I am thinking of a head swap for my 83 TA soon. It already has a 350 with i believe 882 cylinder heads on it. I am possibly able to get a good set of heads from an L-98. Are these good heads? I know they would bump my compression, but how about the springs? How much lift can they handle? Would a 10:1 350 w/ CompCams XE262, Edelbrock Performer, L-98 heads, and good shorty headers be a good balanced combo? How much power would I be looking at(ballpark estimate)? BTW, these aren't the Vette heads, but from an 89 Formula. Thanks in advance.

 

DB355,

Take my opinions for what they are worth, but all the power you'll ever make with an SBC will go through the heads. The cam is part of the equation, but even a great cam profile design can't make up for poor head flows.

You already have five more cubes than a "regular" L98, so why would you want to choke it with those heads? Even in aluminum, those heads don't flow anything near what you need for top-end power. If you had a stock TPI it wouldn't make a lot of difference since the heads are better matched to that intake system. Since you'll be using a manifold, make the most of it.

With some serious porting, the L98 heads can flow pretty well. If you want to weld up the pushrod areas and really reform the ports, you can get very respectable flows. If you have lots of time to do this, go for it. If you are going to pay someone for this, forget it. Most people wouldn't even know where to begin.

As for the springs, the stock springs are far too low in seat pressure for .462/.470 lifts with ramps like the 262 grind has. They are also uncomfortably close to the coil bind spec at those lifts, and the valve springs are not the best place to bottom out the valve train. You'll need to machine the spring seats for larger diameter springs, install correct springs and retainers. Since the heads are going to the shop for that, you shoudl spring the extra fifty bucks and get screwed rocker studs so the Comp ramp doesn't remove the "pull-out" factory studs in the middle of a run. And since the heads are already in the mill, you should seriously consider doing something about the small 1.94/1.50 stock valves.

By the time you are done with the machinist (or he or she is done with your), you'll have spent almost the price of low-end aftermarket heads, and will still have small ports and flows. If you have the heads ported, you've just blown the price of a really nice set of heads out of the water.

You can get new aluminum heads with whatever chamber size you desire, new springs, screwed studs, and new larger stainless valves for around $325.00 each. You'll spend that much without porting at the machine shop if you spend a nickel, and by the tiem you add new vales and springs, you'll be closer to the $650.00 cost of a new pair of Torquer os Sportsman heads.

Just my 2¢

BTW - If the budget is a little more open, the Australian Pro Action cast iron heads look like they have some real flow potential. The iron heads out of the box flow better than most prepped heads from other companies, and when ported well are showing well over 400 SCFM flow numbers. They flow over 200SCFM at less than .300" valve lifts. Looks like the Aussies have been listening, and their toying with all those Holden Caprice LT1 engines has paid off nicely. The cool part is that the bare castings are less than $250.00 each, ready to assemble. For a little more than you would spend on machining your L98 heads to get them back to useful condition, you can have a new set of these.

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Later,
Vader
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[This message has been edited by Vader (edited September 07, 2001).]

 

As you can see from flow test, the 882's are a better flowing head. I had an 882 headed 350 in my 82 Z28 that went 12.50's @ 107 w/ a dual plane intake, 650 Demon, Hedman shortys w/ Y pipe, Edelbrock Performer RPM cam, a small 2400 convertor and 3.42 gears, so the heads actually perform quite well. The only "bad" thing about the 882's is the 76cc combustion chambers, and I had .125 domes in my engine yeilding about 9.9:1 compression. Its kind of a toss up. The Intake will cost more for the L98 heads also, due to canted bolts in the center. You could have the 882's milled and get some compression back that way also. I would get better springs and probably do a valve job on either of the sets you go with. Either way you should have a decent engine. I did also like the fact of proving to people that my mild street car was running 12.50's on motor with 882 heads. Most people think of them as a $hit-head because they were smog era heads, but they actually compete well with the double humps and even the World Products S/R Torquers up to .400" lift, which is where it really matters with a street cam. Remember, that even with a .500" lift cam, it is only at .500" for a brief moment on the very top of the lobe. The mid-lift area (.300" - .400") is where a mild cam needs its best flow.

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82 Z28 383, Ported 215cc Dart Iron Eagle Heads 72 cc Comb. Chambers, Comp custom grind Hyd roller cam, Speed Pro .250" domes, Wheeler Motorsports 4340 I beam rods, Eagle 5140 steel crank, Weiand Team G intake, Holley 830 DP, hedman headers
Trans: Turbo 350 w/ 4000 stall -- Rearend 7.5 w/ Richmond 4.10's, Auburn Minispool
Best ET:11.60 @ 114.56, w/ a 7.34 1/8 @ 93.50, and a 1.622 60'


89 RS, L03 305, Hypertech Chip,cat delete, Dynomax exhaust,K&N open element Filter,160 stat, MSD coil --Trans:700R4 Corvette Servo -- Rearend: 7.5 GM 3.42 w/ posi-lock

Bassett Racing

 

P.S. I agree with Vader. At the very least, before I'd spend money on either one of those heads, I'd at least buy a set of $400 Vortecs. You'll spend that much on a quality set of springs, valves and a vlave job. Check out how much the Vortec flows, even compared with Edelbrocks on the intake. A little porting on the exhaust side of a Vortec head makes them a serious head.

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82 Z28 383, Ported 215cc Dart Iron Eagle Heads 72 cc Comb. Chambers, Comp custom grind Hyd roller cam, Speed Pro .250" domes, Wheeler Motorsports 4340 I beam rods, Eagle 5140 steel crank, Weiand Team G intake, Holley 830 DP, hedman headers
Trans: Turbo 350 w/ 4000 stall -- Rearend 7.5 w/ Richmond 4.10's, Auburn Minispool
Best ET:11.60 @ 114.56, w/ a 7.34 1/8 @ 93.50, and a 1.622 60'


89 RS, L03 305, Hypertech Chip,cat delete, Dynomax exhaust,K&N open element Filter,160 stat, MSD coil --Trans:700R4 Corvette Servo -- Rearend: 7.5 GM 3.42 w/ posi-lock

Bassett Racing

 

That flowbench data is for aluminum L98's....the iron ones are even worse.

You will lose CR with the 882's..but I would guess it's worth the gain in flow.