3FE vs 2/3F carb cyl. head

[Godwin]

Those Remflex gaskets are outstanding, BTW. Used one on the 225 slant in my '74 Plymouth (notorious for manifold leaks) and never once had an issue afterwards.

As far as the bolt patterns go, though we're hunting different objectives here, it looks like (now someone correct me if I'm wrong) I could use a 3FE gasket, retain the extra bolts on my 3FE head, and possibly drill out the mounting flanges on a set of 2F headers to allow them to mount to a 3FE head (drilling them prior to having them ceramic coated). Connecting to the exhaust is a non issue for me since I'll be having a custom system built that can easily be located to mate to the header outlets.

Why would you want to mount 2F header on a 3FE head when the 3FE exhaust manifold is likely superior to a 2F header?

 

[Stumpalama]

Those Remflex gaskets are outstanding, BTW. Used one on the 225 slant in my '74 Plymouth (notorious for manifold leaks) and never once had an issue afterwards.

As far as the bolt patterns go, though we're hunting different objectives here, it looks like (now someone correct me if I'm wrong) I could use a 3FE gasket, retain the extra bolts on my 3FE head, and possibly drill out the mounting flanges on a set of 2F headers to allow them to mount to a 3FE head (drilling them prior to having them ceramic coated). Connecting to the exhaust is a non issue for me since I'll be having a custom system built that can easily be located to mate to the header outlets.

I read that too. The exhaust ports appear the same on both the 2f and 3fe, so exhaust should not have the same issue as the intake.

Looks like I'll be selling my 3f-e head and sending my 2f head out, when the time comes.

 

[Spook50]

Why would you want to mount 2F header on a 3FE head when the 3FE exhaust manifold is likely superior to a 2F header?

I would honestly bet money that they're not. Now if you were comparing factory manifold to factory manifold, then the 3FE would likely be better. But the idea behind headers is that they're (if designed and built right) tuned so that the exhaust pulses of each cylinder exit at separate times, eliminating turbulence and increasing exhaust velocity which will in turn improve the scavenging effect of the system. On an otherwise stock engine this would likely net you little gain, but if you've improved flow in the rest of the exhaust and also in intake capacity via a bored out throttle body and even went a step further by increasing the size of the valves in the head, you could see a big difference especially at high RPM.

@Stumpalama if funds allow for it, I'd be very interested in buying your 3FE head if/when you sell it.

 

[mtweller]

I don't think it would seal, but I have never tried. In my 2FE, it's 3FE head and intake. Now, I've run 3FE mani's on 2F heads with great results in the past... but it sounds like that's not in question.

I'd sell that 3FE head and build the 2F head as desired. Yeah, extra money... but there's very little upside otherwise and high probability of vacuum leaks.

 

[Stumpalama]

I would honestly bet money that they're not. Now if you were comparing factory manifold to factory manifold, then the 3FE would likely be better. But the idea behind headers is that they're tuned so that the exhaust pulses of each cylinder exit at separate times, eliminating turbulence and increasing exhaust velocity which will in turn improve the scavenging effect of the system. On an otherwise stock engine this would likely net you little gain, but if you've improved flow in the rest of the exhaust and also in intake capacity via a bored out throttle body and even went a step further by increasing the size of the valves in the head, you could see a big difference especially at high RPM.

@Stumpalama if funds allow for it, I'd be very interested in buying your 3FE head if/when you sell it.

You will have 1st right of refusal when I get around to moving it out the door. Don't know what shipping would be on a hunk like a 3FE, but if they are still shipping I have a Fastenal right around the corner.

 

[Stumpalama]

I don't think it would seal, but I have never tried. In my 2FE, it's 3FE head and intake. Now, I've run 3FE mani's on 2F heads with great results in the past... but it sounds like that's not in question.

I'd sell that 3FE head and build the 2F head as desired. Yeah, extra money... but there's very little upside otherwise and high probability of vacuum leaks.

I think I determined it won't seal due to the height differential of the tops of 3FE and 2F intake manifolds. The 2F manifold will not seal the 3FE injector cutouts.

 

[GLTHFJ60]

As an alternative, you could braze the injector portion of the intake runner closed on the 3FE head, or perhaps easier, weld an extra protrusion on the 2F manifold to cover the gap, and take advantage of the extra bolt holes.

 

[Stumpalama]

As an alternative, you could braze the injector portion of the intake runner closed on the 3FE head, or perhaps easier, weld an extra protrusion on the 2F manifold to cover the gap, and take advantage of the extra bolt holes.

Boy, would that be a tremendous opportunity to puck that up.

 

[GLTHFJ60]

Welding on the manifold would be low-risk (worst case, vacuum leak) but welding cast aluminum is a PITA.

 

[cruisermatt]

Most original Toyota aluminum castings actually weld pretty decent, probably because they actually use good fresh material back in the day unlike most stuff now which is recycled beer cans. I’ve repaired a few cracked intake manifolds. Still have to spend a lot of time getting the oil/grime soaked material clean.

