SELEXON'S NC29 Pre Modern Racer

[selexon]

Ahh... well that doesn't sound quite right then!

Might be worth checking that you have the correct pressure rad cap (and no damage) and that the thermostat has been removed (won't help when boiling over but will improve the water flow and prolong the boil over).

The thermostat has been removed by the previous owner and I tried two different rad caps and they both let the water through. So all things are pointing to the cylinder head unless I have overlooked something. Should have the head out tomorrow and off to the machinist.

[selexon]

So I took the head over the my machinist today to check it out and he rings me back after having a look at it and reckons its pretty much useless as where it needs to be welded its to close to the seat area and that there wont be enough material to machine off to get it correct with out messing up the cam gear mesh clearance. So I gotta find a new head now.

Whats the go with using a nc23 head are they better to use then a 29? or should I try and find a nice low road mileage 29 head and clean it up?

[uber pikey]

Selexon, that's bad news mate, I don't know which would be the best here but I imagine the original is what you would need. I will keep an eye out for one for you.

[Yakama]

Whats the go with using a nc23 head are they better to use then a 29? or should I try and find a nice low road mileage 29 head and clean it up?

See here re nc23 head on nc29

viewtopic.php?t=10034

[selexon]

Thanks for the link Yak.

I have found a good condition head from a roadie thats only done 10K. I will give the ports a lite lick and bolt it on.

Then it gives me the chance to try and salvage the old head and see what i can machine off it.

[selexon]

So after booking into a track day with a few customers, I had no time to organise the porting of the new head, so I machined .25mm of the head and it cleaned it up quite nicely.

Machining .25mm off means I am now using two old head gaskets that have been cleaned and sprayed with a good does off cooper sealant.

As you can see it still has a few marks around the water jacket holes but it has removed the suspect marks from the squish band.





I also got the rad serviced and they installed a new billet filler neck.

So hope this is the end of the over heating issues.

[selexon]

So all went well at the track day. After 30 odd laps the temp was sweet. didn't get over the half way mark on the std temp gauge. So the 2 head gasket trick has work...

At the end of the day the overflow bottle had about 50ml of water in it. Which I'm guessing is just the excess water that was over the rads happy operation level...

Next on the list is speaking to the guys at Carrillo and costing up some nice H-Beam rods and some forged HC pistons. * would anyone else be interested in these if they are a reasonable price vs performance ? *

[Yakama]

Next on the list is speaking to the guys at Carrillo and costing up some nice H-Beam rods and some forged HC pistons. * would anyone else be interested in these if they are a reasonable price vs performance ? *

I may be interested depending on price. Are keeping standard size of piston?

[CMSMJ1]

@ Selexon - have a crack with Mike Norman at G force - they had some rods made for the 30 - and some Cosworth Pistons...

We also tried to get some oversize pistons from Omega / Accralite - they were useless.

Let us know how you get on..and prices

[Variablevalves suck]

I think Mike had a couple of different conrods made tho im sure the pistons were a one off.
How come you went with two gaskets?