Q: '87 L98 cam switch to ZZ4 cam - do I have everything I need? (list inside)
09-15-2001, 02:40 PM
#1
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Q: '87 L98 cam switch to ZZ4 cam - do I have everything I need? (list inside)
Dropping ZZ4 cam into engine.
Motor is stock 1987 L98 350.
-Stock cast iron L98 heads. No work done to them.
I have K-Motion 700 series springs.
I have the K-Motion 10 degree locks.
I have the K-motion retainers.
I have stock push-in studs (should be screw-in, I know =)
I have stock rockers.
All gaskets and misc. etc. etc.
My only concern (so far) is the Guide clearance. I have read that everyone machines their guides down, but I have seen some posts about using shorter guides and/or seals instead of machining - wanted to clarify what everyone means by that (what brand names and part names applicable)? Also, what timing chain do you guys recommend? Did I get everything I need for this? Thankyou for your time fellow 3rd-gen'rs!
------------------
1987 Trans am GTA
5.7 liter TPI / 700R4
Aus 9-bolt + 3.70 gear
Motor is stock 1987 L98 350.
-Stock cast iron L98 heads. No work done to them.
I have K-Motion 700 series springs.
I have the K-Motion 10 degree locks.
I have the K-motion retainers.
I have stock push-in studs (should be screw-in, I know =)
I have stock rockers.
All gaskets and misc. etc. etc.
My only concern (so far) is the Guide clearance. I have read that everyone machines their guides down, but I have seen some posts about using shorter guides and/or seals instead of machining - wanted to clarify what everyone means by that (what brand names and part names applicable)? Also, what timing chain do you guys recommend? Did I get everything I need for this? Thankyou for your time fellow 3rd-gen'rs!
------------------
1987 Trans am GTA
5.7 liter TPI / 700R4
Aus 9-bolt + 3.70 gear
09-15-2001, 02:51 PM
#2
id get some hardened pushrods and roller rockers, but its not 100% nessicary. you will need a balancer puller so you can remove the timing cover. just a stock replacement roller timing set will be fine. a degreeing card could come in handy if your are not installing the cam "straight up". btw, how do you like the 3.70 gears in your car with a stock L98?
[This message has been edited by u r sofa king we tah did (edited September 15, 2001).]
[This message has been edited by u r sofa king we tah did (edited September 15, 2001).]
09-15-2001, 03:01 PM
#3
FM,
Other than typical shop supplies, it appears you have most of what you need. There may be some things that need attention when you assemble the parts.
* The stock rockers should work with the cam, but you'll have to check all clearances as you assemble the parts.
* Make sure the rocker stud slots are long enough to allow full travel of the valve train. The extra travel of the valve train may bind the rockers at one or both end of their travel.
* Move the engine through the full range of the valve train operation while watching the rockers and push rods and their clearances.
* Make sure the push rod guide holes in the heads allow full free movement. You may have to elongate the head holes to allow clearance.
* Make sure the rockers have adequate clearances through the full range of motion. The rockers need to have clearance at both ends of travel. There must be clearance under the valve spring end when the valve is fully closed, and there must be clearance when the valve is fully opened.
* Try to adjust the valve train to position the rockers perpendicular to the rocker stud (stock 23° heads) when the valve is opened to about 33% of its maximum.
* You may have to adjust push rod lengths. The base circle of the cam may be smaller than the original cam, and may require slightly longer push rods.
* You may also want to check the cam timing to make sure the dowel was placed correctly.
As for the timing chain, I've had good service from the Cloyes double roller sets, and many of their sets come prepared with several keyway cuts to adjust cam timing easily. The GMPP HD single roller chain set is probably equal or better in quality, but does not necessarily offer the timing options without some machining.
Good luck.
------------------
Later,
Vader
------------------
Justice and Freedom will Prevail
Other than typical shop supplies, it appears you have most of what you need. There may be some things that need attention when you assemble the parts.
* The stock rockers should work with the cam, but you'll have to check all clearances as you assemble the parts.
* Make sure the rocker stud slots are long enough to allow full travel of the valve train. The extra travel of the valve train may bind the rockers at one or both end of their travel.
* Move the engine through the full range of the valve train operation while watching the rockers and push rods and their clearances.
* Make sure the push rod guide holes in the heads allow full free movement. You may have to elongate the head holes to allow clearance.
* Make sure the rockers have adequate clearances through the full range of motion. The rockers need to have clearance at both ends of travel. There must be clearance under the valve spring end when the valve is fully closed, and there must be clearance when the valve is fully opened.
* Try to adjust the valve train to position the rockers perpendicular to the rocker stud (stock 23° heads) when the valve is opened to about 33% of its maximum.
* You may have to adjust push rod lengths. The base circle of the cam may be smaller than the original cam, and may require slightly longer push rods.
* You may also want to check the cam timing to make sure the dowel was placed correctly.
As for the timing chain, I've had good service from the Cloyes double roller sets, and many of their sets come prepared with several keyway cuts to adjust cam timing easily. The GMPP HD single roller chain set is probably equal or better in quality, but does not necessarily offer the timing options without some machining.
Good luck.
------------------
Later,
Vader
------------------
Justice and Freedom will Prevail
09-15-2001, 03:49 PM
#4
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Thankyou all for your replies so far. Vader, I will def. use your guidelines to check over my valve-train. As far as the question: How do I like the 3.70's? I like 'em. Big improvement over the 3.27 stocker. Faster rpm reving, but not incredibly fast. Could anyone suggest an alternative to machining the head for guide clearance? I dont really have the resources to re-do the head machine shop wise, so I am looking for parts - shorter retainers/different seals. Any ideas on that? (Assuming pushrods/rockers clearance as close to stock as possible.) Thanks!!
------------------
1987 Trans am GTA
5.7 liter TPI / 700R4
Aus 9-bolt + 3.70 gear
------------------
1987 Trans am GTA
5.7 liter TPI / 700R4
Aus 9-bolt + 3.70 gear
09-15-2001, 04:05 PM
#5
FM,
There is a commercially available drill bushing that allows you to use a standard twist drill bit in an electric drill to elongate the push rod holes. Comp Cams calls it a Louis Tool and offers it for sale. Other manufacturers have similar tools available.
------------------
Later,
Vader
------------------
Justice and Freedom will Prevail
There is a commercially available drill bushing that allows you to use a standard twist drill bit in an electric drill to elongate the push rod holes. Comp Cams calls it a Louis Tool and offers it for sale. Other manufacturers have similar tools available.
------------------
Later,
Vader
------------------
Justice and Freedom will Prevail
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