to 90 MPH (start in second shift to third at the redline) that thing was an absolute beast. It made greater torque/power up to about 4000 revs than the SHP big blocks.
01-19-2009, 01:09 AM
Actual output of 427/390hp engine
Part of the problem with driving a 435 on the street was that the close ratio 4 speed was manditory with it. You really needed a 3:70 or higher rear end for good digs.
I finally solved that by machining the gasket surfaces flat on a milling machine.
