Rocker shaft

[dave jenkins]

I started my RV8 on Friday without too many problems. It starts and ticks over just fine, however, during checks, removing each plug lead in turn and lintening for a change in engine note I noticed that removing No. 1 plug lead made no diference to engine at all.
A compression test revieled zero pressure.
I took the rocker cover off and started the engine only to be showered with a gush of oil, on checking I found that this was comming from under the rocker post. Reason being that the threads in the head were striped and the post would not tightened down.
I looks as if someone has tried to solve the problem using a non standard bolt and this looks to have made things worse.

The question is can this be repaired with something like a heli-coil. I've never used one myself, are they any good?

Could this be the cause of the zero compression or is there likely to be another problem.

Just when it all seemed to be going so well.

[beanpole]

Dave,

I had exactly the same problem , ie no pressure reading on the compression tester, mine was because the inlet rocker arm had broken, hence no pressure, ie the valve was not opening so could not 'suck' in air to compresse.

Bought a new rocker arm , fixed in 10 mins, this also helped to increase my oil pressure, (oil was pi**ing out from the hole normaly covered by the rocker arm.

I always thought mine was ticking over fine, but now I can tell the difference with all 8 firing.

I would have thought a helicoil will do the job, you can get the drill and helicoil kit from

http://www.namrick.co.uk/browse.asp?PCID=28

Best of luck..

Steve

[dave jenkins]

Nice on Steve.

Next question, can anyone tell me the correct bolt size, ie the bolt that holds the rocker post down?
Cheers,

[kirklillis]

Dave,

Rover manual says: 3/8"UNC, Torque 30lbft/40Nm

Kirk

[dave jenkins]

Many thanks, I'll be on the phone in the morning.
Cheers,

[mal]

you can buy correct bolts from rimmer brothers cost is negligable so replace `em all.

[osgood]

Contrary Mary

Dave as stated Helli Coil will be perfectly okay for the job in hand and is probably the cause of the low compression on that cylinder! Just check the shaft is not bent! I have a spare bolt or two if you need one. Reel Steel at West Drayton do the set of APR studs and nuts which in my opinion is a lot better Eric.

[dave jenkins]

Thanks all.
I ordered the bolts from Rimmer Bros. first thing this morning and an "O" ring for my new Mallory dissy. (can you believe you spend all that money and then you need to buy an "O" ring)?
I'm going to see if the new bolt will torque up before I spend £30 on the Helicoil kit as the bottom of the thread looks ok.
Point taken on the ARP studs, but as the rest of the motor is standard, all be it with a 500 Weber, I don't things will be too stressed.
I'll look to see if the shaft is bent, I never thought of that, though with the other bolts torqued up that certainly is a possibilty
Again thanks for all you help.
It's good to know that all the knowledge is out there.
Cheers,

[beanpole]

Dave,

If the shaft is bent, (mine was), it will have spread out where the bolt holes go through stopping you from sliding the posts off,(should you ever need to remove them). A new shaft cost me 15 quid, plus I needed a couple of posts as well as the rocker arm.


Steve

Good luck..

[dave jenkins]

As was pointed out to me, "your spending all that money building that car and you're worying about £30"

Helicoil kit bought and insert fitted, rocker shaft etc refitted, engine started.
Wow, that extra cylinder makes all the difference, starts at the touch of the key, revs and then ticks over with no popping or f#rting.
No knocks or rattles from the engine.
This realy is a quiet engine, unlike the Pinto in my last build.
All quite suprising as the dissy was almost "dropped" in and the 500 Weber is straight out the box with no adjustments at all.
Thanks all.
Oh happy me. -) -)