Photo of Combustion Chamber of Head Casting 2843675?

-
dibbons

dibbons

Well-Known Member
Joined
Nov 6, 2009
Messages
5,738
Reaction score
3,821
Location
La Paz, B.C.S., Mexico
My 318 (1979 block casting) was rebuilt 10 years ago and runs great. I have no idea what the combustion chambers look like in the cylinder heads she uses. I know the valve size must be 1.78"/1.50" but curious about the combustion chambers.

If anyone has a similar head casting laying around, I would appreciate seeing the posting of a photo of the combustion chamber. Thank you.

2843675 cyl head 2.JPG


1622 cyl head.JPG


1732 cyl head.JPG


2843675 cyl head.JPG
 
From another thread here from August of 2013 discussing 675 vs 302 heads.
attachment.jpg

And the thread itself, in case you want to look a little farther. There is a former member in the thread who has some good porting info on them.
318 head flow
 
No, they are open, usually 68cc's. I think even the early closed chamber 273 and 318 heads were closer to being a "semi open" chamber than a true closed chamber like the later 302 fast burn heads.
 
Thanks, it's hard to tell combustion shape from that greasy photo. If anyone has a better photo of a cleaned up 675 head, I would appreciate it. Or a close-up of a single combustion chamber maybe?
 
The 69 318 came with 68/69 CC heads, open chamber....that's if they are the stock heads??? The 69 318 is one of the highest compression engines that Mopar made.
 
Last edited:
Treblig said:
The 69 318 came with 68/69 CC heads, open chamber....that's if they are the stock heads??? The 69 318 is also the highest compression 318 that Mopar made.
Click to expand...
And 68-74 teens used the same head. I wish I had a spec chart of pistons used through those years.
 
Garrett Ellison said:
What's the actual chamber of volume of that closed chamber head?
Click to expand...
Small Block Cylinder Heads

CC's / Port Volume / Size / Flow

1966 - 1967 {273} Casting #2658920

Heart-Shaped Combustion Chamber

Factory CC Level..........................62.0 to 65.5 CC's
Recommended Minimum CC's......57.3 CC's

Intake Port Gasket Size...............1.05" x 2.07"
Exhaust Port Gasket Size.............1.14" x 1.59"

Intake Valve................................1.78"
Exhaust Valve..............................1.50"

Intake Bowl Size.........................1.53" {86% of Valve}

Intake Port.................................125 CC
Exhaust Port...............................61 CC

Intake Flow...............................160 CFM @ .450" Lift
Exhaust Flow.............................107 CFM @ .450" Lift

Intake-to-Exhaust Flow.............64.8%

 
Those flow numbers are way low from what others have measured. My chambers measured 64.8 to 63.6. With a good 3 angle valve job ports flow around 190 cfm intake and 132 cfm exhaust at .500. See post #47.

302 heads
 
Last edited:
66fs said:
273 chambers are closed, similar to 302 heads.
Click to expand...


The last year for the closed chamber heads is 67, they came on both the 273 & 318 that year... The 67 318 being the first year of the LA 318...

In 68 & 69 both the 273 and 318 have the same open chamber heads....
 
Treblig said:
The 69 318 came with 68/69 CC heads, open chamber....that's if they are the stock heads??? The 69 318 is also the highest compression 318 that Mopar made.
Click to expand...


I would say that the 67 318 has the highest compression, it has the four eyebrow pistons and the closed chamber head...

In 68 and 69 the 318 had the open chamber heads which added about 4 - 6 cc's...
dibbons said:
My 318 (1979 block casting) was rebuilt 10 years ago and runs great. I have no idea what the combustion chambers look like in the cylinder heads she uses. I know the valve size must be 1.78"/1.50" but curious about the combustion chambers.

If anyone has a similar head casting laying around, I would appreciate seeing the posting of a photo of the combustion chamber. Thank you.

View attachment 1715592001

View attachment 1715592002

View attachment 1715592003

View attachment 1715592004
Click to expand...


dibbons said:
Thanks, it's hard to tell combustion shape from that greasy photo. If anyone has a better photo of a cleaned up 675 head, I would appreciate it. Or a close-up of a single combustion chamber maybe?
Click to expand...


Here's a set of 675 heads that I had my head guy port and install 1.88" intakes and 1.60" exhaust valves in, I believe they are 69 cc (not for sure):

68-72 SB A01 B.jpg


68-72 SB A03 B.jpg


68-72 SB A04 B.jpg


68-72 SB A07 B.jpg



Here's the 920 closed chamber head with the same treatment, porting with 1.88" intakes and 1.60" exhaust valves... These cc'ed at 63 cc... (that's a for sure measurement - I measured them myself...)

67 SB A01 B.jpg


67 SB A03 B.jpg


67 SB A06 B.jpg


67 SB A09 B.jpg


67 SB A10 B.jpg



There's some info about this in my old thread on trying to bump up the compression on my 318:

How Much Can Heads Improve Compression???
 
Last edited:
So here you are, one pic compared to the other...

675 heads:

68-72 SB A07 B.jpg


920 heads:

67 SB A10 B.jpg
 
krazykuda said:
So here you are, one pic compared to the other...

675 heads:

View attachment 1715592462

920 heads:

View attachment 1715592463
Click to expand...
I would agree that the 67 318 "should" have the highest compression, except for one thing!! The one important thing that also impacts compression is "piston height". If you look at the chart I posted (post number 11), it shows that the 67 318 had a piston height of 1.75. The 69 318 has a piston height of 1.77. Now someone will have to do the math to determine what compression each motor would have with the correct CCs for each head in each year???? I remember seeing a chart of compression ratios on these motors and if my memory is correct the 67/68/69 318 came with 9.2:1 compression.
 
Treblig said:
I would agree that the 67 318 "should" have the highest compression, except for one thing!! The one important thing that also impacts compression is "piston height". If you look at the chart I posted (post number 11), it shows that the 67 318 had a piston height of 1.75. The 69 318 has a piston height of 1.77. Now someone will have to do the math to determine what compression each motor would have with the correct CCs for each head in each year???? I remember seeing a chart of compression ratios on these motors and if my memory is correct the 67/68/69 318 came with 9.2:1 compression.
Click to expand...


.020" height difference works out to be 3.94 cc in a 318...

The difference in the head volumes is about 6 cc...

So the 67 318 will have 2 cc less clearance volume above the piston which will be slightly higher compression...


Now put the 69 318 pistons with the 920 heads and we have something....
 
Treblig said:
I would agree that the 67 318 "should" have the highest compression, except for one thing!! The one important thing that also impacts compression is "piston height". If you look at the chart I posted (post number 11), it shows that the 67 318 had a piston height of 1.75. The 69 318 has a piston height of 1.77. Now someone will have to do the math to determine what compression each motor would have with the correct CCs for each head in each year???? I remember seeing a chart of compression ratios on these motors and if my memory is correct the 67/68/69 318 came with 9.2:1 compression.
Click to expand...


Shame on you for making me do math this early in the morning... :mad:
 
krazykuda said:
Shame on you for making me do math this early in the morning... :mad:
Click to expand...
I was too sleepy to do the math myself, I figured that some coffee guzzling, math whiz on FABO would "jump in". If you do a little research I'm sure you'll find the same chart that I saw, it shows that 67/68/69 factory engines all have the same compression....9.2:1. Maybe the difference was so slight the factory didn't care??? I know that the factory head CCs varied quite a bit.
 
You must log in or register to reply here.
-

Back
Top