Just trying to come up with a final ball park here... TFS 220 as cast heads (64cc) retain stock PTV.... had em milled down to 61cc.. (.006*3=0.018 removed) using a cometic .040 gasket so 0.018 + .010 = 0.028 or lets just say 0.030 less than stock height. cam is a 232/236 .600/.600 114 LSA +4 advance so an ICL of 110. I'm going to use clay to check but does anybody think I should have just stuck with the stock gasket height? Am I gonna see PTV issues? I've been searching everywhere no firm info car is a M6..... Thanks in advance for any help just trying to get everything finalized.

 

I was under the impression the TFS heads had a larger valve drop number due to the small change in valve angle. It will likely come down to the cam and the ramp rates. Not sure if you have the old MLS gasket, but I found if you remove one thin gasket layer or the stock GM MLS gasket you end up with a 0.040" gasket which will mimic the 0.040 Cometics so you don't have to use your new gasket. Also, you can then get an idea on how much the thick gasket will or won't help.

 

Larger valve drop number?

I assumed the lower valve angle number increased clearance. It almost sounds as if you're saying it decreases clearance.

 

I'm assuming thats what vettenuts means as in the valve drop increased there for creating more PTV, I've looked everywhere to try an find how much a TFS 220 head has, I believe a stock head has in the .2xx of vavle drop (including the .051 gasket) so I'm assuming it would be close to that then subtract the milling/cometic gasket ect. I think i'm going to be ok.

 

I think I read it wrong. The first time I read valve drop I pictured it as valve drop toward piston. I'm guessing that meant valve drop into the head.

 

I think you had it right, valve drop is towards the piston as in if there is more drop there is more space for the valve event to occur. like if the valve drops .2xx you have more space than if it only took .15x to reach the piston.

 

I think I keep reading this backwards. I just typed a response and now am posting the opposite.

Are we to be reading "higher valve drop" to mean more available lift before piston contact? Or is higher valve drop meaning the physical location of the valve in relevance to either the head or piston?

I'm also starting to answer my own question since the more upright valve in the TFS head should allow for more lift before piston contact.

 

Yes that sounds correct to me! I'm just trying to figure out the valve events with the cam profile within that range. I've seen some people on here do the calcualtion to show the percieved PTV clearence. There also semed to be some online calculators but I could not get any to work. Any how if anyone has a similar setup or experience please chime in!!

 

Probably ok but you have to measure

 

I really like the used head gasket idea and pulling a layer

 

Ill definatly consider the used gasket trick... if you just bolt one head on with no gasket and say torque to maybe around 10ftlbs measure PTV then add new gasket thickness after? Im sure either way unless you use a dial its not gonna be exact... but im guessing as long as i am in the .070 to .080 intake and .090 to .100 exhaust ill be good with a m6? Should i shoot for dead nuts min of .080/.100? Obviously a larger gap is acceptable but might want to change to an even thinner gasket at that point to tighten her up? Thanks for they advice yall!

 

Valve drop is measured with the head on a flat surface and the valve closed. Measurement it made when valve contact to the flat surface occurs. So yes, more valve drop would be more clearance with a given lift. I measured stock and AFR's at one time but can't find the numbers. You might call TFS and see if they can provide them.

It will likely be tight at best, I would degree the cam and also check PTV using a dial indicator and then clay. This will provide two measurements and this is one area you don't want to make a mistake.

 

No, the pistons come out of the hole around 0.007" average. You need a gasket to allow the piston to reach TDC. I also wouldn't go thinner than a 0.040" gasket (if that is what you are considering). Don't forget, the rods stretch at high RPM and will slightly change length with heat so the piston will get even closer than you are measuring statically on a cold motor.

 

Spoke with Brian Tooley Tech dept yesterday (they are working their magic on the heads) and they are telling me I should be good... obviously they said to double check but should be good with that set up. I apprecitate the comments and ideas..... hoping to put up some good numbers with these heads.

 

Here is another way of checking ptv clearance that imo is much easier then clay on the piston then pulling the head on and off trying to get a good reading.

https://ls1tech.com/forums/generatio...ve-method.html

 

just use an old head gasket but mic it first so you know what thickness it is.