Pop Question about 2F Piston/Head Tradeoffs (1 Viewer)

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also, install a new valve oil seal.. and grind the valves...

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I start work on the engine just in the first year of my Fj40 project.
After spending 3 years on this project ... I have learned a lot.
If you ask me now,... I will only buy from Toyota or a local vendor who has a reputation here.
I don't want to redo it in the near future...

from Toyota:



P.S ^^^^ look in Jim icon here :) I remember he has a thread here: how do not rebuild engine"


edit: I find it How not to build the 2F - https://forum.ih8mud.com/threads/how-not-to-build-the-2f.563170/
 
Last edited:
I start work on the engine just in the first year of my Fj40 project.
After spending 3 years on this project ... I have learned a lot.
If you ask me now,... I will only buy from Toyota or a local vendor who has a reputation here.
I don't want to redo it in the near future...

from Toyota:



P.S ^^^^ look in Jim icon here :) I remember he has a thread here: how do not rebuild engine"


edit: I find it How not to build the 2F - https://forum.ih8mud.com/threads/how-not-to-build-the-2f.563170/

Love the thread @FJ40Jim
 
I don't know for certain... I picked up the engine recently not knowing the year. I cleaned off the SN (2F 037791) and from the MUD Spreadsheet determined it was a 1975 Engine. I'm going with the assumption it's an open chamber with domed pistons. I'm just wondering if I should be thinking about trying to find a closed head. I can probably swap it for one. I haven't started pulling it apart yet and I might not do so until next year, so I won't know for a while. Just thinking ahead.

BTW, I'm in Tempe, just north of you.
Well you can figure out half the puzzle if you look at the cylinder head number cast into the head. What is yours?
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I pulled the head. It’s a 61030 with domed pistons. TBD if the head is good (no cracks) or if the block is going to need to be bored. I was just trying to understand the options if the block did need to be bored given that the domed pistons in a O/S are NLA to my knowledge.
 
Bumping your compression (within reasonable limits) is a great way to increase low end torque.

If domed pistons are NLA as mentioned I would run the closed chamber head if you have one. If you run the closed chamber head and flat top piston you can still mill the head to achieve more compression but you should calculate that out. CC the chambers and know your compressed head gasket thickness. The machine shop should be able to help you with that.

Keep in mind that if you go too high with compression, your octane requirements go up even with retarded timing. So find out the ideal compression ratio for your intended use.

If all you have is an open chamber head and all that is available is flat top pistons you will loose compression and performance unless you bring compression back up by milling the head or find domed pistons. It will still run with the lower compression but you will notice the loss of performance.

What head do you have?

It’s a 61030. I need to get the head cleaned and checked for cracks. It’s pretty corroded. The end freeze plug was totally rusted through.

The pistons (100) don’t look bad. The cylinder walls have some surface rust but no signs of pitting, and no significant ring ridges that I can detect.

I guess a machinist will be able to tell me if I can reuse the pistons and hone the cylinders, or if I have to look at other options.
 

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