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What could one bore out a grey 6 cyl, I thought 0.060 was the go for everything to the max.
On one forum, the old racing dudes are saying only 0.030 for grey and only 0.040 for HJ-X-Z 202 and only 0.030 for blue 3.3L Saying that the bores get to flimsy to make power over that for racing.
Sating that the first of the HQ 202 were the best for meet in the bores.
I thought Repco reco engines were all taken out to 0.060 all the ones I have see were, in just crappy stock reco engines.
They say that only 202 eng split from reving to 7000RPM and 186 did not split across the left side and that the EFI 3.3L block was the best 202 to use as they do not split ?
Has anyone seen a 186 split, I have not seen one do it.
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Hi taxis went out to .080 over......for 202
186 would to 192
Tony....
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186-192 is +0.060". It is the 179's taken out to 192 that are 1/8" overbore.
Apparently blue 173's can be bored to 186/202 bore size which is 1/8" also. |
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Maybe the blue 2.8L is the same block casting as the Blue 3.3L as I think the main bearings are the same size in them ? the red are not.
So maybe it could be true you could drop a 3.3L crank in a blue 2.8L block and bore it out 0.120 to fit a stock 3.3L piston and maybe go 0.060 more as well ?
The 179 block is the same block casting as the 186, so a 179 could go 0.120,
But as to a 173 red it does not and could only go 0.060 to a 179.
I think they do not like to make cyl bores to thick for the reason that if it's to thick it runs hotter as well or if it's to thin is runs to hot. So I don't really think the blue 2.8L is the same block casting some how.
It could be, but if that is so, why did they make a 173 red block as so.
The 149 could only go 0.060 as did the 161.
I think the 138 red is the same casting as the 130 red, just that they had the meat to bore a 130 to a 138, so what's that a bit over 0.060 to make a 130 a 138 ?
The old grey motor had a few different block changes through the years not only 132.5cid to the big 138 grey monster, so that = about 0.060 more.
So could a 132.5 go out as far as the 138 ones ?
Blue and black and the EFI 5.0L V8's can go 0.060 no problems.
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I think 173 went to 202 journal size in the early-mid 70's, only the early ones have the old smaller mains. A few guys on the Torana forum have taken the blue 2.8 out to 202 bore size which is where i'd heard it.
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Did they take the 2.8L blue out to the standard 186, 202 bore ? not the plus 0.060 over a 186, 202 bore ?
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I don't think that a 173 casting would go to 186/202 +0.060" safely. Unless the core centres were all near perfect (very unusual) some walls would end up being too thin.
Getting back to the Grey motors for a sec, this was the foundation of the old 'Canadian Block' myth. The early blocks (FX, prior to eng No. 37832) had thicker walls, due to old style casting techniques. Speedway & sedan racers in the 50s & 60s used to scour the wrecking yards of the day in search of these thicker walled blocks to achieve maximum available overbore size for their race motors. If they were well cast (in terms of core centering) 132.5 + 3/16" (0.1875) (or more) was achieved.
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quote:
Originally posted by Dr Terry
I don't think that a 173 casting would go to 186/202 +0.060" safely. Unless the core centres were all near perfect (very unusual) some walls would end up being too thin.
Getting back to the Grey motors for a sec, this was the foundation of the old 'Canadian Block' myth. The early blocks (FX, prior to eng No. 37832) had thicker walls, due to old style casting techniques. Speedway & sedan racers in the 50s & 60s used to scour the wrecking yards of the day in search of these thicker walled blocks to achieve maximum available overbore size for their race motors. If they were well cast (in terms of core centering) 132.5 + 3/16" (0.1875) (or more) was achieved.
Dr Terry
this is were a good machinist comes to play, even with a relatively poor block with core shift, they machine slightly over centre to make it not quite as bad like we do with stinking Cleveland's, spesh on no.5 cylinder thrust side, its always thin with the sonic tester before a bore. but you still cant go past a big block, you can bore a 454 GEN1V 0.120" without a drama
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quote:
Originally posted by we wreck 81837s only
but you still cant go past a big block, you can bore a 454 GEN1V 0.120" without a drama
I'll have to agree we wreck, & the 307 & 283 SBC were the same. I've had quite a few of these go out from 3.875" to 4.00" (+ 0.125") resulting in std 327ci & 302ci motors respectively. Dr Terry |
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I've had a few 307's at 4" too. The one in my mate's HK was stroked to 3.48" (350 crank) and bored to 4.040". Used to pull sub 13sec 1/4's with a Muncie in it, and copped a flogging for 15 years until a rod bolt broke. I also remember John Cain telling me that half the speedway motors he built in the 70's were 307's bored and stroked to 350 and even those 366-ish strokers they used to build with an offset ground 350 crank and SJ rods. Those things held together pretty well too at big hp. |
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quote:
Originally posted by Dr Terry
I don't think that a 173 casting would go to 186/202 +0.060" safely. Unless the core centres were all near perfect (very unusual) some walls would end up being too thin.
Getting back to the Grey motors for a sec, this was the foundation of the old 'Canadian Block' myth. The early blocks (FX, prior to eng No. 37832) had thicker walls, due to old style casting techniques. Speedway & sedan racers in the 50s & 60s used to scour the wrecking yards of the day in search of these thicker walled blocks to achieve maximum available overbore size for their race motors. If they were well cast (in terms of core centering) 132.5 + 3/16" (0.1875) (or more) was achieved.
Dr Terry
That grey motor 7400479 is a casting number and the block and I seen it on was engine number 1056 the 55th Aussie block cast and it has GMH casting on the block. The ones before eng number 1001 had CWC cast on the blocks.
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