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#1
02-16-2020, 06:41 PM
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isky mega cam question
what valve springs would be recommended for # 901271 270 mega cam Pontiac thanks
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#2
02-16-2020, 07:20 PM
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Not a recommendation but listed for that specific cam from a 2004/05 Isky catalog:
#5005 spring Dual W/damper 1.430 O.D. Rated 125 @ 1.531 285 @ 1.031 320 rate 0.980 coil bind .
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
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#3
02-17-2020, 07:23 AM
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What CID motor and what casting number heads are we talking about here?
From your post I would assume iron I guess, but are they stock? Stock valve installed height in different head castings can veri from 1.540" to 1.580" and that can make a big difference in spring needs,and this does not factor in the sinking of the valves during a valve job, especially if longer then stock replacement valves are used! Crowed springs 68404-16 will work well up to a 1.600" installed height, but if you have less then 1.570" installed height your might need to get the spring seats in the heads cut some. The retainers you will need for these springs are Crower 87050-16" the part number you will need for the valve locks to match these retainers I can't recall at the moment, but a call to Crower would be all that's needed. P.S. Be sure to use a 2 degree Cam advance key to help compensate for normal timing chan stretch , this works out especially good in low comp motors of 400 cid or less. Also note that with the needed Crower retainer you can not run the stock valve stem O ring seal so you will need to have the tops of the valve guides cut for positive seals. This machine work will also serve the purpose of confirming that you have enough retainer to valve seal clearance to handle that Cams .470" lift.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! Last edited by steve25; 02-17-2020 at 08:04 AM. |
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#4
02-17-2020, 02:27 PM
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I have a 30 over 400 engine with 1970 13 heads
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#5
02-18-2020, 07:22 AM
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With stock or stock replacement valves?
I will look into my notes tonight for the stock installed height and post up again in the morning if no one here chimes in before that.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#6
02-18-2020, 09:17 AM
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I just ordered stainless replacement valves, 5.090
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#7
02-18-2020, 01:05 PM
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Ok, I'll get back to you in the morning, thanks!
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#8
02-19-2020, 07:27 AM
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Ok, I pulled a stock #62 head off the parts shelf last night and got these numbers for you.
The head was checked a freshen up valve job and new 5.09" valves. The Intake showed a installed height with a stock Pontiac retainer of 1.562" The Exh showed a height of 1.584. With some minor spring seat cutting the Crower springs I posted you about will the way to go. Be sure to get the valve guides cut for positive seal and run the Viton type, note the white Telfon type!
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#9
02-19-2020, 09:11 AM
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ok thanks for all your help, ill order these springs and give my machine this info. thanks again, tony
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#10
02-19-2020, 09:21 AM
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Welcome!
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#11
02-19-2020, 09:35 AM
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At the 1.562 note your distance from coil bind, assuming 0.465 lift.
.
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
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#12
02-19-2020, 10:11 AM
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I am not understanding your comment here Steve.
With the Crower springs he is getting he needs a minimum of 1.600" installed height so I can't see where running .470" lift will be a issue. The Crower spring calls out coil bind @ .950" which with a 1.600" height would be .650" lift.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! Last edited by steve25; 02-19-2020 at 10:17 AM. |
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#13
02-19-2020, 10:19 AM
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Probably not a big deal and it could be changed. Unless I'm wrong I calculate in theory it will be about 0.147" away from coil bind at max lift on the intake. At the 1.562".
https://www.hotrod.com/articles/how-...rance-is-safe/
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
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