|
Re: comp 948 springs?
[Re: gregsdart]
#529030
11/19/09 09:57 PM
11/19/09 09:57 PM
|
Joined: Jun 2009
Posts: 644
Minnesota
Barnstorm
mopar
|
mopar
Joined: Jun 2009
Posts: 644
Minnesota
|
Love my 948's. Ran K1000h's and they would break over winter sometimes. Mine in at 2.10.
The little old lady from Pasadena is back!
|
|
|
Re: comp 948 springs?
[Re: gregsdart]
#529033
11/20/09 11:02 AM
11/20/09 11:02 AM
|
Joined: Jan 2003
Posts: 19,363
Las Vegas
Al_Alguire
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 19,363
Las Vegas
|
Pardon my ignorance but what is the largest diameter valve spring you can use? Isn't the 948 a 1.650? I ask becuase if you can squeeze in a larger diameter it opens up more possibilities.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
|
|
|
Re: comp 948 springs?
[Re: gregsdart]
#529034
11/20/09 11:57 AM
11/20/09 11:57 AM
|
Joined: Jan 2003
Posts: 1,938
Sonora CA
Mopar_Rich
top fuel
|
top fuel
Joined: Jan 2003
Posts: 1,938
Sonora CA
|
Quote:
My dilemma is not being able to get a correct spring to fit with a 2.050 max installed height, yet still allow .850 net lift.
As much as I like Comp, I'd switch to a PAC spring.
The PAC-1248 will handle a .900 lift easily. Its specs are:
PAC-1248: 350 lbs @ 2.050, 950 lbs @ 1.20
This spring is spec'd to .900 lift
The PAC 1246 is a little less pressure and although this spring is spec'd to .800 lift, I have run them many times with .850 lifts with no problems.
PAC-1246: 250 @ 2.050, 830 @ 1.20
|
|
|
Re: comp 948 springs?
[Re: Mopar_Rich]
#529035
11/20/09 01:08 PM
11/20/09 01:08 PM
|
Joined: Jan 2003
Posts: 4,048
Shelby Twp. Mi
HardcoreB
master
|
master
Joined: Jan 2003
Posts: 4,048
Shelby Twp. Mi
|
Quote:
Quote:
My dilemma is not being able to get a correct spring to fit with a 2.050 max installed height, yet still allow .850 net lift.
As much as I like Comp, I'd switch to a PAC spring.
The PAC-1248 will handle a .900 lift easily. Its specs are:
PAC-1248: 350 lbs @ 2.050, 950 lbs @ 1.20
This spring is spec'd to .900 lift
The PAC 1246 is a little less pressure and although this spring is spec'd to .800 lift, I have run them many times with .850 lifts with no problems.
PAC-1246: 250 @ 2.050, 830 @ 1.20
Pieces like this (among others)makes the thread better...people adding their personal experience data. The post on YB was lengthly back and forth. I summed-up that unless your running specific parts with a spintron, laser and stress instrumentation, confidence in valvetrain dynamics comes from correctly evaluating experience(just like anything else I guess ).
|
|
|
Re: comp 948 springs?
[Re: HardcoreB]
#529039
11/21/09 04:25 PM
11/21/09 04:25 PM
|
Joined: Nov 2003
Posts: 1,664
North Sweden
RT540
top fuel
|
top fuel
Joined: Nov 2003
Posts: 1,664
North Sweden
|
My B1 heads came with PSI-1248 installed at 2.100"
DR1248,Triple,diam1.660",375lbs@2.100",1045lbs@1.200"
coil bind 1.130"
Maybe PSI-1247 would fit at 2.050" installed height ?
DR1247,Triple,1.660",340lbs@2.070",940lbs@1.270"
coil bind 1.130"
|
|
|
Re: comp 948 springs?
[Re: Mopar_Rich]
#529040
11/21/09 07:26 PM
11/21/09 07:26 PM
|
Joined: Feb 2004
Posts: 1,093
Long Beach, CA
Mike Swann
super stock
|
super stock
Joined: Feb 2004
Posts: 1,093
Long Beach, CA
|
Quote:
I don't agree. Here's the data from PAC.
It shows an installed height of 2.1, but in this case the installed height would be 2.050. Even at .900 lift that puts the spring at 2.050 - .900 = 1.150, with stated coil bind not occurring until 1.130.
Rich, if you are really going to lift the valve .900, the installed height should be 2.15-2.2. Even then, you would have infinitesimal performance gain and a lot of heartache with anything short of a late 90's or later series PS head, IMO.
8.30's @3400 lbs
|
|
|
Re: comp 948 springs?
[Re: Mopar_Rich]
#529042
11/22/09 11:48 PM
11/22/09 11:48 PM
|
Joined: Jan 2003
Posts: 9,997
Frostbitefalls MN (Rocky&Bullw...
gregsdart
OP
master
|
OP
master
Joined: Jan 2003
Posts: 9,997
Frostbitefalls MN (Rocky&Bullw...
|
Thanks guys, I really appreciate the input. My choice is for a cost reason; I put so few runs on the car, the 948 would be my choice if I need them. I will check the 947 springs I have to make sure they are close to spec, and am starting the season with the same rocker ratio I have to keep things simple. I can install them at less than 2.00 and still have room.
If i decide to go for this extra lift, the comp 948 springs can be installed at 2.050 and give me 355 seat pressure, and would allow a NET lift of .860 which is .050 more than my proposed change. As mentioned, a larger cam core might be needed, as I run a stock bearing sized cam, and lose a lot of lift just rolling it over on the stand. So not knowing enough about possible consequences at this point, I will wait to make my move.
Last edited by gregsdart; 11/22/09 11:50 PM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
|
|
|
|
|
