Twin cam Valve Guides.

PostPost by: rgh0 » Sat Jul 06, 2013 7:35 am

Johns cams springs and valves are a good way to go for his head. The challenge is keeping the full lift load down to an acceptable level. His springs are stiff and can produce a very high full lift load if you don't set them up carefully and keep the seat load as low as possible. Install height needs to be around 35mm for the spring itself to keep seat load around 60 lb and full lift load for a 0.5 inch lift cam to around 210 lbs. 35 mm can be a challenge to get in a lot of heads without deepening the pockets which you don't want to do with Johns ported heads as there is not much metal between the top of the inlet port and the bottom of the standard spring pocket.

For your push rod you may want to talk to Larner as locally they have built more racing pushrods than anyone.

cheers
Rohan
User avatar
rgh0
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 8425
Joined: 22 Sep 2003

PostPost by: SJ Lambert » Thu May 22, 2014 12:01 pm

Despite the Holden markings these blanks ought to do the job for the new push rod head!!

They're 214N on 9/32" stems.



Image

Image
Last edited by SJ Lambert on Tue May 27, 2014 9:49 pm, edited 1 time in total.
Ford Escort Mk1 Lotus Twin Cam
Elfin Monocoque (Twin Cam)
Elfin Type 300 (Holbay S65 - 120E) mechanic

[email protected]
User avatar
SJ Lambert
Fourth Gear
Fourth Gear
 
Posts: 681
Joined: 19 Nov 2010

PostPost by: SJ Lambert » Tue May 27, 2014 1:01 pm

Whilst chasing some Colsibro Guides to Cosworth MAE spec I discovered TROJAN as an even higher spec material!!!! - I'll be sticking with the Colsibro if I can get it!!


Colsibro

Is a copper-nickel-silicon alloy ideally suited for valve guides for internal combustion engines requiring high thermal conductivity, wear resistance and strength at varying engine temperatures.

Trojan

Is a copper-nickel-silicon alloy ideally suited for high performance valve guides for internal combustion engines requiring high thermal conductivity, wear resistance and improved mechanical properties over Colsibro.
Ford Escort Mk1 Lotus Twin Cam
Elfin Monocoque (Twin Cam)
Elfin Type 300 (Holbay S65 - 120E) mechanic

[email protected]
User avatar
SJ Lambert
Fourth Gear
Fourth Gear
 
Posts: 681
Joined: 19 Nov 2010

PostPost by: SJ Lambert » Wed Jun 04, 2014 11:13 am

Got some colsibro ones to suit 9/32" stems headed my way!
Ford Escort Mk1 Lotus Twin Cam
Elfin Monocoque (Twin Cam)
Elfin Type 300 (Holbay S65 - 120E) mechanic

[email protected]
User avatar
SJ Lambert
Fourth Gear
Fourth Gear
 
Posts: 681
Joined: 19 Nov 2010
Previous

Total Online:

Users browsing this forum: rgh0 and 27 guests