I purchased a 400 sbc complete and disassembled. All the machining has been done, etc, etc..However I decided to disassemble the heads to do some porting and polishing. That is when I noticed that even though both heads ARE for a 400 (the steam holes are there) the casting numbers are different. One head is a 333882 and the other is a 3998997. I looked them up online and they both have 76cc chambers, and are for a 400 block. But my question is this. Will the two different heads somehow affect the performance? I have never used mismatched heads before and I am not sure if it's advisable. Any comments would be appreciated.
400 SBC cylinder head question
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as long as the combustion chamber size and the runner size and valve size are the same, should be fine.
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Bob,
I really hate to burst anyone's bubble, but I feel it is important for you to be aware of one thing. The 882 head is a 75-later head-----------------NOT GOOD.
I don't know how much you may be familiar with SB heads, BUUUUUUUUUUUT, 74 was the LAST year for "good" production SB heads. Beginning in 75, Chevy started cutting corners on the SB heads, and by 77 they were basically junk. The castings became thinner, they got 2 exhaust crossover passages and some of the water jackets had been eliminated. All of this contributes to head cracking. If that 882 head is not cracked now, there is a VERY GOOD possibility that it will after you spend your time and hard earned money having it rebuilt. Depending on the casting date of your 882 head (75 or 76), it could be a marginal head. But, if it has a Aug 77 or later casting date, I would discourage anyone from using it.
The 997 head will likely have a 71 to 74 casting date, and should be a very acceoptable head to use. The 997 heads were among the last of the heavier, thicker, stronger castings.
Also, it is not readily recognizable, the 882 and 997 heads do have a different shape to the intake runners. Now, just how much this may affect performance on a street engine, I can't say. Probably not too much, but it would certainly have an effect on a healthy performance engine.
G
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·And some 400 SBC heads are 1.94"/1.60" valved vs the usual 1.94"/1.50" valved so check here to.. Both have been used is all..........
pdq67
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pdq67
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DZAUTO...I just took a real close look and you are right...the 882 head has cross overs on the two center exhaust ports. The 997 only has one. I compared the runners and they are a slightly different shape. Since I am building this engine for power, I am not gonna take the chance. I am gonna look for a new set of heads. Thanks.
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10,315 Posts
Bob,
If a another pair of heads is the direction that you are going to go, I WOULD REALLY, REALLY ENCOURAGE YOU TO CONSIDER SPENDING A LITTLE EXTRA AND GET A SET OF AFTERMARKET IRON HEADS! Something like a pair of DART Iron Eagles would be about as good as you can get. Over tha past 8yrs, I've bought 3 sets or DART SB heads and have ZERO complaints about them. All three sets were for a SB400, and I ordered them with the steam holes already drilled. The last set I bought was through A D Performance in WA state http://www.adperformance.com/index....fc973ecb23f0a18a1229086f9e038&main_page=index. These went on a 420SB in my boat and they are the ones with 215cc intake runners, 2.05/1.6 stainless valves, angle plugs, screw-in studs and guide plates. Standard intake and exhaust manifolds fit them. UPS to my door was just over $1K.
If a another pair of heads is the direction that you are going to go, I WOULD REALLY, REALLY ENCOURAGE YOU TO CONSIDER SPENDING A LITTLE EXTRA AND GET A SET OF AFTERMARKET IRON HEADS! Something like a pair of DART Iron Eagles would be about as good as you can get. Over tha past 8yrs, I've bought 3 sets or DART SB heads and have ZERO complaints about them. All three sets were for a SB400, and I ordered them with the steam holes already drilled. The last set I bought was through A D Performance in WA state http://www.adperformance.com/index....fc973ecb23f0a18a1229086f9e038&main_page=index. These went on a 420SB in my boat and they are the ones with 215cc intake runners, 2.05/1.6 stainless valves, angle plugs, screw-in studs and guide plates. Standard intake and exhaust manifolds fit them. UPS to my door was just over $1K.
624s are not something you want. more thin wall stuff. you really need to lok at aftermarket heads as Tom pointed out. any of the early stock heads will just strangle a decent 400. a 400 can really use up to 200cc intake ports heads easily, the stock heads are in the 165cc range.
