Ksths2

iTrader: (1)

Hey guys,
Long story short I'm changing cams/springs in my LQ4 swap in a 54 Ford, I know the LQ4 has dish pistons and huge combustion chambers but this cam 231/237 .617/.607 112 has me wanting to check piston to valve clearance anyway. I don't think it'll even be close but I still want to check.

My question is, can I check PTV clearance without removing the heads? Before you say yes by putting a dial indicator on the valve and using low compression springs to test it, what about the lifters not being pumped up?On my race LS engine we've got lifters that I've welded up that we use to check PTV but obviously the heads have to come off to use them.

mchicia1

iTrader: (5)

The lifters won't collapse with the light checking spring.

VerdeZ28

This is correct. go to walmart and buy a toilet paper roll holder and take the spring out of it. its perfect for this purpose thats what I used to check ptv. only $0.97 lol

tashspop

so do you just randomly press the valve in throughout the rotation to check clearance if you're not removing head to see if there's spare room?

usdmholden

Awesome. I'll have to try this. Thanks.

redtan

iTrader: (5)

Put the cam in and spin the engine. If you hear a clunk, you don't have enough PTV. If you don't, you're good to go.

Better yet, use one of those little portable cameras at the end of a wire to put into the sparkplug hole and see how close the valves get to the piston going up.

Ksths2

iTrader: (1)

yeah i understand on the light springs they won't collapse but they have the main beehive spring tension on them now aka already collapsed, how would they get pumped back up? No the engine isn't able to run to pump them up.

I'll stick with my actual low tension springs from Comp but I like the toilet paper roll idea

mchicia1

iTrader: (5)

There is a spring in the lifter. Once you take the tension off, it springs back up.

BlackLS1Bird

iTrader: (2)

Rotate your piston to top dead center. Using a dial indicator on the top of the valve stem and a valve spring compressor, push the valve downward until it lightly contacts the piston. Record the distance measured by the dial indicator. Multiply your cam lobe lift by your rocker arm ratio. Subtract that total valve lift amount from the amount measured by the dial indicator. The difference is what you should have for clearance. If need be, remove the valve spring to avoid coil bind, and move the valve down by hand until it contacts the piston. Then do the math.
Or just talk to some of the vendors and ask if your setup will work, since most of them have seen just about every combo out there.

studderin

iTrader: (28)

ya as everyone says.

soild lifter is the best way, but then you have to take the head off. soo............

now you dont need a valve spring really, the seal will hold it up. you have to be carful for sure. But be smart about it and never put yourself in the postion the val;ve can drop. Just take the spring off with the piston near TDC, and dont turn a crank angle that the valve can fall down the guild far. the piston chases the valves on min PTV, you dont have to check it all 360* FYI,
the common window is in 10-20* on both, so you should be able to jam it out and get it done on a few holes fast.

Ksths2

iTrader: (1)

sounds good, thanks guys!

mchicia1

iTrader: (5)

I used feeler gauges under the rocker tip. I felt it was quicker. I didn't care about the exact number, I just wanted to know I had the recommended .060 int/.100 exhaust

I'm not very good at the dial indicator, it kept slipping off the retainer or moving slightly and skewing my readings.

Old Geezer

iTrader: (3)

Backing away from the bong, B4 making suggestions to help someone!