Mushroom Flat Tappets/Tappet Weight

[frnkeore]

How close can you come to standard, roller tappet, lift rates, with lobe pattern for 1" mushroom flat tappets?

I just bought a couple of 292/312 type mushroom flat tappets (there also used in other OHV Fords in that era), to investigate the idea of installing them in 302 and FE engines. The 302 application would be used with spring oiler's and I think I would have to counter bore the bottom of the lifter bore.

I had seen specs on their weight and that's what gave me the idea. The ones I received yesterday weigh 68 grams each or about 1/3 of a roller lifter. the push rod can also be a little shorter. My light weight, 302, solid lifters weight about twice that, at 128G

How much does the weight on the lifter/push side of the valve train effect increasing the rpm potential?

[dannobee]

Before you go through all that trouble, you might want to make sure that they'll clear the cam lobes on the other side cylinders. IIRC, the cam lobes have to be really narrow to make it all work.

[PackardV8]

How much does the weight on the lifter/push side of the valve train effect increasing the rpm potential?

Those with the money for Spintron time usually say, "Not much." In fact, one pro stock builder is on record as saying, "There's no such thing as too strong a pushrod. The larger we make them, the better the valve control." Of course, he is running huge heavy valves, insanely strong springs and long, large diameter pushrods. How much of that is applicable to your SBF is unknowable.

Thoughts to consider:

In the past seventy years, has any pushrod engine design copied the 1954 Ford mushroom solid lifter? If not, why not? (Hint; it's not because it's a solid lifter and all subsequent engine designs used hydraulic lifters. It's perfectly possible to design a 1/2" diameter hydraulic lifter.)

When NASCAR briefly allowed mushroom lifters, did anyone sleeve the lifter bore down to 1/2"? If not, why not?

[frnkeore]

Before you go through all that trouble, you might want to make sure that they'll clear the cam lobes on the other side cylinders. IIRC, the cam lobes have to be really narrow to make it all work.

Thank you, I hadn't considered that. I'll check it out when I mock it up.

When NASCAR briefly allowed mushroom lifters, did anyone sleeve the lifter bore down to 1/2"? If not, why not?

Packard,
I'm not sure why and I don't remember if they had gone to spring oilers at that time but, if they hadn't and still used pushrod oiling, that may have been the reason or it could have been rule related.

As I am a "old School" kinda a guy and because there is more HP potential in solid lifters. If a engine has adjustable rockers, I want to use it, to advantage.

I had been kicking this idea around, for a long time but, about 10 days ago, I looked at the Howards lift rates for the .903 lifter size. It's enough more than the .875 Ford size that a increase over the .903 to 1" should be a reason to try it.

This is a comparison of lift rates of the .903 FT, to std roller lift and fast ramp roller rates:

Howards .903 lifter
.020 .050 .200 1.6
286 258 177 .405 = .648 -.018
290 262 181 .413 = .661 -.018

Std Roller
291 259 177 .427 = .683 -.016
293 261 179 .433 = .693 -.016

Fast Ramp Roller
288 259 182 .427 = .683 -.016
290 261 N/A .450 = .720 -.016

Howards don't make 258 or 262 lobes in rollers.

[frnkeore]

Those with the money for Spintron time usually say, "Not much." In fact, one pro stock builder is on record as saying, "There's no such thing as too strong a pushrod. The larger we make them, the better the valve control." Of course, he is running huge heavy valves, insanely strong springs and long, large diameter pushrods. How much of that is applicable to your SBF is unknowable.

I think the key here is stiffness.

I watch the the recent Spintron vid and stiffness was a key element to it. Measured to the bottom of the pushrod cup, a Eaton VL48, 128G lifter is 1.67 OAL. The same length for the mushroom lifter is 2.3. That means that the pushrod can be .63 shorter, increasing stiffness and reducing weight.

[PackardV8]

I think the key here is stiffness.

I watch the the recent Spintron vid and stiffness was a key element to it. Measured to the bottom of the pushrod cup, a Eaton VL48, 128G lifter is 1.67 OAL. The same length for the mushroom lifter is 2.3. That means that the pushrod can be .63 shorter, increasing stiffness and reducing weight.

Yes to stiffness. Maybe not to to weight reduction. The .63" shorter hollow pushrod is replaced by a solid lifter body; the weight is probably a wash.

[learner1]

As far as flat tappets performing like rollers you should be looking at valve area comparisons. That's really what matters more than anything.

[frnkeore]

I think the key here is stiffness.

I watch the the recent Spintron vid and stiffness was a key element to it. Measured to the bottom of the pushrod cup, a Eaton VL48, 128G lifter is 1.67 OAL. The same length for the mushroom lifter is 2.3. That means that the pushrod can be .63 shorter, increasing stiffness and reducing weight.

Yes to stiffness. Maybe not to to weight reduction. The .63" shorter hollow pushrod is replaced by a solid lifter body; the weight is probably a wash.

You get the shorter push rod AND the lighter lifter both, with the mushrooms. mushroom = 68G. LW, FT = 128G. 128G lifter is used with the 6.8 push rod, mushroom with a 6.25 push rod.

[frnkeore]

As far as flat tappets performing like rollers you should be looking at valve area comparisons. That's really what matters more than anything.

The Howards Cam specs, indicate that, at least from .050 to .200, it's heading that way, with the .903 lifter. I would like to see what the max lift rate could be with a full 1" dia lifter, compared to the common 3/4" roller. That would be the real story.

[learner1]

Yes larger diameter lifters help but it's a lot better and easier to get there using higher rocker ratios.

[frnkeore]

You can't get where you want. From more than one direction?

You have to activate that rocker some way.

[learner1]

Yes you can and I'm very fond of the .903 lifter but the cost of converting to oversize lifters goes along ways towards new rockers.

[cardo0]

I don't see anyone selling mushroom tappets anymore. Had some ideas of using them but no one even sells them.

Next idea was to just use larger diameter solid or even hydraulic lifter but the more I looked into this the less of an improvement I'm told they can make and hardly worth the effort. At least not the effort for the small amount of racing I do.

[Joe-71]

Hylift Johnson and Trend still make the mushroom lifters for Y Block Fords. Joe-71

[ijames]

I don't know the exact diameter but the old aircooled Type 1 VW engines used mushroom solid lifters with a head about 1" or so diameter. Might be easier to sleeve to fit than the Y block lifter, or not . Stock and aftermarket one are still readily available.