View Full Version : Valve always slightly open when cam fitted
therealnovaboy
01-02-14, 06:36 PM
I'm fitting an ast2 cam to a b+ head. I was trying to find full lift but found that the valve is never fully shut. I fitted the cam to the old head and the valve is open the same. I fitted the previous cam to both heads and found that the valves at always slightly open too.
Ive measured the cam carrier heights and they are all the same. I've measured the valve heights between the std and b+ head and they are the same. Also when the cam carrier is off the head all the valves are shut
so how is the valve open. The only thing I can think of is the hydraulic tappet isn't fully down, but I didn't think this was possible with zero oil pressure
Is it a cam designed for solid lifters maybe?
The ast2 is not a solid profile cam.
can you get a photo of all 4 cylinders with the cam fitted.
has someone skimmed the cam carrier down?
Be rare to have two skimmed carriers mowgli
And have you drained your lifters?
meritlover
02-02-14, 12:02 PM
you seem to have meausered everything and tried as many combinations of cam/carrier/head that would rule out any physical dimensional or cam differences, the only thing that remains is that the lifters are pumped up. Perhaps if you drain them or crank the cam over a few times to 'pump out' the excess oil? If you have a high lift cam on big valves would maybe not be a good idea to do this with the head built up on the block, incase you get some clearence issues. The links below show that this does happen, although the guy seems to have other issues.
http://www.honestjohn.co.uk/forum/post/index.htm?t=46739#m522259
http://www.honestjohn.co.uk/forum/post/index.htm?t=46739#m522265
the world can be such a scary place sometimes. O_o
Be rare to have two skimmed carriers mowgli
And have you drained your lifters?
I was banking on the OP having fitted the camshaft to a carrier, then tried it on 2 heads...
actually, I think the lifters are most likely
therealnovaboy
02-02-14, 06:30 PM
I've tried two carriers with two different cams on two different heads. Both the carriers are the same width. Both heads don't fully shut the valves. This points two being a tappet issue. They must be jacked up somehow, I've never had this problem before. It might be because I've never actually looked at a valve when the carrier is bolted down, and just never noticed. It maybe has always just sorted it's self when I crank it over.
ill have another look later and take a few pics. Pics always help
therealnovaboy
02-02-14, 10:30 PM
http://i1216.photobucket.com/albums/dd375/therealnovaboy/Mobile%20Uploads/6963B187-9D3F-4974-9B27-63235BEE09C0_zpsi5zkfvdu.jpg
http://i1216.photobucket.com/albums/dd375/therealnovaboy/Mobile%20Uploads/BF8C9D35-3028-4E60-9568-858F9C0C9760_zpsjvisrmlr.jpg
http://i1216.photobucket.com/albums/dd375/therealnovaboy/Mobile%20Uploads/C386A15E-C6F5-46F4-B51E-C7905670728B_zpsuqgcbogu.jpg
http://i1216.photobucket.com/albums/dd375/therealnovaboy/Mobile%20Uploads/1668B0E8-50E9-43DA-AC25-7888EFFAED56_zpsbcyosq0h.jpg
therealnovaboy
02-02-14, 10:38 PM
You can hardly make it out bit the valves rant fully shut. I had left the other can to the other head over night and it looked like the valves had gone fully shut. It must just take a a while for the spring to fully compress the tappet. I'll leave it over night and hopefully there isn't a problem.
meritlover
02-02-14, 10:41 PM
Why did you pour red wine on the tappets?
therealnovaboy
02-02-14, 10:43 PM
It makes them taste nicer.
I always drink rink red wine and listen to classical music when building nova engines.
E window for them being shut is very very very small....and gets shorter with wilder cams.
I always drain the lifters when rebuilding a head. I have had cars refuse to start if I didnt.
That'll be your problem
therealnovaboy
03-02-14, 05:59 PM
Looks like it's fixed. All the valves shut.
meritlover
03-02-14, 06:06 PM
Im glad to here it. I will remember to pour wine on them the next time.
Looks like it's fixed. All the valves shut.
So what was it?
therealnovaboy
03-02-14, 09:54 PM
So what was it?
just took a while for the spring to fully compress the hydraulic tappets. They squeezed all the oil out when I left it over night.
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