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Username Post: BBC cylinder head question        (Topic#349384)
joeblow55 
Forum Newbie
Posts: 52

Reg: 05-03-10
01-29-18 09:38 AM - Post#2722563    

Starting to "freshen up" a 396 build from almost 30 years ago. At the time, I recall using closed chamber heads from the original motor (66 caprice). Long story short, car was wrecked after putting about 3000 miles on fresh rebuild...motor has sat on engine stand ever since. Original rebuild used TRW forged pistons, 10.5 : 1 compression ratio as I recall. Everything appears to be in good shape when I disassembled everything last weekend. Question is, if I have a set of open chamber heads, that would effectively lower CR a little and possibly be able to run todays pump gas. Is this ill advised for any particular reason ? I am not concerned with running 11.50 quarter mile ET's ... just want to have a strong respectable BBC / 4 speed muscle car again for cruising.
Comments ?



 




grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17119
grumpyvette
Age: 70
Loc: FLORIDA USA
Reg: 03-16-01
01-29-18 10:31 AM - Post#2722569    
    In response to joeblow55

sure chevy and the after market both, made several stock replacement or aftermarket open chamber heads that will work great on a 396 bbc

https://www.cartechbooks.com/techtips/killerbigblo ...

http://www.superchevy.com/how-to/engines-drivet rai...

http://garage.grumpysperformance.com/index.php?thr...
BBC Heads


330864.....68-84...oval...OPEN...396, 402, 366T,
427T, 454 Truck
330865.....68-84...oval...OPEN...396, 402, 366T,
427T, 454 Truck
330866.....68-78...oval...OPEN...366T, 427T
330867.....68-73...oval...OPEN...427T
336765.....68-78...oval...OPEN...427T
336768.....73-76...oval...OPEN...427T
336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports
343771.....68-86...oval...OPEN...366T, 427T, 454
343772.....68-86...oval...OPEN...366T, 427T, 454
343783.....70-76...oval...OPEN...454 Truck
346236.....75-87...oval...OPEN...454, 120cc chamber, 225/116cc ports
352625.....70-76...oval...OPEN...454 Truck
353049.....73-84...oval...OPEN...454, 122cc chamber, 255/119cc ports
366765.....74-78...oval...OPEN...427T
473328.....68-69...oval...OPEN...366T
3856206....65-66...oval..CLOSED..396, 97cc chamber
3856208....65......rect..CLOSED..396/425hp, 109cc chamber
396/375hp "Z-16" Chevelle
3856213....66-82...oval..CLOSED..366T, 427T
3856260....68......oval..CLOSED..396 Truck
3872702....65-66...oval..CLOSED..396, 427, 98cc chamber
3873858....65-67...rect..CLOSED..396, 427, 109cc chamber
3876875....77-85...oval...OPEN...427T
3904390....67......oval..CLOSED..396, 427, 98cc chamber
3904391....67......rect..CLOSED..396, 427, 107cc chamber
3904392....67......rect..CLOSED..427, Aluminum, L88, L89, 107cc chamber
3904393....68-76...oval...OPEN...366T
3908952....67......oval...OPEN...427, "M.Truck", Marine
3909802....67......oval..CLOSED..396, 427, 101cc chamber
3917215....67-68...oval..CLOSED..396, 427, 101cc chamber
3917219....68-85...oval...OPEN...366T, 427T
3919840....67-69...rect..CLOSED..396, 427, 107cc chamber
3919842....68-69...rect..CLOSED..396, 427, Aluminum L88, L89, 107cc chamber
3931063....68-69...oval..CLOSED..396, 402, 427, 101cc chamber
3933148....69-84...oval...OPEN...'69 396/265hp, 366T, 427T, 112cc chamber
3933149....68-76...oval...OPEN...427T, 122cc chamber
3935401....68-76...oval...OPEN...427T
3946074....69&71...rect...OPEN...'69 427 L88, ZL1, Aluminum, 118cc chamber
'71 454 LS6, "round exhaust port"
3964290....69-70...oval..CLOSED..396, 402, 427, 454, 101cc chamber
Large or small hex spark
plugs used
3964291....69-72...rect..CLOSED..396, 402, 427, 454, 109cc chamber, Large or small hex spark plugs used, crate motor usage in years after 1970.
3965198....68-69...oval..CLOSED..396 Truck
3975950....68-70...oval...OPEN...396, 402 Truck, 366T, 427T
3986133....68-85...oval...OPEN...366T, 427T, 454 Truck
3986135....69-73...oval...OPEN...366T, 427T
3986136....68-84...oval...OPEN...366T, 427T, 454 Truck
3993820....71......oval...OPEN...402, 113cc chamber, 255/114 ports
3993820....71-84...oval...OPEN...454 Passenger and Trucks, 113cc chamber, 255/114 ports
3994026....71......rect...OPEN...454 LS6, 118cc chamber
3999241....72......oval...OPEN...402, 454, 113cc chamber

