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I have a 350 bored 30 over with flat top pistons. The heads I currently have to choose from are the stock 183 heads, which I originally planned to use till I get up the money for some aftermarket builds, or some 400sb heads (not sure of cast #).
So which would be better? The higher compression, or the higher flow?
Are you sure the heads are “183”? Could they perhaps be “188” more specifically, 3927188? If so they are a so-so stock head with 1.72/1.5 valves and 74cc.
The 400 heads you have are probably 3961598 or 3973493 (most common numbers for 400’s). They are not much better, i.e., 1.94/1.5 - 76cc.
Did you have the block decked when you had it bored? If so, what’s the deck height?
The stock height of an uncut 350 is typically 9.025" from crank C/L to the deck.
The compression height of a 350 piston varies by manufacturer (anywhere from 1.53 – 1.56) which will influence the compression ratio.
A bit more info would be appreciated..
Regards,
Glenn
the 350 heads are cast # 14102193 (thought it was an 8)
The block has not been decked
The pistons are a part of a rotating assembly bought from Summit racing part # SCA-1_92300. Not sure what the compression height is and they are already installed
It is equally as important that you tell us your goals.If it is a stick shift or not,what is the rear end gear ratio,what is the rear tire size,what is the vehicle it is going into and the wt.
glen, He's got a Scat kit,heres the specs.
355
Bore (in)
4.030 in.
Bore (mm)
102.362mm
Engine Stroke (in)
3.480 in.
Pistons Included
Yes
Piston Rings Included
No
Piston and Ring Oversize (in)
0.030 in.
Piston Material
Hypereutectic aluminum
Piston Style
Flat top, with two valve reliefs
Piston Head Volume (cc)
+5.00cc
Wrist Pin Style
Press-fit
Crankshaft Included
Yes
Crankshaft Material
Cast iron
Rear Main Seal Style
1-piece
Balanced
No
Engine Balance
Internal
Tell you out front that I am not a fan of you using smog heads and yet I do understand why you are.The smart money spends on the end build with the aftermarket heads and the reason why is your likely going to spend about $200 on the smog heads to make them in decent form.Then which cam you going to use on the smog heads may or may not require additional machine work.So you lose the 200 bucks because no one wants then normally and the cost of the cam and kit for it.You get to buy the cam and kit a second time for the later aftermarket heads too.You might be better off holding off to buy the aftermarket when your more flush with cash.
Just my two cents worth.
I'm no fan of these heads either, they are just what came off the block and I just want to at least get it together and in the truck for now until I can build the top end. The engine is going in a 88 S10 Blazer. I'd like to do some autocross with it but really just want a strong V8 and lots of speed. I dont plan on spending a nickle on the factory heads. So, as the question was, which heads would be better (for now). It will cost me $100 to get the 400 heads from friend, but if they are not that much better than the heads I have then I dont want them, so that is the question, stock 350 or the 400's??
Go with the stock heads that you have as you'll not notice any difference in this build w/400 heads. Make a plan, list what you'd like to have, save your bucks and build the top end. When you get ready, we'll have some good suggestions, in the mean time - drive what you've got and enjoy!
Regards,
Glenn
Thanks Gleen. One more question. I just ordered a camshaft with .454/.454 lift and 272/272 duration, it's a street and strip cam. When I get ready to buy the heads, which ones would you suggest? I'm a Summit Racing customer and thats where I plan to shop