FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#1
|
||||
|
||||
De-tuning
I will be detuning this former 12:1 455+.060) , stock stroke race engine. Replacing the 72cc Eheads round port with the 85cc version. The cam will remain, it's an UD solid roller, 243/251@.050, .640 lift with 1.6 scorpion. Moroso 7qt pan, windage tray and scraper. This engine propel a second generation F body 6.8/6.9 , 97/98 mph 1/8 mile with. T400, 3.50 gear, 32-3400 tci stall. Will exchange the solid roller lifters with a quality hydraulic roller lifter. I'm not a fan of the CC 857. Had a couple of bad experiences when they first hit the market. What is a quality Pontiac hydraulic roller lifter? And with this hybrid setup what's a good tight lash starting point?
|
#2
|
|||
|
|||
Try the newest Comps,just got a set,they have a replaceable cartridge.Butler had them Evolution's.Tom
|
#3
|
||||
|
||||
Tom, have you had the opportunity to installed them? Are they as quiet as advertised?
|
#4
|
||||
|
||||
I recently installed a set in a 1971 455HO and was very impressed with the quality. They were very quiet right away on the initial start-up, I would use them again.
__________________
1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
#5
|
||||
|
||||
Quote:
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 |
#6
|
||||
|
||||
That cam and 87 cc heads ought to hold idle...... better than my cam at 9.00:1 which held idle.
__________________
12.24/111.6MPH/1.76 60'/28"/3.54:1/SP-TH400/469 R96A/236-244-112LC/1050&TorkerI//3850Lbs//15MPG/89oct Sold 2003: 12.00/112MPH/1.61 60'/26"x3.31:1/10"/469 #48/245-255-110LSA/Q-Jet-Torker/3650Lbs//18MPG 94oct Sold 1994: 11.00/123MPH/1.50 60'/29.5"x4.10:1/10"/469 #48/245-255-110LSA/Dual600s-Wenzler/3250Lbs//94oct |
#7
|
||||
|
||||
Idle quality should not be an issue. I have a custom Holley 850 dp built by Jeff >12 years ago, and 1k rpm Idle is SOP for me using street solid roller. And according to Wallaceracing.com site, I'll be reducing cr from 13.2 to 11.4.. Don't know exactly how that will affect power loss.
|
#8
|
||||
|
||||
Quote:
I don't have a Cam Dr file for your cam. This shows a lobe I modified for something else. It is 243.x @ 0.050" and about 0.39" lobe lift. You can see the large increase in seat_to_seat duration which also will increase overlap with reducing the lash setting. 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 Last edited by Stan Weiss; 08-17-2023 at 07:46 AM. |
#9
|
|||
|
|||
I was in the same boat for the same reason. CC early 857 were junk. Made all kinds of noise regardless of the pre load set.
I researched my option to death and decided on going with the JohnsonLifters ST21120PR Sht Trav Preload .030. Of all the lifters discussed in these forums they were the ones with almost no complaints. They were quiet as soon as I started the car and have been since. Granted I just got it road worthy and I have not put many miles on it. On the plus side, I expected to have to change out the pushrods but they ended up being spot on for me. |
#10
|
||||
|
||||
Looks like you will drop off about 2.5% of the power that you had with the higher compression.
Also note that all things being equal bigger combustion chambers will make for less idle vacuum.
__________________
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! |
#11
|
||||
|
||||
what about advancing your cam a smidge?
|
#12
|
||||
|
||||
AG, I'm assuming you're referring to the "evolution: brand?(
|
#13
|
||||
|
||||
Quote:
|
#14
|
||||
|
||||
Something I have considered, but cautionary, since I'm at 11.5 cr with 104 icl..
|
#15
|
||||
|
||||
Yes I am.
__________________
1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
Reply |
|
|