"best" 2F

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Nah, I like the longer stroke. I see no reason to destroke the motor. Besides, the 3F stroke is not that much shorter than a 2F...
 
Mace said:
What is the benefit of closed chambers and flat top pistons?

And yes, this motor will get flat abused. I am looking at well over 200hp at the rear wheels...

And a 6500K redline..

So, every little bit of work will help ;)

I assume you've read my engine thread?
https://forum.ih8mud.com/showthread.php?t=61396

Bathtub chambers are a much better design for LPG (you're still running LPG right?). Especially if you go to almost zero squish.

Over here, I've never seen domed pistons - everything was flat top.

I ran the head off a 1.5F on a 2F block for better compression. I guess for turbo work you wont want to get too carried away with machining for compression.

I've not had any problems with my rod bolts (have had the bottom apart once since the rebuild) - but I did loctite them!

With a turbo, I reckon you should be able to get 300hp out of it :)

Definately do some form of oiling mods though!!!! Mine are outlined in my thread, Mark W I'm sure has his written somewhere - I know they're on the LCML
 
the oiling mods will be performed to the new motor.


Bathtub chambers???

You mean the domed pistons???
 
Chef said:
So Mark, are you just buying psitons and rings and cams etc at Napa as needed?
Northern has "kits," but they're way more than what PacLift used to charge...


I get rings, bearings, pistons, seals and gaskets from a local parts warehouse that sells wholesale only to the local parts stores... and guys like me who have made rhe right connections. ;)

I get my cams and oil pumps and a few other items from different sources I have tracked down.


Mark...
 
Mace said:
So basically, an 84 or 85 block has the best of all worlds in a 2F.

The compression ratio does not worry me particularly due to the turbo, But that is excellent info to have.

I already have over 140 hp at the rear wheels (sm420/dual mini tcases/and a 14 bolt), and that is a Stock motor with over 150K on the ticker. I am thinking that a healthy cam and good balancing will let me get up to the 200 RWHP numbers.

Which bigblock bolts are you eyeing???



BTW, It sounds like a 76 2F block would NOT work with a later 3fe head due to the flat top/dome pistons correct?

BTW, as I assemble this motor I will document it and the Dyno results afterwards....


With a starting CR of 7.8 (or possibly 8.5 in the later motor) yiou still need to worry about it even with a turbo.

I forgot that you were running a turbo. 200+ at the rear wheels should be easy.

A '76 block will work fine with a 3FE head. But '76 pistons will not.

I forget exactly which bolts I have looked into. I've got it written down at the shop. Made by ARP. Looks like they'll be about a .001 -.002 interference fit. A little heat and a press should get them in just fine...


Mark...
 
andrewfarmer said:
Over here, I've never seen domed pistons - everything was flat top.



The domed pistons may be a US thing. I've only taken down one 2F that I knew for sure was a stock Canadian engine. It had flat tops with open combustion chambers.


Mark...
 
Mace said:
Nah, I like the longer stroke. I see no reason to destroke the motor. Besides, the 3F stroke is not that much shorter than a 2F...


I tend to agree about likeing the longer stroke. Or more importantly the longer rods. But the biggest advantage of the 3F for higher rpm is not the shorter stroke but the lighter rod and piston combo. The 3F rod is a LOT shorter, as is the piston. The equates to a lot less weight. It's the weight as well as the stroke that creates the stress at higher speeds.


Mark...
 
DHONDAGOD said:
the shorter rod also reduces torque (piston dwells for less time at TDC)and increases side loading of the piston...



chris:cool:
I wonder if the side loading of the piston is offset by the reduced weight of the rotating mass??


This argument could be an incredible display of bench racing :D


I need to roll the 2F I have in the garage over and see what vintage it is.
 
Mace,
If you had to pick one 2F to build, the 85-end models are best. They have all the upgrades of the 81-85, plus in 85 they got:

-the 3F cylinder head, which gives the option of running the 3F manifolds
-the 3F head gasket with better coolant flow direction
-screw in oil galley plugs (I really like this)
-slight improvement w/ the 3piece thrust bearing
-torx screws in timing plate(which should be added to any engine).

