Cam swap done..... pushrods not even close

[fullforce]

Just got done swapping in a custom lunati cam from. Member here and with my 1.6 rrs they seem to be almost 1/2" to short, is that even possible to be that far off? Not sure what size the base circle of the cam is but obviously smaller.
In fact after installing the pushrod guide plates when I sit the rocker down over the stud the rocker body will just bottom out on the flange of the stud with about 1/4" of slack left in the pushrod.
Just wondering what everyone else measured out to, now I need to buy a length checker and new pushrods.........:(

[SSlowBoat]

Just got done swapping in a custom lunati cam from. Member here and with my 1.6 rrs they seem to be almost 1/2" to short, is that even possible to be that far off? Not sure what size the base circle of the cam is but obviously smaller.
In fact after installing the pushrod guide plates when I sit the rocker down over the stud the rocker body will just bottom out on the flange of the stud with about 1/4" of slack left in the pushrod.
Just wondering what everyone else measured out to, now I need to buy a length checker and new pushrods.........:(
Entire valve train geometry is different, so yes that's normal. Prolly need a 7.3. I run 7.150 with sa rockers.

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[Fastbird]

By a checker, measure out to final length. Don't even question doing anything else.

Also if you reused the lifters make sure they're not collapsing. Ran into that on a buddies car. $780 set of Lunati Tie Bar lifters had taken a shit.

[fullforce]

Checker is on the way...... I'll report back with my findings.
I am reusing the lifters... I hate being broke

[BALLSS]

In fact after installing the pushrod guide plates ........:(

did you use rocker studs for guide plates????

they have a recess to absorb the extra height of the guide plate.

is the Lunati cam base circle smaller than OEM cam?

1/2" is insane amount of difference in PR length....something is way off or measurement procedure is

what is installed height of springs?

PR length checker is needed to measure PR length...one simple one to use is (pic) by Proform for about $10 they make 3/8 & 7/16 size

[fullforce]

I used longer studs, I didn't know they made them recessed though.
The tip of the rocker is contracting the very outside of the valve stem.

[superspirit]

It sounds to me Like the guide plates and studs are incorrect for the application. can you post a pic of the rocker on the stud and the gap on the pushrod. If the stud shoulder is holding the rocker too high to center on the valve then either the heads arent machined for guideplates or the studs are incorrect. A pic would clarify a lot.

[SSlowBoat]

It sounds to me Like the guide plates and studs are incorrect for the application. can you post a pic of the rocker on the stud and the gap on the pushrod. If the stud shoulder is holding the rocker too high to center on the valve then either the heads arent machined for guideplates or the studs are incorrect. A pic would clarify a lot.


did you use rocker studs for guide plates????

they have a recess to absorb the extra height of the guide plate.

is the Lunati cam base circle smaller than OEM cam?

1/2" is insane amount of difference in PR length....something is way off or measurement procedure is

what is installed height of springs?

PR length checker is needed to measure PR length...one simple one to use is (pic) by Proform for about $10 they make 3/8 & 7/16 size
If they are arp studs, they are ALL manufactured for guideplates, and are not recessed, not sure what is meant by that.

The proform tool is great, I have one and just used it and it worked perfectly and quickly.

Just wait till ur length checker shows up, until then, if it comes out to like a 7.8" then be concerned, if not, just calm down and get it right

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[Spartan7]

If they are arp studs, they are ALL manufactured for guideplates, and are not recessed, not sure what is meant by that.

You can use them all with guideplates, but not all of their studs have the locater shank. ARP's site specifically lists which ones have it. I agree with the latter, not sure what was meant by the previous post.

[BALLSS]

Yes ARP makes studs for guide plates with the locator recess.

Sounds like the OP is using longer studs which is raising the rocker to high.....or he is putting the RR fulcrum on the stud upside down. The flat part of the fulcrum goes up.

[fullforce]

Well the pushrods do not appear to be the problem, the rocker body is to narrow to slide far enough down the stud.
http://s467.photobucket.com/user/FirebirdGTAboy/media/IMAG0320.jpg.html
This guy had the same problem, my sweep looks best close to stock 7.2 length.
So looks like I have no choice but to grind a small portion away from the center of the rocker arm on the bottom.
Rockers I bought were some trws off eBay a guy never used.... now I know why, good thing they were cheap

[firebird_1995]

I've had to do that before. I forget what brand rocker they were, I want to say it was an older set of Comp Pro mags.

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[SSlowBoat]

Well the pushrods do not appear to be the problem, the rocker body is to narrow to slide far enough down the stud.
http://s467.photobucket.com/user/FirebirdGTAboy/media/IMAG0320.jpg.html
This guy had the same problem, my sweep looks best close to stock 7.2 length.
So looks like I have no choice but to grind a small portion away from the center of the rocker arm on the bottom.
Rockers I bought were some trws off eBay a guy never used.... now I know why, good thing they were cheap
Watch anything trw or knockoff of them. They can't handle hydraulic spring pressures.

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[BALLSS]

fullforce..

well its your car but IMHO if I had to take a grinder to valve train parts to get the to fit...not something I would do.

if you are going to do this, make sure there is enough material removed to clear the "pivot sweep" of the RR body.

I would even run...cough...Scorpion cheapo ones over those.

IMHO, valve train is not the place to cheap out on.

[fullforce]

I really want to buy the comp cams pro magnum stainless ones but its gonna be the middle of summer before I can get them. And belive me I would rather put the stock stamped rockers on there if they would work without overheating rather than using these....?
I seen something about the increased spring pressure will cause the stamped rockers to overheat??

[fullforce]

well it appears I have thrown away the box I put my stock rockers in already anyways... lol probably a good thing..
maybe the POS cheapos will last a few months

[SSlowBoat]

fullforce..

well its your car but IMHO if I had to take a grinder to valve train parts to get the to fit...not something I would do.

if you are going to do this, make sure there is enough material removed to clear the "pivot sweep" of the RR body.

I would even run...cough...Scorpion cheapo ones over those.

IMHO, valve train is not the place to cheap out on.
I haven't had any issues with scorpions myself. Have them currently on my new motor (sa) and nsa on Ltconvert 383. I think they'd be fine for his application.

I really want to buy the comp cams pro magnum stainless ones but its gonna be the middle of summer before I can get them. And belive me I would rather put the stock stamped rockers on there if they would work without overheating rather than using these....?
I seen something about the increased spring pressure will cause the stamped rockers to overheat??


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[fullforce]

Well once I get my pcm back from moe I'll see what happens...

[superspirit]

Well the pushrods do not appear to be the problem, the rocker body is to narrow to slide far enough down the stud.
http://s467.photobucket.com/user/FirebirdGTAboy/media/IMAG0320.jpg.html
This guy had the same problem, my sweep looks best close to stock 7.2 length.
So looks like I have no choice but to grind a small portion away from the center of the rocker arm on the bottom.
Rockers I bought were some trws off eBay a guy never used.... now I know why, good thing they were cheap

This is exactly what I thought was happening, thats why I asked you to post a pic.

[SSlowBoat]

I still have those 7.150's, I haven't forgot you, just been so busy fullforce

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[fullforce]

I still have those 7.150's, I haven't forgot you, just been so busy fullforce

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Thanks I'm trying to get it going for next weekend if you think you can get them shipped today or Monday, if not it's no big deal I'm gonna run my hardened stockers till I get the pro magnum rockers this summer