I have a 383 that appears to have been decked (no front pad numbers). I am running -5 dish pistons and just put .050 cut TFS heads on. I did not check PTV clearance. My cam is a roller with a .562 lift 108 lsa. Do you think I will have any PTV clearance issues?

 

Lift is not nearly as important as duration when it comes to PTV clearance (when the valve is at max lift the piston is nowhere near TDC).

But I can say with most certainty that you won't have a problem (assuming your duration is somewhere around 23x/24x?

 

Duration @ .050 is 240. Any other issues I should look out for? I wasn't expecting these heads to sit so tight.

 

It's much cheaper to check than it is to build a new motor.

 

Agreed. Can I get an accurate PTV clearance by using a hyd roller lifter and the model clay method? I've seen several threads about checking PTV clearance, some say use solid others don't say. What do you guys think?

 

I can agree with this statement however I can still say with absolute certainty you won't have a problem. I helped a friend of mine build a 252/262 .630/.640 107 LS LT1 with AI 200cc heads with the pistons .010" in the hole and he still had plenty of room.

 

Thanks RamAir. I don't think I have an issue either but I should have checked this BEFORE I put the motor together. I got lazy and kick myself in the ***, I know better than that. I assumed the parts were the same but the new heads apparently were cut more than the last set since the manifold didn't line up or the front accessory bracket holes. Pure neglect on my part. Stupid mistake and I am paying the price. I need to check this since its the right way of building a motor and I have to put this together correctly. I am with you though that it is not too tight and shouldn't have a PTV issue.

While I am there, I might as well check the quench. I've never done that before, can you provide a quick write-up on how to check it and how much is good/bad? Thanks again.

 

Quench on these motors is typically best around .032"-.035", IMO. You find it by adding your deck height + compressed gasket thickness. You don't want to run too tight because once the motor is warmed up and at full speed that distance will decrease tremendously and it is actually possible for the piston to contact the cylinder head. Too wide though and you start sacrificing power. A narrower quench will help to cool CC hot spots and will generally make more horsepower.

 

I check the deck height from the deck to the flat part of the piston, correct? It would seem like I could use a depth gauge (other end of my electronic caliper) on the edge of the cylinder wall. Will that work alright or should I use another method?

 

Yes - to the flat part of the piston. The easiest method that I know of is to use a straight-edge (key stock or something perfectly straight) laid across the cylinder then simply use a feeler gauge to check the distance.

Or you could pick up a deck bridge and a dial caliper if you like.

 

Checker springs on the intake and exhaust valve, setup a dial indicator on the valve retainer and move the crank in 5 decree increments from 15* before tdc, to 15* after tdc at the valve overlap point. Each time you stop at 10* BTDC, 5* BTDC, etc you push down on the valve and read the dial indicator to see what the clearance is.

You would need a solid lifter do do the clay method.

I don't set piston to head any closer than .035" minimum on an iron rod/iron block combo.

 

Thanks guys. I think I have enough now to be dangerous

I ordered a pair of lifters today to be used strickly as test lifters, also order checker springs to add to the arsenol.

The consensus seems to be same for quench.

Appreciate all of the help and input. I'll keep busy this weekend for sure.

Thanks again!

 

OK, I went ahead and checked the PTV and quench and want to know if these numbers sound like I did it correctly. I used the clay method with solid lifters that matched the hyd lifter uncompressed height from the tip of the pushrod cup to the tip of the roller. Set lash at 0 using the spin method.

Intake= .22
Exhaust= .19
Quench= .056 (.015 deck and .039 gasket)

Do these sound alright? I expected the PTV to be closer to .08/.10

Thanks guys.

 

Way too much quench (ideally, you'll want quench around .035").....and I don't think the engine's been decked, either.

Go with the thinnest gasket you can find (maybe a .025" gasket). It'll go a long way in improving your engine's performance.

KW

 

This is how I did it, and it's a piece of cake and a good confidence builder.