Solid Cam Lash Ajustment w/Self Aligning Rockers???
Thread Starter
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
Solid Cam Lash Ajustment w/Self Aligning Rockers???
I have a set of GMPP large port Vortec Bow Tie heads that I am using in a 409 SBC with a flat tappet, mechanical cam.
The questions I have are:
Do they make narrow feeler gauges to set valve lash on heads with 'self aligning' rockers? All the gauges I own or can find on-line or in shops are too wide to fit in between the self aligning 'rails'. Very frustrating. Any advice?
Also, can anyone give me a ballpark figure on what the difference in lash would be on a cold vs hot motor?
My motor is a cast iron block with cast iron heads and stamped rockers. Valve lash spec for my cam is .026/.028 hot. Everything says I need to adjust these hot but how the heck can I even start this thing up unless I can get it close enough to run and not break/bend anything?
I know these are probably silly questions but this is my first solid lifter motor and the last thing I want to do is trash something because I didn't know any better.
Any advice would be greatly appreciated!
Elm
The questions I have are:
Do they make narrow feeler gauges to set valve lash on heads with 'self aligning' rockers? All the gauges I own or can find on-line or in shops are too wide to fit in between the self aligning 'rails'. Very frustrating. Any advice?
Also, can anyone give me a ballpark figure on what the difference in lash would be on a cold vs hot motor?
My motor is a cast iron block with cast iron heads and stamped rockers. Valve lash spec for my cam is .026/.028 hot. Everything says I need to adjust these hot but how the heck can I even start this thing up unless I can get it close enough to run and not break/bend anything?
I know these are probably silly questions but this is my first solid lifter motor and the last thing I want to do is trash something because I didn't know any better.
Any advice would be greatly appreciated!
Elm
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
Use a wire guage for spark plug gapping. I think you should approach this job with care and set lash with engine cold (subtract 0.002" from lash specs for cold motor with Iron heads or 0.003-0.004" for Aluminum heads.) I know you are supposed to lash with hot motor but, I gave that up years ago and do well using cold engine method.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
It would seem like a self aligning rocker would be made for a hydraulic cam
that has the rocker always pushed up tight against the valve stem. will
the clearance on the rocker when the lifter is going around the base circle
of the cam cause a problem for the rocker alignment rails and give the rocker
a chance to work its way off the valve stem?? Never used a self aligning
rocker Im asumming the rails you speak of lap over the sides of the valve
stem to keep it aligned??
that has the rocker always pushed up tight against the valve stem. will
the clearance on the rocker when the lifter is going around the base circle
of the cam cause a problem for the rocker alignment rails and give the rocker
a chance to work its way off the valve stem?? Never used a self aligning
rocker Im asumming the rails you speak of lap over the sides of the valve
stem to keep it aligned??
Last edited by Little Mouse; Jan 4, 2007 at 05:22 AM.
Thread Starter
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
Thank you for the info!
I've thought about the potential of the rocker working off the rails with a solid cam myself but I can't find any documentation anywhere stating that they can't be used with a solid cam.
The documentaion I received from GMPP with the heads only stated that they should be used with self-aligning rockers- Nowhere do they indicate that a solid cam can't be used.
Any suggestions?
I've thought about the potential of the rocker working off the rails with a solid cam myself but I can't find any documentation anywhere stating that they can't be used with a solid cam.
The documentaion I received from GMPP with the heads only stated that they should be used with self-aligning rockers- Nowhere do they indicate that a solid cam can't be used.
Any suggestions?
Le Mans Master
Joined: Mar 2004
Posts: 7,499
Likes: 1,507
From: Little Rock AR
Never much liked the whole "guided tip" thing but lots of people use them every day.
-Mark.
Thread Starter
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
The big port Vortecs come with screw in studs but no guide plates. I could go that route if needed but since I already invested in the self-aligning rockers, I'd prefer not having to buy more hardware unless it's really neccessary.
Thanks!
Elm
Thanks!
Elm
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
self aligning rockers with a soild cam. crane cams phone#
386-258-6174
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Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
I would opt for the 70 LT1 heads and use with conventional long slot rockers instead of self aligning stuff. Thats a carry over from Fords 302`s ect. I would have to make sure the rocker is not pushing on the retainer or the keepers. Or, although I dont approve of roller stuff for the street, a set of [horror] roller rockers.
Thread Starter
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
You guys have me thinkin' now..
GMPP guide plates and studs are fairly cheap and with a set of stamped, long slot rockers (I'm not a big roller fan either) I'm out about $100-
Which is cheap insurance in my book.
Now the question: Stick with the standard 3/8" studs/rockers or go for the 7/16"?!
GMPP guide plates and studs are fairly cheap and with a set of stamped, long slot rockers (I'm not a big roller fan either) I'm out about $100-
Which is cheap insurance in my book.
Now the question: Stick with the standard 3/8" studs/rockers or go for the 7/16"?!
