Re: Mushroom Tappet Cams
[Re: polyspheric]
#646925
03/22/10 11:24 AM
03/22/10 11:24 AM
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Joined: Jan 2003
Posts: 2,763 Walton's Mountain, Pa
Steve1118
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master
Joined: Jan 2003
Posts: 2,763
Walton's Mountain, Pa
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The mushroom deal was actually developed for the NASCAR program....Chrysler wanted the big numbers, and they were not feasable with a flat tappet. Rollers were illegal in NASCAR....hence the develpment of the mushroom tappet. Those old "mini express" worked real good, too.
"Old age and treachery trumps youth and enthusiasm, every time!" East Central Director / Chrysler Power Magazine www.reasbeckracing.webs.com
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Re: Mushroom Tappet Cams
[Re: polyspheric]
#646926
03/22/10 12:11 PM
03/22/10 12:11 PM
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Joined: Jun 2004
Posts: 1,226 Peoples republic of clackamas ...
atoetly
pro stock
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pro stock
Joined: Jun 2004
Posts: 1,226
Peoples republic of clackamas ...
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Quote:
the huge radius at the bottom
You're confusing me (fairly easy to do). Do you mean at the body/base intersect (below the tappet gallery bottom), or at the contact surface?
The radius is where it transitions from from main body into the 1 inch portion of the lifter. Not where it rides on the cam.
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Re: Mushroom Tappet Cams
[Re: atoetly]
#646927
03/22/10 06:50 PM
03/22/10 06:50 PM
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Joined: Oct 2007
Posts: 4,210 New York
polyspheric
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master
Joined: Oct 2007
Posts: 4,210
New York
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Thanks, that makes more sense. BTW: there are really big radius flat tappets for other engines: 3".
Boffin Emeritus
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Re: Mushroom Tappet Cams
[Re: Bighead440]
#2233675
01/13/17 07:41 PM
01/13/17 07:41 PM
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Joined: Nov 2004
Posts: 6,890 North Alabama
Monte_Smith
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Posts: 6,890
North Alabama
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I don't think some understand the purpose of the mushroom tappet. First, it is not mushroom shaped at all. It just looks like a regular lifter with a 1" diameter base welded on it. So it's flat on the bottom and is STILL a flat tappet lifter and as such is limited on spring pressure just like any other flat tappet. It provides no more lift. The ONLY things it does is move the valve events. Meaning the lifter starts up the ramp and comes down the ramp at different times because the diameter is larger. The larger diameter means it contacts the ramp earlier. That's ALL, nothing else. Why was this needed? Because at the time, cam cores were very limited as to the valve events that could be ground into them. So you fixed that with a larger lifter. With cores available today, the mushroom lifter is NOT needed. You can get cores to get about any events you want within reason
If you look at the drawing linked to above, it shows exactly what I am explaining. But you can also accomplish the same thing with a cam with more of a roller profile on the lobe.......or just put 1" lifters in the motor.
With the roller profiles available today and everything we have to choose from, it baffles me though why guys even WANT a flat tappet though. Just as David Reher addressed in that article, there are so many potential issues with a flat tappet
Last edited by Monte_Smith; 01/13/17 07:48 PM.
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Re: Mushroom Tappet Cams
[Re: Monte_Smith]
#2233803
01/13/17 11:14 PM
01/13/17 11:14 PM
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Joined: Apr 2006
Posts: 4,220 West Plains, MO
DrCharles
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Posts: 4,220
West Plains, MO
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With the roller profiles available today and everything we have to choose from, it baffles me though why guys even WANT a flat tappet though. Just as David Reher addressed in that article, there are so many potential issues with a flat tappet At a given maximum lifter acceleration, you can get more lift out of a 1.00" tappet than you can with a .904". My refaced Mini-Express is .652 gross lift (.018 lash), 272@.050. I feel safer running it on a 1" lifter than an Ultradyne .640 on a .904, which is 277@.050. The mushroom has more lift with less duration. Sounds kind of like a roller... There are also potential issues with roller lifters on the street... depends on who you talk to. Like everything else here, there are multiple opinions. Perhaps more importantly, not all of us have John Force's budget for engines and components. A good set of roller lifters alone costs more than I have in my mushroom cam & lifters, pushrods, used Isky rockers, and Comp springs
Last edited by DrCharles; 01/14/17 12:46 AM.
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Re: Mushroom Tappet Cams
[Re: Bighead440]
#2233813
01/13/17 11:24 PM
01/13/17 11:24 PM
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Joined: Jun 2014
Posts: 5,183
Porter67
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Joined: Jun 2014
Posts: 5,183
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I would think if they were the end all of camshaft/lifter designs they would still be made today.
Its easy to fully understand the budget! At times we do, only what we can do which is better then nothing.
The shubeck puck solids at 69 grams and $700 might seem like alot of money upfront, I just sold a set I used on six cams over a five year period with zero issues for $350.
In those six different cams at $150X6 a set of regular lifters Im far ahead of the lifter game.
As well Ive resold the cams, cheap but they would still rotate a new set of lifters.
I really wanted the cam/lifters I mentioned off ebay but I just didnt have a reason.
As far a solid roller lifters, for the street if you can find a old reed cast core roller and matched lifters you can run a gentle roller cam for a long time.
Or if like some on here that god blesses you everyday, you can run a normal roller cam and lifters.
Last edited by EV2Bird; 01/14/17 01:53 AM.
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Re: Mushroom Tappet Cams
[Re: Bighead440]
#2233829
01/13/17 11:44 PM
01/13/17 11:44 PM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
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Joined: Sep 2014
Posts: 4,457
Washington
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One of the issues I have is that the valve gear on OE heads just isn't rigid enough for the spring pressures a roller needs. If all you are doing is beat the hell out of the valve gear you aren't doing much.
That's why I used a SFT in my last build. When I do the W-2 heads I may use a roller. Or, I may say piss on it and use a mushroom lifter.
Like I said, I have the lift I wanted with a .904 lifter or I'd have used a mushroom this this time. But much over .600 lift and it's hard to get all the valve train correct.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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