Input on power gains by swapping head.

[moelk]

True!

[AK260]

My Z is on a strict diet of pump RON 99 in the UK at $8 a gallon

[jonbill]

My Z is on a strict diet of pump RON 99 in the UK at $8 a gallon

Where do you even get 99 Ali? Mine is happy with 95.

[munters]

A side note.

Europe 98RON =94us (Ron+MON/2) and 95RON =91us.

[AK260]

Where do you even get 99 Ali? Mine is happy with 95.

Shell V-power Nitro, local garage

[moelk]

Question: Valves for my ”new” E88 EFI head  have 42mm intake and 35 exhaust valves. 

Intake valves will be swapped for bigger ones, but how big? 44, 45, 46mm?

What about the ex valves, keep the 35mm or go bigger?

Were to buy valves? Any recommendations/links to a good shop?

L28 + 1 mm, flattops (no valve cut outs) 535 lift cam.

[Zed Head]

Here's a good older thread about that.  Not much room past 44.

https://www.classiczcars.com/forums/topic/49057-l28-bigger-valves/

 

[moelk]

Here’s an E88 Efi Head with 46mm intake valves so it can be done. This head was/is on a 88mm bore L28. Don’t know if i really would need to go any bigger then 44mm. It’s not a race car i’m building but i don’t want to go to small either.

[jonbill]

Kameari sell larger valves. I'm sure many others do too, but I like Kameari stuff.
https://www.rhdjapan.com/search/engine/nissan_fairlady-z_s30-l28-10-1971-08-1975/model/nissan_fairlady-z/car/nissan/category/cylinder-head-and-valvetrain_valves

[madkaw]

IMHO - 44 for your engine size . If it was a bigger liter motor , or you were planning on spinning it way up high rpm , then maybe bigger valves . Can you go too big - I doubt it , so no time then the present to cover all the bases .

Quite sure you can buy valves from Rebello - and he would give some free advice since your buying ?

Edited December 13, 2018 by madkaw

[240260280]

I recall seeing ratios for exhaust  to intake ~67% for some reason.  I may have averaged racing head data in this book long ago:

[moelk]

Will go with these valves https://www.rhdjapan.com/kameari-l-type-lightweight-big-valves-set-in-45-ex-36-5-118-l6.html

What about valve guides?

I see two different sizes here, anyone like to explain why? https://www.rhdjapan.com/search/engine/nissan_fairlady-z_hs30-l24-10-1971-01-1974/model/nissan_fairlady-z/car/nissan/category/cylinder-head-and-valvetrain_valve-guides