Thread: Checking tolerances

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I was trying to check piston to valve clearances with clay but the hydraulic roller lifters are not pressurized so I didn't get a good reading. How do I check this without have to buy solid rollers?
My engine is a 454 bored 60 over with stock rods and Speed Pro H693CP .210 domes. The deck only has .005" off to square.
The cam is a Comp Cam XR276 with .510 lift and roller lifters and 3/8" push rods and stock rockers. Installed straight up.
The heads are stock peanut ports 236 with Comp springs, retainers, and keepers to match cam.

Should I be concerned with this 'mild' build about piston to valve clearance?

Also, do you think the stock rockers will work without being 'long slot'?

go to the hardware and buy a very lite(weak) setup springs for intake and ex you will need to take off your intake and ex springs .then use the set up springs .all the time checking that you are not pushing the plunger down in the lifter . the wire size on the spring s i have for checking hyd lifter cams is about 030 thick or less just needs to hold the valve up no more....... 510 should go with out long slots but you can check from the under side of rocker slot to rocker stud with a paper clip bent out so you can slid it up there. it should have alot of room 510 is not bad put many together with 500 with stock rockers . check any ways its good thing to do

Originally Posted by 18436572

Also, do you think the stock rockers will work without being 'long slot'?

Use a piece of solder, then measure the clearance exactly with your dial calipers.

Originally Posted by techinspector1

Use a piece of solder, then measure the clearance exactly with your dial calipers.

i think the push rod will push the lifter plunger down before you dent the solder were if you can move a thick paper clip you have room your good to go

Is this an acceptable alternative?

With the engine at TDC, I have removed the valve springs and have a zip tie around the valve stem holding the valve in place. Measure stem height. Depress valve to touching piston and measure stem height. Subtract the two, add head gasket thickness and subtract cam's lift.

I know this doesn't take into account any manufacturing tolerances and rotational dynamics, but if I come up with 0.080 to 0.100" amount I should be ok. Right?

What should I expect as far as cranking cylinder pressure. I may check this prior to firing the engine.

Thanks for the advice!

p.s. How are you doing Pat? Back to 100%?

080 and 100 is fine .i am ok.. thanks

However the valves are closer to the pistons at about 10 degrees before and after tdc than they are at top

The lite springs and modeling clay are the way to go and it will also give you side clearance to the notch

Originally Posted by jerry clayton

However the valves are closer to the pistons at about 10 degrees before and after tdc than they are at top

The lite springs and modeling clay are the way to go and it will also give you side clearance to the notch

yep but i know guys that ran 500/500 marine cams but were on a 114or112 brain fade ? when take outs where $35 and never check any thing if the heads are not chop down or the intake valves are not setting on the deck of the head or he has stock intakes and not 2.250 intakes in thar ..... he should have alot of room thar s alot of or s in there.... i know but its not that hairy of a cam i think that cams on a110 with that cam. the marine cams were in stock flat top 454 with all stock gm parts and fit fine. i know guys that ran cams at 060 for PV room just keep out of valve float

I have ordered springs from an on-line hardware store McMaster-Carr and I will do it right with modeling clay. The idea I had about checking at TDC is all wrong because no #1 valves are open when #1 piston is at TDC. I have printed the cam spec sheet and will use it. This is not a radical build I am just being cautious.
Thanks for your responses.

Pat
I wasn't referring to any particular cam, just his method--

When I have had to correct valve/piston clearance issues, generally it wasn't because of total lift issues but the location of the notch, angle of the cut or issues around the valve od because of diameter

I have run valve/piston as close as .020but always tried to get more around the valve edge because if you do ever tap one and bend it slightly you need some comfort room

Another area not talked about is valve to valve interferance and cylinder wall prox

Originally Posted by jerry clayton

Pat
I wasn't referring to any particular cam, just his method--

When I have had to correct valve/piston clearance issues, generally it wasn't because of total lift issues but the location of the notch, angle of the cut or issues around the valve od because of diameter

I have run valve/piston as close as .020but always tried to get more around the valve edge because if you do ever tap one and bend it slightly you need some comfort room

Another area not talked about is valve to valve interferance and cylinder wall prox

yes jerry i know what you were talking about.i fly cut some pistons and i go 050 more on the od if i can get it.... i was just talking about the cam he had

Any snow up there Pat??

Originally Posted by jerry clayton

Any snow up there Pat??

snowing but not sticking .right now it raining ice/snow and some thunder cold and damp . some one needs to move a shop were its warm

Originally Posted by pat mccarthy

snowing but not sticking .right now it raining ice/snow and some thunder cold and damp . some one needs to move a shop were its warm

Better be south of me same here rain cold wind

I still don't have the springs yet but I was still messing around with this. With the intake off and the cam card I can watch the lifters move up and down. I turned the crank to where it said max lift for each valve and did the following check. I have a zip tie around the valve stem. I measure the valve stem height with the valve closed. I added valve lift and additional clearances and lowered the valve stem that much. Did not touch the piston. In fact I pushed down the valve stem some more and still did not touch the piston. So I think I am good. Do you agree?
Remembering what Jerry said about being really close around TDC I did the following:
I left the valves open and turned the crank slowly towards TDC. The piston did bump the valve a little around 20 degrees before TDC. I measured this height. Looking at the cam card showed the pistons only being open around 0.150". I had about 0.300" additional clearance. So I think I am good. Do you agree?
This is all until I get the test springs then I will do it with modeling clay.
Thanks for you time and responses.