HELP

[Howard Hull]

I have the 333 heads, rocker arm post milled down to except screw in rockers and McQuillin guide lates. I have Scorpion rockers. I have ARP 200-7201 screw in rocker studs. I have set the pushrod length by the mid cycle technique.
Now I only have about 4 to 5 threads of the poly lock holding.
The 354-7204 are 2.70 long, is the craze long, can I just cut them down to fit?
The base thread is also .850, and because of the McQuillen quide plates I have less than 1/2 threads down there also.
Or do you have a better pushrod stud # then those I have ?

2nd Question
I changed head gaskets to .040 thick from .065, now I only have .050" clearance on the exhaust valve to piston clearance. I have some witness marks on the exhaust ports at the piston relief from past valve float, should I go back up to .050 gaskets?
The piston is zero deck.

Thanks

 

[Ishiftem]

334-7202 is likely the stud you need. You really only need thread engagement to be equal to the stud diameter though of course more is better. You can cut down a stud but it has to be done in a mill. The to surface needs to be flat and perpendicular to the stud 100 percent or else the locks will loosen. You should have the exhaust vale pocket in the piston cut deeper. A clearance of .060 is too tight and a .065 gasket makes the quench way to big. Cutting the valve pocket is the only proper way. You could advance the cam and that will gain some p/v clearance on the exhaust but you will lose intake clearance. I would like to see .080 exhaust p/v unless experience with that combination says it could go a little tighter. Since a little too close will cause catastrophic failure, error on the cautious side.

 

[409]

Howard,

The 334-7202 as mentioned above works well.
.850 base -3/16 (.188) guide plate leaves plenty of stud on the bottom.

Carl

 

[La Hot Rods]

What Dan said is your best bet. ^^^

 

[Murphdog]

ARP website shows your 200-7201 stud as having 1.900 installed height.
235-7204 & 235-7207 are listed with 2.000 installed height. This will give you 2 more threads on top to grab.
334-7202 & 334-7203 are listed with 2.100 installed height. This will give you 4 more threads on top to grab.
Some of these have more than the .750 of thread on the lower end, which is what your current stud is listed as.
Rule of thumb is you want 1.5 times thread diameter minimum for best strength. .437 x 1.5 = .656 engagement.
You are close (.563) with your .750 length lower end after you take your 3/16 guide plate thickness out. The
part # Dan & Carl referred to (334-7202) will probably work best. It will give you .662 engagement on the bottom
& 4 more threads engagement on the top. Like Dan says you do not want a thicker head gasket. Your 0 deck clearance
and a .040 gasket are ideal. You need a deeper valve notch. Preferably .100-.120 for exhaust & .080-.100 for intake. You
can go tighter .08 & .06 but you better have GOOD springs and not over rev it/valve float. If push comes to shove &
real estate becomes an issue AND you checked piston to valve clearance with ZERO valve lash, you can add the lash
number to your current reading.
Jeff

 

[Howard Hull]

Sounds good, thanks, that is what I'll do.
Can the pistons be machined with rods on? or broken down completely, done in a mill or Isky PNT 216 piston notching cutting tool?

 

[Greg Reimer]

The cutting tool that goes through the valve guide and machines the pistons with the head on would be a good way to do it as long as you can assure some kind of uniformity of results.Some kind of positive stop would have to be created to limit the depth of the cut. After the piston and the valve train fit perfectly, the short block would have to be re balanced. Hopefully, you haven't had that done yet. That's why making eight identical cuts is absolutely necessary, then the rebalancing would remove a bit of weight from the crank counterweights to compensate for the metal taken off the pistons. Seems like within the wide wide world of engine building, something done one place always needs to be compensated for someplace else.

 

[Ishiftem]

I don’t believe balancing would be needed. Considering some balance assemblies 50 percent +- 2 percent, the 10 grams max the pistons would be lightened won’t make a difference.

 

[Howard Hull]

OK I have the 334-7202 studs , Will permatext be enough, or do I use permatex on the lower 1/2 and plastic sealer on top 1/2?

 

[Ishiftem]

Just permatex should be sufficient.