Cast Iron Canadian Heads Question
- Thread starter Dennis/Arkansas
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Dennis/Arkansas
Senior Member
Thank you very much Jim for providing the information I needed. It proved most helpful! Dennis/Arkansas
If the specs are the same for both alum. and cast iron why would aluminium have an advantage?
Jason M.
Senior Member
In my experience those heads in the photo came on truck and industrial engines. I have recently seen two 46-48 trucks with these heads and I have a set that came on an engine that apparently ran some sort of pump. The other 59A I have says 59A on the heads but also "Made In Canada"
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blown49
Senior Member
Specs not the same. The aluminum heads have smaller combustion chambers @ 69.5 to 70 cc's. Smaller combustion chambers between the two heads (aluminum vs. cast iron) is 6.8:1 for the aluminum and 6.4:1 for the aluminum. they were sold over the counter at Ford dealers as "High Altitude" heads.
I've been working with Bruce Lancaster since April developing excel spreadsheets for Ford & Merc compression ratio charts. Each chart is done with bores of: Std, +0.030", +0.040", +0.060", +0.080", + 0.125" and + 0.1875". Strokes are listed @ 3.750", 4", 4.125", 4.250" and 4.375".
Charts (18 pages) include Ford USA heads as will as Canadian heads and a bunch of aftermarket heads on 8BA, 8RT, 9CM, 59A, 239 cu/in engines from 1938 thru 1942 and the 221 engines from 1938 thru 1944 (41A).
I will be posting on the HAMB & here as a PDF file in the next several days.
Jim
Dennis/Arkansas
Senior Member
Will prove an excellent research source for info on the various heads. Thanks to you and Bruce!! Dennis/Arkansas
Bruce Lancaster
Member Emeritus
Some heads are getting scrambled here...The "Denver" heads are iron small CC chamber heads made by Ford USA for high altitude or natural gas engines in several versions. The Canadian C7RA aluminum ones are standard production Canadian heads with slightly higher than iron head ratios (about 5cc smaller), probably to make up for the higher heat/power loss of the aluminum and/ or to take advantage of the greater compression tolerance from this heat loss...
The Denvers were USA with "S" in the number prefixes, meaning "special" or not used in production...parts counter only. I don't think any Canadian heads were sold here by Ford, though many were brought in for racing use in stock car leagues requiring stock heads and sold as speed equipment by speed dealers.
The Denvers were highly desireable racing heads (smallest was 60 CC's), but were always rare...I think the factory stopped making them before racers found out about them!
The Denvers were USA with "S" in the number prefixes, meaning "special" or not used in production...parts counter only. I don't think any Canadian heads were sold here by Ford, though many were brought in for racing use in stock car leagues requiring stock heads and sold as speed equipment by speed dealers.
The Denvers were highly desireable racing heads (smallest was 60 CC's), but were always rare...I think the factory stopped making them before racers found out about them!
Bassman/NZ
Well-known member
I have a C59A out of a 47 Ford sedan (original engine) and it has the same heads, so I'm thinking maybe all export Fords had them.
Not so, I have a C59A out of a '47' here in Aussie with standard heads, and most other engines I've seen have not had C7RA's. The C7RA heads have always been rare both here and NZ, the speedway guys were after them 'back in the day' for an easy power upgrade.
It's rumoured that Phil Weiand used a pair of C7RA heads for his version of aftermarket aluminium heads. I am presently waiting for a set of cast iron C7RA's to arrive in Sydney from the U.S. when they arrive I'll compare the chambers and report back to the Forum.
Bassman/NZ
Well-known member
So you're saying my C7RA-A heads are what? Higher compression? Better chamber shape?
Brian
Well-known member
Fe26, They can't be that rare; I've got both versions and I'm not even a hoarder/collecter. I don't see anything special about the cast iron version, the aluminium ones however have much tighter comb chambers, and no doubt would have been the ones the speedway boys used for the higher compression they would have had [at the sacrifice of breathing ability though]. They do closely resemble those Wieand cheater heads you talk about. Brian
I think Bruce Lancaster may have provided an answer to the differences between cast iron and aluminium C7RA head configurations. If I read his response correctly he surmises that aluminium heads have a smaller combustion chamber to compensate for the inherent characteristics of aluminium as compared to cast iron. If this is so then essentially the heads will perform the same *once operating temperature has been reached.
