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Chevy SB mushroom cam and lifters

 
69Zfan
I love my Chevy Chevette!
Posts: 2
Joined: 09/12
Posted: 09/10/12 04:13 PM

Way back in the mid to late 70's I bought a GM cam and mushroom lifters from Chevolet. They have never been used and are still in the boxes. The camshaft box has printed Gr. 0.519 CAMSHAFT  1#366293 and the lifter boxes have 1#366253 GR. 0.459 printed on them. The lifter boxes each have a sticker glued to them that has printed on the top SPECIAL PARTS NOTICE. The sticker goes on to say that the part has been specifically designed for Off-Highway application only. The sticker has a date of 2-22-73 printed on it. I can't find any information about this camshaft and lifters. If I remember right these were listed in the GM Performance parts catolog back in the 70's, but I no longer have one. I was wondering if anybody here could help me out? Are these of any value? Any help would be greatly appreciated.
Thanks,
Steve  

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76Skylark
Big Block power for the win
Posts: 868
Joined: 12/11
Posted: 09/10/12 04:38 PM

welcome Steve, when you bought them you knew what the lifters offered in the way of performance(duration).but today they just Grind the cam to offer more,springs are better and the ramp on the lobes can now tolerate more abuse,all the while thinking of all the lobe Wiping Incidents we discuss here. nowadays we just buy roller stuff but back then that was race only Stuff for most people.and now they,mushroom lifters,are little more than Nostalgia parts,not having an old book to look at is unfortunate because having those would be cool on my Shelf.If you want to Sell them I would Suggest some place like Hemmings Rather than Racingjunk to find a market that can appreciate them. that's a cool Find, even If you had them all along,how Much ya want?  

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waynep71222
I have an SS396 tatoo
Posts: 448
Joined: 03/12
Posted: 09/10/12 08:30 PM

366293 comes back to a corvair part

the mushroom cam has this description..  

302 through 400 , mushroom type lifter. Off-road racing, third design, good medium or long track cam. 0.560 inch intake lift. 0.575 inch exhaust lift with 1.5 ratio rocker arms. use valve spring #366282... cam id number 366293,  valve set 0.025" intake and exhaust

399293 is a mushroom lifter.. mechanical type with a 0.960-inch diameter foot.


388282 dual valve spring with damper..  use with 302 to 350 with max high lift or roller cams,  1.525" od. outer spring..   requires other than production type valve seals.  128 pounds at 1.70" installed height..  1.26-inch solid height  406 pounds per inch.


these require a special machining process to counter bore the lifter bores from the bottom to allow the lifter foot to move upward. .. i don't know where my 70s power manual is...  i actually found this online.. in an interchange book..

hope this helps..

there was NO duration listed on the cam.. as these were kinda kept secret..   bob.. pepsi1 probably knows about these as he used to race nascar..  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 09/11/12 09:22 AM

Welcome to CHP Steve:

The mushroom cam was made mainly for the NASCAR circut. The GM Hydraulic or Solid flat tappet lifters were all the small O/D. If you look at the Ford, and Chrysler lifter O/D you will find they have a larger O/D.

Those lifters can only be used if the underside of the engine lifter galley is properly machined, so it has room to operate, and prevent damage to the lifter or cam.

Bob  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 09/11/12 10:06 AM

Steve:

GM GM lifter    O/D .842
Chrysler lifter O/D .904
Ford lifter     O/D .874

So as you can see the difference in O/D NASCAR had to do something to equalize the lifter to cam contact area....

Bob  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 09/11/12 10:11 AM

Steve:

These are the numbers I was able to get.
Lifters #366253 Mushroom Type....
Cam #366293
.560/.575 lift
.254/.264 duration
107 LSA
.025 Valve lash in./ex.
Used in off road applications for 302 to 350.

Bob  

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69Zfan
I love my Chevy Chevette!
Posts: 2
Joined: 09/12
Posted: 09/11/12 06:19 PM

Thanks for all the information. Way back when I brought this I wanted to build a engine for my 69 Z/28 to use this cam in. I had all the parts and block for another 302 shortblock separate from the one in my Z. It just never got done and then life took over and I sold most of what I had along with the Z/28. This cam and lifters was just some of the things I never got rid of. I ran across them the other day and was just wondering about them again. Didn't really know if they would be something anyone would be interested in anymore. Now that all the kids are grown up and gone, I'm really starting to get the itch to build something again.
Steve  

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waynep71222
I have an SS396 tatoo
Posts: 448
Joined: 03/12
Posted: 09/11/12 10:00 PM

there are probably a bunch of nascar restorers that might be interested in those..

its going to be very VERY expensive to find a machine shop who might have the ability to properly mill the block for those... there are a few members here who actually run performance machine shops..

when GM mentioned medium to long tracks.. you are going to have to understand...  long tracks in nascar terms..  talladega and daytona would be long tracks.. i am making a wild guess that this is what they were talking about..

you might be better off with a current design roller cam...  if you get a high enough offer for those OEM race parts.. i don't know if the mushroom lifters are still available..  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 09/12/12 12:20 AM

You can use the Cam. It's only the lifters that were different. Like Wayne said a good machine shop with the newer equipment can do that very easily.

When they made Cam changes on those Mushroom Tappet cams they would hold the lifters up with clothes pins so the cam could be removed. That is one wild Cam Wayne. It's a little less Cam then the Duntov .030/.030.  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 09/12/12 12:24 AM

Steve:

It's funny how we have to make those choices in life. My family is all grown up also. They now have families of their own. We all have those stories. I;d do it again with the same woman...

Bob  

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