Camshaft choices

[fifty-one f-1]

I am building a 53 8BA.It has been bored out .080, with a merc 4 inch crankshaft, Edmunds heads (not sure of compression ratio) and a Edmunds 4 barrel intake with a holly 390 cfm carb. I am using a MSD ready to run distributor. Hooked up to a C-4 auto and a 9inch with 3.55 gears and 225-70-15 inch tires. It is going into a 51 ford truck. I have a choice of cams. A reground 8CM or a new Crower F12750. I have never used any other cam in a flathead other than stock ford. The Crower specs are: Lobe lift at .050 is .352 and the duration is 228 and the separation is 110. How would this cam match with some of the other popular cams? Like so many on this site I am looking for good low end, up to highway speed performance. I appreciate the help.

[cadillac512]

It's really hard to beat an 8CM camshaft for the driving speed range you're considering. I have a .030 over Merc with milled iron heads, Rochester 2G carb, converted Chev distributor, 3.54 gears with 29" tires. It pulls hard right from idle and cruises beautifully at 65 mph. The 8CM would be my choice.

[tubman]

I agree with the above. I had a MAX-1 I was going to put in the 255" Merc in my '51 Ford coupe. After much research and discussion here and on the H.A.M.B. I decided to keep the stock 8CM cam. I am glad I did, as it is a relatively heavy car and the extra torque is beneficial. I have about the same setup as"caddillac512" above and got the same results.

If you haven't seen it, here is an interesting link : https://www.tildentechnologies.com/C...rformance.html.

[Flathead Fever]

It's all about what rpm you intend to use the engine at and how much the vehicle weights. When you go racing you want to shave weight off the vehicle and move the power band up because you need that torque at the high rpms to go fast. You want the maximum pressure in the cylinders at those high rpms. You don't care that about the cylinder pressure loss you will be creating at the low rpm range because you will never be below 2000 rpms.

An aftermarket camshaft moves the power band around the rpm range.
The higher duration of the cam the more cylinder pressure you will lose at those lower rpms. You're sacrificing the compression at the lower rpms for increased power at the higher rpms. Ford knew what they were doing when they deigned the original camshaft. It was designed to produce the maximum torque at an rpm that would produce the greatest fuel economy and engine longevity. And we have to remember it's a very small V8 engine with very little horsepower, it's not a small block Chevy with extra low rpm torque to spare that we can sacrifice for a good sounding camshaft.

If you have ever read a camshaft manufacturers recommendation for a "hot" camshaft it will say the camshaft is only suitable for a light cars like roadsters with high compression heads and big cubic engines. Th\at is because camshaft won't produce as much torque as a stock camshaft at normal driving rpms. A heavy vehicle needs all the torque it can to get it moving when the light turns green so this would not make a pleasna vehicle to drive at low rpms. Even in a lite roadster it would need higher compression and more cubic engines, to compensate for the low-end torque lost with a big camshaft so it can be comfortably street driven. That is why a big camshaft will always tell you need more compression and more cubic engines to make it work right.

The problem is the "wow" factor. It's hard to not fall in love with the sound of lumpy-lump camshaft like an Isky 400 JR, Clay Smith 272, Potvin Super 3/8th..., And they can be perfectly street driven in a light vehicle, you just need to remember they will not pull as hard as a stock camshaft at lower rpms. My dad's roadster I inherited has an Isky Max #1 in an 8BA. The first time I drove it I could not believe how hard that little flathead pulled street driving. But it has no lope to it at idle which is real disappointing. Even though I know that lope is the sound of a flathead with pneumonia at idle. I have about a dozen big camshafts, and I'll probably stick one of them in there and it will sound great, but I bet it will never pull as hard between lights as it does now.

[flathead4rd]

I like the rear end ratio choice but the 9" will will take about 10% of your horse power.

[Ol' Ron]

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I like the EAB cam for the truck. Have a 3.73 rear and a T-170 TRANS (3 SP+OD) AND IT PILLS ALL THE HILLS IN VermontN I od.
Gramps

[tubman]

All good information, especially since the O/P stated the engine is going into a '51 F-1, which again, is a relatively heavy vehicle.

[Ross F-1]

Originally Posted by tubman

All good information, especially since the O/P stated the engine is going into a '51 F-1, which again, is a relatively heavy vehicle.

Not so much the weight (~3200 lbs) but the aerodynamics of a barn door. They need good torque at highway speeds or you'll be into the power valves. I'm geared about the same (3.50) with 28" tires, 239 +.060", with an EAB engine including EAB cam. It does nicely. Likes to run 2300 - 2500 on the highway.

[tubman]

This whole thing has got me thinking (which can be dangerous). The "Tilden" chart has the specs for the 8BA and 8CM camshafts. The 8CM is clearly superior, the most obvious advantage is 10% more lift. It does not have the specs for an EAB cam; does anyone out there have them? Is it similar to the 8CM (or maybe the 8BA)? Is there such a thing as an EAC cam? If so, it should be the ultimate Ford stock camshaft.

[FlatTopFreddie]

How does the 8BA. or 8CM compare to the Kiwi-L100?

