I posted this on CF forum as well as part of my engine build thread, but I think this is the more engine technical of the two sites... just want to make sure I did everything right and I am ready to bolt my heads down, this is the process I used:

I used the clay method to check my PTV clearance. Overall it seemed to work and gave me a good visual of what was actually going on in there but there were a few things I didn't like about it. Measurements seemed inaccurate leaving you with merely a ball park of the distance of the pistons from the valves. Clay is a PITA and gets all over everything. Trying to make hydraulic lifters into solid lifters is a pain as well. I wound up having to weld them to get them to hold under the spring pressure.


I started by going to the local hobby store and purchasing clay. I don't frequent hobby stores. I was surprised to see no less than 50 types of clay on the shelf. I didn't know which one to choose so I started molesting the packages (sounds so dirty) to see which one would suit my needs best. This is what I chose,



I installed my now welded lifters in the bores, then I installed my new head gaskets. I balled up some modeling clay and flattened it out in my cylinder making sure it was not high enough that it was going to touch the top of the chamber, but not low enough that I wasn't going to get an accurate depiction. Picture shows a lot of clay. There is a learning curve to using this stuff. After a mess in a cylinder or two I removed and added enough that it made a great outline and didn't make a mess.

Unfortunately some of this stuff did get on the edges of the gasket which left me cleaning in between the 7 layers with a damp rag for nearly a 1/2 hour.



Next I ran some 10w-30 motor oil over the valves to keep them from sticking to the clay and I installed the head using 4 bolts placed in various locations. I torqued the bolts to 22 ft/lbs, just enough to compress the gaskets but not enough to damage them.



Next I dropped in my 7.400 Lunati push rods. I originally started messing with my adjustable pushrods as recommended by the machine shop but there is limited space and it was proving to be a pain. The 7.400s were just slightly too long but it really shouldn't mater anyway right? Because I set them properly to Zero lash INSTEAD of 22ft/lbs. It seemed easy to find zero lash with solid lifters. Just about the point where the bolt tightens up, the rocker no longer rocks, the push rod no longer spins, and the valve feels like its just about ready to come off the seat.



I know, the pictures suck

After the rockers were set at zero lash I slowly spun the motor over two times, removed the rockers, push rods, head bolts, heads, and this was what I was left with



First I took the back post on my micrometer and checked the clearance with that. You can see the two holes in the picture above. Next I dissected the clay into 3 sections. I tried to visually see where the clay looked the thinnest and that's where I made my cuts.
(Pictures were taken at various times)

Then I removed the slices VERY CAREFULLY and made as many measurements as I could to both slices (sides) of the intake and exhaust imprints. I took the lowest values.



These pictures are from the #1 Cylinder which I actually measured twice as the measurements i got the first time were not in line with any of the other measurements I got of the other cylinders. In the end the #1 cylinder turned out to be the one with the least amount of clearance. These are the photos:





And this is a RANDOM phone of one of the cylinders and how I CAREFULLY checked it



These are the values:

Cylinders INTAKE EXHAUST
1 .0970 .1380
2 .1400 .1655
3 .1385 .1615
4 .1470 .1940
5 .1425 .1705
6 .1200 .1355
7 .1505 .1725
8 .1335 .1400

When I rechecked cylinder #1 I came up with

1 .1275 .1330

keep in mind a complete valve job was done on these heads and they were milled .004.

How do the values and process look?

DG

 

Easier and more accurate in my book is to use a dial indicator without the gaskets. Remove as many known variables from your equation as you can. You know your gasket thickness so why risk messing it up putting it together, and taking it apart time and time again?

Try the dial indicator and compare that to what you got with clay and you will be surprised how different they are.

 

Also, did you factor in lifter preload to your measurments,?

 

?

I used solid lifters at zero lash

DG

 

Brain fart. Sorry.

 

I would be scared to put modeling clay in a cylinder, what if it gets into the rings?

 

I agree with the dial indicator, but recommend using an old/spare gasket. Many builds can't use no gasket because the piston is out of the hole by 0.010-0.015 and would smack the quench area of the head.

I've seen too many people welding lifters to make them solid.. It's just too easy to pop the lifter retainer, drop the body, and stack washers in place of the plunger spring to make a solid testing lifter.. Only takes one errant welding splat or heated swelled lifter body to score a lifter bore to be SOL..

 

Good advice,

That never crossed my mind. Unfortunately its too late. I tried to make sure any of the rough edges left by the welding were ground down before sliding the lifter in the bore, and they seemed to slide in the bore pretty easy. But In the future I will stack the washers,

Thanks,
DG

 

I think my results were suitable considering... however I would like to recheck using the dial indicator. Any threads outlining this process?

DG

 

I posted some pictures of my process in post #21 below

https://ls1tech.com/forums/generatio...lots-pics.html

its a simple concept, check the PtV at about 2-deg intervals from -25 to +25 TDC by pushing the valve down by hand. Secure a dial indicator to the retainer and measure the travel until the valve hits the piston. in my case I had to multiply the measured values by Cos(15) due to the valve angle. Also, you can use normal lifters with the checker springs, no need for solid lifters. good luck man

 

Thanks!

I am happy with the results. The bottom line is I am well over .100 on both intake and exhaust on all my cylinders. I am still going to do the process you mentioned above anyway just for fun and that additional security factor. However I think this really comes down to which site you are lurking on. If its an old school hot rod site, you better believe the preferred method is the clay method. This could be because the clearances tend to be larger and more manageable or as mentioned on most of the "hot rod" sites, there is no way to check the radial clearances without using the clay method. Looks like these guys like to visually see what is going on. I also read on more than one site another excuse for using the clay method, and I quote, "if it was good enough for Smokey Yunick, its good enough for me." Now if you hit the higher tech sites, and the Corvette Sites the dial indicator method seems to be the method of choice. I guess the bottom line is to be extra special sure, you should do both
DG