[markham]

My question is I have a sbf 418, 14.1 compression afr 225 and my piston to valve on the exhaust side is .100 and the intake is .060 do u thank that the intake side will be alright. the motor will never see over 7400 rpm thanks for any information.

 

[EHA Racing]

I wouldnt risk it. Not worth the damage.

 

[SGHITR]

.060 on the intake is plenty i've ran them much tighter than that.

 

[blackwell82]

i would make both at least .100 IMO!! Thats what i did with my set up (740hp 400sbc NA)

 

[dfree383]

it will live, just keep up on the valve springs and check them often.

 

[blackwell82]

Dfree383- Thats a very good bit of info to keep in mind

 

[Warp Speed]

With the proper radial clearance, .06 is plenty on the intake side. If your stuff is out of control enough for the valve to chase that piston down, you have already blown up!

 

[frdboy]

Plenty of room, run it!

 

[flyin ryan]

You've got lots of room, but with that said you haven't said anything about what your doing for valve springs either...

 

[Uncle Paul]

Remember the golden rule:
The piston chases the closing exhaust valve and the opening intake valve chases the piston.

 

[E.R. Racing]

Plenty for the intake. As said, intake valve chases the piston.

 

[388Monte]

Rule of thumb for p to v clearance we go by is . . .

Intake - Total Quench plus .020 - so if your using a .040 gasket + .020 will give you .060. That is plently enough.

.100 on the exh. is plently enough also.

 

[JShelton]

plenty of clearance..run it. as said before here check your valve lash and springs in the garage at home before every race day or weekend! just good practice!

 

[scott foxwell]

Run it.

 

[scott foxwell]

With the proper radial clearance, .06 is plenty on the intake side. If your stuff is out of control enough for the valve to chase that piston down, you have already blown up!

Can an intake actually hit a piston if it clears during mock-up? How early on a lobe can a lifter start "lofting"?
I've heard some guys say they run .010 on the intake.
Any input?

 

[rustang]

Running .095" I recently bent six of my exhaust valves. Did it on the motor's first pass. This happened after the motor made repeated engine dyno runs to 7800. I had the chip set for 8200.

This is probably not typical because this cam has a crazy profile (flat tappet)

So be careful!

 

[stix818]

it will live, just keep up on the valve springs and check them often.

I agree.. As mentioned before, the exhaust is typically the one you need to worry about.. Check seat pressure regularly.. Should be good.. We run .100" on EX with no issues.. Motor turning 8400.. If your worried about it you could get a thicker head gasket, just a thought..

 

[markham]

Thanks everybody for the information I didn't think about the intake valve chasing the intake valve but your right. thanks again.

 

[markham]

Thanks everybody for the information I didnt thank about the intake valve chasing the piston you guys are right. Thanks again.

 

[Ron Clevenger]

Can an intake actually hit a piston if it clears during mock-up? How early on a lobe can a lifter start "lofting"?
I've heard some guys say they run .010 on the intake.
Any input?

Scott, I've run as little as .010 on the intake successfully. I always check it with a dial indicator and clay both for they will give you different reads.
Under running condition it actually opens up to a little more clearance as everything twisting to retard the cam.

Pro Stock engines actually set it up with a couple of thousands interference between intake valve and piston. Not a good idea for us bracket racers.

Blessings.........R