However, if you start w/ a 4230cc engine that is 8.3:1, then punch it 1.5mm OS, the result is 4367cc at 8.57:1. Usually the head is milled a little to clean up the face, which will get up to 8.7:1. If the engine is gonna be blown on, that's a pretty high CR, without modern feedback control systems.

The lightened valvetrain came along in mid 1979.

On the rods, newer is definitely better. As Mark mentioned, it's marginally lighter, but it's also much stronger because of the extra finishing on the I-beam.
I've got a picture here of the 79-earlier rod vs. the 80-later rod, but can't figger out how to post it.:doh:

If the engine is gonna be spun, it should be balanced to zero. Early 2F and all F engines are often out by several OUNCES. No, not grams. Rods are out by 20 grams or more, cranks off by 50, flywheels off by 30. The only thing that keeps a 1971 F engine together at speed is sheer stubbornness. The 81-newer engines were destined for cushy FJ60 wagons, so they finally started paying attention to balancing. They are usually only out by an ounce.

HTH
 
FJ40Jim said:
Mace,
If you had to pick one 2F to build, the 85-end models are best. They have all the upgrades of the 81-85, plus in 85 they got:

-the 3F cylinder head, which gives the option of running the 3F manifolds
-the 3F head gasket with better coolant flow direction
-screw in oil galley plugs (I really like this)
-slight improvement w/ the 3piece thrust bearing
-torx screws in timing plate(which should be added to any engine).

However, if you start w/ a 4230cc engine that is 8.3:1, then punch it 1.5mm OS, the result is 4367cc at 8.57:1. Usually the head is milled a little to clean up the face, which will get up to 8.7:1. If the engine is gonna be blown on, that's a pretty high CR, without modern feedback control systems.

The lightened valvetrain came along in mid 1979.

On the rods, newer is definitely better. As Mark mentioned, it's marginally lighter, but it's also much stronger because of the extra finishing on the I-beam.
I've got a picture here of the 79-earlier rod vs. the 80-later rod, but can't figger out how to post it.:doh:

If the engine is gonna be spun, it should be balanced to zero. Early 2F and all F engines are often out by several OUNCES. No, not grams. Rods are out by 20 grams or more, cranks off by 50, flywheels off by 30. The only thing that keeps a 1971 F engine together at speed is sheer stubbornness. The 81-newer engines were destined for cushy FJ60 wagons, so they finally started paying attention to balancing. They are usually only out by an ounce.

HTH
Now all I have to do is figure out what engine # they started doing all of these mods ;)


In the long run it really looks like the newer the motor, the better the choice.
 
" BEST " 2F.....

The one that has good compression and oil pressure DUH!!! ;)



Jim-

Here are the pics:
Conrod01.webp
Conrod02.webp
Conrod03.webp
 
I wonder if any strength is lost with the lighter conn rods....
 
In the photo, the lighter rod is the one that *appears* to have the i-beam machined. It is not machined, it has been "forged" along the i-beam. While the rod is still red-hot, the beam gets smacked in a press which compresses and aligns the grain on the edges of the I-beam. The flat areas are not machined away, but are made stronger. The rod picks up fatigue resistance by dint of the edges of the I-beam being much more crack resistant. The actual tensile strength of the rod beam is not significantly improved, but it is much stronger/durable in use because failures usually start as a crack at the outside edge of the beam.

more resistant to edge cracking = more resistant to ultimate failure

Thanks Steve for posting the pics:beer:
 
So what does casting numers 11411 61041 mean??

The head has a 48 cast into the top (under the valve cover) and a bolt in the weep hole...
 
You sure about the 61041?
Heads are 61030 or 61031, open chamber, or
61040, 61070 closed chamber.

blocks start off as 61011 in 75-76, then step upward to 61014 in late FJ60's

Should we start a sticky thread about dating parts, w/ pictures of all the components that have dates stamped or cast (blocks, heads, diff gears, carbs, fuel pumps, T-cases,etc.), and how to decipher them?

Where's the stupid noob thread about posting pics, I need to read that again?
 
Pick up a star there Jim, or you will not be able to post up very many pics...


I think that would be a great idea for a stickie...


Start a thread, and I will stick it for a bit! :)


:beer:
 
This was kinda designed to do exactly that
 

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