Piston to Valve confusion

MikeUrban

Member

May 30, 2010

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Chantilly, VA

Feb 17, 2013

#1

• Feb 17, 2013

• #1

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

I leave the horn on while driving

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Feb 17, 2013

#2

• Feb 17, 2013

• #2

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

GTFO you fat, heavy bastard

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Feb 17, 2013

#3

• Feb 17, 2013

• #3

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

 

Bullitt347

I have been doing it wrong this whole time

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Feb 17, 2013

#4

• Feb 17, 2013

• #4

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.

 

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Rick 91GT

Mustang Master

Nov 29, 1999

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Feb 17, 2013

#5

• Feb 17, 2013

• #5

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

5 Year Member

Oct 1, 2005

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Feb 17, 2013

#6

• Feb 17, 2013

• #6

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

Mustang Master

Nov 29, 1999

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Feb 17, 2013

#7

• Feb 17, 2013

• #7

FordRacing302 said:

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.

Click to expand...

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

Member

May 30, 2010

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Chantilly, VA

Feb 18, 2013

#8

• Feb 18, 2013

• #8

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

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Oct 7, 2003

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Feb 18, 2013

#9

• Feb 18, 2013

• #9

MikeUrban said:

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!

Click to expand...

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.

 

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clement

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Oak Cliff

Feb 18, 2013

#10

• Feb 18, 2013

• #10

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

Member

May 30, 2010

187

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19

Chantilly, VA

Feb 19, 2013

#11

• Feb 19, 2013

• #11

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

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Feb 20, 2013

#12

• Feb 20, 2013

• #12

MikeUrban said:

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.

Click to expand...

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.

 

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