Topic: L-36 engines
in Forum: C3 Engines
Already a Member?
Click Here to Login
Not yet a Member?
Click Here to Register for Free!
Former Member
Send PM
Pocatello, ID - USA
Joined: 8/4/2009
Posts: 10
Vette(s): 1969 L-36, 427- 390 hp. coupe. 4spd. air.
I'm planning on a rebuild of an original 427-390 hp L-36 motor. My idea is to use modern technology to upgrade for weekend driving. Probably will only see 3-5 thousand miles a year. Looking for 450 hp and bulletproof reliability. I'd appreciate any thoughts or suggestions. Thanks
SPONSOR AD:: (Our Sponsors help support C3VR)
Former Member
Send PM
Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
You're going to need a camshaft at minimum to accomplish that. I'm no expert on cam specs and what works best, but I've heard great things about Lunati Voodoo cams. I would call their techs and find out which will accomplish what you want.
You'll need some machining done on your heads, or even replacing them with quality aluminum heads, like Edelbrock or GM Performance. If you decide to keep your original heads, they'll need porting and polishing by a good shop. That may actually cost more than replacement units, so it's up to you much originality matters.
You'll need a good set of headers...I recommend Sanderson, but there's many good brands.
I think where your problem may be is an intake...it may well be difficult to find an intake that won't cause clearance problems with a stock Corvette hood. If you plan on keeping the stock intake, that won't be an issue.
You're going to hear a lot of differing opinions on a carburetor. I believe an L36 came with a Quadrajet...an excellent carburetor but even GM didn't install it on 427's rated more than the 390 (they used triple Holley 2-barrels or a huge Holley on an L88).
If you want to stick with the Q-jet, have it rebuilt and set up by someone who knows them well. It will require re-jetting and re-calibration for a different cam. If you want to change carbs, I'm a fan of Edelbrock carburetors, as I think they're an excellent street carb, but for pure performance, you might consider a Demon or Holley. Between the two, I prefer Demon.
Building your engine won't be really difficult...it takes the right mix of parts that work together to accomplish that goal. Simply throwing a lot of high performance parts...no matter what brand or high a quality...they won't do the job if they're not properly matched. Places like Summit Racing or Jegs have tech departments that can make recommendations.
Former Member
Send PM
Mounds View, MN - USA
Joined: 5/24/2007
Posts: 1031
Vette(s): 70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe
I agree with all of that. More than one horsepower per cubic inch is a lot. Expect to have a rough idle and minor driveability issues. Horsepower only matters if you are racing and willing to wind to the necessary RPMs to reach that power level. You might want to change your focus and concentrate on getting maximum
torque at low RPM. That is what you will feel in a regularly driven
car. Then your existing intake and carb will be fine. I would also use long tube headers. I have heard from our customers that Heddman fit well.
Have fun
Larry
Have fun
Larry
Former Member
Send PM
Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
The issue of rough idle is why I suggested looking at the Lunati VooDoo cam...it has an asymmetrical lobe design they say delivers power and reduces the rough, loping idle to tolerable levels. As I said...I've heard great things about it.
Lifetime MemberHOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
Try calling comp cams. They were very helpful in spec'ing out my application and we wound up with a custom grind. The work dome to the heads also make a world of difference and is moneyvalwell spent.
Decide carefully and buy a light set of shoesbto compensate for the heavy right foot!!
Decide carefully and buy a light set of shoesbto compensate for the heavy right foot!!
LukesVette Homepage
Veteran of Operation Iraqi Freedom
101st Airborne(AirAssault!)
God Bless America
Support Our Troops 
the L88 came with Holley 850 cfm rated at 430 hp, the 400hp(390 hp with 3x2's) and 435 hp( more cam, compression and heads, L71/89 alum heads) had 3x2's, the L-88 was really underated by somewhere around 100+ hp. probley cause it didn't have a heater or radio,
anips 2009-08-06 14:29:16
Former Member
Send PM
Pocatello, ID - USA
Joined: 8/4/2009
Posts: 10
Vette(s): 1969 L-36, 427- 390 hp. coupe. 4spd. air.
Thanks for the feedback. The point about torque is valid and makes sense. I just had the carb rebuilt by Sean Murphy in Huntington Beach, he's really good. I probably will go with aluminum heads as an improvement and as a weight savings. That's the other part of my plan, to get some of the weigh out of the car.
in Forum: C3 Engines
SPONSOR AD: (Our Sponsors help support C3VR)