Heads and Cam

[dk1977]

I am planning on updating the motor in my '77 L48 this winter. It is stock internally. I have already put on an Edelbrock Performer, Accel distributor & coil and Dynomax headers with true duals. It has a turbo 350, 2000 stall convertor and a 355 rear gear.
I want to update the heads, carb and cam to get more low end / torque as well as increased HP. I want a good sounding "racy idle", but realize the vacuum / trans restraints. I don't want a Drag car, but a good sounding, part time driver.
I am considering:
GM Perf Parts "Fastburn" vortec iron heads (small valves). 64cc
Used / Reconditioned GM "434" casting # heads. 2.02 x 1.60 and milled to 62cc
Holley Street Avenger, 570 or 670 cfm
CAM????
Any success stories out there?

 

[mike weyman]

if you put vortec heads on you will need to use an adapted intake to run a carb . also i heard there is some issue about the center holes not lining up with the older 350 blocks also i think there is something to be done to the steam holes.vettehead mikey can probbly take the ball when he looks at the post , he'll probably know more about it.

if you can get some old 882 casting heads , they are supposed to be the best of the junk heads , if you are going to put money into a machine shop for work , you will be better off to just bite the bullet and buy a set of aftermarket heads. then you can start saving for a new bottom end next season. man don't you love these old vettes ? mike.

 

[wallyknoch]

Any 202 valve heads would be an improvement along with the GM 151 hydraulic cam and a dual plane intake. The cam is from the 327/350hp mid 60`s Vette engine.

 

[Bob Chadwick]

Make sure everything matches or you may not get what you want and in fact could be very disappointed. A manifold that works best at low RPM from a power perspective needs to be matched with heads and a cam that also work best in that range. While you can do it buying parts individually from different manufacturers, have you considered the cam and heads that Edelbrock sells that are part of the Performer series. They have spent a lot of time and money matching those parts to make sure you get the performance that you are paying for.

 

[Ryan]

I went with the Holley systemax II engine kit from Summit. I kept my original L48 block and added this kit to it. It consists of bigger aluminum heads and intake, double roller timing gears and chain, lunatti racing cam and new pusshrods and lifters. This will give your engine approx. 220 extra Horses.

I paid $1300 for the kit and I added aluminum underdrive pulleys, dynomax headers, sidepipes, 2400 stall converter, 750 cfm edelbrock carb., and I got rid of the stock radiator fan and replaced it with an electric fan and an aluminum radiator.

I'm more than pleased with this kit and there is about 400Hp in there and alot of torque.

So try Summit or give them a call!

Greetings ,

Ryan

 

[rob77]

Holley SysteMAX II

I went with the Holley systemax II engine kit from Summit. I kept my original L48 block and added this kit to it. It consists of bigger aluminum heads and intake, double roller timing gears and chain, lunatti racing cam and new pusshrods and lifters. This will give your engine approx. 220 extra Horses.

I paid $1300 for the kit and I added aluminum underdrive pulleys, dynomax headers, sidepipes, 2400 stall converter, 750 cfm edelbrock carb., and I got rid of the stock radiator fan and replaced it with an electric fan and an aluminum radiator.

I'm more than pleased with this kit and there is about 400Hp in there and alot of torque.

So try Summit or give them a call!

Greetings ,

Ryan

I'm also considering going with the Holley SysteMAX kit. I have a 77 with a 355ci under a stock hood. My questions are:
1. Will it fit under a stock hood? I'm assuming it would with a drop air cleaner base and a 2" or 2.5" filter.
2. Is the cam too much for the street? The kit includes a Lunati hydraulic cam with 235/240 duration @.050".
3. Will there be enough vaccuum to properly operate the headlights, etc.

Any feedback would be appreciated.
Rob

 

[Glensgages]

2. Is the cam too much for the street? The kit includes a Lunati hydraulic cam with 235/240 duration @.050".

Everybody's opinion of "too-much-for-the-street" is different from everybody-ELSES.....

I ran a 244* @ .050" cam (CompCams292H) in my Z28 for a few summers, basically to/from the strip, and it wasn't "too-bad", but it didn't have hide-away headlights, either.

