Piston to Valve confusion

[MikeUrban]

Hey all,
I have a bone stock 88 gt, and I'm in the process of getting the parts together for my little build. I already have the 96 explorer heads, intake, and throttle body, along with everything for my mass air conversion. I've run into an issue though, I don't understand how to figure out what cam I can use in it without buying a cam and doing the play-doh PTVC thing. Anybody running this setup know for sure what my limits are as far as cam profiles?

Thanks
Mike

 

[RangerJoe]

There is no sure way to know without checking with the actual cam, heads and pistons you are using. Most cam manufacturers will list whether or not their cams are designed to work with stock pistons or whether they require aftermarket pistons. I'm not real familiar, first hand, with the comp cams, but I know they have many that have been used with your combo to success. The E cam, TFS 1 and Anderson N41 should all clear stock pistons. Just remember, milling heads and thinner gaskets will all affect PTV clearance. I would find a cam that has specs which look good for your combo, then call the manufacturer and ask if it is designed for stock pistons.

Joe

 

[Chuckman]

a lot of people go with the tfs stage 1 or something similar with no issues.

 

[Bullitt347]

If you keep duration @.050 to 220 degrees or less, and if you keep your LSA @114 degrees or more, you could run over .700 lift if you wanted to with no piston to valve clearance issues at all, assuming the valve springs could handle that much lift. It is not how much lift the cam provides.....but WHEN (duration and LSA) it opens and closes the valve.

 

[Rick 91GT]

With that combo the TFS Stage 1 will work ok, or Id look at some of the smaller XE grinds from COMP. It depends on your valve springs and a few other factors...

 

[FordRacing302]

I'm kind of in the same situation...I have TFS 170's in the mail and was wondering if I could run the Comp XE270HR-12 on stock pistons, I would just hate to spend $280 on a cam and find out it doesn't work in my motor.

 

[Rick 91GT]

I'm kind of in the same situation...I have TFS 170's in the mail and was wondering if I could run the Comp XE270HR-12 on stock pistons, I would just hate to spend $280 on a cam and find out it doesn't work in my motor.

It "SHOULD" fit but youll have to check, the TFS arrangement will allow you to put a slightly larger duration cam in and still give you adequate clearance. Id personally go with something on a 114 LSA and a little less gross lift.

 

[MikeUrban]

So it's the pistons that limit you and not the head/piston combination? I think I'll just call up some of the manufacturers that I'm interested in and post back up what I find. Thanks!

 

[90lxcoupe]

So it's the pistons that limit you and not the head/piston combination? I think I'll just call up some of the manufacturers that I'm interested in and post back up what I find. Thanks!

not necessarily. when , where, and how much the cam opens and closes the valves is going to determine if there is interference. You can measure PTV without the plah doh method. We did it on my motor at the machine shop with a dial indicator on the retainer, and opened the valve by hand very carefully to see how much clearance i had.

 

[clement]

you need to check it, a cam can be cut off. however, if you degree the cam and the intake opens at TDC or a degree or 2 before you will be fine. same goes for exhaust. AFM N41 always seems to works well.

 

[MikeUrban]

I'm cutting so close on my budget now. I want a cam, valve springs, and long tubes/mid pipe. I can afford two haha.

 

[clement]

I'm cutting so close on my budget now. I want a cam, valve springs, and long tubes/mid pipe. I can afford two haha.

if that is the case and it were mine, i would put fresh lifters and valvesprings (valvesprings for a stock cam are cheap, check ebay. i got a set of PSI 570lb dual 1.55 springs used for $30) in it and buy headers. leave the stock cam in it.