Under some other topics there were some posts re the uncertainty over the wall thickness of the later 173s. Anyhow, I finally got hold of a couple of blue 2.8's (one of which even had the nice '755 head) and yes, the blocks definitely use the 202 coring. So not only do you get the 202-size main tunnel but you also get about 0.060" additional cylinder wall thickness. Even a 0.060" oversize 2.8 will have 30 thou thicker walls than a virgin 202. All we need now is for someone to unearth a suitable long rod/3.530" piston combo and we'll have the ideal raw material for our little sixes..
I'm not sure if I'm doing the right thing by posting this; the 173's seemed to be the first to go into the simsmetal bins and maybe I should be hoarding what's left. Anyway, if you've got any laying around please don't scrap them..
Which six cyl. block?
Started by
_oldjohnno_
, May 06 2010 08:50 PM
10 replies to this topic
#2
greens nice
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Posted 06 May 2010 - 09:03 PM
nice find, have you dummied a head with bigger valves up on a std bore 173?
is getting over 550" lift going to be a problem?
is getting over 550" lift going to be a problem?
#3
_oldjohnno_
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Posted 06 May 2010 - 09:11 PM
nice find, have you dummied a head with bigger valves up on a std bore 173?
is getting over 550" lift going to be a problem?
No, but I'd imagine most 2.8's would need at least 30 or 40 thou to clean up, and naturally they are going to need slightly bigger valve reliefs than a 202.
#4
yel327
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Posted 07 May 2010 - 07:09 AM
Why wouldn't you just bore them to 3.625"? Is it hard to get decent 202 pistons in STD bore?
#5
yel327
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Posted 07 May 2010 - 04:00 PM
Johnno
I had a look today in the ACL catalogue and found this:
1970's-1980's Cortina 2L, Escort 2L, RS2000, Sierra 2L 4cyl.
STD piston is a 3.5748" (90.8mm). 0.5mm, 1.0mm and 1.5mm oversize available.
This would give you +0.075, +0.095, +0.114 and +0.134" leading to capacities with 202 crank of 196ci, 198ci, 200ci and 202.24ci. Only the 1.5mm oversize is actually oversize on a 202 bore (+0.009").
Comp height is 41.12mm.
Pin size is 24mm.
Standard 202 comp height is 42.164mm so just under 1mm of block decking is required, plus whatever you'd take off to get good quench area.
Standard 202 pin is 22mm so little ends of rods needs a 2mm bore.
The other bonus is I think these engines were modified by Cosworth for the Sierras so there would be some good pistons available, especially for turbo applications.
I also noticed that 4.2L Jaguar 6cyl pistons are the same bore size as 202, and 41.5mm compression height, so awful close to 202. And a Landcruiser F engine piston is a 3.5433" bore with 47mm compression height, so possibly of some use with a shorter rod. Some of the Ford 6cyl pistons are in between 173 and 202 bore sizes but have different compression heights too. The 307 Chev pistons is spot on compression height for a 202 but too big unfortunately.
I had a look today in the ACL catalogue and found this:
1970's-1980's Cortina 2L, Escort 2L, RS2000, Sierra 2L 4cyl.
STD piston is a 3.5748" (90.8mm). 0.5mm, 1.0mm and 1.5mm oversize available.
This would give you +0.075, +0.095, +0.114 and +0.134" leading to capacities with 202 crank of 196ci, 198ci, 200ci and 202.24ci. Only the 1.5mm oversize is actually oversize on a 202 bore (+0.009").
Comp height is 41.12mm.
Pin size is 24mm.
Standard 202 comp height is 42.164mm so just under 1mm of block decking is required, plus whatever you'd take off to get good quench area.
Standard 202 pin is 22mm so little ends of rods needs a 2mm bore.
The other bonus is I think these engines were modified by Cosworth for the Sierras so there would be some good pistons available, especially for turbo applications.
I also noticed that 4.2L Jaguar 6cyl pistons are the same bore size as 202, and 41.5mm compression height, so awful close to 202. And a Landcruiser F engine piston is a 3.5433" bore with 47mm compression height, so possibly of some use with a shorter rod. Some of the Ford 6cyl pistons are in between 173 and 202 bore sizes but have different compression heights too. The 307 Chev pistons is spot on compression height for a 202 but too big unfortunately.
#6
_oldjohnno_
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Posted 07 May 2010 - 09:36 PM
Johnno
I had a look today in the ACL catalogue and found this:
1970's-1980's Cortina 2L, Escort 2L, RS2000, Sierra 2L 4cyl.
STD piston is a 3.5748" (90.8mm). 0.5mm, 1.0mm and 1.5mm oversize available.
This would give you +0.075, +0.095, +0.114 and +0.134" leading to capacities with 202 crank of 196ci, 198ci, 200ci and 202.24ci. Only the 1.5mm oversize is actually oversize on a 202 bore (+0.009").
Comp height is 41.12mm.
Pin size is 24mm.
Standard 202 comp height is 42.164mm so just under 1mm of block decking is required, plus whatever you'd take off to get good quench area.
Standard 202 pin is 22mm so little ends of rods needs a 2mm bore.
The other bonus is I think these engines were modified by Cosworth for the Sierras so there would be some good pistons available, especially for turbo applications.
I also noticed that 4.2L Jaguar 6cyl pistons are the same bore size as 202, and 41.5mm compression height, so awful close to 202. And a Landcruiser F engine piston is a 3.5433" bore with 47mm compression height, so possibly of some use with a shorter rod. Some of the Ford 6cyl pistons are in between 173 and 202 bore sizes but have different compression heights too. The 307 Chev pistons is spot on compression height for a 202 but too big unfortunately.
Thats interesting yel. The Ford pistons look promising; if the rod needs to be bored to suit anyway it'd be nice if it could be offset-bored a little to avoid taking so much off the block deck. What'd be really nice is a piston that matched a 5-3/4" or so rod..
From memory - and I may be wrong here - the Jag pistons have a very pronounced, almost half round dome on them.
#7
yel327
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Posted 07 May 2010 - 10:13 PM
I've got a full ACL catalogue here. What is the difference in length between a Holden rod and 5 3/4"? There were a lot of pistons with the right bore sizes but too small in the comp height. Longer rods and all could be sweet.
#8
_Bomber Watson_
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Posted 08 May 2010 - 01:56 PM
Considering the rods are to short to begin with lets look at that proposition....Custom rods arnt that expensive.
Cheers.
Cheers.
#9
_oldjohnno_
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Posted 08 May 2010 - 03:30 PM
I've got a full ACL catalogue here. What is the difference in length between a Holden rod and 5 3/4"? There were a lot of pistons with the right bore sizes but too small in the comp height. Longer rods and all could be sweet.
The standard rod is 5.25". Anything around the 5.75" to 6" range would be good.
#10
yel327
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Posted 08 May 2010 - 05:47 PM
I've looked at VL and Gemini so far but big end is too big.
#11
_oldjohnno_
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Posted 08 May 2010 - 06:08 PM
Quad 4 rods are available in 5.71" and 5.806" lengths, and use the same big and small end sizes.
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