 

[FJ40Jim]

@FJ40Jim
Are the valve seats are hardened on either of these heads?
I’m assuming the stainless valves are ground to 45deg. Do you resurface to 44.5 per FSM or does final lapping remove this in the end?

There are hardened seat inserts in all US spec cyl heads.
The new valves are installed as delivered. Seats are cut (not ground) at 44.5, along with top & bottom angles, all in one go with a Serdi machine.

what is the reason a late 2F exhaust header wouldn't work with a 3FE head? Or is it simply because it wouldn't be a bolt-in solution with the 3FE exhaust's downpipes?

And the more important question, @FJ40Jim are you (or anyone) selling upgraded 3FE heads?

A 2F exh header will bolt to a 3F head. It will interfere with 3FE intake manifold.

I can rebuild your 2F or 3F core head, but don't have extras to sell.

Two simple questions: Will a 2F intake (3FE head locating pins removed) and header fit and properly seal on a 3FE head? If not, what are the issues that prevent this fitting up?

Edit: Found this: View attachment 2616909
I have a 1981 FJ40, so, based on the above information, does that mean I have the kidney shaped valve shrouds? If so, It may be worth the extra week or so and $$ to have the SS valve put into the 2F head.

2F intake will not seal on a 3FE head.
Sell the hot-rodded 3FE head and do the SS valves, mill, oil plug on a 81-later 2F head.

Glad to see someone else with the same question as me.

As far as the SS Chevy valves, are they larger than the stock 3FE valves?

Yes. Intake goes from 1.80 to 1.84, exh from 1.47 to 1.50. It's a small increase, small enough that the hardened seat inserts don't need machined out & replaced.

 

[Stumpalama]

There are hardened seat inserts in all US spec cyl heads.
The new valves are installed as delivered. Seats are cut (not ground) at 44.5, along with top & bottom angles, all in one go with a Serdi machine.

A 2F exh header will bolt to a 3F head. It will interfere with 3FE intake manifold.

I can rebuild your 2F or 3F core head, but don't have extras to sell.

2F intake will not seal on a 3FE head.
Sell the hot-rodded 3FE head and do the SS valves, mill, oil plug on a 81-later 2F head.

Yes. Intake goes from 1.80 to 1.84, exh from 1.47 to 1.50. It's a small increase, small enough that the hardened seat inserts don't need machined out & replaced.

Thanks @FJ40Jim. Solid information, as usual.

 

[Spook50]

A 2F exh header will bolt to a 3F head. It will interfere with 3FE intake manifold.

Aaaaahhhhhh, there's the big caveat then. I had been hoping it was only due to the extra bolts/pins and the location of the 3FE downpipes.

 

[FJ40Jim]

I have a 2F header and 2F intake on a 3F head, utilizing some of the extra bolts to retain the header.

 

[Spook50]

I have a 2F header and 2F intake on a 3F head, utilizing some of the extra bolts to retain the header.

Too bad the 2F intake would NOT be able to utilize the 3FE's throttle body. That would make for an interesting Frankenmotor...

 

[Seth S]

Too bad the 2F intake would NOT be able to utilize the 3FE's throttle body. That would make for an interesting Frankenmotor...

It could be adapted

 

[Spook50]

It could be adapted

The temptation is there, if for no other reason than "could I do it".....

 

[FJ40Jim]

I have a 2F header and 2F intake on a 3F head, utilizing some of the extra bolts to retain the header.

Pics, or it didn't happen.
Here's a 3F head on 2F, typical 1987 2F.

First step is to transfer the additional 3F manifold bolt holes to the FelPro Graphlex (tm) manifold gasket.

Then put the gasket against the header and use it to transfer the hole locations. Drill the holes, and notch the holes that fall on the edge of the header flange.

The header can be installed using the additional 3F bolts. They all clear the 2F intake manifold.

Last step is to install the intake manifold using the standard 2F manifold hardware.

 

[Spook50]

Pics, or it didn't happen.
Here's a 3F head on 2F, typical 1987 2F.
View attachment 2619751

First step is to transfer the additional 3F manifold bolt holes to the FelPro Graphlex (tm) manifold gasket.
View attachment 2619753

Then put the gasket against the header and use it to transfer the hole locations. Drill the holes, and notch the holes that fall on the edge of the header flange.
View attachment 2619755

The header can be installed using the additional 3F bolts. They all clear the 2F intake manifold.
View attachment 2619756

Last step is to install the intake manifold using the standard 2F manifold hardware.View attachment 2619758

You are making me REALLY want to try my hand at machining an adapter to put the 3FE throttle body on the 2F intake and totally Frankenstein the bajeezus out of my engine.....

 

[FJ40Jim]

Here's a crazy idea: install the 3FE throttle body on a large volume tuned runner intake manifold with port injection.
Fixes the unequal runner length tuning problem, and the unequal mixture distribution wet manifold problem.