230/251 Cam Specs...

[maineSS]

I'm sending out a couple of 230 cams for measurement. One is a stock M-37 cam, the other a "High Performance" regrind sold by George Asche. I also ran across some specs for the stock 230/251 cam from an Army TM and an old Motors Manual (same as posted on Mecanique's website).

The durations are not at today's .050" measurement- they had a number of different techniques in the old days, and if anyone knows how Dodge did it, please post soon so I can have the cam measured that way along with the .050" spec.

The 230 cam- Intake Opens @ 8 deg BTDC Exhaust Opens @ 37 deg BBDC
Closes @ 36 deg ABDC Closes @ 7 deg ATDC
Intake Duration- 224 deg @ ? Exhaust duration- 224 deg @ ?
Overlap- 15 deg
Intake Centerline- 104 deg Exhaust Centerline- 105 deg
Intake Lift- .375" Exhaust Lift- .375"
Lobe Separation Angle- 104.5 deg
Advance- .5 cam deg

The 251 cam- Intake Opens @ 12 deg BTDC Exhaust Opens @ 50 deg BBDC
Closes @ 44 deg ABDC Exhaust Closes @ 6 deg ATDC
Intake Duration- 236 deg @ ? Exhaust Duration- 236 deg @ ?
Overlap- 18 deg
Intake Centerline- 106 deg Exhaust Centerline- 112 deg
Intake Lift- .379" Exhaust Lift- .379"
Lobe Separation Angle- 109 deg
Advance- 3 cam deg

I calculated everything after the valve closing data- hopefully my cam math is correct. I've heard that these cams were usually installed "straight up", so the advance figures may not have been used much "back in the day".

[maineSS]

V-Bulletin editing...

I see V-Bulletin scrambled my headings very nicely- great job! 230 Intake should be "open @ 8 deg BTDC, close @ 36 deg ABDC ", Exhaust should be "open @ 37 deg BBDC, close at @ 7 deg ATDC".

251 Intake should be "open @ 12 deg BTDC , close @ 44 deg ABDC . Exhaust should be "open @ 50 deg BBDC, close @ 6 deg ATDC ." Sorry for the confusion- I had such beautiful headings!!!!!

[maineSS]

I got my cams back from Delta Camshaft in Tacoma, WA- they measured an M-37 cam and a reground 230 cam bought from George Asche. They also sent along specs from the cam used in Dodge 218 and early 230 engines. I had them regrind the M-37 cam to their 400M spec, which is an "RV style" grind for heavy vehicles that need some midrange. The specs were measured using Cam Analyzer 3.2, and they charged $10 to do both cams. It's free if you have a cam reground, which cost me $70. I thought the the bearing journals were iffy, but they polished up nicely. Turnaround was about 2 1/2 wks using UPS Ground.

Here are the OEM 230 specs @ .050" lift (They couldn't duplicate the OEM measurement process- no one seems to know how it was done back then).

Early 230-

Intake Opens @ -5.6 deg BTDC, Closes 32.6 deg ABDC
Exhaust Opens @ 32.1 deg BBDC, Closes @ -5.6 Deg ATDC
Intake Duration- 207.1 Crank Deg @ .050"
Exhaust Duration- 206.5 Crank Deg @ .050"
Overlap- -11.1 Crank Deg
Intake Centerline- 109 deg
Exhaust Centerline- 108.8 deg
Intake Lift- .3719"
Exhaust Lift- .3722"
Lobe Separation Angle- 108.9 Cam Deg

M-37 Cam-

Intake Opens @ -3.5 Deg BTDC, Closes @ 31.9 Deg ABDC
Exhaust Opens @ 31.2 Deg BBDC, Opens @ -2.5 Deg ATDC
Intake Duration- 208.4 Deg @ .050"
Exhaust Duration- 208.7 Deg @ .050"
Overlap- -6.1 Deg
Intake Centerline- 108.0 Deg
Exhaust Centerline- 107.3 Deg
Intake Lift- .384"
Exhaust Lift- .382"
Lobe Separation Angle- 107.7 Deg
Retarded .4 Cam Deg @ .050"

The 400M Regrind-

Intake Opens @ -.6 Deg BTDC, Closes @ 35.8 Deg ABDC
Exhaust Opens @ 44.3 Deg BBDC, Closes @ -11.2 Deg ATDC
Intake Duration- 215.2 Deg @ .050"
Exhaust Duration- 213.1 Deg @ .050"
Overlap- -11.8 Deg
Intake Centerline- 108.0 Deg
Exhaust Centerline- 118.3 Deg
Intake Lift- .397"
Exhaust Lift- .400"
Lobe Separation Angle- 113.2 Deg
Advanced 5.2 Cam Deg @ .050"

Delta has sold about 200 of the 400M- should be interesting to see how it performs in the PW. Intake and Exhaust should be upgraded to get the most out of this cam. The early 230 specs appeared to have been done with a different measurement program, as the specs were printed in a different format.

