7 replies to this topic

[babsbrown]

Good evening guys. 

 

I have an A+ 998 high compression flat top piston mini with stage 1.

I'm working on a 12g202 head to gain a little more bottom end torque (fingers crossed) .

 

I've been looking at a lot of Vizards material. 

 

I'm thinking of fitting the 30.86 valves from the 12g295 head, but if my estimations are correct it will mean deshrouding the combustion chamber around the valve In order for me to benefit from the enlarged valve. I will be skimming the head considerably to get the CR back up. I also intend the work on the short radius, throats, light porting and guide boss.

 

Has anyone done any similar in fitting the larger valves to the head? 

 

Cheers Babs

[DeadSquare]

Just put it all back together, with a minispares Evo 001 cam.

[stuart bowes]

following with interest because I also found cheap unmolested 202 head, also a 1100 crank which has been ground once, not exactly decided what way I'm going with it yet (currently totally standard A+ 998) but having the options there on the shelf at decent prices seemed like a good idea

 

I was thinking Evo cam but then someone mentioned the SW5 the other day and I started looking at the kit with vernier duplex and oil pump and it seemed to make sense

 

at this point all totally up in the air much more research first before spending proper money

Edited by stuart bowes, 07 January 2024 - 12:15 AM.

[timmy850]

I’ve got a fairly modified 202 head done by Russell Engineering in Australia. He uses the same size valves and similar port and chamber mods to these by Keith Calver. Valves are made by REC/Paul Ivey
31.75mm inlet
27.2 exhaust

https://www.calverst...re-60-and-over/

https://www.calverst.../cylinder-head/

[Bjarnetv]

I have a 202 head with 12g295 valves - didn't do the modifications myself though, so i have no real technical knowledge of how it was done.

will be fitting it to a 1098 i am currently building up with slightly higher comp Hepolite 16179 pistons and a piper 255 cam.

[Turbo Phil]

Yes you definitely need to deshroud the valve otherwise fitting the larger valve will be pointless.
I’ve a few videos on YT of a 295 I modified with bigger valves if it’s of any help.
https://youtube.com/...fit5puJCMmFI8oD

Phil.

[babsbrown]

Evening guys, thanks for your help. It's fantastic having a font of knowledge on this forum. I'll post the results on here, once it's done. 

[timmy850]

It’s also worth noting that if you go too big on the valve size and you have a standard bore there’s a possibility that the valve will hit the top of the bore at full lift.