Wish I could help more.....

 

[curtis]

Excellent for me was the vortec heads, comp cams Extreme Energy 262H, Performer vortec intake and 600 cfm Edelbrock. Runs great on 89 octane. Super torque (about 430 lb/ft) and almost 400 hp.Idle not hardly lumpy at all. Vacume 18 at idle. Why spend as much money on old style iron heads with all the changes when you can buy the latest port technology and the heads already assembled for the same money? You could run a bigger lift cam if you really want the "lopey idle", but the trade off is lower torque numbers with a minimal power increase on top. Also a bigger cam would require the vortec heads to be modified for the increased lift (you can buy these already modified for a bout $150 extra) . My engine will jam you into the seat from 2000 to 5600 rpm. The smaller carb also gives you great throttle response for in town hell raising. Abigger carb, say 750 would get me about 10 hp on the top but weaken signal at lower rpm for a loss of low speed torque. Also running Hooker competition headers with Hooker 2 1/4 mandrel bent dual exhaust w/Monza mufflers. Get the vortecs, sticking bigger valves into old heads often loses flo if the porting is not done perfect.

 

[dk1977]

Curtis, thanks for the feedback. Where did you get the vortec "goodies"? Did you use the smaller valve, cast iron heads? Did you use the stock springs, pushrods, etc?Thanks again...

 

[Bill75]

Vortec Heads

Curtis,

Did you see mike wayman's comment on the Vortec heads not lining up with older 350 engines? Any comments on it? Did you have any issues?

 

[curtis]

Got all my stuff at Pace Performance. Scoggin Dickey also carries it. I ordered the entire kit to upgrade to the vortecs. Included things like all gaskets and bolts needed for the change. Super package. I had absolutely no problems putting this on my 76 block. Got the headers and exhaust pipes from Summit and the monza mufflers from Mid-America. My heads have the 1.94/1.50 valves and the stock springs as they came on the heads. Running stock length pushrods new from Jegs (block did not need any significant surfacing).Lifters came with cam package from Comp Cams. I had not put together an engine since 1979. This is only the second engine I have bolted together. Basic hand tools and a quality torque wrench was it. Took my time and it was easy. The power change from the stock motor to this is incredible. My machine shop did all the block work and returned to me the assembled shortblock with 30 over hypereutectic pistons and new cam installed and degreed in for less than $600.I am completely satisfied. Best 1/4 mile was 14.2 @99mph. Had some rather severe traction problems off the line and at gear changes. What a ride!

 

[Bill75]

Great info Curtis, thanks. I'm out of money from this winters rear end/swingarm rebuild, so maybe next year. Although the way it's been snowing outside I might have time to do it before the stuff melts!

Thanks

 

[celeryman22]

I just pruchased edelbrock heads, intake, pushrods and crane rocker arms. I am waiting on the proper gaskets then it will be going back together. I will be putting an Edelbrock carb on it also. If you email Corvette Central they will special order Edelbrock parts. Here in Canada it was eaiser to get them from CC then Summit Racing, since CC takes care of the brokerage and taxes. I 'm using sealed power pistons, and rings. Summit Racing cam.
This is my first engine rebuild.

www.vette-restoration.com for some pitures.

Regards,
mike

 

[Jack]

Regardless what motor you're upgrading ... if you put high comp heads atop well-worn/old rings&bearings that have lotsa wear ... you could be in for a short-lived power party. Vortec heads are direct fit to older blocks ... but vortec heads do not bolt up to older intake manifolds ... the mismatches are in the intake manifold bolt-head bolthole patterns and in port locations.
JACK:gap
"It is not necessary to change. Survival is not mandatory."
W. Edwards Deming, manufacturing systems pioneer

 

[dk1977]

Will my current headers ('77 L-48) fit the vortec heads? I understand the intake is different, but I just bought / installed the headers.

 

[Jack]

Will my current headers ('77 L-48) fit the vortec heads? I understand the intake is different, but I just bought / installed the headers.

Yes, if the old headers have six (6) flange boltholes, they should fit the vortecs.
JACK:gap