Piston valve clearance

[DirtyDogs446]

So I have a hemi predstor 212 It is milled .40 and ported I got 1.2 ratio rockers the ones with the adjuster on the opposite end of cap. I got standard push rods and stainless valve kit all instructed by arc racing also 26 lb valve springs. Will the valve springs fit properly also do you believe I will have any valve to piston clearance issues? Thank you everyone for all your help

 

[ol'joe]

From your description, almost impossible for most folks to tell.

If I were you, even if I got some answers, I would want to check the fit in the real world, so I would assemble the whole rig right down to tightening the bolts to proper torque, but before buttoning it up I would roll out a layer of modeling clay and put it on top of the piston. With the whole thing ready to crank up, I would turn the engine over a few times with the starter rope, then take it back apart and get a really good sense of how far the valves would miss the piston. If the thickness of the clay between the valve and piston is to little to assure you of enough clearance, you need to start over.

Do NOT forget that at high speed the clearance will almost certainly be less, NOT MORE, and you only get one chance to save all of those expensive parts to fight another day.

Wishing you the best of good fortune in your experiment.....Joe

 

[DirtyDogs446]

From your description, almost impossible for most folks to tell.

If I were you, even if I got some answers, I would want to check the fit in the real world, so I would assemble the whole rig right down to tightening the bolts to proper torque, but before buttoning it up I would roll out a layer of modeling clay and put it on top of the piston. With the whole thing ready to crank up, I would turn the engine over a few times with the starter rope, then take it back apart and get a really good sense of how far the valves would miss the piston. If the thickness of the clay between the valve and piston is to little to assure you of enough clearance, you need to start over.

Do NOT forget that at high speed the clearance will almost certainly be less, NOT MORE, and you only get one chance to save all of those expensive parts to fight another day.

Wishing you the best of good fortune in your experiment.....Joe

That was exactly what I was looking for thank your for the response. So say you want .50 and your at .40 can you just get a gasket .10 larger then the one your using and that would work I'm not sure on these things

 

[landuse]

From your description, almost impossible for most folks to tell.

If I were you, even if I got some answers, I would want to check the fit in the real world, so I would assemble the whole rig right down to tightening the bolts to proper torque, but before buttoning it up I would roll out a layer of modeling clay and put it on top of the piston. With the whole thing ready to crank up, I would turn the engine over a few times with the starter rope, then take it back apart and get a really good sense of how far the valves would miss the piston. If the thickness of the clay between the valve and piston is to little to assure you of enough clearance, you need to start over.

Do NOT forget that at high speed the clearance will almost certainly be less, NOT MORE, and you only get one chance to save all of those expensive parts to fight another day.

Wishing you the best of good fortune in your experiment.....Joe

Good advice right there

 

[Brianator]

Good advice right there

Darn tootin'! Lol

 

[Whitetrashrocker]

When claying an engine. Don't just yank on the rope.

Leave the sparkplugs out and roll the engine over slowly by hand using the flywheel.

This way if you do have interference you can feel it and stop before any damage happens.

There no feel and stopping short when you yank the rope.

 

[KartFab]

dont forget spark plug to piston clearance too. You can check that with a little bit of math and a striaght edge over the mating surface of the head with the head off.

I had a head milled .030 and the spark plug was protruding into the piston if turned too far one way or the other. just FYI.

 

[anickode]

Some fresh Play-Doh works better than clay IMO. It's much softer but will still hold its shape. It's just a little easier to squish as you turn it is all.

 

[ol'joe]

All excellent points....I tend to forget about the "gently" part once I get to running my mouth... …..Joe

 

[DirtyDogs446]

All excellent points....I tend to forget about the "gently" part once I get to running my mouth... …..Joe

So doni measure play doh maybe with feeler gauges or what is the best way

 

[Whitetrashrocker]

See where the valves pressed the clay?
Take a razorblade and cut it vertically where the valves came closest to the piston. Then use your calipers to measure the thickness.

 

[DirtyDogs446]

Sé where the valves pressed the clay?
Take a razorblade and cut it vertically where the valves came closest to the piston. Then use your calipers to measure the thickness.

Thank you everyone for all your advice and helpful tips got her going before the new head and rockers and springs and what not it was going 34 mph top speed now I got it to 43 then let off. Good improvement I would say I'm hearing an odd noise now almost a ticking noise coming from near the head but I'm not sure it's hard to hear it but it's there Watch Tapping sound
https://vimeo.com/418170087

 

[DirtyDogs446]

Pushrods

I wonder if the pushrods are too long because this head is milled 40 thousandths of a inch and I'm using a. 09 gasket. Would too long pushrods make noise

 

[Whitetrashrocker]

Check for coil bind.

You don't want the coils on the springs to get close. It might be ok at a hand turn. But at several thousand rippums the will touch and make a noise.

 

[ol'joe]

"rippums".... …..Joe

 

[DirtyDogs446]

Check for coil bind.

You don't want the coils on the springs to get close. It might be ok at a hand turn. But at several thousand rippums the will touch and make a noise.

How do you check for it can you take valve cover off while its running?

 

[Brianator]

This is a good question! It's not a pressurized oil system so splatter should be minimal but theres always the risk of a projectile.... maybe it's possible to make a cover out of plexiglas and film it at 60fps (minimum) to spot something? Honestly though I think paint as I suggested in your other thread would either prove or debunk it much quicker and cheaper.

 

[Whitetrashrocker]

Valve cover off and roll engine to where the valve is fully open and spring compressed. Then use feeler gauges.

 

[DirtyDogs446]

Ty all for the help means alot that there is people here to turn to for help

 

[madtom]

I just installed 1.2 ratio rockers from arc and they're site says to use 5.26 height pushrods, stock are 5.54. Also you need to clearance the valve cover for the rockers as well ( could be the tapping noise). I'm using the thinner metal gasket and the 5.26 rods are perfect. Also using the s.s valve kit with 26 lb springs. CM grind cam
I see you milled the head and are using a thin gasket so your rods are definitely too long .

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