sharkthehunter77

Been to the various websites and read all types of claims. Being on a small island demands i get feed back from U all before deciding. AFR, looked good, edelbrock seems a little tame for my Performer intake. The GM stuff seemed OK. 23 degree aluminum heads are good? The list goes on and on.
Got my engines plans almost all done because of this forum. Found the headers and Cam I will get. Now just need to pick out cylinder heads and pistons to complete my rebuild

Aaron-74

AFR's are probably the BEST way to go if money permits....

SRP, JE, KB...all good pistons. 10-10.5:1 would probably be the best ratio. :chevy

jdunne

Chevy Hiperformance has a long running comparo test on its website for virtually all sb heads.....don't forget that most/all new heads will benefit from some hand finishing from someone who know exactly what they are doing.....i have Brodix Track1 so i am probably biased, with short skirt SRP pistons.....dont forget that you will have to specify straight or angled plugs with your heads....if you have the headers already,do a mock up fitting to see which plugs will fit best...john :chevy ;)

Stingraycrazy

Brodix Track 1 CNC 2.08 X 1.6 :crazy:

nunus79

If you aren't changing pistons on a smog-motor, stick with a small chamber iron head. If you are changing pistons, go with aluminum heads & at least 10 to 1 compression. For a Vette, go with the larger valve sizes if available.

The next decision you gotta make is intake runner size, i.e., 170 cc, 180cc, etc. Too big a size will slow the intake velocity and make throttle response lazy. Too small will restrict flow at upper rpms. Some think 200 cc runners are too big for a 350, I don't. It maybe too big for a heavier vehicle with non-performance gearing, but not for a Vette. OK my flame suit is on, flame away.

FYI, that Performer intake is only a step above the stock manifold. There are even higher performance manifolds that would better match the larger intake runners of performance cylinder heads. So, don't let that manifold limit you in your buildup.

What cam did you decide on? That would help in finding you a good matching head.

terryrudy

I have the trick flow 23 degree heads. They were among the cheapest aluminum heads I could find. I'm sure I have a lot of tuning to do, but just bolting them on gave my 77 a sizeable kick in the pants.
-terry

sharkthehunter77

The 260H comp U mentioned earlier seems like a winner. I would like to avoid changing the manifold if at all possible, but, i am learning that these things can often be purchased in packages so A performer RPM with all edelbrock stuff ( heads, cams, pistons?) and headers of my choice may be more economical in the long run!

PatsLs1vette

im runing sportsman 2 's

redwingvette

One of the problems with the L-48 is the deck height is around .035 so going to a small chamber is needed. I bought Performer RPM's but haven’t run the engine yet. The other thing you need to consider is the trans and rear gear. A high lift cam and good flowing heads won't work well if you can't get the car off the line. Large ports are only good for top end and hurt low-end torque so you need to ask yourself what you want out of the car (street/strip, strip only, etc.) Spending more for heads because there are bigger may disappoint you in the end.

Edzred72

I agree. After comparing flow #'s AFR's are pricey...but great. My ProTopline heads are similar in flow #'s but I wouldn't recommend them for a lawnmower. I've had too many valve related problems with them. Good luck in your search
Eddie :smash: :smash:

nunus79

Use that High Energy 260H cam if you are going to stick with the stock heads. Definitely step up the cam if you decide to go with AFR heads.

I ran out-of-the-box Sportsman II heads with a 222 duration/.447 lift cam bolted on to an otherwise stock L48 smog motor shortblock. Got it into the 13s.

I believe you talked to Maurice about the Edelbrock Performer RPM package. As skeptical as I am, I have to say that combo worked, his 1/4 mile time slips don't lie. Lumpy idle, headers needed, higher stall converter helped too. Do you want something like that?

Ryan77

:iagree:

sharkthehunter77

I would love to run in the mid-high 13s ( or lower) but it appears getting out of all this without changing the manifold is a bit much to ask for. Why are u skeptical of the performer RPM and if i dont change the psitons wha is the deal with using small iron heads?

