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Rebuilding my L20B


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#221 flatcat19

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Posted 24 December 2017 - 02:24 AM

Blah, blah, blah...engine math...yawn.


Be careful where you use power tools.

If it had a measurable tolerance, remove and torque down by hand.

If it is a sealing surface, torque by hand.


I just rebuilt a Camry(2009) 2.4 liter motor yesterday. I use 5 different torque wrenches to assemble one as per the repair manual. And that ain't even for my car!

When I assembled my L, I brought home 3 "way too nice for a Datsun" torque wrenches.

You can't hang if your nuts haven't dropped...it's physics


#222 datzenmike

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Posted 24 December 2017 - 07:56 AM

Is this A87 a closed chamber head??? I just read A87 on the last page.

 

Can you confirm if open or closed?


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#223 ErickwithnoK

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Posted 24 December 2017 - 08:28 AM

It's closed chamber.

I definitely plan on trading in my harbor freight click style torque wrench for a bar style wrench so I can be accurate. Unless someone has a different recommendation.

Wayno I wanna stay away from race motor thing a because it's my first rebuild. Welding inside my distributor sounds a little intimidating and hopefully if I choose the right hardware, unnecessary. It seems like the determining factor is whether or not the block or head have been shaved. I can measure the head with my calipers I think but the block is definitely too tall for that. What should the head height be?

Are there other piston options with more or less bore and lower CR?

#224 datzenmike

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Posted 24 December 2017 - 08:57 AM


#1 Stock L20B compression .......................................................... 8.4
 
#1 with closed chamber head......................................................... 8.9
 
#1 with L28 dished 86mm bore pistons..........................................  8.6
#1 with L28 dished 86mm bore pistons, closed chamber head....... 9.12

 

There are no other pistons available you can use without also changing the rod lengths to compensate.


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#225 ErickwithnoK

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Posted 24 December 2017 - 09:13 AM

L28 dished it is then!

Thank you Mike for doing the math for me.

Should I rely on the machine shop for bearings seals and head components or source them myself?

Is rock auto head stuff junk?

#226 Stoffregen Motorsports

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Posted 24 December 2017 - 09:30 AM

Rod and main bearings are available in different materials. The best material is the classic tri-metal construction, but they are getting hard to source. Clevite bearings tend to be tri-metal. If they have a "NDG" stamped on the back of the bearing shell, they are OEM grade.

 

King and other brands are mostly aluminum material and don't hold up well to abuse. They chip and chunk off and muddle and squish under poor running conditions. They do not like detonation (pinging).

 

I would ask your parts house guy if he can find a good tri-metal set of bearings. If he shrugs it off, go find another source. Your machine shop should know the difference.

 

Also, some main bearing sets are full groove, some only have half grooves. If you have the choice, pick the full groove bearings.



#227 ErickwithnoK

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Posted 24 December 2017 - 09:44 AM

Thanks that's great information! I'll remember that when I get in touch with machine shops

#228 flatcat19

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Posted 24 December 2017 - 10:45 AM

I definitely plan on trading in my harbor freight click style torque wrench for a bar style wrench so I can be accurate. Unless someone has a different recommendation. 

 

 

​The HF wrenches aren't inaccurate. Without spending Snap-On money, you really can't go wrong. 

 

What torque wrench to buy yourself really depends on what size you need. This is an area where you get what you pay for. 


You can't hang if your nuts haven't dropped...it's physics


#229 datzenmike

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Posted 24 December 2017 - 11:00 AM

If the fully grooved bearings are impossible to source get two sets and use only the tops. Make damn sure the oil hole is not obstructed.  Factory bearings are not fully grooved and they are fine for the majority of applications..


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#230 ErickwithnoK

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Posted 24 December 2017 - 02:30 PM

If i get what I pay for and i spent 10 bucks then i should probably spend more on a torque wrench haha.

I did notice the oil holes and will not forget about them on assembly...

#231 ErickwithnoK

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Posted 24 December 2017 - 02:32 PM

Oh, and Merry Christmas! Thanks for the help guys ☺

#232 ErickwithnoK

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Posted 04 January 2018 - 09:25 AM

Back again. Having trouble sourcing 280zx dished pistons without having to buy used or in a set of 6.

Is there any difference between a +0.04" l20b piston and an 86mm 280zx dished?

#233 banzai510(hainz)

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Posted 04 January 2018 - 09:33 AM

they close to the same  L20 is like 11.36 and 280zx is like 10.9.   most people want the flattop but with cheap gas these days I would just run the dished with a closed chamber head if you rellay need to up the compression


Throw on some Weber sidedrafts, Rising Sun hood.... call it good

#234 ErickwithnoK

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Posted 04 January 2018 - 09:55 AM

I'm not trying to get compression that high but I am using a closed chamber a87 on an l20 block. Hopefully it isn't that high with dished l20 pistons? I'll try to use that calculator thing...

#235 datzenmike

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Posted 04 January 2018 - 12:45 PM

Closed chamber on L20B is 8.9 so 1mm oversize L20B pistons will be barely just over 9 

 

 

edit: 9.06


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#236 Str8jacket

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Posted 04 January 2018 - 04:14 PM

Blow through 32/26 weber. Standard engine standard cams. 8 PSI boost. = poor tyre life.
Use a td04hl sized turbo or a small blower off 2lt toyota.

If you want more to dream about.

#237 ErickwithnoK

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Posted 04 January 2018 - 07:54 PM

Hey thanks Mike. That's where I want to be I think. That gives me some wiggle room if I need to deck the block or head

#238 Stoffregen Motorsports

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Posted 05 January 2018 - 10:04 AM

If they are still available at the dealer, they sell them individually.