Has anyone fitted larger valves to their K series engine, if so what engine were they from? I have done a bit of searching but not come across anything as a direct replacement. I'm thinking going from 36mm std to 38mm should help with top end.

Most people do the datsun A15 valve upgrade which are 37mm intake, and 30 mm exhaust. So 1mm oversize on both sides. 

They are different stem length to the k series, but I am told if you have adjustable rocker gear and a reground cam, it all works out.

You can alse get L series datsun valves. There is a 38mm which seemed to be a much better matching stem height when I looked into it.

http://www.swmotorsport.com.au/index.php?cPath=9_20

 

 

 

 

 

Edited May 21, 20179 yr by 7000rpm

22 hours ago, 7000rpm said:

Most people do the datsun A15 valve upgrade which are 37mm intake, and 30 mm exhaust. So 1mm oversize on both sides. 

They are different stem length to the k series, but I am told if you have adjustable rocker gear and a reground cam, it all works out.

You can alse get L series datsun valves. There is a 38mm which seemed to be a much better matching stem height when I looked into it.

http://www.swmotorsport.com.au/index.php?cPath=9_20

Thanks for the info!

 I know I can go 1mm over using the factory valves seats but i'm wondering if its worth fitting new valve seats and going up to the 38mm, I haven't played with bigger valves before so not sure how much difference 37-38mm would make. Any ideas?  

22 hours ago, 7000rpm said:

 

 

 

 

 

 

Haven't seen any back to back results to compare.

Out of interest, what other mods have been done to your engine?

I have used a15 valves In my 5k you need to use blue 202 valve springs datsan colets and a12 pushrods and 3k adjustable rocker gear  and you have to make 3mm spacer to space up the rocker gear

You have to get the seat recut to suit the valves and porting the head will also help with flow You have to trim the rocker gear adjustment screw 

 

Edited May 22, 20179 yr by joshua.mathews
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Great info mate, given me a good idea. How much have you shaved the head? comp ratio?

 

Edited May 22, 20179 yr by megamannz123

37 minutes ago, 7000rpm said:

Haven't seen any back to back results to compare.

Out of interest, what other mods have been done to your engine?

40thou over, 10:1 comp, twin 40mm Dellortos, light flywheel, electronic ignition, ported head, double valve springs, big cam, extractors, rebuild.

Sounds like a nice build 

Glad there are a few k series builds happening out there

 

1 hour ago, megamannz123 said:

Great info mate, given me a good idea. How much have you shaved the head? comp ratio?

 

If you read my 5k build post it tell everything i did

 

I didnt take much off the 3kb head as I'm running a zero deck height and machined the 0 dish pistons down to a near flat top

Edited May 22, 20179 yr by joshua.mathews