[Asphalt Jet]

I am currently sitting on a set of type B Poncams, and a timing belt kit, Poncams are supposed to be drop and go, however reshimming would be advisable.

My question is instead of doing all the required measuring of the gaps, which is time consuming and would no doubt become a pain in the a**, and then determining how much to shim the gap. Couldn't I just get some new factory spec tappets, springs and shims drop those in with the cams and just call it the day? Other than cost which is not a Factor, this should work correct. I have every thing to do the job my self including the monster torque wrench for the crank pulley bolt, picking up new tappets, springs and shims is literally a ride down the street. Am I missing something here?

 

[kismetcapitan]

in theory yes, but the gaps need to be very precise. You could just throw everything in, but when you go in with a feeler gauge I'll bet anything a couple of them will be off. Murphy's Law...

 

[GT-R Glenn]

Umm....
Im confused.
To replace the cams, it can be done with the engine inplace with the head on....
those cams should drop in and the clearances should be near as dam it to close enough.
But obviously you would check them...
To replace the springs is a head off job, so if you were going to do that then replace everything you have with new factory stuff, isnt that a bit ass about face ?
Once the head is off you might as well do the springs and then its pretty straightforward to set the clearances up perfectly ...

 

[bigkev]

i agree with glenn, if your happy to take the head off and replace springs and tappets etc. why not just reshim while your there?

are we to assume that you didnt think it was a head off job to replace springs?

either that or you dont have a feeler guage?

i also agree with toby, its probably best to check all gap sizes, sods law says even if you buy new factory spec parts they will still need shimming in.

kev-san:thumbsup:

 

[Autosaurus]

Tomei cams are ground from Nissan blanks and are usually pretty much bang on. However each engine will have slightly different clearances due to manufacturing tolerances, and over time possibly a bit of wear, which is why there are different sized shims available... In my experience they are usually so close to the recommended that it wasn't worth taking them all out to machine 0.01mm from a shim...

You can change them with the head on, I have changed valve stem seals without taking the head off. Sykes Pickavant make a tool for this, you just need a high pressure air supply to pressurise the cylinder and keep the valves seated so they don't drop... But as mentioned earlier it is probably easier and quicker to measure the clearances and alter any that are too far out...

 

[Asphalt Jet]

For some reason I thought the springs could be pulled out through the top, I hadn't really researched that, can't recall where I got that notion from. That being the case, I will regroup, going to the search button and looking up shimming the cams threads. Thanks for pointing out my error. Peace

 

[a2hox]

you can take valve springs out with the head on by filling the bore with compressed air from an air line i have done this myself so i know its possible just need a tool to bolt to head to push down the retainer and take collets out and the air holds the valves closed