I'm taking my 350 Chevy into a local machine shop soon. The block is a 2-bolt 3970010 casting, heads are 882 (76 cc) castings. I was talking with the owner of the shop, he nixed the aluminum heads I had in mind, he suggested some that are better, but more expensive. He also showed me a chart of piston and combustion chamber values and said there is a way to get to 9:1 using the 882 heads, providing they check out. This would require new pistons, he estimated mine at around 8.2:1. My existing pistons have to be pressed off to check the rods, so only the price of the new pistons comes into play. If my heads do check out, I'll still be into them for the basic valve job and related parts, plus new springs, screw in studs, guide plates, etc. It could add up fast. I did run across some Dart Wissota claimer type heads for $430 each. The base dart number is 10024361. They have a 67 cc chamber, 1.94/1.50 valves, screw in studs, 165 cc intake runner. I would need guide plates and of course rockers and push rods. I want to run a flat-tappet cam like a XE262H. If I could retain my '68 Q-Jet intake, that would be a plus budget wise, unless someone can suggest a spread-bore aluminum intake to go with the Dart heads. If anyone has an opinion on the Dart Wissota heads, I'd like to hear it. Thanks, Bob
882 castings are junk smog era heads - I wouldn't put any money in them. sounds like this is an OT type build (spreadbore carb, etc) so the "cheap" dart s/r heads might be a good option (sounds like thats what the claimer heads are)
There are a lot of aluminum heads on the market. I would stay away from Pro Comp heads. There is a head on the market called ProMax. This is the re-formed Patriot company. I have heard a lot of good things about them. They are in the $850 range assembled. I went for Profiler heads. Very good quality and performance. Cast, machined and assembled in Ohio. $1150 range. I would recommend new aluminum heads over the reworked 882's or the Dart heads at about the same price of aluminum. Aluminum is good for a full point more compression, too! The 165CC intake runners in the Darts are kind of anemic. The bigger intake runner volume of the aluminum heads have a lot more power potential. Your deck heights need to be established before you can begin calculating your compression ratio. A specific piston and chamber volume is not enough to calculate CR. You must know how far the piston is down in (or out of) the hole at TDC and the bore and thickness of the head gasket and the volume of the dish or dome or valve reliefs. Wallace Racing has a great CR calculator. If your engine is all stock, the piston is probably .025" in in the hole. Piston to head clearance should be between .035" and .045". Aluminum heads normally use a .039-.041" gasket. This means your block needs to be zero decked to give you the proper quench distance for detonation control. Then pick your chamber volume to give the desired CR. With alum heads you can get away with 10.5:1 CR or maybe a little more. I'm running 11.1:1 CR on the street with 93 octane. For intake I suggest Edelbrock RPM and a 750 QFT carb. For a cam I would stay away from a hydraulic flat tappet. Too many cams being wiped out on startup today besides having to mess with ZDDP additives the rest of the engines life. I know a roller cam can stretch the budget, but well worth it over the life of the motor. Sorry, long winded. I just went through all this on my new engine.
The engine is at the shop now, being hot-tanked & evaluated. The existing pistons are deemed as junk, so something new will be obtained. I can go with a CR between 9.5:1 to 10:1 and be happy. I will trust the advice of the engine builder for piston selection, etc. Also looking at Dart aluminum head top end kits (64 cc combustion chamber, 180 cc intake runners. Heads, manifold (dual plane), all hardware, gaskets, etc. One stop shopping. I have a square-bore Holley on hand too. I talked with Comp Cams yesterday and they suggested an XE268H grind, I'll discuss the flat tappet/ roller options with the engine builder. I figure to be using a good oil with ZDDP already in it.
The DART heads should be just fine- the Wissota tag means it was cast for that sanctioning body (WISSOTA modifieds) They will be the same as the other DART heads in that group without the Wissota tag on them. The tag was there to keep claim class racers from spending too much $$. Another really good option would be World Products sportsman II. I use those and love them, you can get them in several chamber sizes and runner volumes.
I had a set of dart s/r torquer heads 2.02 valve 67cc chambers... Had them on a street s-10 with lunati 280 duration .480 lift cam with northern engine kit holley 750 dp .. Truck would pull car trailer an run 11.90s at strip.
The heads I'm looking at are Dart SHP aluminums, they'll work with the cams I'm considering (single valve springs recommended by Comp Cams). I liked the World heads too and the $$ is pretty good. The engine builder has steered me towards the aluminum heads and intake. The Dart line is attractive since it comes with almost anything I need, less rockers and push rods.
That's what people think , I saw flow charts once and the reality is the numbers were pretty darn close to that of the vortec heads , I have had two 350s with flat tops and 882 heads ... They ran really well
I am a fan of those heads, especially with some well thought out port work. I just wish the nominal chamber size was a tad smaller.
The 882 head is still a 1.94/1.60 valve head with a bigger combustion chamber, 76cc. So the basic flow is all Chevy, just need a way to boost up the overall CR.
Old tech was to put a piston w/a dome in to raise comp. ratio...new tech says use a dish top[d-shaped ] piston & run a small cc head & deck the block to up comp..... if those 882's[or 993's] aren't cracked , they will be... sooo much better heads out there [cheap] ,you'd be foolish to put any $$ in the old heads.. dave
I figured for what I would have to have invested in the old heads ($750 and up...) I'm 1/2 way to a new set of aluminum performance heads. The Dart head & manifold kit is only $1500 at Summit. Win, win.
The Jalopy Journal
