Corvette Forum : DigitalCorvettes.com Corvette Forums banner
1 - 5 of 5 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter · #1 ·
Guys, I have a 78 L-82 4 speed that internally is totally stock except Comp cams roller tipped 1.5 rockers with 65,000 miles. The engine has the OEM aluminum intake, a 650 Holley 4175 spreadbore replacement, zero pollution control (no EGR valve, heat riser valve, No AIR pump and hardware etc), shorty headers, 2.5 true duals, and Monza Turbo mufflers. The engine burns zero oil, the valve train is whistle clean, and I am going to take a look at the bottom end this spring when I replace the rear main seal for a leak there. I am also replacing the oil pump at that time since I am already in there. here is the question:

I am looking for a little more power, not big power, from the stock L-82 but I do not want to change heads-I know that the stock L-82 882 heads are 76 cc and smog heads that are not very good-but again, want to keep the engine stock and to use the OEM valve covers as well. If I keep the OEM intake and Holley carb and just port the OEM heads and change the cam (thinking of the comp cams 268H), what kind of power difference can I expect? Should I add the cam and leave the heads alone? Is it worth porting the heads and how much to do that?

I have a 2010 Z06 for big power so that is not the goal-just a decent amount of an increase with stock components!

Thanx for your responses!
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #4 ·
Thanx to both of you two above for your opinions.

I really do not want to go the aftermarket head route since I do not want to junk the heads unless I have to. I am either going to have the heads ported VERY CAREFULLY and very minorly and I like the idea of porting the OEM aluminum intake manifold. Either that or just leave the heads alone and port the intake and add a cam along with a new timing chain and gears.

What does a matched set of gaskets mean exactly? I didn't figure that the gaskets would play a big role in this change.
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #6 ·
Gasket matching is a MUST if you are spending the time and money to port. Use a set of very specific gaskets that you will use for your build. They become the template for the ports on the intake, and the heads...where the two meet. The more linear the travel path is for the air, meaning it slips through perfectly where the intake and head meet at the gasket, the better.
Thanx for the explanation!
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #7 ·
Ok Guys, I have been doing some research and I am now considering a top end change for the L-82 even though it only has 65,000 miles on it since I figure that I can keep the 882 smog heads, the cam (if someone wants it if the car is sold) and intake. Just read an article in Super Chevy magazine where they dynoed a bone stock L-82 at 313 Gross HP at 5,500 RPM and 355 torque @3,800 which are right on the money in terms of RPM for a stock motor and about 250 HP Net. With the changes only described below the new numbers were 414 HP @5,900 RPM and 415 torque @ 4,100 RPM-Gross again. Here are the 3 changes:

RHS 64 CC 200 CC runners-aluminum heads-$650 per side=$1,300
Pro Comp Dual Plane manifold-$125
Comp Cams XE274H-$350

I would reuse my Holley 4175 650 CFM spreadbore and my comp cams 1.52 roller tipped rockers. I figure about $2,000 for the heads, intake, new valve covers, gaskets, 274 complete kit with Timing chain, springs etc.

Good deal? Recommendations if the combo is better than above for the same money.
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #10 ·
Thanx for the feedback about the setup! I will definitely check about the 200cc runners versus the 185 CC runners to make sure that it will fit under my hood and I can use the stock air cleaner.
 
1 - 5 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top