flat tops vs valve lift

[360moparjunkie]

The 360 pistons we are using have no valve reliefs.

Is there a valve lift limitation in our case since there are no valve reliefs in the piston?

If so, what would be the largest allowable valve lift in this case so that cam choices are feesable or realistic.

Please advise.

Thanks a million.

 

[70aarcuda]

valve to piston clearance is not critial at max lift since the piston is down the bore aways...

v to p clearance is most critical during the overlap period of the camshaft...

exhaust closing/intake opening...it more like how much lift per degree of duration is happening....or howfast the valves are opening and closing in relationship to the piston moving....

you will need to know how far your pistons are down in the bore...what head gaskets are you going to use....

so what camshaft are you looking to use?

 

[360moparjunkie]

Thanks for such a fast response!

Pistons are down .1092 @ tdc

Head gasket measures .0475

Would like to run #20-600-4 comp. thumper cam
.486/.473 279/296 227/241 @.050

If this is even possible w/ the flats, I was looking at mopars p4120249 valve springs that are advertised .430-.500 lift range (1.497od / .206 wire dia.)
w/ factory type retainers.

Thanks again.

 

[360moparjunkie]

You 10.77 / 11.03 e.t.'s are impressive.
How much does it cost to go that fast?

 

[Babyblue66]

Just get new pistons that are not down so far and have valve reliefs. In the long run you'll be much happier.

 

[360moparjunkie]

If that is the case, is there brand, part # , source sugg.?
Which would be most cost effective.

Thanks.

BTY, actual static comp. calculation proved 8.472
good? mediocre? poor?
IMO, mediocre.

 

[Babyblue66]

If that is the case, is there brand, part # , source sugg.?
Which would be most cost effective.

Thanks.

BTY, actual static comp. calculation proved 8.472
good? mediocre? poor?
IMO, mediocre.

Not so good.

Kieth black 107 or speed pro 116, both have higher comp pistons.

 

[360moparjunkie]

I'll look into it.

Thanks bb66.

 

[Babyblue66]

http://www.summitracing.com/parts/TRW-8KH116CP30/

 

[moper]

With the flat top so far down you dont need to worry about piston to valve clearance until you get over .570 advertised lift. Way bigger than anything you'll be running anyway.

 

[Cudafever]

Just get new pistons that are not down so far and have valve reliefs. In the long run you'll be much happier.

x2!
That is some horrible quench!!!!! .100" down WOW!!!

Whats the compression ratio figure with them pistons......7.0:1???????????