joshp14

iTrader: (5)

Just got done measuring pushrod length and PtV clearance on my AFR/F13 setup. (Just got my F13 replacement cam TODAY after my other one was eaten by the lifters). Anyway, the heads were shaved down to 62cc and I'm using a .040" cometic. I didnt have a caliper that big so I used the marks on the length checker. I finally got zero lash at 7.275" using the pushrod length checker after countless checks to get it just right.

For the lifter preload, here is what I received for info:

Thunder said .060-.070 w/Heads/Cam Cars and stock is .080-.090
Texas-Speed said .020 (they also recommended to use Lunati Specs)
Lunati said .030-.040
AFR said .100

I am running Lunati/Morel lifters so I think I'll run between .030 and .050 based on the info above. Based on that, here is what my preload will be with the available pushrod lengths:

7.300 - .025" preload
7.325 - .050" preload
7.350 - .075" preload
7.375 - .100" preload

So what would you go with, the 7.300 or the 7.325?

Also, my PtV meaurements were so sloppy I couldnt get a good measurement...from what I could tell they were around .065", which is ok according to Tony Mamo @ AFR...

PREDATOR-Z

do you want a longer lasting setup?
If so put a MLS gasket on and increase your PTV.
yes you'll change your quench but nothing that will make your car a poor performer.
With that 3.50s will work fine.

joshp14

iTrader: (5)

Well considering I already researched this, got lots of opinions from board members and AFR and other sponsors, bought the gaskets, coated them with copper spray, and bolted the heads down, been waiting for a month to get this back together...I think I will stick with what I have already. Also, I'm already running a MLS gasket and I want to keep my quench down. Thanks for the input...anyone else?

Patrick G

iTrader: (14)

I would err on the side of deeper plunger depth. The problem with running the hydraulic lifters too shallow is a loud valvetrain. I would not consider going smaller than a 7.325" pushrod.

My heads have been milled .034" and I'm running a .040" gasket. I have 7.400" pushrods. This gives me a touch over 1 turn pre-load. With the XE-R lobes, I had .105" preload and with LSK lobes I have .0825" pre-load using the 7.400" pushrods. I would assume that the base circle dimension of the F-13 to be somewhere between the XE-R 1.440" and the LSK 1.395".

PREDATOR-Z

Man, I think I know that Cometics are MLS.
But after all this research, didn't you come to the conclusion that running less than .080 PTV on a street setup in an M6, is well: risky.
You quoted Tony Mamo who builds some of the best thought of combos, why don't you ask him what were those little eyelashes he was surprised to find , when he tore down his 346/AFR/ 224,228 combo
I dunno, I guess I'm conservative but on the street, .080 and .100 are my margins.

joshp14

iTrader: (5)

....and MLS stands for Multi Layer Steel.....lol j/k.

I did find the .080/.100 rule but I was assured by Tony that I would be OK when using his rule of .065/.080. I rarely run the thing up past 6500, and it hits the track once MAYBE twice a year...I dont beat on it too much. Thanks for your input though.

PREDATOR-Z

I is gonna be wicked, that is for sure. Leave some $$$ for dyno tuning time.
Keep us posted how it goes.

Xtnct00WS6

iTrader: (8)

I’ll be doing this shortly, so I wanted to make sure I knew exactly how to do this.

The comp cams checker starts out at 6.800” and every complete turn and alignment of the white line equals .050 right?

I need to make sure the lifter is on the base circle of the cam and not on the lobe when measuring. So how do I do this? I think you can tell by where the piston is, but where would it need to be? I’m guessing it needs to be at Bottom Dead Center?

So let’s say I measure 7.275 at zero lash. I'll be going a bit more conservative than above so I think about .90 will be good for the street? I just need to add that desired preload to that measurement, which would be 7.275+.090=7.365 (~7.375)?

Thanks!

joshp14

iTrader: (5)

Yes, each turn is .050". I started at 7.200", installed and checked lash, then I movd up from there moving 1/4 turn each time. Make sure that the lobe you are measuring is on the base circle. I did this by installing a pushrod and hold your finger on it while rotating the crank and feel to make sure the valve isnt on the opening/closing part of the lobe...doesnt matter where the piston is. Yup, just add the desired preload to your pushrod length checker and round to the nearest PR size.

Xtnct00WS6

iTrader: (8)

As a general rule, is it better to be slightly longer or shorter on the PR length with stock lifters?

777

iTrader: (21)

I'd say longer if you want a quiet valvetrain.

SideStep

joshp14

iTrader: (5)

So you think .050" preload will be good with these lifters?

bigdsz

iTrader: (1)

All this preload discussion is fine , but no one has mentioned the rocker pattern on the valve stem tip. It obviously needs to be centered.