Xu10j4rs valve to valve clearance

[jamie_1992 66 1 Cars]

I’m about to start checking the valve to valve clearance after fitting a pair of Newman ph4 cams 

dose anyone know what the “safe” tolerance would be for these? 

[welshpug 1,649]

do you have uprated valve springs and aftermarket pistons?

[jamie_1992 66 1 Cars]

1 minute ago, welshpug said:

do you have uprated valve springs and aftermarket pistons?

Yes 

[welshpug 1,649]

just realised you said valve to valve, if they're timed correctly  that should not be a concern.

[jamie_1992 66 1 Cars]

18 minutes ago, welshpug said:

just realised you said valve to valve, if they're timed correctly  that should not be a concern.

Sandy brown is going to map the car and has asked what the valve to valve clearance is 

I assume he needs to know when adjusting timing that there is no chance of v2v contact 

 

[petert 581]

Sandy has asked you a very difficult question. It's impossible to measure without having the head fully assembled and timed on the bench. With big valves and big cams you need to verify this figure through the full engine cycle. I use this jig below and set the timing where it needs to be and then wind it around. The generally accepted figure is 0.030" min.

 

The other pic is a fail, where I used Ø36.5 inlets and Ø30.0 exhausts with monster cams. If I had of used Ø35.5 inlets it would have worked. It becomes a case of you can't have your cake and eat it too. I had to use a smaller inlet cam to solve it.

 

Are you sure he didn't mean valve to piston clearance?

 

Edited 2 hours ago by petert

[jamie_1992 66 1 Cars]

I’ve got the head off currently and on the bench to do it, set up with some helper spring to make it easier to turn over 

It was a while back that I spoke with him about it but he said he can set the timing very accurately but needed to know v2v clearance 

I was going to make up a chart something similar to what I saw in an online video