Will I have problems with this head?

[Maui Cruiser]

It's a '73 F motor, and it has domed pistons. The head I got to put on has a different shape to the combustion chamber than the one I took off. The new one is smaller and oval shaped as opposed to the old one that is rounder and deeper.
Will this even work? Anybody ever done this swap?

Pictures on post #4

 

[Poser]

Ummmm....

 

[pbgbottle]

Nice! great pic Poser

 

[Maui Cruiser]

Yeah, yeah, yeah...here's the pics

I'm an idiot.
Domed piston first, old head, then newer head last.

 

[Maui Cruiser]

About the domed pistons

Are they assymetrical? It looks like the center of the dome is slightly to the passenger side of the motor. Perhaps this would help it clear the valves... I hope.

 

[SD_rdcruzer]

From another thread

If you have dome pistons you should have a 61031 cast into the top of the head.

https://forum.ih8mud.com/40-55-series-tech/286726-cruiser-gods-punishing-me.html

 

[Maui Cruiser]

I've seen the pistons for '73-'74 referred to as having "slight dome". Pre-'73 was flat top piston with a "bathtub" style chamber on the head. The head I want to use is a '68-'69 from what I remember. I'm thinking later on the 2F went with a larger domed piston, and I was thinking that was what that post was referring to with the 61031 cast number.

My current head is cast with a 60050 (open chamber), the one I want to use is a 60031 (bathtub/closed chamber). Hopefully this means something to someone, and I can find out if this works without lifting that heavy sucker up there in place!

 

[SD_rdcruzer]

Here are some links from the FAQ page.

And from Mark W

Pre '68 F engines used siamesed exhaust ports and a deep "bathtub" style combustion chamber. They're pretty much on their own so far as interchanginf anything.

From then until '72 the F engine used a flattop piston and a closed combustion chamber.
'73 and '74 F engines used an open combustion chamber and a very small dome on the piston.

'75-'80 US variant 2Fs used an open chamber and a domed piston.

'81 and later 2Fs used a closed chamber and a flat top piston.


A '73-'74 F head will be a bolt on swap to any of the 2F, producing more compression on the '75-'80 blocks.

A pre '73 F head will swap to the later 2F engines once the rocker arm oiling is addressed. There will be piston/head interference on the early 2Fs

You can install an early 2F head on a late 2F engine. You will loose compression.

You can install any 2F head on the pre-'73 F engines. Again, you will loose compression, especially if you install an early 2F head with the open chamber.


Mark...

HTH
https://forum.ih8mud.com/40-55-series-tech/105385-2f-head.html


https://forum.ih8mud.com/40-55-series-tech/143065-head-comparisons-faq.html

 

[Maui Cruiser]

This is the quote of Mark W.:
"From then until '72 the F engine used a flattop piston and a closed combustion chamber.
'73 and '74 F engines used an open combustion chamber and a very small dome on the piston."

What constitutes a "very small dome"?

Could somebody tell me once and for all, can I put a 69 head on a 73 block? Will I be banging the piston into the head?

Sounds like the 73 head is interchangable among the F blocks, but not vice versa.

 

[FJ40Jim]

No, the pictured closed chamber head will not work with the domed pistons.

Either rebuild the block w/ flattop pistons,
or fix the open chamber head & reinstall it.

 

[Maui Cruiser]

Thanks! That's all I needed to hear.

 

[Maui Cruiser]

So I went ahead and did it anyway

Guy at the machine shop did a few measurements and figured there were no clearance issues with the closed chamber '68 head on the '73 block with the slightly domed pistons. Tightest spot with the head gasket in place was .060+. Means nothing to me.

Sooo... I slapped it on and it runs great. The F now feels, um... perky. Who'da thunk it?

 

[fireflyr]

I thought the '73 Transition engine had different oiling for the top end? I remember my '67 F had an oil tube that transferred oil to the head, while the '73 was completely different, more like the 2F. How is your rocker arm assembly getting oil? I didn't think you could do this. Live and learn.

 

[FJ40Jim]

The rockershaft is lubed via the external line on 8/73-older engines. So it is possible the 68 head would work on the 73 block, if it is prior to 8/73.

It is possible to go the other direction, installing a 74 head on a 72 block for example. It requires reusing the early external oild rockershaft assembly and ignoring the holes drilled for the later internal oiling setup.

 

[Maui Cruiser]

Pretty sure the transition was in '74. My '73 still has the copper oil line feeding the rocker assembly.
I was just worried about the slightly domed pistons.

 

[Trollhole]

I would be interested in knowing what your compression ratio is now. That has got to be way over spec.

 

[Maui Cruiser]

Trollhole, What do you think might happen?

I was told by the machinist that it would be 7 or 8 to one originally to run on (in his words) "third world jungle gas". He figured it might get up to 9:1 or so, but assured me no need for higher octane. I have not had any abnormal pinging so far. No compression #'s yet.

This was all done mostly to see what would happen, the rest of the engine is still untouched, so who knows what mayhem may ensue.