Different Canadian heads C7RA & C91A aluminum

[36coupe]

What is the difference between aluminum Canadian heads C7RA & C91A?
C7ra are the later ones, what are C91A?
Thanks

[Brian]

C91A originally came out on 39 221's. Both heads are high compression, visually very similar. Check for valve interference in the 91A head if using on 59A block [different valve angles]

[G32]

Brian & 36Coupe
What Canadian domestic vehicle used 239ci engine with C99A head 39-42? Ford trucks?
Mercury car sold under another name?

Gene Tulsa

[Brian]

Gene, C99-6050 ally heads I guess were used on 39 [and later?] Merc's. I understand, trucks used cast iron heads, but could not conclusively tell you which part numbers. I do have some cast iron C81T heads, which also have a big T cast on them, which are obviously truck, but I'm damned if I can see any difference between combustion chambers of cast iron C81A heads which have a big A cast on them??? I personally always run ally heads; have a C99 engine in my shed with C81-6050 ally heads fitted, good compression increase coupled with the +.100 overbore.

[RalphG]

Just to add further information (or confusion) to the discussion, here is a photo of the numbers on the heads of my 46 Ford truck engine. It appears to be C81A-6049A1.

[Brian]

Sponsored Links (Register now to hide all advertisements)

I have used C81A cast iron heads on C59 series engine, and had to 'tickle up' around the eyebrows to acheive valve clearance. Whilst, by doing so, they can be made to work, they certainly would not be originally fitted as such from the factory.
Disclaimer; I am merely assuming that the engine in your 46 truck is a 59A series, could well be an earlier engine, in which case the 81A heads would be a direct bolt on.

[G32]

Guys:
On pre War 221 and 239 24 studs left side head is 6050--right
side is 6049 due valve angle difference between sides.
Post war engines removed this and used 6050 heads both sides-
interchangeable side to side. People think they should match!
Well valve clearances should always be checked.
Pre war 221 heads (81A-not 81T) on larger 239 99 or
post war 1945 59 gave higher compression--- if valves clearanced.

Fun--fun! Thanks
Gene Tulsa

[G32]

Originally Posted by Brian

C91A originally came out on 39 221's. Both heads are high compression, visually very similar. Check for valve interference in the 91A head if using on 59A block [different valve angles]

I thought C7RA head was post war for the 1945 59 engine.
Is C7RA-A different?
US 59 heads are generally lower compression --and dealer replacement
heads for pre war 24 studs 221 and 99 engines.

Gene Tulsa

[Bruce Lancaster]

C7RA--B aluminum heads are specified at 69.5--70 CC with 7.2 ratio on 239.
C91 aluminums came in 3 flavors, with different suffixes ranging from 69 to 74 cc's
C99A B1 is 74-77, B2 is 80.5--83
Finally found the blasted chart.

[RalphG]

I hope this photo image is big enough to read numbers. It is a page out of my Ford Fast Moving Parts catalog from 1929 to 1949 Canadian edition.

[Bruce Lancaster]

The Canadian service bulletins have the most thorough head chart I've seen...it lists almost every USA and Canadian head, including the 3 Denvers, lists CC spec, and works out compression for use on both 221 and 239 engines regardless of original application.
Canada used 3 heads for '46-8, there's a C59A that is about like our 59a, presumably 1946 use, and for '47-8 a C7RA-A iron head exactly equivalent to USA 59AB, and the C7RA-B aluminum one with slightly higher compression.

[G32]

Originally Posted by RalphG

I hope this photo image is big enough to read numbers. It is a page out of my Ford Fast Moving Parts catalog from 1929 to 1949 Canadian edition.

RalphG; FastMove book shows replacement parts
from FMC-CA dealers.
If one bought a late 40s early 50s rebuilt pre
war engine from Ford dealer it would have
the then current replacement heads-
the post war C59A C7RA 6050 -both sides.
FastMove shows as replacement heads for
24 stud 39-48.
Mr Bruce has gathered better detail/data
He's FORD man!
I'm trying to learn more Canadian Ford.

Thanks for post.
Gene Tulsa

[Bruce Lancaster]

Ford Canada of course had its own parts books, since many parts were Canadian sourced with differences from USA, put out some nice manuals, and did its own Service bulletins, not just a copy of USA one. Their cars are all over the world, since they were the main supplier for the British Empire, and they cranked out huge numbers of flathead vehicles during WWII.
They used a lot more aluminum than Ford USA, likely because of untaxed trade with Jamaica.

[G32]

Were C81A heads factory on 1938 only?
What is difference with C91A? Optional?
1940/41/42 Canadian 81s used what heads?
Are all C81A blocks cast with "C81A"?
Curious about pre-war Canadian Ford/Mercury
Gene Tulsa

[Bruce Lancaster]

I have here at work only the CC chart, with no applications. Need the big parts book for that.
But, I can tell you the Canadian cylinder head people were BUSY right before the war!

Looking at just the Canadian numbers, they made3 different C81A versions, four C81T, 3 C91A, and 2 C99A! Some are aluminum, some iron, considerable range of CC's.
Some of the 81 variants may just be the differences in the small water holes required for the several gauge and heater changes along the way.

[G32]

Thanks BruceL!
Have good day. Later,
Gene Tulsa

[RalphG]

My 39 has the cast iron C7RA heads but as stated earlier it is a Ford rebuilt engine dated 1952.