I find this opinion interesting and valuable, not only because Bruce is a very learned man and acknowledged by his peers as an expert in Fords (and who knows whatever else). But also how his observation gives rise to the notion that one piece of information cannot be read in isolation to all other pieces of information that may contribute to understanding the whole, as opposed to using selective pieces of information out of context.
My interest is drawn to the notion that Cylinder Compression is often stated as a desirable characteristic when seeking to increase engine power/ speed. However it seems that to take one piece of information selectively i.e, an aluminium heads higher compression, and then say that is more desirable than a cast iron head because the cast iron head has a lower compression, is to miss the point. As observed above, if the difference in cylinder head volume is by way of compensation for differences in metals, then to promote one over the other is clearly wrong.
To further my point I suggest had there been any discernable difference in performance between the two metals, Ford would have not designated either aluminium or cast iron with exactly the same Letters and Numeric (C7RA). Rather, Ford would have used a different number or character on one type of metal (probably the aluminium) to indicate it had better performance characteristics than its poor cousin (cast iron).
It may be that for years those seeking to increase engine performance have mistakenly preferred aluminium over cast iron for no better reason than the aluminium heads higher compression number. If this is so then the ‘myth has been busted’ as they say.
*My conjecture on operating temperature. My thinking here is that as both metals will behave differently as the heat increases to operating temp. no meaningful measurement could be made. Once temp. Has been reached then a meaningful measurement can be made as the metals have reached a steady state.
Brian from NZ, if you want to sell your 'common garden variety' lol aluminium heads please PM me.
I find this opinion interesting and valuable, not only because Bruce is a very learned man and acknowledged by his peers as an expert in Fords (and who knows whatever else). But also how his observation gives rise to the notion that one piece of information cannot be read in isolation to all other pieces of information that may contribute to understanding the whole, as opposed to using selective pieces of information out of context.
My interest is drawn to the notion that Cylinder Compression is often stated as a desirable characteristic when seeking to increase engine power/ speed. However it seems that to take one piece of information selectively i.e, an aluminium heads higher compression, and then say that is more desirable than a cast iron head because the cast iron head has a lower compression, is to miss the point. As observed above, if the difference in cylinder head volume is by way of compensation for differences in metals, then to promote one over the other is clearly wrong.
To further my point I suggest had there been any discernable difference in performance between the two metals, Ford would have not designated either aluminium or cast iron with exactly the same Letters and Numeric (C7RA). Rather, Ford would have used a different number or character on one type of metal (probably the aluminium) to indicate it had better performance characteristics than its poor cousin (cast iron).
It may be that for years those seeking to increase engine performance have mistakenly preferred aluminium over cast iron for no better reason than the aluminium heads higher compression number. If this is so then the ‘myth has been busted’ as they say.
*My conjecture on operating temperature. My thinking here is that as both metals will behave differently as the heat increases to operating temp. no meaningful measurement could be made. Once temp. Has been reached then a meaningful measurement can be made as the metals have reached a steady state.
Brian from NZ, if you want to sell your 'common garden variety' lol aluminium heads please PM me.
Bruce Lancaster
Member Emeritus
OK...the numbers are not surmised, they are straight from Ford Canada spec pages. Actual volumes of course vary somewhat randomly from spec, but I'll post the evolution from factory. Bassman, the heads are based on ORIGIN of export Fords. In NZ, Australia, South Africa, etc. the Fords came from Canada and will have Canadian heads. In South America or China, Fords came from USA and will have those heads. Origin is largely a matter of tax and tariff...Empire could get Canadian cars cheaper than US because of that.
So, '46-48 evolutions:
USA Ford
59A.....77-79cc, 6.75-1
59AB....73.5-75.5cc, still spec called 6.75
Canadian Ford
C59A............74.5-76 cc, spec called out as 6.8
C7RA IRON....73-75.5 6.8
C7ra ALUMINUM....69.5-70 7.2
So the later iron Canadian was a slight bump from 59A, a bit more than similarUSA bump fron 59A to AB.
The aluminum was a bigger bump (probably about late '47-8) taking advantage of aluminum characteristics.
The C7RA numbers are actually not the same, I was just abbreviating! Iron is C7RA prefix with suffix A, as in C7RA-6050-A, Aluminum is C7RA-6050-B. The C7RA part just indicates Canadian, 1947 intro, A means first designed for passenger car. The Suffixes identify them as entirely different heads.
