problem with tapping from rocker arm
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Joined: Aug 2000
Posts: 67
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From: Hilton Head south carolina
problem with tapping from rocker arm
On my 81 vette I just put a new motor in it a pretty high lift cam and 1.6 roller tip rockers.Wellone stud in the head seems to be pulling out of the head.I have no idea what to try.
Le Mans Master
Joined: Jul 1999
Posts: 9,206
Likes: 17
From: Sewell NJ
Re: problem with tapping from rocker arm (81vetteman)
If you have a high lift cam and 1.6 rockers you should be using screw in studs. The press in studs tend to pull out under these circumstances. You may end up haaving to pull the heads and send them to a machine shop to have the studs pulled , the holes taped and screw in studs mounted. Sorry for the bad news.
Melting Slicks
Joined: Aug 2001
Posts: 2,833
Likes: 15
From: Southeast La
Re: problem with tapping from rocker arm (vettfixr)
If you have a high lift cam and 1.6 rockers you should be using screw in studs. The press in studs tend to pull out under these circumstances. You may end up haaving to pull the heads and send them to a machine shop to have the studs pulled , the holes taped and screw in studs mounted. Sorry for the bad news.
Drifting
Joined: Jul 2001
Posts: 1,418
Likes: 1
Re: problem with tapping from rocker arm (81vetteman)
You can if you have to put grease around the area to catch the metal and drill the boss to pin it with a Mr Gasket pin kit.The others will probably pull though eventually making this really not worthwhile.In old days have seen them beat back in on the side of the road and peened with punch to get home.
Was the springs checked for coil bind at that lift with the 1.6 rockers?That will pull the studs.
This is the very thing that makes the iron Vortecs not such a good deal when you consider the price of upgrading them.Screw in stud machining,valve spring upgrade, center bolt valve covers or adapters and still wind up with a light duty,thin deck head prone to cracking.
[Modified by mountainmotor, 9:11 AM 3/1/2002]
Was the springs checked for coil bind at that lift with the 1.6 rockers?That will pull the studs.
This is the very thing that makes the iron Vortecs not such a good deal when you consider the price of upgrading them.Screw in stud machining,valve spring upgrade, center bolt valve covers or adapters and still wind up with a light duty,thin deck head prone to cracking.
[Modified by mountainmotor, 9:11 AM 3/1/2002]
Le Mans Master
Joined: Sep 2000
Posts: 9,078
Likes: 7
From: DFW TX
Cruise-In VII Veteran
St. Jude Donor '07
Re: problem with tapping from rocker arm (mountainmotor)
I think your going to have to pull them and have them tapped. Before you do it, check for coil bind. If you are using stock coils then upgrade to stiffer Manelys.
Drifting
Joined: Mar 2001
Posts: 1,396
Likes: 6
From: Indiana
Re: problem with tapping from rocker arm
Also keep in mind that the bosses must be machined down for the standard screw in stud. There is also screw in studs that are straight with no shoulder/flange and resemble the pressed in ones. It is possible to tap the heads and install this type while on the car. BUT, I have done this for other motors when one or two pull out, but for all of them, I would pull the heads and do it right.
Tom
Tom
Burning Brakes
Joined: Dec 2000
Posts: 1,183
Likes: 2
From: Des Moines Iowa
Re: problem with tapping from rocker arm (tsw71)
Tom's right, you could just do the repair with head on engine for the one stud, however it's likely that others may pull out later. You could just repair this one, then change over to 1.5 rockers, whiich will put less stress on the pressed in studs, until you have time and $ to pull the heads and have them machined and drilled to install screw in studs the preferred way.
If you perform the single stud repair with head still installed, take all precautions possible to catch/vacuum all of the metal filings/shavings from performing this job.
If you perform the single stud repair with head still installed, take all precautions possible to catch/vacuum all of the metal filings/shavings from performing this job.
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: problem with tapping from rocker arm (81vetteman)
It is possible that 1.6 rockers can cause a clearence problem where the pushrod passes through the head. This can mess up the geometery pretty bad. Some machining may be needed there. Also, what type of rockers are they and what type of rocker nuts are you using? The stock style crimp nuts have a tendancy to back off causing valve tapping. A good set of polylock rocker nuts can solve this problem.
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