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Username Post: BBC head chamber identification        (Topic#228403)
BBC-454 
Senior Member
Posts: 1400
BBC-454
Loc: Edmonton, Alberta
Reg: 05-11-03
10-25-09 03:28 PM - Post#1794247    

I have found some heads for sale, the seller claims they are 1972 454 heads, casting number 336781. i looked up the casting number and it states these are open heads. Looking at the pictures in the ad it appears they are closed chamber though. Here is the link to the ad with pictures.

http://edmonton.kijiji.ca/c-cars-vehicles-auto-p ar...

I also have the option of some unknown casting number early 70's heads which have hi perf pass cast into them. Would these be better due to the hi perf designation? I am trying to get the casting number off them as they are 100 miles away and I have to rely on a third party to obtain them.

Thanks for any help!
Josh R.L.
Licensed Automotive Mechanic
1966 Buick Special 2 door
1961 Chevrolet Apache 10 panel van
1995 GMC K2500
2011 VW Jetta TDI


 
fritz1990 
Senior Member
Posts: 6389
fritz1990
Age: 52
Loc: Kansas
Reg: 02-16-03
10-25-09 04:15 PM - Post#1794280    
    In response to BBC-454

The 781 are all open chambered and will run anywhere from 119-124 cc. These are the best oval port factory heads along with the 049 castings, last three digits of casting #.

Need the casting numbers off the other heads to know for sure what they are.


Regards, Jeff
1998 K1500 6.5 Coal burner
1965 C10 with 498 BBC AFR Heads
1964 C10 Ran 348W for 6 years, now SBC.

Corvettes owned: '74 '77 '78 L82 Silver Anniversary, 2002 LS1

Don't have a nervous come together!

http://picasaweb.google.com/fritz199090


 
Impala65SS 
Valued Contributor
Posts: 3651
Impala65SS
Loc: Sweden
Reg: 08-23-07
10-25-09 05:55 PM - Post#1794338    
    In response to BBC-454

  • SBC283 Said:
I have found some heads for sale, the seller claims they are 1972 454 heads, casting number 336781. i looked up the casting number and it states these are open heads. Looking at the pictures in the ad it appears they are closed chamber though. Here is the link to the ad with pictures.

http://edmonton.kijiji.ca/c-cars-vehicles-auto-p ar...

I also have the option of some unknown casting number early 70's heads which have hi perf pass cast into them. Would these be better due to the hi perf designation? I am trying to get the casting number off them as they are 100 miles away and I have to rely on a third party to obtain them.

Thanks for any help!


It seems everything is in order. Those are open chambers of the sort to be expected for #781.

The "Hi-perf" is always square port and "early 70s" is most likely open chamber. #990 and #188 are the most common over the counter heads from GM during the 70s. There is a chance/risk of closed chamber - for some time the 1970 LS6 head - #291 closed chamber with 2.19/1.88 (only closed chamber head with 1.88 exhaust) was also sold as a replacement part. I'd get hold of them if the price is great - but I'd rather build a street engine from a pair of oval port heads. Particularly the 291 heads if they are unmolested - the LS6 1970 is of course a collectors item.
http://www.youtube.com/watch?v=SXn2QVipK2o&a mp;fea...


 
BBC-454 
Senior Member
Posts: 1400
BBC-454
Loc: Edmonton, Alberta
Reg: 05-11-03
10-26-09 09:57 AM - Post#1794665    
    In response to Impala65SS

Thanks guys, so are closed chambers undesirable for big blocks?
Josh R.L.
Licensed Automotive Mechanic
1966 Buick Special 2 door
1961 Chevrolet Apache 10 panel van
1995 GMC K2500
2011 VW Jetta TDI


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 15987
grumpyvette
Age: 66
Loc: FLORIDA USA
Reg: 03-16-01
10-26-09 10:23 AM - Post#1794681    
    In response to BBC-454

  • SBC283 Said:
Thanks guys, so are closed chambers undesirable for big blocks?




that depends on the application, closed chamber heads raise the compression ratio and have dual quench areas making them good for low-mid rpm torque, but the open chambers breath slightly better in the upper rpm ranges, what most guys forget if that while you might be down a few hp at peak rpms, with closed chamber heads you've usually gained measurable torque over much of the rpm band due to the higher compression, if I was building a street 396-427bbc used to tow a trailer in a truck or car or just a car used for cruising Id prefer the closed chamber design, especially the oval port closed chamber heads.
where you probably don,t want closed chamber heads is on a high compression high rpm rectangle port 396-427 combo cammed to run up over 6000rpm, because the better oval port heads with open chambers will tend to produce better power, but don,t think they are slugs, one look at the super stock records will show you that closed chamber heads make serious power if the right combos used
" " IF YOU CAN'T SMOKE THE TIRES FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK !"


Edited by grumpyvette on 10-26-09 10:30 AM. Reason for edit: No reason given.

 
Impala65SS 
Valued Contributor
Posts: 3651
Impala65SS
Loc: Sweden
Reg: 08-23-07
10-26-09 10:36 AM - Post#1794683    
    In response to BBC-454

  • SBC283 Said:
Thanks guys, so are closed chambers undesirable for big blocks?


Only reason I pointed out OC, I got the impression you needed that (perhaps already bought pistons et.c.).

Personally I prefer closed chamber - particularly the semi open type like 290, 063, 215, 802. For open I prefer 820, 148. Reason is I want a bit higher SCR but prefer flatter pistons so the ignition wont have to be set so early. I have 34┬░ with my semi-open, where most guys have 36┬░ with open chambers.
http://www.youtube.com/watch?v=SXn2QVipK2o&a mp;fea...


 
BBC-454 
Senior Member
Posts: 1400
BBC-454
Loc: Edmonton, Alberta
Reg: 05-11-03
10-26-09 09:54 PM - Post#1795029    
    In response to Impala65SS

I have a core right now and am trying to piece together the components before I tear into it. I was planning to run iron eagle 308's, but then these oe heads surfaced so I am considering them.

I was also planning this engine for a mud bogger, but that plan has almost took a back seat depending on whether or not I get what I am asking for my 4x4 parts.

Either way I am going to build the engine, obviously if I use it in a street rod application I will have alot more cash available for better engine parts as I wont have to rebuild two diffs, a tranny and a tranfer case!
Josh R.L.
Licensed Automotive Mechanic
1966 Buick Special 2 door
1961 Chevrolet Apache 10 panel van
1995 GMC K2500
2011 VW Jetta TDI


 
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