6272292....70-78...oval...OPEN...402, 454
6272990....70-up...rect...OPEN...454 service replacement, used on some MKIV crate engines, 118cc chamber
10045427...........rect..........Pontiac/Chevy Aluminum, 91cc chamber
Large Port, race
10049875...........rect..........Pontiac/Chevy Aluminum
Small port, race
10051128...........rect..........Bowtie, Aluminum 72cc chambers
Symmetrical ports
10051129...........rect..........Bowtie, Aluminum "raw"
casting, Symmetrical ports
10052902...........oval...OPEN...MkIV, 427T
10101140...91-up...oval..CLOSED..Gen.V 366T, 427T
10114156...91-up...oval...OPEN...Gen.V & VI 454, 118cc chamber
10141279...96-up...oval..CLOSED.."Vortec 7400", 100cc chambers
10487052...77-90...oval...OPEN...366T
12363391...96-up...oval...OPEN...Bowtie, Aluminum, Signature
Series, fits MKIV, Gen.V, Gen.VI, 110cc chamber
12363401...96-up...rect...OPEN...Bowtie, Aluminum, Signature
Series, fits MKIV, Gen.V, Gen.VI, 118cc chamber
12558162...01-up...oval..CLOSED..Gen.VII,"Vortec 8100", 8.1L, 496, truck
12560241...98-up...oval..CLOSED.."Vortec 7400", 100cc chambers
12562932...91-95...oval...OPEN...Gen.V, truck crate motor, 118cc chambers
12562933...91-95...oval...OPEN...Gen.V, 118cc chambers
12562934...00-up...rect...OPEN...Gen.VI 502 Marine
14011077...69-up...rect...OPEN...Aluminum, fits MKIV, "C-port"
118cc chamber, also sold as a "solid" head
14044861...84-96...rect..........Bowtie, Aluminum, MkIV,
"raised runners", 1st design, 105cc chamber
14044861...96-up...rect..........Bowtie, Aluminum, Signature
Series, fits MKIV, Gen.V, Gen.VI
"raised runners", 2nd design, 115cc chamber
14044861...84-96...rect..........Bowtie, Aluminum, MkIV
"raw" casting of "861" MKIV
1st design
14081045...78-87...oval...OPEN...454
14081052...85-87...oval...OPEN...366T, 427T, 454 Truck, Marked "HiPerf"
14092359...86-90...oval...OPEN...366T, 427T, Marked "HiPerf"
14092360...86-90...oval...OPEN...454 Truck, "peanut" round ports
14096188...70-71...rect...OPEN...454 service replacement, also used on later Mark IV LS-6, LS-7 and 454 HO crate motors, 116cc chamber
14097088...91-up...rect...OPEN...Gen.V 454/502 HO, 118cc chamber
24502585...97......rect..........Olds/Chevy, DRCE 2,
Pro Stock aluminum, for blocks w/4.900" bore spacing
25534404...04......rect..........Olds/Chevy, DRCE 3, Pro Stock, aluminum, for blocks with 4.900" bore spacing


IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


 
Shepherd 
Frequent Contributor
Posts: 1156

Loc: Lake George, NY
Reg: 11-11-15
01-29-18 12:52 PM - Post#2722595    
    In response to joeblow55

Expensive but you could run oval port aluminum heads with the 10.5 compression.



