Bad cam news
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Jun 2003
Posts: 1,876
Likes: 1
From: Mount Dora, Fla
Bad cam news I've got AS 5.3L heads, 11/1 CR CC978 springs. Currrntly have a TR 224/224.563.563 112+4. I'm getting ready to install a CC 228/230 XER and have been worried about coil bind because I have only .047 clearance. Terry at Racetech has very nicely made me up some new reatiners to resolve that problem, that is if they ever get here.
Anyway, today I checked my valve drop at TDC and it was .177 not too bad since I have 2.04 valves. Then I checked my P/V clearance at 8-12* ATDC, how about only .035, SCARY. I checked it three times.I used a soft spring and a dial indicator, and made sure the rocker was set at 0 lash and that the valve was not slightly depressed.
I have a CC adjustable timing chain I'm wondering if my timing could be too far advanced since when I dynoed the engine with the TR224 peaked at 5,700 RPM. If I am too far advanced wouldn't that make the P/V alot closer.
Anyone have any other ideas, I'm really afraid to put in the new bigger cam with these tolerances. HELP!!!!
Anyway, today I checked my valve drop at TDC and it was .177 not too bad since I have 2.04 valves. Then I checked my P/V clearance at 8-12* ATDC, how about only .035, SCARY. I checked it three times.I used a soft spring and a dial indicator, and made sure the rocker was set at 0 lash and that the valve was not slightly depressed.
I have a CC adjustable timing chain I'm wondering if my timing could be too far advanced since when I dynoed the engine with the TR224 peaked at 5,700 RPM. If I am too far advanced wouldn't that make the P/V alot closer.
Anyone have any other ideas, I'm really afraid to put in the new bigger cam with these tolerances. HELP!!!!
That's why I stayed with 2.02"s on the 5.3 heads with an F14 cam. The valve drop alone on a 5.3 is .030"
I wanted 2.05" valves badly, but not with a big cam, high compression stock piston LS1.
You going to lok at flycutting?
I wanted 2.05" valves badly, but not with a big cam, high compression stock piston LS1.
You going to lok at flycutting?
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Jun 2003
Posts: 1,876
Likes: 1
From: Mount Dora, Fla
I am going to fly cut, probably .040 possibly .050 just to be safe or if I decide to go bigger at a later time. My earlier measurements were in error I measured about another 20 times and came up with ~.055. Setting the rocker at 0 lash with a soft spring introduces a lot of error.
Excuse my ignorance but what does it mean when you set the rocker at zero lash and how do you do so? I've also heard that you should use solid lifters to do the measuring. Is that absolutely neccessary? Thanks.
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Jun 2003
Posts: 1,876
Likes: 1
From: Mount Dora, Fla
Zero lash means that your rocker arm is making contact with the end of the valve stem but not to the point where there is significant pressure. It is particularly critical when using a soft spring. When your normal valve spring is installed zero lash is the point at which you can still turn the push rod between your thumb and index finger but bearily.
Is there a writeup somewhere on how to check p/v clearence. I haven't been able to find one. I have the comp cams kit with the wheel, soft springs and caliper. How do I check the clearence if the spring is holding it up?
