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First Engine Rebuild - Decisions?

Old 11-01-2017, 01:01 AM
  #16  
Humboldtgrin
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Honda went to a smaller rod journal on there engine's a long time ago due to oil beaking down at the speed the bearing spins. Mitsubishi rods are a pretty good idea for that reason on these crankshafts. You can even get super light aluminum Mitsubishi rods for a prettier penny, although they have no windage characteristic at all (like a brick in the wind, windage ports would be a must IMO). Or Have Michael Mount do the "rod mod" to use better NASCAR style bearings and keep the stock rod journals, which is cheaper and very effective. Both are an improvement and well worth doing.
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Old 11-01-2017, 03:44 AM
  #17  
FRporscheman
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When you use block filler, I recommend not to go by the instructions on the bottle (if you use Moroso like I did). They say that the bottle comes partly empty to give you room for water, and that you should add water into the bottle and shake it. That's what I did, and after shaking it for at least 30 minutes straight (and having cramped arms) and attempting to stir with a long screwdriver, it turns out that the water and filler did not mix fully. After I filled my block, I poured the rest of the block filler into a small pothole in my driveway, and holding the bottle upside down, there was still an inch of condensed block filler powder stuck to the bottom of the bottle.

And the filler in my engine block cracked after it dried, being too high in water content.

So mix it in a bucket and use a cement mixer tool.

Regarding height, basically you fill it "as much as possible" which is to the bottom of the upper water pump port. You can dam off a passage to the lower water pump port (I did), but I don't think you really need to, you can just cover it with tape and let it get blocked with filler. And I ran a rubber vacuum hose through the coolant drain plug hole, so a passage to that would be open after the filler was poured in, but I wouldn't bother with that either; I'd rather have more filler in place. 2.7/3.0 blocks didn't have that drain anyway.

About 4k miles on this engine so far, and the coolant temps have been rock steady at the normal levels, so filling the block that high has been totally fine for me.
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Old 11-01-2017, 03:57 AM
  #18  
Dave W.
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Originally Posted by ekoz View Post
Thinking about this option.

Go with the Mitsubitshi Rod, 4g63. Grind the 4 crank journals to fit, the question is there a way to use my current piston which has the stock pin? the stock is 24mm versus the 4g63 which is 22 mm. Can I machine the center of 4g63 pin or is that too much material? when I dropped off the crank, my machinist mentioned that a lot of guys are going to smaller crank journals because is reduces the speed between the bearing and the crank. Never really thought about that but it would be true. Maybe this has been thoroughly discussed but it would be another reason to use the mitsubushi rod.

in my case if I need a new rod it is almost as expensive as four mitsu's
It's a matter of geometry. The offset grind will increase the stroke, so you can't use your current pistons since the comp height is too tall. Mitsu rods and stock rods are both 150mm long. When the stroke is increased the piston is pushed up higher at the top of the stroke, so the piston needs to be shorter so it's flush with the top of the block when it's at TDC.
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Old 11-01-2017, 08:12 AM
  #19  
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Originally Posted by Dave W. View Post
It's a matter of geometry. The offset grind will increase the stroke, so you can't use your current pistons since the comp height is too tall. Mitsu rods and stock rods are both 150mm long. When the stroke is increased the piston is pushed up higher at the top of the stroke, so the piston needs to be shorter so it's flush with the top of the block when it's at TDC.
Unless he was just cutting to center the rod journal and not an offset grind. Which I believe he was talking about.
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Old 11-01-2017, 10:27 AM
  #20  
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Originally Posted by Humboldtgrin View Post
Unless he was just cutting to center the rod journal and not an offset grind. Which I believe he was talking about.
yes, plan on keeping same stroke just grinding down to smaller journal. My problem is the wrist pin on existing pistons. Its stock size 24mm mitsu rod is 22mm So in theory I could bore out to bigger size and hope for the best. I think they do that for the chevy pistons but its like 23.5 so I would be going .5 mm more. Any hybrid guys have thoughts on that.

I have to replace on rod for sure, so that is why I'm debating this route.
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Old 11-01-2017, 03:22 PM
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How bad is the crank? Would undersize bearings with stock rods not work?
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Old 11-01-2017, 10:00 PM
  #22  
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Crank is not bad...I could use undersized bearings (still a chance I could stay stock) I was told undersize run about $400 a set versus $100....So I was trying to stay on the less expensive side as I plan to replace after about 3 track sessions just to have a look. Most racers (Im not one but do like to run hard at DE's) change bearing quite often. If that's what I need to do, then $100 a set is a no brainer.

I like the idea of using the mitsu rod just because they are less expensive and have the smaller journal.

Drilling that small side of the mitsu out to 24 MM from 22 MM is uncharted water I suspect so in the end, I'll probably just replace existing rods and either go stock bearing if possible or undersized. Because of the 104 MM bore, I would have to get new pistons or custom rods...neither is a cheap option.
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Old 11-01-2017, 10:29 PM
  #23  
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I asked Eagle about that - they said you could "probably" take the 4G63 rods to 24mm pin if you made it press-fit.

Just not enough meat for a floating pin-bushing.
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Old 11-01-2017, 10:52 PM
  #24  
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Originally Posted by V2Rocket View Post
I asked Eagle about that - they said you could "probably" take the 4G63 rods to 24mm pin if you made it press-fit.

Just not enough meat for a floating pin-bushing.
I asked Eagle the same thing a few months ago and got the same answer. Should be ok. Also, the machinist said we could convert to a press fit pin to help save material.
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Old 11-02-2017, 01:29 PM
  #25  
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Thanks,
I went ahead and called eagle today. If you remove the bushing it has a .922 ID. 24 MM is .944 so just remove some material and run without the bushing.

My machinist seems to be on board with this plan. have to double check all my measurements before I start, but this seems like a good plan.

straight grind the crank with no offset to accept mitsu rods. bore out pin to accept 24mm pin with no bushing and use existing 104 mm pistons. If this works well its a nice rod replacement for any stock project as well.
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Old 11-05-2017, 11:15 AM
  #26  
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replace the oil pump? the pump housing has a groove worn in. It will catch on finger nail so I assume I would want to replace.



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Old 11-05-2017, 03:09 PM
  #27  
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Yes replace the oil pump.
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Old 11-06-2017, 04:41 AM
  #28  
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Yes, that`s the last part you want to "save" money on.
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Old 11-06-2017, 01:03 PM
  #29  
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Originally Posted by ekoz View Post

straight grind the crank with no offset to accept mitsu rods. bore out pin to accept 24mm pin with no bushing and use existing 104 mm pistons. If this works well its a nice rod replacement for any stock project as well.

watching with interest...
would make possible using stock 944/968 104mm pistons with an offset ground crank, itd pull the pistons a little down in the hole (lower CR)...
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Old 11-06-2017, 11:55 PM
  #30  
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Originally Posted by V2Rocket View Post

watching with interest...
would make possible using stock 944/968 104mm pistons with an offset ground crank, itd pull the pistons a little down in the hole (lower CR)...
you suggesting to do a little offset and lower CR for this project? I believe this engine was set up at 8:1. I haven't measured volumes yet but I was just planning to keep it the same.
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