sharkthehunter77

The local hot rod shop has the Worlds iron cylinder heads in the i think 67cc and 76 cc chambers. Which is best for a daily driver with the edelbrock performer and what cam will subsequently go best with that. My research says the small 67cc ones may increase the compression too much for my L-48 on pump gas and a chevy cam with something like 220 duration with the 76cc ones might work best. A somewhat loppy cam is OK (again driven on the street often but no daily driver) the car will see 1/4 mile track use maybe twice a month. If the engine can handle the 67cc's what else has to be done? I believe the choices of cam change quite a bit depending on choice of cylinder heads.

Fevre

Bigger cams like higher comp at idle to run run smoother. 220 duration is pretty big for a l-48 even with 67cc heads. Mine is not a daily driver but runs fine on 87 oct at about 9.3 comp but I have alum heads and 220 and 230 duration. 67cc should give you about 9 to 1 which should be OK for iron heads a 87 oct. Again since mine is not a daily driver I can't rocomend a cam for that purpose but I would think you will be happier at about a 210 duration. If you have an auto and low gears, a big cam is out unless you want to change your torq conv and lower your rear gear.


[Modified by Fevre, 11:14 AM 1/21/2003]

Metal Wulf

go with the 67cc heads and comp cams xe262 :thumbs:

MRZ28HO

Well, I went with a 212/218 Comp Cam (114 LSA). I am hoping my Mechanic buddy can find good 64cc heads, they will compliment my Father's L48 well. :) Otherwise, we will have to settle for the 76cc ones. :( And it will be a sunday driver for a person who cannot tolerate (my kind of) "performance" engines. I'd go with the 67cc heads. JMHOT

sharkthehunter77

I screwed up, the small heads are 64cc instead of 67. Is this too much compression fo an L48? Will the 262Xe still jibe with that also?

Ryan77

Get the 64cc heads, they will not raise your compression so high that you can not run it on premium pump gas, but if you're really worried, see if you can get aluminum heads. For the cam I have a Comp Cams 268XE in my daily driven '77 4 speed, but with your auto trans I would stick to the 262XE :yesnod: The Performer manifold should also work perfectly with this cam.

sharkthehunter77

thanx a million, i just got throuh tellin somone in anothger post to forget all the vette magazines and just use the forum for all vewtting needs. These fast ,free, accurate and prompt response are why!

nunus79

You just got an "F" on your research paper. :jester

64cc chambers on an L48(76cc) using stock steel shim head gaskets would net you a one point compression gain, i.e., 8.5 to 9.5. Many performance head gaskets are thicker than the steel shim type. So, a full point gain is about the best you'll be able to see. 9.5 to 1 comp ratio using pump premium is doable, especially if the heads you choose have high swirl characteristics. That leads to more efficient burn and less chance for uncontrolled preignition. World Products SR Torquers supposedly have good swirl & combustion characteristics. Most popular aftermarket heads should also. So, stick with the lower cc combustion chambers for L48s.

I used the factory 222 degree cam with 76cc heads on an L48 before. I literally had to wait until the engine revved up enough for that cam to kick in. Poor off-idle throttle response. Very lumpy idle. Bad gas mileage. Had to raise initial advance to like 26 degrees to lessen the severity of the conditions mention before. These are typical "too much cam for too little compression" symptoms. I then threw on 64cc heads and all of those problems went out the door. You see, that factory cam was meant for a 67 manual trans, 327 w/10 to 1 compression. Point of the story, don't over cam.

You got a couple of recommendations for the Comp Cams XE series cam. Should be good. BUT, beware that you should use Comp Cams' recommended valve springs with that cam series. Check to see the compatibility of the springs installed on the heads you plan on buying with the springs recommended for whatever cam you're purchasing. Swapping springs with the heads off are much, much easier than with the heads mounted.

FYI, the stock L48 springs and the High Energy 260 are compatible. That's one of the reasons why I recommended using that cam if you weren't going to change your heads.