TedH

DART Iron Eagle (cast iron) heads. 72cc combustion chamber, 180cc intake runners (perfect for my single-pattern 272H Energizer cam), 2.02/1.60 stainless valves, guideplates, screw in rocker studs. Purchased for $850 plus S&H. You can get them for $800 now. Not emissions legal (no heat cross-over). Best (and most expensive) addition to my '80 L48 hop up.

AFR offers a cast iron, emissions legal, head now that is comparable in price (I think). That would be my choice if I had to do it over.

nunus79

Iron heads supposedly make more power than aluminum. It has something to do with the heat dissipation characteristics of each metal. With the stock dished pistons of a smog motor, the highest compression ratio you can achieve using out-of-the-box small chambered heads and thin head gaskets is in the range of 9.5 to 1. That is a decent compression ratio for a street engine running on pump gas. To me running a 9.5 to 1 compression ratio with an aluminum head when it could run better on a 10.5 to 1, is a waste of money. Yeah, you are getting a weight savings, but you are not getting the full benefit out of the aluminum head. BTW, the rule of thumb is that you can run a full point higher compression with an aluminum head vs. an iron head. The higher the compression ratio you have, the bigger the cam you can run. Thus, you can make more power with the aluminum head if you are willing to spin the engine to higher rpms. RPMs are what causes most engine failures. Spinning a stock L48 short block to 7000 rpm is not wise.

That’s why if you are going to be rebuilding the short block with new pistons, etc., you should install balanced parts that can withstand high rpm operation along with higher compression pistons. Then add the aluminum heads and matching cam to that short block to give you killer results!!

The Edelbrock RPM cam looked a bit wild for the street. That was my main concern.

sharkthehunter77

I love this topic, and the last two post really really really brought the performance picture into focus for me. My final question is this. Since after market iron heads are preffered should i still get new pistons, the performance mods websites often mention getting stronger psitons when you research their cams. So i could keep the same "smog" pistons and just spend about $700-800 on iron heads and $200 for a cam set? If this all matches my edelbrock performer and dual exhaust, then what would be my theoretical benefit

Alwyn678

Gm O41 heads with 64cc chambers

nunus79

Yes, you could do just an iron head & cam upgrade IF your short block is sound. That would produce a huge performance gain in itself. If that short block is worn, going the total rebuild w/aluminum heads route makes better sense.

At this point in your setup (adequate intake & exhaust), a cam change alone would net you a real nice, noticeable gain. Are you in a hurry to go fast? Or do you want to do things in steps (budget limited)? For me, doing things in steps was easier on the pocket book while it kept the performance passion going for a long time. I loved thumbing thru the performance catalogs, looking for that next performance part to buy.

Set your performance goal and buy the parts that will get you to that goal. If you know that you are eventually going to rebuild the short block, buy the AFR heads now and use them, even with the low compression pistons. Beware, if you set your goals too low and later find that you want more, you'll end up spending money again on same parts just to upgrade.

Bullyj

I'e been considering getting the Holley systemax kit when I get my income tax check. I have a stock L48 engine. Any thoughts on this setup? It comes with cam, lifters, pushrods, timing set, heads and intake.

TedH

In addition to the heads and the Crane Energizer 272H cam, I added flat top (with valve reliefs) Federal Mogul Hypereutectic pistons (approx 9:1-9.4:1 CR), Heddman Jet-Hot Coated EGR headers, 2.5" true duals, Dynomax Super Turbo mufflers, rebuilt q-jet (Lars), K&N air filter, edelbrock Performer intake, Accel Perf Replacement Distributor, and fresh 350 rebuild components (timing chain, oil pump, moly rings, bearings, gaskets, etc.). 1800 Stall converter, 700R4 and 3.54:1 Spicer gears in a fresh diff.

I may have missed a few items but that's the high points... :cheers:


[Modified by TedH, 9:45 PM 12/12/2002]