I have a TR224 and stock pushrods/lifters/rockers on stock, unmilled LS6 heads. If the base circle on TR's cams is .030 smaller than stock, does that mean my valves are only opening .532 instead of .562? Are the heads, in a sense, too far from the cam not allowing the valves to lift all the way, or do the hydraulic lifters make up for this? Just something I thought about last night while I was laying in bed

 

If the base circle on the 224 is .030 smaller its only .015 shorter because you only count one side of the cam, tho hydralic lifter should take care of that.

 

someone correct me if i'm wrong, but i believe stock pushrods are 7.380" long. most aftermarket pushrods are .020" longer than this at 7.400". with the base circle making the lobe .015" further, the longer pushrod should actually make the preload .005" more than stock.

 

base circle doesn't affect lobe lift..so it doesn't affect valve lift. I'm pretty sure that the thunder cam is .060" smaller on the base circle and .030" smaller on the radius

 

Running a smaller base circle with hydraulic lifters does not change valve lift. It reduces the lifter preload. The lifters compensate for the smaller base circle.

My 98 cam's base circle was 1.552 diameter. My 224 cam is 1.480 approximately. That's .036 longer push rod required to load the lifters to stock loading. I am running my stock pushrods and getting lifter/rocker noise.

My factory push rods are 7.400. Not 7.380, but mine is a 98. The new years might be 7.380. I would run a longer push rod if they made one .030 longer but I don't want to run .050 longer and get too much preload. So I live with the noise.

 

So can anyone confirm if base circle is based on radius or diameter?

 

(Unaffiliated Racing) works for Comp Cams, so I think he knows what he`s talking about. Nice Vortech lids by the way Brian.

 

Ok thanks.

So if I milled my heads .030 the valvetrain should have perfect geometry, correct?

 

No. You said the base circle on your new cam is .030 smaller than your factory cam. You would need .015 longer push rods to equal factory preload. The base circle is the diameter each lobe would be if it did not have the lobe.

Factory cam base circle minus new cam base circle divided by 2.

 

sshhhhhh!..lol..thanks....If it's a Comp cam..which it is..it should be about .060" smaller base circle.. .030" difference

 

So a .030 milling would be perfect, right?