1997 3.0LX rocker studs

jhobbs26

Cadet
Joined
Jul 6, 2015
Messages
18
I bought the boat last June, it had sat for 4 years. Everything pretty much ran good except it had a tick. Pulled the valve cover and noticed the #3 intake rocker arm stud had started to pull out of the head. I pulled the head off, took it to my machine shop and had all new screw in studs installed on all 8 valves. Used the boat the rest of the summer with no problems.

First time out memorial weekend and cruising along at 3700rpm and the #4 exhaust rocker arm stud broke. Not sure why, possible just a bad stud (not ARP). Anyway I put in a new stud and planning on taking it back out this coming weekend.

I was talking to a buddy of mine who has a 4.3L boat and he said he carries spare studs in his because he's broke a few too.

Is this a problem with these boats? This is my first boat, baby the heck out of it on the lake. No tubes or ski's pretty much just cruise around the lake with it at the same speed etc.

I'm in the process of upgrading the rocker studs to 7/16" to prevent this from probably ever happening again. I've got the studs left over from my dirt track racing days, just need to acquire BBC rocker arms. Hard to find just 8 of them, don't need/want full set of 16.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Where are the studs breaking? If they appear grooved where the rocker arm pivots then there is a geometry problem. Hydraulic lifters adjusted too tight would bend push rods before breaking the studs but bent push rods can cause a geometry problem.
 

jhobbs26

Cadet
Joined
Jul 6, 2015
Messages
18
No grooves, just a clean break, that's why I think it might have just been a defective cheap stud. I know what to look for as far as the geometry goes and it all looks good.
 

Fishermark

Vice Admiral
Joined
Oct 19, 2003
Messages
5,617
I would go with a defective stud as well. These engines are not known to have issues with the rocker studs.
 
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