T&D rockers and pushrods.
- Thread starter GONABITE
- Start date
V10 MOJO
Enthusiast
what size rockers are you using? 1.6, 1.65, 1.7, or 1.75?
S
SUN RA KAT
Guest
Is there sufficient clearance with the 1.75 rollers or is 1.7 the highest safe ratio?
Doug Supercharged Vipers
Enthusiast
Anytime you change the rocker arms you need to check the rocker arm geometry. Suffice to say, there's not always "one size fits all" when it comes to the proper setup.
To start: T&D supplies a bag of shims - .040" & .080." Start with the .080" shims on a stock car. We glue them to the rockershafts with 3M adhesive. (Number one mistake) -- make certain the stamped "V-10" faces the valve stem! Use a stock pushrod for starting point or T&D can supply you with a mock-up pushrod upon request.
Now check your geometry:
Rocker arm geometry is critical to valvetrain stability, durability and accuracy. The vertical location of the rocker shaft is a significant factor in valvetrain geometry.
The correct shaft centerline position will locate the roller tip at the same position on the valve stem tip when the valve is closed and when it is at full lift. At the valve closed position, the roller should be slightly behind the valve stem centerline. The roller tip should sweep across the tip to slightly ahead of the stem centerline as the valve opens to the half lift position, sweeping back to its starting point behind the centerline at full lift. This keeps the roller travel centered on top of the valve with the least possible movement, reducing valve guide wear to a minimum.
Good luck!
Doug
To start: T&D supplies a bag of shims - .040" & .080." Start with the .080" shims on a stock car. We glue them to the rockershafts with 3M adhesive. (Number one mistake) -- make certain the stamped "V-10" faces the valve stem! Use a stock pushrod for starting point or T&D can supply you with a mock-up pushrod upon request.
Now check your geometry:
Rocker arm geometry is critical to valvetrain stability, durability and accuracy. The vertical location of the rocker shaft is a significant factor in valvetrain geometry.
The correct shaft centerline position will locate the roller tip at the same position on the valve stem tip when the valve is closed and when it is at full lift. At the valve closed position, the roller should be slightly behind the valve stem centerline. The roller tip should sweep across the tip to slightly ahead of the stem centerline as the valve opens to the half lift position, sweeping back to its starting point behind the centerline at full lift. This keeps the roller travel centered on top of the valve with the least possible movement, reducing valve guide wear to a minimum.
Good luck!
Doug
GASDOC
Enthusiast
Can you use the stock pushrods with the 1.7 Rockers??
Mike Adams
Enthusiast
I have found that most cars require the large shim and a comp cam push rod number 7963 which is a 7.70 length. To check postion of rocker tip on valve take a black marker to mark the top of the valve before putting push rod in, bolt the rocker to the rail and slap it on top of the valve. It will make a line on top of the valve. And like Doug says it should be just to the rear of centre.
S
SUN RA KAT
Guest
repost - <FONT size="5">Is there sufficient clearance with the 1.75 rollers or is 1.7 the highest safe ratio?</FONT s>
GTS-R 001
Enthusiast
Hey Yellow one of 83,
I just put 1.7 T&D's into my 2000 and there was tons of room even with a new and fairly lumpy cam. Why do you want to run 1.75's ? Are you keeping performance secrets from the rest of us?? Just Kidding.
Steve
I just put 1.7 T&D's into my 2000 and there was tons of room even with a new and fairly lumpy cam. Why do you want to run 1.75's ? Are you keeping performance secrets from the rest of us?? Just Kidding.
Steve
S
SUN RA KAT
Guest
Sssssshhhh! Here's my speed secret!
Sean Roe Supercharger coming very soon now...
Sean Roe Supercharger coming very soon now...
GTS-R 001
Enthusiast
ronviper
Pistons are still stock, I am presently contemplating either pulling them and ceramic coating them or getting some new forged ones. Greg lowered the compression on my heads when he did the "job" on them to approx. 9.1 so once I bolt on the SC I should have some latitude before I start to hurt the stock pistons.
Steve
Pistons are still stock, I am presently contemplating either pulling them and ceramic coating them or getting some new forged ones. Greg lowered the compression on my heads when he did the "job" on them to approx. 9.1 so once I bolt on the SC I should have some latitude before I start to hurt the stock pistons.
