This may be a question for pdq67, will I have any valve to piston clearance problems if I use the old 30/30 cam #346 in a stock flathead piston 327/300 hp with 2.02" intakes in the heads? I am concerned about the intake valve edge interferring at the piston eyebrow edge when fully opened. We both know thousanths do make a difference. I do not want to pull a head to clay a piston. This is a hastle with the engine in the chasis and the cold weather here in NJ. Thanks in advance.
Bill

this may be of help, but the 30/30 cam was the dz302 cam, correct?

if so, they used the cam with domed 11:1 comp pistons, i dont think you would have a problem with a flat piston

dont take my post as a fact though

You are correct, this cam was used in both the 327 /365 horse as well as in the 302. The valve relief in the forged 11 to 1 piston is very wide; compare this to the stock flat top with 4 valve reliefs and you will understand my concerns. The four reliefs are very small in dimensionwhen compared to the forged piston single relief. I too believe there should be no interference issues, but I would like to hear from someone that has already done this. before

Bill, I don't think you'll have a problem, but it's best to measure it. Lay a wad of silly putty on top of a piston and wrench her around.
Silly putty works good, it will stay stuck to the piston and won't come apart like clay. Snug the head with 2 or 3 bolts using an old gasket and have at it. Spray the valves and chamber with pam so the putty doesn't stick.

Note also that when the valves are fully opened, the piston is at the bottom of the bore.

P/V clearance problems happen around 20-30 degrees before or after TDC on overlap, when the piston is chasing the closing exhaust valve while the intake is opening down toward the rising piston.

Bill leave the heads on . put a set of checking springs on #1 cyl. put a dial indicator on the retainer roll the crank 10* at a time then push down on the valve very easy till it stops . read the indicator that will be your clearance. thats the only way I check. never had this not work. good luck Doug.

Bill leave the heads on . put a set of checking springs on #1 cyl. put a dial indicator on the retainer roll the crank 10* at a time then push down on the valve very easy till it stops . read the indicator that will be your clearance. thats the only way I check. never had this not work. good luck Doug.

I have known this to work every time. In this case I would say you will clear by over .100. Throw some rocks at me if I am incorrect.
I would be more worried about the condition of the valve springs.

My 350 has small chamber 202 fuelies , head and deck has been skimeed a few times with ACL flat tops giving a CR just under 11:1
The cam is a very high lift from memory .520
Heaps of clearance
I found as Jim says above clay
I used childrens play moulding clay
Dropped the heads on without gasket, not torqued down, and turned over by hand

thank you for the replies.
Bill

If I remember the duntov cam has under .500" lift. wont your standard flat top 4 valve relief piston clear at least that? I know my 333" with stock type 4 valve reliefs and 2.02/1.60's will clear with .500" and it's been decked and milled and so on.
Is it the valve timing on the 30/30 that makes piston to clearance problems or what?

Piston to Valve clearance is more affected by the installed position of the cam. The Valves are closest to the piston when the Intake is opening and the Exhaust is closing. Not at TDC. Valve lift for Street/Strip Cams are generally not really a factor but longer duration cams and over sized valves pose a greater risk. The Mfg’rs recommended ICL (Installed Center Line) position usually takes this into consideration for OEM Specked Engines, that is NOT decked or heads milled: however, depending on the profile you can may be able to gain Piston to Valve clearance by either advancing or retarding a particular profile 2 or 4 degrees. No matter what you do when playing with a performance valve train you always check the piston to valve clearance. You use plumbers putty or play dough as suggested when building an engine. You use a dial indicator with a set of pseudo springs when installing or changing the ICL of a cam in an built engine. Often a builder will advance or retard a cam for a various reasons – Dynamic Compression Ratio (DCR), whatever – and no one can say that a piston will not kiss a valve unless they have personally checked the engine using the above procedure. .080"/Int and .100"/Ext is considered safe; however, I know some push it to.060"/Int and .080"/Ext. This can happen if you change head gaskets from a .039' Composite to at .019" Steel Shim design so always check your Piston to Valve clearance if you want to gain that extra 1/2 Static Compression by installing a thinner Head Gasket unless you know that you have sufficient clearance from the time YOU last performed the measurement. Keep in mind that loose or worn timing chains can cause the Piston to Valve Clearance to change.