valve/ piston clearance?

[Superelbert]

Hi guys!

I have a '71 318 engine in to which i plan to install a new cam and 1.6 ratio lifters. The max lift @ the exhaust valve will be around .450". Is this cool with the standard flat top 8,75 com pistons, or is there a risk of clearance issues here?

Looking forward to any answers!

 

[ramcharger]

Is the .450 advertised lift? If it is, it is based on a 1.5 ratio. Get the lobe lift specs and multiply by 1.6, this should give you the true lift at the valve. You most likely won't have to worry about P/V clearance, but I would definitely check your retainer to valve guide clearance. Do it with a solid lifter!

 

[Superelbert]

Good point!

The ,450" lift is the resultant lift with 1.6 ratio lifters.

Well, from what you're saying I guess i should be fairly safe.
I'll remember to look at the retainer/guide clearance!
Frankly, I thought that valve/ piston clearance was more of an issue, but then again, assumption is the brother of all F...-ups!

Thank's for your answer!

 

[dusterdon]

Any time you change rockers, valve sizes, cam, or even just change cam timing you should check piston to valve clearance. .090 minimum. Be sure, not sorry.

don