Spring locator for PAC-1218X spring
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Spring locator for PAC-1218X spring
I’m trying to find the correct locator for a PAC-1218X spring. Spring dimensions are 1.290” base OD, .885” base ID.
Relevant head dimensions are 1.540” spring pocket, .560” guide OD.
The supplied springs that came with these heads are dual springs with 145 pounds on the seat, 325 open at .600” which is lighter open pressure than what my cam calls for by about 25 pounds, but the seat pressure is ok.
Relevant head dimensions are 1.540” spring pocket, .560” guide OD.
The supplied springs that came with these heads are dual springs with 145 pounds on the seat, 325 open at .600” which is lighter open pressure than what my cam calls for by about 25 pounds, but the seat pressure is ok.
Re: Spring locator for PAC-1218X spring
I wonder how much the open is rpm dependent? I have never checked open pressure on a spring in all my years...travis wrote: ↑Wed Nov 20, 2019 7:12 pm I’m trying to find the correct locator for a PAC-1218X spring. Spring dimensions are 1.290” base OD, .885” base ID.
Relevant head dimensions are 1.540” spring pocket, .560” guide OD.
The supplied springs that came with these heads are dual springs with 145 pounds on the seat, 325 open at .600” which is lighter open pressure than what my cam calls for by about 25 pounds, but the seat pressure is ok.
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
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Re: Spring locator for PAC-1218X spring
I would be looking at spring rate for application
Open load - seat load
Divided by net lift at valve
Equals spring rate
Eg- 325-145 = 180/0.600"
300 psi/ rate
I run 380-400 on my cast core comp cams oval track cams to 6800 rpm
No valve float or cam wear after 12 months on street and track
Open load - seat load
Divided by net lift at valve
Equals spring rate
Eg- 325-145 = 180/0.600"
300 psi/ rate
I run 380-400 on my cast core comp cams oval track cams to 6800 rpm
No valve float or cam wear after 12 months on street and track
steve c
"Pretty don't make power"
"Pretty don't make power"
Re: Spring locator for PAC-1218X spring
Per Mike Jones, “For spring pressure, I recommend 130/320lbs for a beehive spring, or 140/350lbs for a double spring. I ran the PAC 1218X.”
Maybe what I’ve got is close enough?
Maybe what I’ve got is close enough?
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Re: Spring locator for PAC-1218X spring
My flat tappet stuff is dual spring
145-345
0.500-0.520"lift
What net lift are you using??
145-345
0.500-0.520"lift
What net lift are you using??
steve c
"Pretty don't make power"
"Pretty don't make power"
Re: Spring locator for PAC-1218X spring
This is a hydraulic roller...264/268@.006, 218/222@.050, .544/.544 liftsteve cowan wrote: ↑Thu Nov 21, 2019 1:55 am My flat tappet stuff is dual spring
145-345
0.500-0.520"lift
What net lift are you using??
Re: Spring locator for PAC-1218X spring
If this was a less aggressive cam like a FMS E or X cam, I would run it as is. These are advertised as hydraulic roller springsGARY C wrote: ↑Wed Nov 20, 2019 11:16 pmI wonder how much the open is rpm dependent? I have never checked open pressure on a spring in all my years...travis wrote: ↑Wed Nov 20, 2019 7:12 pm I’m trying to find the correct locator for a PAC-1218X spring. Spring dimensions are 1.290” base OD, .885” base ID.
Relevant head dimensions are 1.540” spring pocket, .560” guide OD.
The supplied springs that came with these heads are dual springs with 145 pounds on the seat, 325 open at .600” which is lighter open pressure than what my cam calls for by about 25 pounds, but the seat pressure is ok.
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Re: Spring locator for PAC-1218X spring
Travis,
I still believe you need to check open load at the lift you are intending to use.
The 1218x spring has a rate of 313lbs/in
This is fine for mild hydraulic roller but the rate is calculated for 328lbs at 0.600"
You won't have 328lbs at 0.544"
Your spring rate will be under 300lbs/in
More like 270-280 lbs/in
If someone can confirm that is ok for the cam you are using then all good but I don't know.
Just trying to help, I have beat up plenty of valve tips with wrong springs over the years.
I still believe you need to check open load at the lift you are intending to use.
The 1218x spring has a rate of 313lbs/in
This is fine for mild hydraulic roller but the rate is calculated for 328lbs at 0.600"
You won't have 328lbs at 0.544"
Your spring rate will be under 300lbs/in
More like 270-280 lbs/in
If someone can confirm that is ok for the cam you are using then all good but I don't know.
Just trying to help, I have beat up plenty of valve tips with wrong springs over the years.
steve c
"Pretty don't make power"
"Pretty don't make power"
Re: Spring locator for PAC-1218X spring
With 140 pounds on the seat, I calculated 310 open at .544” lift with fresh springs. That does seem a little light. Hopefully Camking will chime in here.
Granted, I’m looking at 6000-6200 max rpm, so maybe that was a consideration when he recommended those springs?
Granted, I’m looking at 6000-6200 max rpm, so maybe that was a consideration when he recommended those springs?
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Re: Spring locator for PAC-1218X spring
The 1218X sets up at 140 @ 1.800. With 0.544 lift your open height will be 1.256" and will net roughly 309 lbs. Spring is fine for what your doing.
Seat P/N is PAC-S111
Seat P/N is PAC-S111
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Re: Spring locator for PAC-1218X spring
Turbo
Thanks for confirmation
Thanks for confirmation
steve c
"Pretty don't make power"
"Pretty don't make power"
Re: Spring locator for PAC-1218X spring
Yes with the more aggressive lobes and the weight of a hyd roller it would probably be more critical.travis wrote: ↑Thu Nov 21, 2019 4:29 amIf this was a less aggressive cam like a FMS E or X cam, I would run it as is. These are advertised as hydraulic roller springsGARY C wrote: ↑Wed Nov 20, 2019 11:16 pmI wonder how much the open is rpm dependent? I have never checked open pressure on a spring in all my years...travis wrote: ↑Wed Nov 20, 2019 7:12 pm I’m trying to find the correct locator for a PAC-1218X spring. Spring dimensions are 1.290” base OD, .885” base ID.
Relevant head dimensions are 1.540” spring pocket, .560” guide OD.
The supplied springs that came with these heads are dual springs with 145 pounds on the seat, 325 open at .600” which is lighter open pressure than what my cam calls for by about 25 pounds, but the seat pressure is ok.
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!