How did the harmonic balancer thing go?

sharkthehunter77

The damper was simply fascinating, there was som sort of melted hard plastic thingy stuff goo around the threads were the pulley meets the damper coming from under the damper but yet not part of it?!?!? thingy and such and such. the damper was just fine and in no state of disrepair, but that other stuff , i removed and put her back to gether and everything seems cool?!?! But seriously, theres was something not part of the darn thing coming out fdromunder the darn then so now its gone. I even had very very very experienced smart people over check ma work over and all is well. Know on to the important crap, i did some more research( uh-ohh) Ithough i heard that you guys used 220 or 222 cams but i was unaware that you were not happy with it. The vacuum issue did cross my mind. the 260H has a duration 212/212 a lift .440/.440 with a 110 lobe. The XE262 has a duratiojn of 218/224, a lift of 462/470 and a lobe of 113. I do not have my Lingenfelter book in front of me as i am BS at work but is not the smaller one better. i should get the one with the 113 lobe right ..riight. i told my friends about my "F" and they think its hilarious, i told them i suck so its no surprise!!!

nunus79

Don't get me wrong. A 220-225 duration cam can work fine in a street engine PROVIDED that the engine has enough compression to support it. Just don't go too big on the cam or else you'll need more compression than what the L48 dished pistons can give you. If you decide that you need a big cam, then changing pistons and going to aluminum heads will enable you to run 10+ to 1 compression on pump gas.

sharkthehunter77

read U load and clear wing commander. I was wondering about the vacuum /compression issue and gotconfused. truth is, i want a mid 13's car while i am here on the island and as soon as i transfer back to the mainland a crate motor(either ZZ4 or Big Block) long block is going into the car. So, all this stuff about using aluminum heads seems counter productive from a cost prespective right now since i would need to change the pistons as well. I like either the 260H or the XE262 cam, i will get the iron heads and with headers i should be in the zone, i hope.

nunus79

Hummm, ZZ4....... If you are serious, then maybe take another course of action. Concentrate on the things that will be needed to support/compliment the ZZ4 like the headers and a high stall torque converter. The verter will give you a good SOTP improvement. Add a performance shift kit and a tranny cooler to round out the package.

But definately replace the cam. Great bang-for-the-buck. You'll learn a lot about the engine by doing a cam swap. That's a bonus. Save the head money for the ZZ4. You'll probably end up in the lower 14s with those mods alone with traction. And I agree with you, if you then throw in a set of performance heads, you will be deep into the 13s.

tnt76vette

Nunus79: You continue to be a WEALTH of information.......but I STILL swear my '76 L-48 had flat top pistons w/valve indents. Maybe I got a Hybrid Huh? BTW Friend: I hope you are enjoying your warm Hawaiian Weather, as it is a BALMY +10 F here in MI.........ENJOY! :D :D :D :D :D

nunus79

Tom
You could very well be right. The earlier year L48s could've had flat-tops. That would account for the slightly higher compression ratio of 8.5 to 1 vs. 8.1x to 1 for a 79.

So, if that is the case, I stand corrected. Thank you for pointing that out to me.

We've been getting that cold North air blowing thru our islands lately. Brrrrrr........ some nights have been in the high 50s :jester

Keep Mama warm!
Aloha, Norris

8T1-7T9 BIONIC VETTE

Hey nunus79,
Since you're the expert around here....how about some help on my Bill Mitchell....
I have AFR 210 CNC and Ported Heads sitting in a box and a Comp Hydrualic Roller Cam with lifters waiting to go onto the Bill Mitchell.
I'll pull engine.....have it on a stand....I would prefer someone with a knowledge about cams and clearances close by so I don't screw this baby up......I'll probably need help in dailing in the cam too. Two heads are better than one...... :seeya Cappy

redwingvette

My 73 had dished pistons until I rebuilt it. Even with the flat top pistons it had a deck height of .037" plus gasket thickness of .039 and 64cc heads put compression at 9.7:1. Pump gas works well until you get above 10:1 with Iron heads. What do you have for a rear gear?

nunus79

OK, back to square one. I dunno Tom, maybe your Vette WAS alien abducted or something :D

Cappy,
I wince at the thought of changing anything on that beauty motor you got in there now. But it sure would make for an interesting comparo.........?????? How's this for a plan, get your better-half hooked on the 1/4 mi with the 7T9. She'll soon be asking for more power. Then build her engine with those AFR heads.

Regardless of which engine you want to tear into, I'll be more than eager to help out.
Norris

8T1-7T9 BIONIC VETTE

Right on nunus79,
We can also consider the Beck 383 Max Velocity Plus Engine....This engine is already sitting on the stand.
I can order the Hardcore all forged 383 internally balanced rotating assembly from Bill Mitchell....and turn that one into a beast too. :hurray: :seeya Cappy

Maurice

Keep it up Cappy and you will be looking for two roll bars :)

gkull

Cappy instead of going road racing in Feb. I should have been smart and hopped on a plane to HI for some wrench time:) The cost is about the same.

:jester I forgot! We would have a language barrier until I cought up on pigeon!


[Modified by gkull, 2:38 PM 1/23/2003]