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Discussion Starter · #1 ·
can anyone help me with the stock engine specs for a 1.9 gt engine?
bore ,stroke,rod length,pin size,deck heigth. also i keep reading about
making a 2.0 out of a 1.9 using stock parts please help :confused:
 

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Bore: 93 mm
Stroke: 69.8 mm
Rod length: 128 mm
Pin dia.: 23 mm
Deck height: 208 mm


HTH,
Bob
 

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Factory Upgrade

IN 1979 Opel (and Vauxhall in UK) upgraded their 1.9L motor to 2.0L by increasing the bore to 95mm (3.74"). Standard 2.0L pistons are available from www.opelgtsource.com

Since the bore is very close to the standard 3.750" of the 265 Chevrolet motor and the piston pin height very similar, pistons for this engine are often used for a 1.9L to 2.0L conversion. There are obstacles to overcome such as the Chevrolet pin size being a larger 0.927" (23.56mm). Custom hi-performance pistons are available quite easily for the Chevy motor too and can be sourced with smaller (Ford!) pins at 0.912" (23.16mm) but these are still slightly bigger than the standard Opel pins which are 23mm even.

Later Opel/Vauxhall increased the size of the motor to 2.2 L by using a longer stroke crankshaft and finally reached 2.4L with yet another increase in stoke but both still with the 95mm bore. The external dimensions of all the motors from 1.5L through to 2.4L are similar and have the same bolt patterns for bellhousing. head and front cover - so all the parts can be interchanged with appropriate modifications.

These motors are known as Cam-In-Head (CIH) Opel motors due to the unique positioning of the camshaft. There are also six cylinder versions used in larger Opel/Vauxhall cars too. If you enter "Opel CIH" in your web search engine it should find some interesting information - particularly conversions done by David Jackson in the UK. Worth a look!
 

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Travis said:
69.8mm?

-Travis

Yea, go figure. Don't know why Opel didn't just make it 70 mm.

93 mm x 69.8 mm = 1896.57 cc's (listed as 1897 cc's)
93 mm x 70 mm = 1902.01 cc'c
 

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Discussion Starter · #6 · (Edited)
Thanks For The Info. I Own An Automotive Machine Shop In Northern California And Have A Customer That Wants To Upgrade His 1.9 But Even With All My Sorces For Engine Info The Opel Stuff Is Lacking. I Have Not Disassembled His Engine To Measure Any Of The Components. Can You Tell Me What The Max Over Bore Is On The 1.9 ? Without Causing A Over Heating Condition. Also Is There Enough Material At The Pin End Of The Rod To Bore It For A .927 Chevy Pin? CAN YOU TELL ME WHAT THE COMPRESSION HEIGTH IS ON A STOCK 1.9 AND ARE THE VALVE RELIEFS IN THE 265 PISTONS IN THE CORRECT POSITION?

Thanks Aaron
 

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RallyBob said:
Yea, go figure. Don't know why Opel didn't just make it 70 mm.

93 mm x 69.8 mm = 1896.57 cc's (listed as 1897 cc's)
93 mm x 70 mm = 1902.01 cc'c
It is actually 2.75" metrificated!
69.8mm = 2.748" - I suspect the stroke is actually 69.85mm = 2.750"
70mm = 2.755"
 

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Bore and rod small end

ENGINE MAN said:
Thanks For The Info. I Own An Automotive Machine Shop In Northern California And Have A Customer That Wants To Upgrade His 1.9 But Even With All My Sorces For Engine Info The Opel Stuff Is Lacking. I Have Not Disassembled His Engine To Measure Any Of The Components. Can You Tell Me What The Max Over Bore Is On The 1.9 ? Without Causing A Over Heating Condition. Also Is There Enough Material At The Pin End Of The Rod To Bore It For A .927 Chevy Pin?

Thanks Aaron
The 2.0+ blocks are the same as the 1.9, except for bore, 95mm vs. 93mm. 1.9 block (93mm) can be bored safely to 96mm (= .040" over 2.0 block). 95mm and over bore (2.0) must use 2.0 head gasket, anything under that uses the 1.9 head gasket. Gasketwise, everything else is the same.

There is enough meat in the Opel rod small end for a "pin-fitted" .927 Chevy, but not for "floating" it (no bushing).
 

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Actually Jim, it is listed as 2.748", not 2.75".
 

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ENGINE MAN said:
CAN YOU TELL ME WHAT THE COMPRESSION HEIGTH IS ON A STOCK 1.9 AND ARE THE VALVE RELIEFS IN THE 265 PISTONS IN THE CORRECT POSITION?

Thanks Aaron
Opel valve reliefs are not symetrically located, but unless you are running a very large cam and large valves, the standard 265 Chevy reliefs should be okay.

The compression distance seems to vary (Opel themselves lists various compression height pistons available for the same engine), but I have seen an average of 45 mm (1.7716") for the 1.9. This is typically .004" to .007" below deck for the piston.
 

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PIn Height

Opel pin height is 45.1mm = 1.776"
Chevy 265 pin height is 1.805"

Yes the Opel rods are big enough on the small end to be opened out to .927" as long as the "pressed pin" is retained and nothing fancy like bushing them is done. Use the Chevy press fit specifications.

People cheerfully bore 1.9L blocks out to 2.75" for the Chevy pistons but I guess if the water jacket is badly rusted then problems with cylinder walls can eventuate.

I am using 305 Chevy pistons myself but this involves stroking the crank and using non-Opel con rods - Dodge Neon actually though 2.3L Ford can be used too. The point being the notches in the 305 pistons are near to spot on for position - though as always with non-stock components a lot of checking is mandatory.

Greensmurf20 has a thread called "Economical CIH Rebuild" that covers the trials and tribulations of enlarging and Opel 1.9L to 2.0L with Chevy 265 pistons and Nobody has a thread "2.0L Rebuild" using forged, pop up 3.75" pistons that provide some very good reading. There are heaps of other engine info in the Performance Engine section of this site too.

Also I cannot recommend too highly "Opel GT Owners Workshop Manual" by Brookland Books OWM 727 ISBN 1 870642 864 Which correctly covers the camshaft and distributor timing procedures for the CIH Opel motor and has some excellent drawings of the motor in it. The book is often available on EBay - it is dark green with yellow writing and has a GT on the front drawn against graph paper like squares. If you have never timed and Opel 1.9L motor you need this book!
 

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Different strokes

RallyBob said:
Yea, go figure. Don't know why Opel didn't just make it 70 mm.

93 mm x 69.8 mm = 1896.57 cc's (listed as 1897 cc's)
93 mm x 70 mm = 1902.01 cc'c
Same thing with the 3.9 in my Bitter . . . it's usually listed at 90mm stroke (3828cc), but is actually 90.5mm (3849cc). They could've just as easily made the stroke 91mm for 3870cc, but maybe it was a combination deck height and piston availability issue. :confused:
 

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Imagination .....

RallyBob said:
Actually Jim, it is listed as 2.748", not 2.75".
I can imagine the arguments between German Opel and UK Vauxhall engineers and draftsmen over whether the crank pin offset should be 0.001" (NO 0.0254mm) larger or smaller! :) Wonder what the production tolerences actually were ........??
 

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