My 36 Coupe 221cu has a cam with a T-5 stamped on the front. (pressed on gear) Lift measure at .308.

Any ideas?

[Bored&Stroked]

Just so you know, the 'T-5' or '5-T' markings are not a special grind or performance mark from a cam grinder - it came with the cam from the factory.

I've seen many different stock cams with these markings (going back to the mid 30's) - don't believe it signifies a grind in Ford nomenclature (on that I could be wrong - just a hunch).

[FlatTopFreddie]

Correction -- its marked 5T

[tubman]

Originally Posted by FlatTopFreddie

How does the 8BA. or 8CM compare to the Kiwi-L100?

My 36 Coupe 221cu has a cam with a T-5 stamped on the front. (pressed on gear) Lift measure at .308.

Any ideas?

According to the "Tilden" chart, '37-'48 (as well as 8BA) came have a lift of .307. Since your measurement is only .001 different, that cam is nothing special.

If you have the specs on the L-100, you could check them against the Ford cams in the "Tilden" chart.

[fifty-one f-1]

Thanks to everyone who has helped. I have read about cams on this site and books (Rons, and JWL) and looked at the Tilden chart, but it helps to have people who have used different cams talk about what has worked for them. What would be the be the recommened choice for valve train. I am going to use the 8CM cam and the valve seats are the stock 1.5. I am thinking about using the stock valves and springs or something different? Or try not to reinvent the wheel and put it back the way Henry did it. Thanks again.

[cadillac512]

New stock springs will work well, as will "LZ" ( Lincoln Zephyr) springs from suppliers like Mike at Third Gen. Stock valves are fine as well. I prefer to use stock non-adjustable lifters but I have the equipment to grind them for finish and lash. Others choose high quality adjustables.



Denny- you asked about comparing 8CM and EAB cams. I degreed and measured both in my engine. They are very very close to identical when measured with a degree wheel- Far closer than published specs would indicate.

8CM intake open/close @ .050 7 atdc/33 abdc EX 33 BBDC/7 BTDC
@ .014 lash 9 btdc/53 abdc EX 50 BBDC/7 ATDC


EAB intake open/close @ .050 11 ATDC/33 abdc EX 32 BBDC/7 BTDC
@ .015 lash 5 BTDC/59 abdc EX 49 BBDC/15 ATDC

8CM lobe separation angle 109.5/ EAB 111


Advancing an EAB 4 degrees will nearly match the 8CM in opening/closing specs. Lift is within .005 of each other regardless of what the published specs say. (.330/.325) The 8CM has 4 degrees more duration at .050



Those are what I found with a degree wheel and dial indicator. I chose the 8CM for the added duration at .050 and closer lobe sep, but I'd bet the EAB is every bit as good a runner.


Terry

[tubman]

Terry,

Thanks for the information; I have asked several times, both here and on the H.A.M.B. and never received an answer.

I'm gonna stick with the 8CM in my '51. However, I put the MAX-1 in the fresh 258" engine I'm putting in my 1500 lb "Tub". Hope that works out too.

Probably no such thing as an EAC cam.

[Flathead Fever]

Originally Posted by flathead4rd

I like the rear end ratio choice but the 9" will will take about 10% of your horse power.

I agree with not needing a 9-inch. As a kid I did terrible horrible things to the 8-inch in my '65 Mustang and never broke it. That was with a stock 289 with 200 horsepower and wide tires trying to do burnouts. I doubt that a flathead could hurt an 8-inch. All the extra weight and gear friction from a 9-inch is just going to suck up your power.

Depending on your tire diameter the 3.55 gears are perfect. I had Mustangs with 3:00.1 and they sucked for acceleration. My ''66 GT-350 has 3.89s and it whining away at 70 mph and not comfortable to drive. I had one Mustang with a 9-inch with 3.50s and that seemed to be the happy spot for good acceleration and freeway driving.

I Looked up the diameter of your 225-70-15 and its 27.4 inches, exactly the same as the 7.75X15 Goodyear Blue dots on my Shelby. That car is a little uncomfortable to drive on the freeway for long periods with those gears It's fun for short drives but you would not want it as your daily driver with 3.89s. I think you will have fun with 3.55s. The rpms on the freeway will be higher than your use to with modern overdrives but its the best compromise between fun acceleration and freeway driving.

[Ol' Ron]

The EAC cam was used in the late 1951/53 255ci Merc engines. The EAB cam was in the ford 1951/53 239 engines. Both cams had around .330" lift amd used valve rotators and short valves and springs. I use them with thes cams with a .060" shim. The engines pull good to 4K and get pretty bood mileage as well as great lowend torque.
Gramps

PS the best partis you don't need adj lifters and aftermarket cam. saves over $500 bucks

[flatjack9]

Originally Posted by flathead4rd

I like the rear end ratio choice but the 9" will will take about 10% of your horse power.

Compared to a 12 bolt GM rear, the Ford loses about 2% as does the Dana.

[fifty-one f-1]

Cadillac512 what are the advantages of Lincoln Zephyr springs over stock springs.Ron what are valve rotators?
Thanks Jack for the rear axle update.