72Tornado

Okay, so I'm going to be buying some sort of heads/cam package for my 72 soon...here are the current specs:

72 L-48
Long tube headers into true duals through Dynomax Super Turbos
Holley Street Avenger 670
Edelbrock Torker I intake (not the newer Torker II...want to swap out soon as well)

The engine was rebuilt not long ago, and is running great...anyway, I'm basically looking to get as much power as possible out of this L-48 without having to mess with the bottom end. The car needs to remain streetable, though my definition of the word is fairly loose. I have plenty of cash to spend, so money is not too much of a concern, but I would like to keep costs as low as I really can (say, $2000 as an absolute upper limit, would like to keep it to $1500 or less though)

So, I'm looking for the best heads/cam performance available for this L-48 without pulling the motor, while still keeping the car streetable. What are my options? Thanks in advance

wills670

what kind of rear gear are you running? i would loose the torker intake and install a dual plane intake. when the engine was rebuilt did you put in good rod bolts and what kind of pistons did you use. you need to match cam with the right rpm and engine componants. 1500.00 is not much you can blow that in heads and cam very easy. you would probaly see more performance with intake and rear gear change and ingintion upgrades.

72Tornado

I'm running 3.23's in the rear I believe...already upgraded the ignition, it was running a Mallory dual-point distributor which I have since replaced the guts with a Mallory electronic system...I don't want to switch to 4.10's or even 3.73's because I'm running an M-22, no overdrive...I might switch to 3.43's though. I can't imagine the intake change alone would benefit me too much, since the engine isn't starving for air running the stock heads and cam.

I'm not sure of what was put in during the rebuild, going to call the guy I bought it from and ask...he took really really good care of the car so my guess it was with fairly high-quality parts. I know I need to match intake, heads, and cam, hence why I know I'll be swapping out that Torker soon. Any recommendations on some good heads and how wild of a cam I should go with?

MotorHead

This combination made 300RWHP and 334RWT on my L48 : First get a steel shim head gasket ( I have the part number) to raise compression. Next Sportsman II heads, and either a CC 270H or 282S solid cam or the dual pattern equivalents of each cam (XE268-74 and XS282? ) With the 64cc heads and steel shim gasket you should be just shy of 10:1 CR.

For the intake go with RPM Air Gap or just plain RPM and your carb should be fine. Recommended this combination to a fellow CF member but he only did half of it and didn't get what he was looking for so you have to install all the parts because it all works together as a package.

72Tornado

Awesome, thanks a ton for the advice - this is exactly the kind of combo I'm looking for. Got a dyno graph? Interested as to what the powerband looks like...

MotorHead

I'll post it when I get home

MotorHead

Nce power/torque for the street or strip

72Tornado

Nice graph, that is one helluva broad torque curve Exactly what I'm looking for too, I want to make good power on the high end while keeping lots of low-end torque for the more fun aspect of it Were you running a stock bottom end?

Matt Gruber

motorhead has good results, but his combo does not work well w/ 02 sensors
if u can*aford $950 for heads, get the canfields.

Yellow73SB

The guy before me had put on aluminum heads before i got so i was lucky. i spent the money and had a 1000 port and flow job done. I dont have the numbers yet but he siad they flowed pretty good. im going to run .516 cam becuase they couldnt make it any bigger. I think with a .516 lift it should be streetable since its not that big.

MotorHead

Sure you can pay the money and get better aluminum heads there is always something better but do you need it ? For the money the Sportsman II heads are great heads, do you need 5 more CFM at 600 lift, probably not for a street motor and the mid flow numbers for the Sportsman II heads are as good as any out there.

My L48 was rebuilt using stock bottom end crank and rod and aftermarket hyperutectic heads for about 10:1. I used the CC270H and got aobut 10 less HP the dyno graphs above were with a CC282s soild cam. This is a proven combination that works, no smoke no mirrors, copy the parts and tune it properly and you will get the same dyno numbers. Actually I never even got to dyno tune that motor so there is probably a lot more in that combo.

How many 350ci's on the forum can say they are at 300RWHP ? ..not many


BTW O2 sensor now works great, now I have to hook up the tach input

Matt Gruber

canfield vs sportsman
.400 247/175 225/150
.500 258/190 240/164
will blow your doors off!

twistdpair

Can you post the part number for the steel shim gaskets?

72Tornado

Canfield vs Sportsman II (iron), assembled

$1,329 vs $879

The Canfields will also empty your wallet very nicely

If I had the money, perhaps I'd consider them...but that extra $450 won't be available to me this summer, and I'm not gonna have much disposable income during the school year

Carl Granquist

I'm one of those out here always looking for a good combination to modify my stock '71 L-48. Keep the numbers coming!

MotorHead

Where did you get those numbers, off the Canfield site

To get those numbers tested independantly by CHP you have to go to 220cc heads not too good for a 355ci. Let compare apples to apples here, you could have saved a few hundred bucks and got the VIc Jrs that will blow the doors off the Canfields





BTW a E/I ratio of 71% sucks

Matt Gruber

i can direct u to the vendor selling canfields for $950. e-mail me
#'s come from CHP site THEIR TEST NOT CANFIELDS
.
195CC better velocity than sprtsman
and 50# less on the nose
sporstman were hot years ago now they are obsolete
plus they like lower octane so u can save on gas!

MotorHead

Obsolete yea right, that's just plain silly, got a pair of Canfields you want to flog I assume ?

Guys at the dragstrip have ported Sportsman II heads supporting 500+HP in some very fast cars. Heil how many Gross HP do you figure 300RWHP is, my guess is about 425 - 450HP right out of the box

I am not denying the Canfields are might be slightly better I really don't know, and if he can get them for the same price them maybe that is way to go but you don't have to bash a good set of heads.

72Tornado the steel shim head gasket is FelPro part # 7733 SH-1

desi

Hey,I did more than half of it.... I don't think I can make 296rwhp hp with TH400. I figure with an additional 10% loss, I could have only made 265rwhp. With my cam smaller than 282S and lower compression, I would be happy with 250 rwhp. That's only 24 more hp I need to sqeeze out of this combo I think with different carb (jetted properly) and playing with timing I can get there

Anyway, there are guys who are running 240rwhp with stock bottom end and heads. Key is to select the right cam and tune the motor properly.

Good Luck

twistdpair

I thought the iron GM Vortecs are really good...? Apart from having to get another intake, what's the issue there?