What's the difference in a 2F & 3F head?

[thetoyotaman]

Also would like to know if the 2F manifolds bolt up to a 3F head and any pics of the 2F and 3F valve covers. Thanks.

 

[rsbcruiser]

combustion chambers for one, the 3f chambers I've seen are almost non-existent.

 

[jmylie]

Run a search, I believe some have used 3F heads on a 2F to go the fuel injected route.

Like this post:

https://forum.ih8mud.com/40-55-series-tech/134529-2f-3f-e-=-2f-eti-into-my-fj40-20.html

or:

https://forum.ih8mud.com/40-55-series-tech/219407-fuel-injection-worth.html

 

[3_puppies]

I'm almost certain you need to keep the manifolds with the heads. if you look at the gaskets, they are different, between the 2F and 3F

 

[FJ40Jim]

What's the difference in a 2F & 3F head?

Nothing.
Starting in 1985, the 3F became world standard, and the one market (USA) that soldiered on with the 2F got the 3F cylinder head. Head gaskets are also the same.

Also would like to know if the 2F manifolds bolt up to a 3F head and any pics of the 2F and 3F valve covers.

Yes, the 2F manifolds bolt to a 3F head. That's how they come from the factory for 85-87 2F engines.
Also, 3F manifolds bolt to any 2F head, although if it is an 84-earlier 2F head, there will not be the extra bolt holes for the additional 3F manifold bolts.

Valve cover mounting varies over the years of F, 2F, and 3F. Not because of the cylinder head, but because of the height of the rocker arms and studs.

 

[67azcruizr]

Yes, the 2F manifolds bolt to a 3F head. That's how they come from the factory for 85-87 2F engines.

Not to be mistaken with a 3FE head, correct?

 

[Poser]

Correct.

3FE head is a very different casting.

 

[matt.mcinnes]

3F and 3FE are completely different as far as the head goes, yes a 2F, 3F and 3FE will all bolt up to the same block. As mentioned above they all use the same head gasket.

The 3F is a carbi version of the 3FE and not restricted quite so much by all the emission controls the 3FE had to meet for the USA requirements. Why build an over complicated and more expensive system such as the 3FE when a 3F is really just as good. The answer is emission laws.

The 3FE however stripped of all its emission systems such as mine is a different story even without the turbo and race build, but still over complicate in my opinion with the 3FE ECU. MY Wolf V500 although far more powerful in its ability to control the engine is actually far more simplistic too. Mainly again due to emission.

I doubt you will find a 3F head in the USA but I maybe wrong.


https://forum.ih8mud.com/60-series-wagons/143089-3fe-vs-2-3f-carb-cyl-head.html#post1949137

 

[thetoyotaman]

Ok. I didn't know there was a 3F and a 3FE head that were different. So, in 1985 did the compression go up in US model FJ60's?

 

[FJ40Jim]

No, the compression stays the same on all 81-87 2F engines, 8.3:1.
The same head on the slightly smaller 3F bottom end results in the lower 8.0CR of the 3F.

 

[Delancy]

Also, 3F manifolds bolt to any 2F head, although if it is an 84-earlier 2F head, there will not be the extra bolt holes for the additional 3F manifold bolts.

Is it necessary to tap an early 2F head to accommodate the additional 3F manifold bolts?

Better question:

Is it advisable to tap/fill the head for the additional 3F manifold bolt bolts?

3F manifolds and carbs are readily available new, the reason for posing.

Side note, since the following was based upon this thread and other content similar.

2F/3F head with 3F manifolds/3F carb is a good fit for the '76 air cleaner assembly. A late 2F/3F valve cover/cleaner would be a bolt on affair and the early '76 of both, utilized here, were damn near.