need advice...I'm changing things on the motor....

may have found a cam....

Ok...I think I may have found a cam....let me know what you guys think about it...

.644 Int .644 Exh 258 Int 270 exh 110 deg.

I could manipulate the lift a little bit with some 1.72 rockers that i have so I was thinking about running a 1.6 on the Intake and a 1.72 on the exhaust....

remember that this is a nitrous cam so it's bigger than if I was just running on motor....

 

What deck hieght are you running and what rods? Clearance problems would dictate this cams choice among other things.

 

it's a standard 8.2 deck height with a 5.315" rod....

is it piston to valve clearance that you are concerned about??

 

Steve,

I'd be careful about creating a spring beater. A 1.72 rocker will put your lift at near .700. That extra .050 valve lift may dictate a different spring. It will be very important to keep on top of your spring pressures as valve float will b the quickest way to self destruction. I know that I am preaching to the choir but, along with valve to piston clearance, make sure you check for coil bind and retainer to guide interference. Obviously, you are more likely to encounter issues in these areas.

I don't know too much about NOS cams but is it necessary to increase the exhaust lift when there is a 12 degree spread between intake and exhaust? I don't know, just curious.

Good luck with it. Hope it all works out as planned.

P.S. - Why not keep driving it on the street after you make the changes?

 

Well, I took the insurance off of it due to an excessive speeding/racing ticket that I got back in May. I went ahead and ordered the cam that I listed in the earlier post so I guess I'll see how it does... I'm switching to 1.6 rockers so my lift will be at .644....I don't want to go much higher then that....the open pressure is 550 and seat pressure is 200....does this sound like enough?? I went ahead and got the Titanium retainers.....

A guy at Coast High Performance told me that I couldn't mill my heads enough to obtain the 12.0:1 compression that I want....what's you guys opinion on this?? I thought you could mill the heads enough but I'm not sure of the dynamics involved, I just figured that I may end up having to fly cut the pistons more, but they already have some massive valve releifs so I guess i'll find out when I check piston to valve clearance!! Since I"m at 10.5:1 with the 60 cc head what do you guys think I should mill the heads to to obtain a good ratio with the bigger cam?? Alot of this is unexplored territory for me so any help is appreciated!!!!!!

 

I'm do not like the idea of milling an aluminum head unless it is necessary. Assuming the cam and pistons are not going to change, it sounds like you have no alternative other than milling the heads and running thin head gaskets (which is out since it seems that you plan to use copper gaskets). I would look toward milling them to get the highest possible compression without compromising the strength of the head (anticipate having to mill the intake as well). Did CHP tell you how much compression you could gain by milling the heads?

As for spring pressure, I am sure it's safe as long as you do not turn the motor highr than the cam manufacturer's rcommendation. The higher you turn it, the more spring pressure you need. I always like a little extra pressure on sold rollers to compensate for spring fatigue and extra protection from valve float.

 

Also, one other thing: You will more than likely need longer valves to accomodate the higher spring installed height. Make sure you get valves that can handle the abuse.

BTW - Titanium retainers are a must with solid rollers IMO.