| FAQ |
| Members List |
| Social Groups |
| Calendar |
| Search |
| Today's Posts |
|
#1
07-08-2018, 10:33 PM
|
||||
|
||||
rocker arm sweep, pushrod length ?
I used the mid-lift method, came out to 9.420 for pushrod length. I then subtracted lifter preload to check sweep pattern. The sweep is .040 wide but is only .050 to .090 from the edge of the valve.
.100 shorter pushrod, .050 wide sweep, .060 to .110 from the edge .200 shorter pushrod, .080 wide sweep, .080 to .160 from the edge Are any of these ok or do I need different roller rocker arms? It has been 5 years since I drove/raced this car. Finally assembling the engine after most of the inner valve springs broke. Plan is to run low 12's |
|
#2
07-09-2018, 12:40 AM
|
|||
|
|||
|
Quote:
Then subtracted lifter preload? I guess I don't understand your procedure. At any rate, "I" would go with the .040 sweep. You're not so close to the valve edge that I'd be concerned. Ideally, you'd find rockers that were a little shorter from fulcrum to tip. Probably not essential. |
|
#3
07-09-2018, 05:55 AM
|
||||
|
||||
|
What rockers are you using? Ratio - brand.. You're definitely getting the centreline of the trunion and roller 90* to the valve at mid lift?
__________________
'71 Holden HQ Monaro - 3850lbs race weight, 400c/i - 11.4 @ 120 '66 Pontiac GTO - 389, 4 speed street cruiser |
|
#4
07-09-2018, 06:08 AM
|
||||
|
||||
|
Yes, what ratio are those arm's?
__________________
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! |
|
#5
07-09-2018, 03:02 PM
|
||||
|
||||
|
Go with the skinny pattern. Sounds like you are doing it right, such that your pushrod length with preload (1/2 to 3/4 turn on a 7/16-20 stud) gives you the skinny pattern.
__________________
"...ridge reamer and ring compressor? Do they have tools like that?" |
|
#6
07-09-2018, 05:38 PM
|
||||
|
||||
|
Are the valves longer than stock? If so, you may need to go to a SB Ford rocker to get the roller centered. Otherwise, narrowest is bestest.
__________________
Paul Carter Carter Cryogenics www.cartercryo.com 520-409-7236 Koerner Racing Engines You killed it, We build it! 520-294-5758 64 GTO, under re-construction, 412 CID, also under construction. 87 S-10 Pickup, 321,000 miles 99Monte Carlo, 293,000 miles 86 Bronco, 218,000 miles |
|
#7
07-10-2018, 08:26 PM
|
||||
|
||||
|
Valves have 1.700 installed height on the 670 heads that have been milled many years ago. Rockers are Harland Sharp 1.65 ratio. Cam is the Crower 60919, so not much lift.
How does the SB Ford rocker ( what brand do you use ) compare to the Scorpion Pontiac rocker for distances from pushrod to trunion and trunion to the roller center? |
| Reply |
|
|
The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.
Linear Mode
