From: Kristian Jonsson
Date: Fri, 22 Jan 1999 08:18:45 +0100
Subject: [imps] Re: Head and valves
But very expensive ?? And you to make the groove in the head right!?
But then any head gasket problem are gone forever. Is it an 'overdo' for a standard HP Imp
Kristian J
Date: Fri, 22 Jan 1999 09:07:27 +0000
From: Andrew W. MacFadyen
Subject: [imps] Re: Head and valves
Not really practical for a small bore engine as I don't think the special smaller wills rings which were at one time available for standard cylinder liner are made anymore. But for 998+ engines it is a complete cure even if the engine gets really roasted they will seal when it cools down again.
Andy
From: Impmann@aol.com
Date: Fri, 22 Jan 1999 04:36:23 EST
Subject: [imps] Re: Head and valves
Hi Kristian & Andy,
To add to what Andy has said, you can't use Wills Rings on an 875 safely, as they cut into the top of the cylinder liner on these engines.
On an 875, the tops of the liners are soft alloy (with the cast in steel insert). On a 998 or 1040 these liners are steel. Therefore, if you try to compress a metal ring between the head and the liner, the ring will not compress - the liner will.
A few tuners tried wills rings on the standard bore (mainly 900cc+ engines by Melvyn Adams - I've had a couple of those) and eventually they develop problems, that just cannot be solved (apart from relinering to 998 - but the wills rings grooves in the head are then the wrong diameter).
Nope, wills rings for 998+ ONLY.
Cheers,
Tim
Date: Fri, 22 Jan 1999 14:25:02 +0000
From: Andrew W. MacFadyen
Subject: [imps] Re: Head and valves
Once again You CAN safeley use Wills Rings on an 850/875 BUT special Wills rings these were used by Hartwell amongs others to produce 850cc class shortened stroke race engines to take on Minis racing in the 850 cc class. If you look up a Hartwell parts list from the mid seventies you will see the spec for the 850 race engine.
Andy M
From: Kristian Jonsson
Date: Fri, 22 Jan 1999 15:44:25 +0100
Subject: [imps] Re: Head and valves
So..... but they are probably not avaiable today, and what about the soft alloy area where they are going to rest, as mentioned below.
Kristian jonsson
From: Impmann@aol.com
Date: Fri, 22 Jan 1999 13:12:51 EST
Subject: [imps] Re: Head and valves
Andy,
I agree that they were available........
It's just that they weren't any good for road engines. They were developed for 850 short stroke screamers, which if they lasted two races they were doing well...
Ray Payne (and George Bevan for that matter) have said to me never to use Wills Rings on any engine that does not have steel liner, as you are asking for trouble.
You also have to ask yourself the question why they are no longer available.......
Cheers,
Tim
From: Richard Owen
Date: Sat, 23 Jan 1999 06:08:28 -0000
Subject: [imps] Re: Head and valves
On the subject of Wills rings used on 875cc short stroke engines [850cc].
Would i be wrong in assuming, that the alloy on top of the 875 liners is removed when the block is shortened .
Revealing the tops of the steel 875 liners?
A couple of months ago i asked,
"Is it possible to use 998 Wills rings on a 930 motor ?"
Nick Cleak replied,
> it's ideal if they rest on Steel liners rather than the standard 930
> alloy , but i have been running them on my 930 for 40000 miles so far
>If the engine is not highly modified , a normal gasket would be ok
Its just that i have a new 930 short motor and a Wills ringed Chesman head; [off my 998] ported + chambered but with sport size valves [not yet measured, but look like they are ], along with an R17 cam.
Is the alloy above the liners on a new 930 block, any thicker than that on a never skimmed 875 block ? Or a harder alloy maybe ? So, should i or should'nt i ?
The compression ratio may work out to low anyway.
Whatever i use the head on, its going to need welding between plugs 2+3.
Assuming the face of the head is now flat, will it remain so after welding?
Cheers
Richard
From: Nickcleak@aol.com
Date: Sat, 23 Jan 1999 04:36:02 EST
Subject: [imps] Re: Head and valves
> if you try to
> compress a metal ring between the head and the liner, the ring will not
> compress - the liner will.
That's what i thought too , however my 930 has done 40000 miles so far on wills rings and also my friend has a similar set up and doing fine . We took the head off his recently to fit some valve seals and there was no evidence of marked liners ..
It's still not recommended though ..
Nick ...
From: Nickcleak@aol.com
Date: Sat, 23 Jan 1999 05:47:31 EST
Subject: [imps] Re: Head and valves.
> is the alloy on top of the 875 liners
> removed when the block is shortened .
> Revealing the tops of the steel 875 liners?
No, the liners are very thin about 2 mm thick with no flange on the top. They have a sort of course screw thread on the outside to anchor them to the alloy. They are actually put in the mould and the alloy cast around them ..
> i have a new 930 short motor and a Wills ringed Chesman head;
Can you use a normal gasket ? where will the wills ring grooves sit on it ?
Maybe the grooves would nip the gasket in just the right place if you were lucky ..
But as the Imp head isn't doweled it can move around slightly so care needed ...
> Assuming the face of the head is now flat, will it remain so after welding?
It's likely to need facing again . however perhaps not if it is welded whilst bolted to the block ... only the local area will get hot then ...
Nick ...
Date: Sat, 23 Jan 1999 12:22:42 +0000
From: Andrew W. MacFadyen
Subject: [imps] Re: Head and valves.
Can't be very much needs machined off the block without doing the sums I would guess about 80 thou/2 mm