924Board.org

MikeJinCO · Posted: Fri Mar 09, 2018 1:05 am Post subject: Valves?

Does anyone have a source for the intake and exhaust valves for a NA? I talked to SI Valves and the said haven't had the 9mm stem ones for a couple of years although in the 2016 catalog. They referred me to KPMI who make a lot of hot rod specialty parts particularly for bikes and UTV's and they haven't returned calls or emails. I can't go the the large valve setup.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

morghen · Joined: 21 Jan 2005 Posts: 8879 Location: Romania

Use whatever is available (thinner) and get custom valve guides, this is also a noticeable performance upgrade since more air will get into the engine as less volume is occupied by the valve.
_________________
https://www.the924.com

MikeJinCO · Posted: Fri Mar 09, 2018 3:21 am Post subject:

Morghen
Would like to go that way, found from SI catalog both BMW and Fiat 8mm valves guides with the same OD and close length, nothing in the 7mm tho. This is sort of an interim motor to get the car running and learn how to drive it. A lot of this is the learning curve for building a reasonably powerful, but reliable motor without spending $10-$15k with one of the 2 or 3 folks in this country who know what to do with this motor.

Today, I'm sending parts off to a local race car machinist who has done this type of thing before. His comment was that he has a 196-- Citroen running on Mitsubishi valves, so it should be doable.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

gegge · Joined: 27 Jul 2007 Posts: 1124 Location: Sweden

I used $25 6mm Ferrea valves from the Competition Plus series, long blanks. The spring was a Ferrea beehive made for Ford SOHC 24V. So was the reatiner.
_________________
Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

MikeJinCO · Posted: Mon Mar 12, 2018 3:16 am Post subject:

I checked into that setup and appears that both intake and exhaust will have to be made smaller, intake by 2mm and exhaust by 1mm. For valve guides I could only find rough 6mm blanks by SI that would have to be turned down to size and shortened. It would provide a much lighter valve train and also solve the problem I have found with NA motors with the valves wearing out on the valve guides. I'm going to look further into this scheme.

I have taken apart 4 NA heads and valve stem wear has been a problem with all of them. It is probably due to the motor sitting at an angle along with very heavy valves. With the last head I did I had a total of 10 or 11 intake valves to work with including 2 or 3 new ones. My stash is now 3 so out of 2 heads I got nmt 2 reusable valves. On the exhausts I had 16 valves and have 3 left, some of them were burned rather than worn out. The one 931 head I have the valves appear to be good.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)