[durmalbs]

I am new to Hotrodding. I bought a 75' Corvette with a 400 SBC. It had a bad hydraulic lifter I had these replaced and they said there was no cam damage but the valve stem was mushroomed. I had Edlebrock aluminum heads 64cc Chamber, 170cc/60cc Int/Ext runner, 2.02/1.60 int/ext valves, and .575" max lift, Performer RPM intake, Edlebrock 750 4 BBL, 700R4 AT with 3400 stall. I recently had it Dyno-tuned with only 278RWHP and 319 ft/lbs torque. This seems awful low does anyone feel that this should be producing more? I am running 12 degree timing with 38 degree total and vacuum advance, manifold ran, not ported vacuum, and MSD HEI Ignition. Any suggestions are welcome

[durmalbs]

I am new to Hotrodding. I bought a 75' Corvette with a 400 SBC. It had a bad hydraulic lifter I had these replaced and they said there was no cam ( don't know what cam is in it but it's not stock) damage but the valve stem was mushroomed. I had Edlebrock aluminum heads 64cc Chamber, 170cc/60cc Int/Ext runner, 2.02/1.60 int/ext valves, and .575" max lift, Performer RPM intake, Edlebrock 750 4 BBL, 700R4 AT with 3400 stall. I recently had it Dyno-tuned with only 278RWHP and 319 ft/lbs torque. This seems awful low does anyone feel that this should be producing more? I am running 12 degree timing with 38 degree total and vacuum advance, manifold ran, not ported vacuum, and MSD HEI Ignition. Any suggestions are welcome

[Deuce]

278 horsepower at the wheels ?
... seems like it is doing pretty much what it should. You have a parasitic loss of HP in the transmission and the rear end ... so at the flywheel you would be closer to 400 HP.

Just my nickel ...

[durmalbs]

do you think the 3400 stall is too much? It sure is great off the line.

[techinspector1]

Originally Posted by Deuce

278 horsepower at the wheels ?
... seems like it is doing pretty much what it should. You have a parasitic loss of HP in the transmission and the rear end ... so at the flywheel you would be closer to 400 HP.

Just my nickel ...

I agree. 400 at the flywheel with a 30% drivetrain loss gets you right there. In my opinion, the intake runners are a little small to feed a 400, but hey, if they work for you, great. You're probably making more power under curve with the smaller heads than you would with bigger heads anyway. Total horsepower at top end is over-rated.

If that converter works for you, again.....great. Depending on your cruise rpm's and rear gear, it's probably slipping quite a bit and building a lot of heat. Take steps to remove the heat with an appropriately sized cooler or suffer the consequences.

[techinspector1]

"the valve stem was mushroomed"

I'm gonna make a wild stab here and guess that with that much cam lift, either the spring went into coil bind or the retainer was banging on the guide boss or the valve was bangin' on the piston . I don't know how else you're gonna mushroom a valve stem without mechanical interference.

Of course, I could be wrong.