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7,294 Posts
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Good plan,,
Heed Tom's advice, the late heads are more likely to be cracked or will crack in the future
The 624 is junk too.
It is well worth the extra expense to get some decent heads if you are building for power & I would highly encourage you to go to an aluminum head if it is within your budget
If not, the 200cc Dart Platinum's would be my first choice in cast heads
The SR or Street replacement heads from Dart & World are just that, a copy of the best of the early GM heads & while excellent castings with screw in studs & hard seats are not really a performance head with the newer better combustion chamber shapes.
There is a lot of power in cylinder heads, good place to spend your money
EDIT
OK, NOW BOTH TOM'S
go to the link in Tom's post, go to Cylinder Heads/Dart/Iron Eagle, look at the 180 or 200cc. down at the bottom see options assembled with 1.25" springs, straight plugs, 72cc chamber. Ask them to drill the 400 steam holes.
If you're wanting to run a more aggressive cam check the 1.437 better valve spring option.
If you building a stock replacement engine you could use the 165cc port heads. I have these on my 406 small block but really, really wish I had gone for the 180 or 200 cc version. Make sure you get the 72cc chamber.
If you're wanting to run a more aggressive cam check the 1.437 better valve spring option.
If you building a stock replacement engine you could use the 165cc port heads. I have these on my 406 small block but really, really wish I had gone for the 180 or 200 cc version. Make sure you get the 72cc chamber.
You convinced me!...thanks for all the help..I don't know what I'd do without this site! I am gonna stick with a slightly larger chamber since I already have the rotating assembly finished with a set of new flat top pistons. I wanna try to keep it on pump gas if i can....
flattops in a 400 are going to give you a non-pump gas compression ratio with any normal chamber heads. Did somebody here advise you to build a pump gas 400 with flattops?
4.155 bore
3.75 stroke
72 cc chamber
6 cc valve notch
.039 gasket
.020 deck clearance
around 10.1:1 this is not really pump gas friendly with a normal street cam and iron heads. You might get by with retarded timing, but that's a drag.
IMHO, YMMV, all that
4.155 bore
3.75 stroke
72 cc chamber
6 cc valve notch
.039 gasket
.020 deck clearance
around 10.1:1 this is not really pump gas friendly with a normal street cam and iron heads. You might get by with retarded timing, but that's a drag.
IMHO, YMMV, all that
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6,401 Posts
Why not use some Vortecs with about a 16cc reverse dome or dish? Should be budget.
G
Guest
·I don't think a complete Vortec head conversion PLUS switching out pistons and re-balancing it will be cost effective, imho...
Please look into the CHEAP heads, cast-iron AND aluminum Hotrodsusa sell's down the line..
http://www.hotrodsusa.com/
Other's sell similar heads too down the line if you look around!! NOT race heads, but still good value IMHO... I figure the 190 cc jobber's will do you nicely...
pdq67
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Please look into the CHEAP heads, cast-iron AND aluminum Hotrodsusa sell's down the line..
http://www.hotrodsusa.com/
Other's sell similar heads too down the line if you look around!! NOT race heads, but still good value IMHO... I figure the 190 cc jobber's will do you nicely...
pdq67
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
those heads are 64cc, not a step in the right direction.
funny, according to their charts their 210 raised runner head only outflows their 190cc standard head by a few CFM. Wonder what's up with that deal. I'd be embarrassed to post that.
funny, according to their charts their 210 raised runner head only outflows their 190cc standard head by a few CFM. Wonder what's up with that deal. I'd be embarrassed to post that.
My 70 Chevelle has the factory 300hp 350 w/10.25:1 CR; run fine on premium pump fuel but the timing has been retarded a bit and engine cooling has been upgraded with a 4 core radiator.
I do have a 400 sbc on the stand with flat top std. bore pistons, but it does have Canfield aluminum heads on it so the higher CR should be ok.
I do have a 400 sbc on the stand with flat top std. bore pistons, but it does have Canfield aluminum heads on it so the higher CR should be ok.
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