Steve
Edmonton GTS i spoke to Jason Heffner about the pistons he informed me that the 2000 and new have a longer rod therefore they moved up the pin which means the rings are closer to the top of piston. If you do anything change to forge. Good luck with your project would love to hear the result when it's finished.
Larry Macedo
Enthusiast
If this car is a Gen II, you'll most likely be using the .080 shim between the rocker stand and the cylinder head boss. I use an adjustable length pushrod and start at 7.700" which usually puts the adjuster just one thread (2 turns) under the jamb not. At this position you'll find maximum oiling of the rocker arm. This is zero lash + one full turn. Apply some white grease, paint, etc to the valve tip and install the rocker arm. Make your adjustments, turn the motor over 4-5 times, key off with a trigger attached to the starter and remove the rocker arm. At this point you'll be able to see where the roller tip meets the valve tip. Like Doug stated, the mark left should be just off the valve tip centerline.
Doug Supercharged Vipers
Enthusiast
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by SUN RA KAT:
repost - <FONT size="5">Is there sufficient clearance with the 1.75 rollers or is 1.7 the highest safe ratio?</FONT s>
<HR></BLOCKQUOTE> <FONT size="5">HOPE THIS HELPS</FONT s>
I'm not sure what clearance you are referring to? "Coil bind" or "piston to valve clearance?" Either way, there's no simple answer. Piston to valve would be sufficient with 1.75 ratio rockers. There are too many factors that come in to play with "coil bind" which brings us to another question: What lobe lift, how much gross lift, spring pressures closed & open etc. Coil bind & spring pressures must be checked with these specifications and with 1.75 rockers. Coil bind (the distance between the underside of the valve retainer and top of the valve seal must be within a margin of around .100" of clearance or damage could occur with too much lift). Of course, now you must take into consideration spring pressures, closed pressure & at full lift.
But why 1.75 ratio? The vast majority of Viper tuners (other than Lingenfelter Performance) utilize 1.7 ratios that suffice for almost every application. T&D doesn't stock 1.75 but can build them upon request. The net gain of lift going from 1.6 to 1.7 yeilds .032" additional lift, now, go from 1.7 to 1.75 nets another .016" additional lift. The addition of .016" is a bit negligible when your considering a mild supercharging application.
Regards,
Doug
repost - <FONT size="5">Is there sufficient clearance with the 1.75 rollers or is 1.7 the highest safe ratio?</FONT s>
<HR></BLOCKQUOTE> <FONT size="5">HOPE THIS HELPS</FONT s>
I'm not sure what clearance you are referring to? "Coil bind" or "piston to valve clearance?" Either way, there's no simple answer. Piston to valve would be sufficient with 1.75 ratio rockers. There are too many factors that come in to play with "coil bind" which brings us to another question: What lobe lift, how much gross lift, spring pressures closed & open etc. Coil bind & spring pressures must be checked with these specifications and with 1.75 rockers. Coil bind (the distance between the underside of the valve retainer and top of the valve seal must be within a margin of around .100" of clearance or damage could occur with too much lift). Of course, now you must take into consideration spring pressures, closed pressure & at full lift.
But why 1.75 ratio? The vast majority of Viper tuners (other than Lingenfelter Performance) utilize 1.7 ratios that suffice for almost every application. T&D doesn't stock 1.75 but can build them upon request. The net gain of lift going from 1.6 to 1.7 yeilds .032" additional lift, now, go from 1.7 to 1.75 nets another .016" additional lift. The addition of .016" is a bit negligible when your considering a mild supercharging application.
Regards,
Doug
S
SUN RA KAT
Guest
Doug -
I'm planning on keeping the stock 2002 cam and if I go with 1.7 rollers would the 1.75 rollers be the same basic installation, or would more have to be changed?
I'm planning on keeping the stock 2002 cam and if I go with 1.7 rollers would the 1.75 rollers be the same basic installation, or would more have to be changed?
Ok I found that I don't need to use any shims, has anyone ever experienced this I made an asjustable pushrod checker and found the correct height to be 7.709 so I ordered a set of 7.700. I hope this all works out well the tip ran across the top of the valve never nearing the edge.
