has anyone stroked out a F-head?

I was on walcks4wd, and found the over sized pistons and rings.
I have always been told not to go past .60, but they have a .80 set, wondering what kind of reliability that may be, along with horse power.

 

I personally doubt it would be worth it, and I wouldn't bore cylinders any more than they absolutely need to clean up and fit the next size pistons. JMHO, YMMV.

 

Dont think it would be worth it myself.

 

Yeh probably not worth it. Just because you have more room to fit air does not mean you can get it in. The F-head just does not "flow" like a modern motor.

 

Stroke or bore? Methinks you mean "bored out."

The 134 is a really old design, and anchor heavy. Lots of iron in the block, so I'd expect you could go way past .080 if you wanted to. I expect the 80-over pistons are provided so that you can save those old blocks, not becasue that's the limit.

For an overbore, a lot depends on how well the original block casting was made, so-called core shift. Old engines will be heavier and thicker, but the casting quality was also lower. If the core was off-center at casting time, then the cylinder walls will have thin spots. A shop can sonic-check the bores to see what the thinnest spot is. With hi-po engine builders, it's common to pick and choose between blocks till they find one that can be bored out. The other possibility is to bore and then sleeve, but that would make the block way more expensive than than the engine is worth.

Re stroke, forget it. The 134 already has (IIRC) the longest stroke to displacement ratio of any widely produced passenger car engine.

Re the performance increase, you have two effects. The power will increase by the increase in displacement, roughly. For a stock bore of 3.125", that's about 141 cid or maybe 5%. You'll also raise the compression ratio by the increase in volume, which will increase power some (but certainly less than another 5%).

 

FWIW, when I rebuild my Fhead I'm going to see what I can do to the head as far as cleaning up the intake ports with a Dremel. See if I can smooth things up a little, but nothing drastic.

 

Dont polish the intake side, gasket match it.

 

I have a 134f with .60 over and a 134f .10 over NO notible difference, If anythng the .10 runs better. FWIW.

 

Good one Billy! R)

 

Am I missing something or are they that bad Billy?
But seriously when polishing the ports , always polish the exhaust as clean as you can get them, the intkae side just clean up any flaws and leave the rough surface and then match it to the gasket on both intake and exhaust.
The rough surface on the intake creates turbulence which causes the air/fuel to mix better.

 

This thing must have the intake cast as part of the head I'm guessing.
You guys and your antique tractor engines.

 

You got only one hole in................................................................R) "course if you want to play around under the valves that's your biz. For all of 70ish HP and a low RPM threshold I'd spend my time and $$ on a decent carb.

 

It would cost me about $500 to prove you wrong, but once I sliced that manifold from the head, studded it and made a gasket I think I could polish the intake and gasket match it.

 

Gotta love what works. Any 100 page threads on f-head tuning here? (no offense to the parties involved)