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173 extra cubes?

Started by gad05 , Jan 27 2014 01:20 PM

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34 replies to this topic

#1 gad05

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Posted 27 January 2014 - 01:20 PM

Hi Guys,
Not sure if this is a silly question but here goes.
Can you fit a 202 crank in a 173 block to increase capacity ?
I want to keep the original numbers 173 block.
Cheers Graham .

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#2 _Bomber Watson_

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Posted 27 January 2014 - 02:07 PM

Yep.

You need to get the mains machined down to the 186/176 journal size, and Pistons are gonna be a BIG issue.

THis is relatively common with 186 blocks as they share the same bore as a 202, so you just run 202 compression height slugs.

With a red 173 on the other hand you will need to get some custom slugs made. Not overly scary, probably looking at around the $1200 mark.

You will end up with around 190ci, cbf'd working it out properly.

So yeah, doable, but pricey.

Cheers.

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#3 Potta

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Posted 27 January 2014 - 02:24 PM

Other option is to pull the original motor and put it somewhere safe and oily and drop in whatever you want :spoton:

Less mucking around for sure.

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#4 _Bomber Watson_

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Posted 27 January 2014 - 02:26 PM

Grind the 202 off the side and put 173 there in texta....

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#5 gad05

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Posted 27 January 2014 - 02:50 PM

Thanks Bomber,
Probably out of my budget,but good to know its doable.
Cheers Graham .

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#6 Dr Terry

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Posted 27 January 2014 - 02:56 PM

Holden made the later 173 main journal bearings the same size as 202, to commonise the parts sometime in the mid-70s.

I'm not sure exactly when this change took place, but I'm sure if you use a late Red 173 or a Blue 173 block, the 202 crank will fit straight in.

However, as Bomber has said you will need custom pistons, because the pin height will be different.

Dr Terry

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#7 Dave6179

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Posted 27 January 2014 - 03:19 PM

You could bore the 173 out to 186 if the walls are thick enough. I had a similar idea in the past, keep the 173 but actually have a 192. Was told it was possible... with two or three borings.

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#8 _Bomber Watson_

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Posted 27 January 2014 - 03:29 PM

Red 173 does not have enough in the walls.

Blue 173 does, and as stated the crank drops in TMK, but it has 2.8 on the side so defeats the purpose outlined in the first post.

Cheers.

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#9 wot179

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Posted 27 January 2014 - 03:46 PM

The solution is a mould made of bog and some fiberglass resin...

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#10 Dr Terry

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Posted 27 January 2014 - 03:53 PM

Red 173 does not have enough in the walls.

Blue 173 does, and as stated the crank drops in TMK, but it has 2.8 on the side so defeats the purpose outlined in the first post.

Cheers.

I'm sure the bearing journal size change happened a long time before 2.8 appeared on the block.

I'm guessing around HX/LX, maybe earlier.

Dr Terry

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#11 _Bomber Watson_

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Posted 27 January 2014 - 04:02 PM

But did the casting differences happen before that?

Ie being able to fit a 3.625" slug in the 3.5" bore without her crying and spillign water everywhere?

Cheers.

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#12 _Lazarus_

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Posted 27 January 2014 - 04:13 PM

Don't they put 173 pistons in the Rover (Buick) alloy V8 block ?

Might be worth checking what pistons are available for them.

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#13 _Bomber Watson_

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Posted 27 January 2014 - 04:18 PM

Suppose if you could get a 1.68-1.71" compression height slug for a rover it might be worth looking at....

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#14 _Lazarus_

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Posted 27 January 2014 - 04:39 PM

Not positive but I think it's the 4.4 they do that with which was used mainly in trucks (and the P76) as far as I know.

.

Edited by Lazarus, 27 January 2014 - 04:40 PM.

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#15 _Muzzy_

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Posted 27 January 2014 - 04:50 PM

I'm sure the bearing journal size change happened a long time before 2.8 appeared on the block.

I'm guessing around HX/LX, maybe earlier.

Dr Terry

I have a LH 173 and it has smaller mains than a 202

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#16 rodomo

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Posted 27 January 2014 - 04:56 PM

I used 173 rings in my Rover build. Was cheaper to buy 2 sets of 173 rings than 1 set to suit rover.

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#17 _Mint_

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Posted 27 January 2014 - 05:18 PM

Not positive but I think it's the 4.4 they do that with which was used mainly in trucks (and the P76) as far as I know.

.

the P76 was a truck :stirpot:

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#18 rodomo

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Posted 27 January 2014 - 05:29 PM

No. The Leyland Terrier was the truck that shared that engine.

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#19 _STRAIGHTLINEMICK_

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Posted 27 January 2014 - 09:29 PM

If the engine is out of the car then you could get the bores sonic tested for wall thickness , If there is enough thickness then you can bore it to 3,625 and fit the 202 crank .

Also I have a complete lj 173 engine and 202 cranks here if you want to keep yours aside .

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#20 _tryhard_

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Posted 27 January 2014 - 09:50 PM

I have bored the red 173 out to standard 202 pistons and never had a problem

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#21 yel327

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Posted 28 January 2014 - 10:42 AM

I think RS2000 pisons go close from memory.

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#22 Dave6179

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Posted 28 January 2014 - 03:36 PM

I have bored the red 173 out to standard 202 pistons and never had a problem

Told ya. Wasn't hearing things!

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#23 yel327

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Posted 28 January 2014 - 04:09 PM

173 has a 3.5" bore (88.9mm), 1.78" (45.2mm) comp height and 0.866" (22mm) pin.

With a 202's stroke you want a comp height of 1.68" (42.672mm).

2.0L Ford piston is 3.5748" (so 75 thou over on the 173) with 24mm pin (so bore the little ends out 2mm) and 41.12mm comp height (deck the block 1.55mm or 62 thou).

You should be able to buy good quality pistons for the Cosworth 2.0L engines too.

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#24 yel327

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Posted 28 January 2014 - 04:17 PM

Also never realised how close to a 202 piston a 4.2L Jaguar piston is:

3.625" bore, 41.4mm comp height, 22.23mm pin. Higher performance ones of these might be useful for 202's in the future?

Edited by yel327, 28 January 2014 - 04:18 PM.

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#25 yel327

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Posted 28 January 2014 - 04:25 PM

Volvo pistons (4cyl B20 and 6cyl B30) are very close to a 173 as well. Flat top, 3.5" bore, 0.866" pin height and 1.81" comp height. So piston top is only 30 thou taller than a 173, probably would make them sit right at deck height!