[Jason Mills]

Does the 400M regrind require different springs? it looks like a noticeable improvement. interested to hear how it runs differently.

[OLD DODGE]

20+ years ago Crane Cams started specifying duration at 0.050" lift. Before that it was called "advertised" duration, measured at near zero. This was a subjective way of measuring when the cam lobe started to lift. Different people/companies could come up with different results for the same cam. The 0.050" spec was a way of implementing a standard so you could compare apples to apples and know exactly what you are getting.

[maineSS]

If you want to enter these specs into an engine simulation program, make sure it can convert .050" specs to seat-to-seat specs, or your results won't be very accurate. I haven't seen any flathead-specific simulations out there, most use a "low performance" mode based on OHV engine characteristics, which may be off quite a bit, considering things like siamesed intake ports, etc. If you have actual port flow data, that would help accuracy. Didn't ask about special springs- maybe this is VPW's HP cam?

[maineSS]

I checked back with Delta Cams and found that special valvesprings are NOT required for the 400M cam.

[Jason Mills]

Wonder how it is different than the cam VPW sells. That one is sold with a stiffer spring. Seems as if both would benefit from a better Intake manifold. Maine, are you planning a different intake on your buildup?

[maineSS]

I'll likely try the Fish carb out with the OEM intake/exhaust manifold, and when I do the Mikuni triple carbs, I'll go with individual intakes and some form of split exhaust- probably cast headers. I've also heard interesting things about the 40mm Keihin carbs used on Harley's- they have an accel pump, and are used on motors up to 80 cu in (each cyl =40 cu in, the 230 cyl are 36 cu in each).

[maineSS]

Well, I just ran some simulations on my Dyno 2000 program, and the 400M didn't fare so well. I had to simulate a flathead as a low-efficiency V8 with a single-plane manifold, which gave surprisingly close estimates of HP for the OEM cams- it started at 2000 rpm, so I couldn't compare torque @ 1300 rpm.

The 380 Asche cam did a lot better after 3000 rpm, but so far the winner is the late OEM 230 cam up to 3000 rpm. I'm going to send the specs out to Roadrunner Engineering, who does Ford Flathead simulations to see if their program agrees with my results given the same data.

[Jason Mills]

does the 400m cam do any better with a dual plane intake? Headers? or a better head/breathing combination? That is to say by fiddling with the simulator can you get the cam to 'wake up'? and find out what it needs to perform?

[maineSS]

Uncorking the exhaust made a very noticeable gain for all the cams, so did increasing compression. I ran 6.7:1 & 8:1 for the early OEM, 7:1 & 8:1 for the late OEM, and 8:1 for the Asche 380 and 400M. Exhaust mods went from stock, to Hi-flow, to small-tube headers with mufflers. I'll post some numbers later, but you should definitely look at splitting the exhaust with Langdon's cast iron manifolds or having some headers made up. I'm puzzled by the 400M numbers, as people would have been complaining by now, given the number they've sold. If the computer is right, I wouldn't have had my M37 core reground to 400M specs, I would have had cleaned up instead. However, the computer may not be right in this case. I'm going to try Individual Runner simulation for triple carbs and see what happens. Dual Plane manifold did up the hp/tq numbers on all the cams, but I don't think it accurately models a log-type intake.

[maineSS]

Here's the results I got from my simulations. Pic #1 compares the Early OEM cam at 6.7:1 C.R., 3" Hg intake depression, single plenum manifold, stock low efficiency head with actual valve sizes, stock exhaust manifold and mufflers. We're severely handicapping an OHV V8 to simulate a flathead, and by 3000 rpm it appears to be gaining when compared to the 1951 Dyno sheet. The numbers in parentheses are my interpolations of the graph's gross Hp & TQ.
Part 2 continues with the Cam Comparisons...

[maineSS]

Cams continued...

Pic #2 compares the Early and Late OEM cams to the 380 Asche and the 400M at 8:1 compression and the "Stock" conditions of the 6.7:1 Early OEM test. I tried less restrictive exhaust, and individual carburetion, but the results were similar for all the cams at higher HP/TQ levels.

So far, it looks like the Late OEM is the best at RPM levels PW owners realistically use. This may be an artifact of the simulation, or due to some error I made setting up the sim. When I get the results of Roadrunner Engineering's sim, I'll post them.

[maineSS]

Here's the results of Roadrunner Engineering's sim- it was done on a more sohisticated program that has been tweaked for Ford flatheads. A baseline was run with the Early OEM cam at 6.7:1 CR, which agreed surprisingly well for Net Hp/Tq values- engine run with fan, waterpump, alternator, aircleaner, and mufflers. The three following tests were done at 8:1 CR, and show Net Hp/Tq values for the Late OEM, Delta 400M, and the Asche 380. Once again, the Late OEM is superior at RPM's PW users are likely to use. The next post will show the Asche 380 teamed with dual carbs and split exhaust.