375 Y Block makes 613 HP with single 4V.

[CamKing]

There are a lot of 1" designs out in the marketplace for Mopar applications using mushroom tappets. Nobody seems to list them anymore.

Because they're 40 years old.

[PackardV8]

There are a lot of 1" designs out in the marketplace for Mopar applications using mushroom tappets. Nobody seems to list them anymore.

Because they're 40 years old.

Hi, Mike,

Assuming today's profiles, if one had the choice between a .904" roller and a 1" flat tappet, would anyone today choose to run the flat tappet?

[CamKing]

Hi, Mike,
Assuming today's profiles, if one had the choice between a .904" roller and a 1" flat tappet, would anyone today choose to run the flat tappet?
[/quote]
No one I would want to work with.

[Walter R. Malik]

There are a lot of 1" designs out in the marketplace for Mopar applications using mushroom tappets. Nobody seems to list them anymore.

Because they're 40 years old.

Just curious ... If an older !" diameter lobe is already designed for maximum acceleration and peak velocity at that lifter diameter for a given lift then it probably has more lobe area than a modern .875" profile.
In older 440 Chrysler Super Stock engines they would rev past 7,000 rpm with valve springs not even close to what we have to choose from, today.
Even the NASCAR .960" mushroom lobe profiles would probably be some advantage in a Y-block.

[frnkeore]

I looked into the 1" FT's a couple of years ago, when I saw what the Howards flathead lobes had to offer. As I said, I contacted Ben Herheim, at Howards at the time, and asked him about it. So he designed a .016 lash, 1.6 rocker version of that lobe and sent me the specs for it:

309° @ .010, 260.14° @ .050, 185.19° @ .200, Area 37.39 @ .050, with a .9694 lifter (.0153 edge)

About the same time, I opened a thread here, regarding it and asked about 1" lifters and Mike replied that the edge could be as little as .008, almost 1/2 of what Ben's data was for. That would increase lift and duration, a little more than my lobe above.

So, I did a comparison of .874, .904 and roller cams, as follows:

CC, .904 lobes
#6588 293 267 185 .411

Howards
#FF2684147A 296 268 185 0.415, .874 tappet
#FM2664164A 294 266 185 0.416, .904

28° major intensity, roller cam
#R2634164 306 291 263 185 0.416

Fast ramp roller
#AR259427 303 288 259 182 0.427 (no 260° cam)

Similar Bullet roller cams
#R301/435 301 268 185 .4350
#R291/452 291 260 184 .4520 (highest .200 dur, 260° cam, not asymmetrical)

[CamKing]

So, I did a comparison of .874, .904 and roller cams, as follows:

CC, .904 lobes
#6588 293 267 185 .411

Howards
#FF2684147A 296 268 185 0.415, .874 tappet
#FM2664164A 294 266 185 0.416, .904

28° major intensity, roller cam
#R2634164 306 291 263 185 0.416

Fast ramp roller
#AR259427 303 288 259 182 0.427 (no 260° cam)

Similar Bullet roller cams
#R301/435 301 268 185 .4350
#R291/452 291 260 184 .4520 (highest .200 dur, 260° cam, not asymmetrical)

For comparison, here's a Asymmetrical Roller design I did a few years ago, for the Race Engine Challenge.
283@.020", 258.5@.050", 189@.200", .469" Lobe Lift.

To make this exact valve lift curve for a flat follower, you would need a follower diameter larger then 1.164".

[CamKing]

If I designed a flat tappet profile with the same lift and seat duration, as the NASCAR intake lobe Joe is running now, here's where it would gain.

NASCAR .875" flat tappet profile:
320@Lash point
298@.020"
268@.050"
237@.100"
187@.200"
134@.300"
041@.400"
.409" Lobe Lift

New design for 1" diameter flat tappet profile
320@Lash point (same)
297@.020" (-1)
269@.050" (+1)
239@.100" (+2)
191@.200" (+4)
138@.300" (+4)
044@.400" (+3)
.409" Lobe Lift (same)

[frnkeore]

This is Bens lift curve.

[Joe-71]

Mike, would this new profile work with the Trend lifters, and would it actually improve the performance over the camshaft I have currently? I still have about .135" intake valve to piston clearance, .112" exhaust valve to piston clearance. I am working with a 53.4 cc combustion chamber, 1.970/1.510" valves. I cannot go to any larger valves with the 3.862" bore. Joe-71

[CamKing]

Mike, would this new profile work with the Trend lifters, and would it actually improve the performance over the camshaft I have currently? I still have about .135" intake valve to piston clearance, .112" exhaust valve to piston clearance. I am working with a 53.4 cc combustion chamber, 1.970/1.510" valves. I cannot go to any larger valves with the 3.862" bore. Joe-71

It would work with the Trend lifters.
It would pick up some top-end power, but probably only 5-15 hp.

[Diodedog]

Could you share the head flow numbers with mani.

[Stan Weiss]

Mike,
As you know I am not a cam lobe designer, I just like to play around. Here are 2 profiles I generated use the numbers for the Howard numbers posted above. Graph one shows that the lobe lifts are almost identical. The velocity is somewhat a different story. Have you ever designed a cam with a velocity curve like the green line?

Thanks,
Stan

Howards_Lobe_Lift.gif

Howards_Lobe_Velocity.gif

[Joe-71]

Could you share the head flow numbers with mani.

I have ported several sets that flow over 290 cfm with the 1.960/1.970" intake valves and 210 cfm on the exhaust without a pipe. These are better. The dual plane intake flows 340 cfm average, Single Plane 348.23, Single Plane-Dominator 354.86, and the tunnel ram nearly identical to the SP-D. I try to get the intakes to flow 115-120% of the head whenever possible. Joe-71

[frnkeore]

Stan & Mike, here is the full report, if that helps any.

[CamKing]

Mike,
Have you ever designed a cam with a velocity curve like the green line?

Only about 100 or so.
That's what are EMV Series flat tappets are. Extended Maximum Velocity.
It's harder on the valvetrain, but when you are limited by a given fl;at tappet lifter diameter, it's the best way to get the area you need.