Shorter rod to drop CR??

I was hoping to drop some compression and seeing how I was going to buy new rods, was thinking of using a shorter rod to get some compression out.

What is the furthest in the hole some guys drop the piston without hurting quench? I understand each combustion chamber is going to be different, but as a general rule of thumb… is there a “ point “ that you don’t cross. Ie .030


Wedge head, 4.5 bore with a small dome. .025 thou in the hole now, .005 deck (when it had a steel rod), and .020 for the alum rod growth.

Input?

 

How much compression are you trying to kill?

 

With the rod, maybe .3

I think ..020 in the hole more, was like .5 of a compression point, I dont have my calc on this puter.

 

why not use a little thicker head gasket? you can get just about what ever you want that way. just a thought

 

comp ratio

Change head gaskets, They are alot cheaper than rods, and you can change the tune-up when ever you want. Don

 

If this is a blown alcohol deal, than that is one thing. But on naturally aspirated deals, don't go over .025 in the hole. In fact, stay north of that. Detonation starts to take place on the corner of the block of that piston drops too low. Not a big deal on alcohol, but if this is a gas engine, I think you are about as low as I would want to see.
I like the head gasket talk. Seems way more wise.

 

Ok I have to ask.....what would be a maximum head gasket thickness you can run?
Blown alky.....

My deal is I have a ten bolt head not an 18 bolt head and I am worried about gasket thickness.

Block is O ringed. is .085 too thick?

 

When we ran a ten bolt head we found that the thicker gasket was stronger and did not distort as much.
We used the thickest one we could buy at the time .082
Try to get them to fit the bore the best so there is not a gap between the head and block.
Oringed the block with a matched reciver grove in the head.

 

I actually have a .125 gasket, but I wonder if that is TOO thick. I havent run it yet.

 

Its already a .060 MLS cometic gasket. 18 bolts. No problems with sealing, would hate to find out any thicker creates problems.

Any input on MLS maximum gasket thickness.

 

Man, run that combo would ya.

 

What 10 bolt head do you run ?......

I tend to think that quench is a non issue with blown alky. Gasket thickness should not matter all that much, provided the O-ring protrusion and receiver groove are sized proportionately (protrusion, depth, width, etc.). I would rather see the O-ring in a groove in the head, if the head is aluminum, and the receiver groove in the sleeve. That way the heads won't indent with repeated on/off service.

 

If you change a fair amount in head gasket thickness be sure
to double check for pushrod length.
Typically one knows where they want to be for compression ratio,
and knowing also they are able to lower or raise +/- the comp ratio with head gasket thickness without the rocker arm falling short,
or off the lash cap.

check with valve fully open and closed

 

not that I know anything but have been told to go no thicker than .080 because of "squirm" of the gasket. also no thinner than .030. as always its my .02cts. worth about that much. im actually now playing with comp ratio with my new engine. going with a rod length so I can run 11-1 and up to 12-1

 

Trick Flow early "A" wedge heads for big block Ford.

Its probably too late to put the oring in the head, its already in the block.

 

why? is it similar to yours?

I havent run that thick gasket. ( .125 ) I just have one because the fellow I bought the blower intake from was also running a big Block ford and he threw them in with it.

JS

 

Maximum gasket thickness ?
Remember, "I'm just a welder" but loving a good mystery and having no money to hurt things, before being a has been, I'd study a used gasket. Flip it over and measure the height of the "push" into the receiver groove. That's what is needed to seal. Compare the height of a .040-.050 to the height of a .080, then think about if you've got the guts to run it.

It costs nothing to think!

 

When we were fighting head gasket problems, blown BBC, Clark from Clark Copper Head Gaskets thought it was fine to run thick gaskets, .120" range. Supposedly at the time TF guys were doing it.

 

SoDak; that's just exactly my point ! T/F guys are doing it!
Those are the ones with the brite white/orange flames at the finishline! (not from the headers)

 

Was the cure going to a thinner gasket?