 
IgnitionMan 
Valued Contributor
Posts: 3257

Reg: 04-15-05
01-30-18 08:33 AM - Post#2722698    
    In response to joeblow55

Make sure the quench is right, and you will be able to run today's pump fuels. Quench and intake valve closing point are the keys.



 
joeblow55 
Forum Newbie
Posts: 52

Reg: 05-03-10
01-30-18 02:25 PM - Post#2722750    
    In response to IgnitionMan

"Make sure the quench is right, and you will be able to run today's pump fuels. Quench and intake valve closing point are the keys."

Not entirely sure what you mean ... I thought the quench area was defined by the actual shape of the combustion chamber when piston is at or near TDC. With regard to intake valve closing, wouldn't that would be determined by camshaft profile ? What am I missing ? I will have to cross reference the list that GrumpyVette provided above to know exactly which heads I have, but I seem to recall they were a
70 - 71 era 454 cube open chamber head. It has been a really really long time since I have built a motor, and the heads that were originally used were the originals ... oval port, 1966 396 closed chamber heads. I will look up casting numbers on both sets and let you know what I have. Then we can bench race and determine the best overall option, all other things being equal. I wanted to make sure there would be no funny business going on in the combustion chamber during the "boom" stroke due to piston dome design being closed chamber and head design being open chamber ... if that makes any sense ...



 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17119
grumpyvette
Age: 70
Loc: FLORIDA USA
Reg: 03-16-01
01-30-18 04:42 PM - Post#2722767    
    In response to joeblow55




http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

links may help

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


Edited by grumpyvette on 01-30-18 04:44 PM. Reason for edit: No reason given.

 
Shepherd 
Frequent Contributor
Posts: 1156

Loc: Lake George, NY
Reg: 11-11-15
01-30-18 06:58 PM - Post#2722784    
    In response to grumpyvette

Nice drawing, old school engine blue printing term was deck height. Still applies!



Edited by Shepherd on 01-30-18 07:33 PM. Reason for edit: No reason given.

 
joeblow55 
Forum Newbie
Posts: 52

Reg: 05-03-10
02-13-18 04:16 PM - Post#2724298    
    In response to Shepherd

Good info fella's ... thanks for your replies. I was able to dig up the following information on the 3 sets of heads I DO have. From Grumpy's very exhaustive list above, I have the following:
3872702 65-66 oval port closed chamber 98cc (the original heads from that motor)
3993820 71 oval port open chamber 113cc's
and 3919840 / 3873858 rectangle port closed chamber, 107-109 cc's ... the rectangle port heads are clearly not a matched set, although I am not certain that matters much. I did some reading to freshen up a bit and educated myself on the whole quench thing...makes more sense to me now. I would like to decide which heads to use on this build, as it will probably be the last one for quite a while. I have read some pro's and con's regarding the use of the closed chamber type of piston dome (10.5:1) with the 1971 open chamber heads. As I questioned above, is there a particular reason why this might be a bad idea ? I have not been able to find a lot of SPECIFIC info, but I am aware that you cannot go the other way... ( Open chamber piston dome with a closed chamber head )From what I think I know, the open chamber head will lower the CR a bit, although I don't know how much, but should also breathe a little better. Aluminum aftermarket heads are not in the budget. With the right hydraulic roller cam kit and intake, I am leaning in the direction of using the oval port open chamber heads to get the most bang for the buck here. Given those choices, what do you all think ? Thanks again for your replies and sharing your collective knowledge.



 




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