How much lift?

[haoleboy72]

I just picked up some TW heads and an XE270HR cam. My question is how much lift can I get before I need to start worrying about notching pictions, etc.? (totally stock bottom end) When I bought the heads they had 1.72rr which would give me about .550 lift, with 1.6rr lift would only be .512 which I should be able to run without any notching...right? All help appreciated.

 

[Maryland Stang]

The TW heads have a big intake valve and the 270 cam is relatively long duration. You may have problems even at .510 lift. There are others here who have a lot more experience than me with this but it would make me nervous. When I was looking at heads I wanted nothing bigger than a 1.94 intake valve so I could look at more cams.

 

[2002BLGT]

put it together and clay the piston to check the clearance you have and then decide , its worth the time to check it

 

[Grn92LX]

No problems with that cam. Lift has NOTHING to do with it. Like said above though, measure to be sure and to become familiar with how to do it.

 

[wicked84gt350]

lift only plays a small part in measuring for valae clearence if your pistons have no notches at all them you could as stated before you might have a problem at 500 lift because the trickflows have a different valve placement then the stock head but the main reason you measure for clearence is if the valves float because the piston will hit then because the valve timimg is changed.

 

[Mustang78]

saying lift has NOTHING to do with piston-to-valve clearance is crazy...check with clay or do another method, install the heads and on 1 cylinder, replace both valve springs with some soft ones(good luck finding a couple) of relatively the same diameter, put the piston at TDC and push on the valve stem by hand until it contacts the piston, you need to check this with a dial indicator. I can explain in more detail if you like but im off to bed, ask a machine shop they should know what to do

~Mark~

 

[haoleboy72]

just figured there's a lot of people running TW heads and somebody was bound to know if there is a valve to piston clearance problem...but if nobody knows for sure then I will probably either talk to the machine shop my heads are going to or use the clay method.

 

[black94gt50]

Every motor is different, check it and save yourself possible heartache.