oztrack

I have a LS1 with Dart 225s and its using 0.040 gaskets and Morel Lifters.

I am using the Mamo cam - the 224 228 114 with XER lobes at the moment. But im considering going with something else a bit bigger eg the Trak cam?

Im wondering what i can slot in safely without having P to V issues. It is a heap of extra work taking a head off to check. Any suggestions for a good street/strip cam

The car has a 4200 Circle-D converter going in next week and has 4.11 diff gears already. Its PB so far is 11.32/119.8 at 3575lb with driver and a 1.53 60 footer.

oz304

you dont have to remove the head to check the p-v clearance
whats the pushrod length compared to the stocker when you ran the factory heads?
very fast car you got there.

oztrack

It has 7.35s and it has about 1.5 turns pre-load using YT 1.7s and the Dart Springs.

oz304

2 good aspects a/ theres provision for clearance via lifter preload.b/ you are running conservative ratio which can steer some advantage,do you remmember the stock pushrod length?

oztrack

I think its 7.385 someone might correct me.

The Alchemist

iTrader: (19)

How else do you measure then? I guess you could pull a plug and still a thing surgical camera into the plug hole and see how close the valve is to the piston (just kidding)

Do you put in a soft spring and slowly go past TDC and see how much valve drop you have with a gauge? Just curious because I'm wondering how much PtoV I have and realized that claying would be the only way to really tell.

oz304

the closest the valves meets the pistons is around 8 deg at the crank back +from tdc.i always use clay on solid cam engines
that is one reason why i loath using hydraulic lifters on a bigger cam engines you just cant measure it as pecise, none the less theres been a whole lot of budding racers out there that performed the flycutswith hydraulics and got away with it (some even on the gas!)
if one wants to verify p-v without the clay and assuming a cam has .330in lobe lift x 1.7 rocker ratio=.561lift at the valves
dummy fit your head with cardboard and nip up 4 corner headbolts so as dimensions are close as identical to original head gasket compressed dimensions as possible for new engines(good idea to research compressed heights if utilising other type of headgaskets. or for existing engines proceed and make sure the piston is at the highest point with dial indicator for new engine or piece of coathanger through the plug hole +go by feel (you can never take harmonic balance line marks for granted,good time too to check if the balancer timing marks line up,refference a new line if needed.next remove in +ex valve springs,pull up the valve as hard as you can and refference the tip height,then push it down till it touches the piston and note down the total
clearance.subtract .561in from the total amount and the remainder is your p-v
clearance,adjust accordingly to as much as you dare if needs be done, good idea to assume the cam a tad larger that the calculated lift because theres other variables like pushrod geometry too. so a tad of a buffer ontop of the min clearance wont go astray for this method or for more accurracy you can fit the rockers and pushrods and assume the preload as a buffer ontop of you p-v clearance.
if i opted for aftermarket heads i would ask the merchant how its dimensions compare to the factory head as i would ask the machinist
how much has been removed from the deck + face,then look into others combinations that run similar setups give a base idea,if your lucky your cam grinder may very well know this off hand.