So, '46-48 evolutions:
USA Ford
59A.....77-79cc, 6.75-1
59AB....73.5-75.5cc, still spec called 6.75
Canadian Ford
C59A............74.5-76 cc, spec called out as 6.8
C7RA IRON....73-75.5 6.8
C7ra ALUMINUM....69.5-70 7.2
So the later iron Canadian was a slight bump from 59A, a bit more than similarUSA bump fron 59A to AB.
The aluminum was a bigger bump (probably about late '47-8) taking advantage of aluminum characteristics.
The C7RA numbers are actually not the same, I was just abbreviating! Iron is C7RA prefix with suffix A, as in C7RA-6050-A, Aluminum is C7RA-6050-B. The C7RA part just indicates Canadian, 1947 intro, A means first designed for passenger car. The Suffixes identify them as entirely different heads.
Bruce, I don't believe I said the data was surmised, only the differences between aluminium and cast iron materials when in use.
Thank you for providing more info on the C7RA heads. The question remains, does the difference between the different cylinder head volumes (alum. Vs cast iron) equate to the difference in materials when both types of head are at operating temperature.
To use average measurements of the difference between Alum. and CI and then average those measurements I get 2.5cc. If your proposition is correct (and I suspect it could be) then my conclusion remains unchanged. I believe it is possible that the differences in materials performance ie Alum. Vs C.I. is small enough to be essentially one and the same at operating temp. Although I must say I have no extensive knowledge of aluminium or cast iron. My expertise is in steels and the forging of.
Your clarification of Fords identification between Al. and C.I is appreciated, however apart from identifying each material Ford does not distinguish Al. from C.I in terms of performance. This leads me to believe that Ford designed the Al. heads with the smaller chamber to compensate for the co-efficient between materials.
Thank you for providing more info on the C7RA heads. The question remains, does the difference between the different cylinder head volumes (alum. Vs cast iron) equate to the difference in materials when both types of head are at operating temperature.
To use average measurements of the difference between Alum. and CI and then average those measurements I get 2.5cc. If your proposition is correct (and I suspect it could be) then my conclusion remains unchanged. I believe it is possible that the differences in materials performance ie Alum. Vs C.I. is small enough to be essentially one and the same at operating temp. Although I must say I have no extensive knowledge of aluminium or cast iron. My expertise is in steels and the forging of.
Your clarification of Fords identification between Al. and C.I is appreciated, however apart from identifying each material Ford does not distinguish Al. from C.I in terms of performance. This leads me to believe that Ford designed the Al. heads with the smaller chamber to compensate for the co-efficient between materials.
Bruce Lancaster
Member Emeritus
Could be...but look at it this way: The heat conductivity of the aluminum is both an advantage (better cooling, resistance to pinging) and a disadvantage...the advantages involve heat being sucked out of the combustion chamber, leading to a loss of power compared to an iron head with all else equal.
Smokey Yunick was the sort who thought and worried continually over this. His practice mentioned in his writings was to coat aluminum heads internally with water glass/sodium silicate to LOWER their conductivity for the power benefit. His imagined idea of an ideal head was a composite one with iron chambers/guides in an aluminum top! Apply the weight savings and extra cooling AFTER the heat has done its actual work!
Fords actual high-comp heads, the 3 kinds of Denver heads, were iron, and they were made at a time when many cars were still being assembled with aluminum versions of the 81 series...
Maybe aluminum heads with minor compression increases were made to compensate for the minor power loss. Above that, likely the ability to get more compression without knocking produces more power than that lost.
Aftermarket heads are a different kettle of fish because of 2 things: Small companies making small numbers of heads could make aluminum ones when cast iron tooling and foundry work was prohibitive AND rodders immediately fell in love with the shiny!
Smokey Yunick was the sort who thought and worried continually over this. His practice mentioned in his writings was to coat aluminum heads internally with water glass/sodium silicate to LOWER their conductivity for the power benefit. His imagined idea of an ideal head was a composite one with iron chambers/guides in an aluminum top! Apply the weight savings and extra cooling AFTER the heat has done its actual work!
Fords actual high-comp heads, the 3 kinds of Denver heads, were iron, and they were made at a time when many cars were still being assembled with aluminum versions of the 81 series...
Maybe aluminum heads with minor compression increases were made to compensate for the minor power loss. Above that, likely the ability to get more compression without knocking produces more power than that lost.
Aftermarket heads are a different kettle of fish because of 2 things: Small companies making small numbers of heads could make aluminum ones when cast iron tooling and foundry work was prohibitive AND rodders immediately fell in love with the shiny!