Long Reach Plugs in P6 Heads

Robrover · Post by **Robrover** » Tue Oct 16, 2007 4:14 am

Can the long reach plugs as used on all post 1976 RV8s be put into the earlier P6B heads? Are there any damaging or advantageous consequences, like

- hits pistons at TDC?
- reduces swirling in the combustion chamber?
- raises the compression ratio by intruding more into the chamber?
- puts the spark more into the centre of the chamber?

Post by **katanaman** » Tue Oct 16, 2007 8:47 am

I thought they had a different thread as well but basically don't do it. For the sake of a few quid go buy the proper plugs and then you cant have any problems.

jrv8 · Post by **jrv8** » Tue Oct 16, 2007 9:50 am

Hi,
The threads are the same and they won't hit the pistons.........But don't fit them.
The BIG problem is that because the end of the thread protrudes into the cylinder, it gets carboned up, making it almost imposible to unscrew them, without damaging the thread in the head.

Jim

ChrisJC · Post by **ChrisJC** » Tue Oct 16, 2007 2:56 pm

You could remove the redundant part of the thread.....

Chris.

jrv8 · Post by **jrv8** » Tue Oct 16, 2007 9:20 pm

ChrisJC wrote:You could remove the redundant part of the thread.....

Chris.

Chris , would it not be easier just to fit the correct plug ?
Jim

stevieturbo · Post by **stevieturbo** » Tue Oct 16, 2007 11:35 pm

ChrisJC wrote:You could remove the redundant part of the thread.....

Chris.

If you were to grind off these threads, you would risk polluting the plug with metal from grinding.

You would also need to ensure the thread is clean afterwards, so it doesnt damage the Alu head when you screw it in.

Much easier just to use the correct plugs.

ChrisJC · Post by **ChrisJC** » Wed Oct 17, 2007 8:29 am

jrv8 wrote:
Chris , would it not be easier just to fit the correct plug ?
Jim

It would, but there might be a tradeoff to be had if some of the possible benefits listed by the OP turned out to be real, which I think was the reason why he asked.

Chris.