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#1
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Mushroom tappets?
Since it's only roller lifters which create enough side-load to break lifter bores, let's discuss flat-tappet options. The move to roller lifters in motorsports was primarily to allow lobes to have more aggressive profiles. Mushroom tappets provide almost as much lobe design freedom as roller lifters. If you weren't messing with engines when OHV V8s started to take over ('49 Olds, etc.) you probably don't remember the popularity of mushroom lifters- not just in flathead V8s, but also for a decade or so in overheads.
Label this an academic exercise; I don't expect anyone to convert their Pontiac to mushroom tappets. Just food for thought...
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Anybody else on this planet campaign a M/T hemi Pontiac for eleven seasons? ... or has built a record breaking DOHC hemi four cylinder Pontiac? ... or has driven a couple laps of Nuerburgring with Tri-Power Pontiac power?(back in 1967) ... or has a Pontiac born the same year as Jim Wangers? (1926} |
#2
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Jack, does anyone still manufacture Lee-Wilcox type lifter for any engine other than the flathead Ford? We used them in the majority of Lycoming aircraft engines but even NASCAR stopped using them decades ago.
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“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#3
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Jack, I have A Tempest 4 banger with an Isky solid cam in it with mushroom lifters!
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Keith Collier 61-63 Pontiac Tempest Tech advisor POCI.org |
#4
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Jack,
In away that technology is still being used in modern engines. The lobe profile should be no different than is used with a OHC running on a large diameter bucket. Stan
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
#5
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UD Harold said that there was power to be had with larger lifters.
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#6
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Quote:
I also heeded the warning not to wind up with Chevy lifters in our Pontiac. We are using Comp Cams hydraulic roller lifters and cam in the 421 now. |
#7
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Just have to remember T G I F !!!
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Keith Collier 61-63 Pontiac Tempest Tech advisor POCI.org |
#8
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Quote:
I have never even heard of anyone doing it. But I do not see why it could not be done. Solid .904s are cheap compared to high end solid rollers. I would think all I would have to do is get the custom cam and standard Mopar lifters and the right length pushrods. I bet you could end up with a sft with the big lobe that is not far off in performance as a std core solid roller. I would not have to worry about needle bearing failure. The steel cam would be very tough. I just bracket race the car. I have not bought a 55mm cam yet and have a nice set of Jessel .904 lifters for the wide ports. BUT, I don't think a flat tappet cam can work on wide ports since they have the offset lifters. Everything has to be centered as the flat tappet lifter rotates. So I would have to use my std High Ports. Easy to get them to flow like my E heads, or close to it and just use my Norris rockers and stud girdle. Will it work ? Crazy ? Heard of anyone doing it ? |
#9
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Keith- I'd like to see a picture of a mushroom tappet of your four. Any photos or catalog pictures?
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Anybody else on this planet campaign a M/T hemi Pontiac for eleven seasons? ... or has built a record breaking DOHC hemi four cylinder Pontiac? ... or has driven a couple laps of Nuerburgring with Tri-Power Pontiac power?(back in 1967) ... or has a Pontiac born the same year as Jim Wangers? (1926} |
#10
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The only picture I currently have.
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Keith Collier 61-63 Pontiac Tempest Tech advisor POCI.org |
The Following User Says Thank You to mechanickeith For This Useful Post: | ||
#11
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Jack, I will try & get you better pictures. You want dimensions also??
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Keith Collier 61-63 Pontiac Tempest Tech advisor POCI.org |
#12
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No, I don't care about dimensions. Thanks for the photo. Are they about as light as any other flat hydraulic tappet?
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Anybody else on this planet campaign a M/T hemi Pontiac for eleven seasons? ... or has built a record breaking DOHC hemi four cylinder Pontiac? ... or has driven a couple laps of Nuerburgring with Tri-Power Pontiac power?(back in 1967) ... or has a Pontiac born the same year as Jim Wangers? (1926} |
#13
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Don't have a scale but feels about the same. Nothing noticeable.
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Keith Collier 61-63 Pontiac Tempest Tech advisor POCI.org |
#14
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Wide/mushroom lifter idea is good to run to ground. Wondered as such when studing cam time events, and equalizing the loads on Flat HYD lifter faces, bore side loads.
Wiped-cam lobes Problem always been an On-ramp to peak lift issue. never really seen the lobe fail on the closing event due to valve bounce, but maybe the lifter face gets damaged enough to grind out the On-ramp. Always wondered why "rev-kits" didnt stick around to keep the lifters weight on the cam lobe with RPM |
#15
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On rollers they do help keeping the cam looking good but in my opinion they are an installation and maintenance nightmare.
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Monty Frerichs B&M Machine Box Elder SD |
#16
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Brfore my time, i found ISKY had such rev-kits for the Valley area. But were not for sale when i was looking to buy.
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#17
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I dug out my '79 Isky catalog. It still lists for sale Mushroom lifters and the Installation tool. .995" Diameter mushrooms.
Stan
__________________
Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
The Following User Says Thank You to Stan Weiss For This Useful Post: | ||
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