differences between opel 1.9 engines from 69 to 75

TB_6230 · 11-18-2003

What are the differences between opel 1.9 engines from 69 to 75?
Steven

BQS4 · 11-19-2003

The earlier motors (69-71?) had hi-compression pistons (9:1) and solid lifters. Then the compresson ratio was dropped for the 72-75 motors (7.6:1) and hydralic lifters. Then in 75, only, F.I. was used instead of a solex carb. You can tell the difference between the hi-comp and lo-comp pistons, by the fact the hi-comp pistons have 2, 1/2 moon valve reliefs cut in the top, whereas the lo-comps have a dish in the entire top of the piston.

Long-gone · 11-19-2003

Is there anyway to tell the differance without pulling the head.

greensmurf20 · 11-19-2003

you can pull the starter and look at the casting numbers on the block, which will tell you if the the high comp or low comp motor, or what most people do i just pull the plugs and have a look inside when the piston is at TDC. 68-70 had high comp pistons, solid lifters and forged crank, 71 and up had dish pistons, cast crank, hydrolic lifters, 75 switched to fuel injection.

mjewell · 11-20-2003

hello all.

i just bought a '72 gt, and i'm wondering about the difference in engines between the early and late models. can one put hi-top pistons (9:1) in a 72 block? would i have to change to an early cam and lifters?

also, are there any real performance differences between hi-comp and low comp? both 1.9 liter engines, right?

thanks for any help someone may provide.

mike

greensmurf20 · 11-20-2003

blocks are the same...
Early model engines:

forged crank and rods
flat tops
solid lifters
3 cam bearing camshaft

Late model engines:
cast crank
dish pistons
hydrolic lifters
4 cam bearing camshaft

far as i can remember, they are damn near identical outside of these factors.

kwilford · 11-20-2003

Aside from the obvious, most parts are interchangeable.

The obvious? Well, don't put a 3 bearing cam in a 4 bearing head, as the empty bearing race will dump all the engine oil pressure. But I believe you CAN do the opposite, in a pinch. And I believe you CAN use the three bearing cam in a 4 bearing head if you remove the empty bearing and install it with the oil hole intentionally misaligned. And beware of using a solid lifter cam with hydraulic lifters, as the ramp-up is much steeper. The opposite might work, but why would you?

Pistons are interchangeable, and it's VERY desirable to get the flat-top pistons. I believe that the difference in advertised horsepower was 102 HP down to 76 HP. Even factoring in advertising exaggeration, you're looking at a 25% increase with just HC pistons. So long as the rest of the engine is up to snuff. It won't help to have the flat-top pistons if your cam is worn flat, or you have burnt valves, or the carb is flooding (spelled Solex), or ....

I believe the heads are interchangeable, and you can even use a later ('72 and later) head gasket with the two extra (12 in total) bolts. Preference seems to use the '71 head, which has the 4 bearing cam but is less prone to cracking than the later flame hardened valve seats (get stelite seat inserts installed).

There are a couple TERRIFIC threads on the topic of engine performance. Try:

http://opelgt.com/forums/showthread....&threadid=2305

and have a "search" around.

HTH

11-18-2003	#1 (permalink)
TB_6230 Opeler Join Date: Jul 2003 Location: Pleasant Hill, MO Posts: 53 Classified Rating: 0% (0)	Unanswered: differences between opel 1.9 engines from 69 to 75 What are the differences between opel 1.9 engines from 69 to 75? Steven

11-20-2003	#5 (permalink)
mjewell Opel Junkie Join Date: Nov 2003 Location: kansas, gardner, kansas city Posts: 116 Classified Rating: 0% (0)	engine differences hello all. i just bought a '72 gt, and i'm wondering about the difference in engines between the early and late models. can one put hi-top pistons (9:1) in a 72 block? would i have to change to an early cam and lifters? also, are there any real performance differences between hi-comp and low comp? both 1.9 liter engines, right? thanks for any help someone may provide. mike

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11-19-2003	#2 (permalink)
BQS4 Southern Red Neck Join Date: Mar 2002 Location: Snellville, GA Posts: 5,058 Classified Rating: 0% (0) Provided Answers: 1	The earlier motors (69-71?) had hi-compression pistons (9:1) and solid lifters. Then the compresson ratio was dropped for the 72-75 motors (7.6:1) and hydralic lifters. Then in 75, only, F.I. was used instead of a solex carb. You can tell the difference between the hi-comp and lo-comp pistons, by the fact the hi-comp pistons have 2, 1/2 moon valve reliefs cut in the top, whereas the lo-comps have a dish in the entire top of the piston.

11-19-2003	#3 (permalink)
Long-gone Opeler Join Date: Jul 2003 Location: Troy Al. Posts: 17 Classified Rating: 0% (0)	Is there anyway to tell the differance without pulling the head.

11-19-2003	#4 (permalink)
greensmurf20 OPEL-LESS!!! Join Date: Mar 2003 Location: Gobles michigan 49055 Posts: 2,110 Classified Rating: 0% (0)	you can pull the starter and look at the casting numbers on the block, which will tell you if the the high comp or low comp motor, or what most people do i just pull the plugs and have a look inside when the piston is at TDC. 68-70 had high comp pistons, solid lifters and forged crank, 71 and up had dish pistons, cast crank, hydrolic lifters, 75 switched to fuel injection.

11-20-2003	#6 (permalink)
greensmurf20 OPEL-LESS!!! Join Date: Mar 2003 Location: Gobles michigan 49055 Posts: 2,110 Classified Rating: 0% (0)	blocks are the same... Early model engines: forged crank and rods flat tops solid lifters 3 cam bearing camshaft Late model engines: cast crank dish pistons hydrolic lifters 4 cam bearing camshaft far as i can remember, they are damn near identical outside of these factors.

11-20-2003	#7 (permalink)
kwilford Über OpelGT.com Moderator Join Date: Mar 2002 Location: Calgary, Alberta, Canada Posts: 3,773 Classified Rating: 0% (0) Provided Answers: 1	Aside from the obvious, most parts are interchangeable. The obvious? Well, don't put a 3 bearing cam in a 4 bearing head, as the empty bearing race will dump all the engine oil pressure. But I believe you CAN do the opposite, in a pinch. And I believe you CAN use the three bearing cam in a 4 bearing head if you remove the empty bearing and install it with the oil hole intentionally misaligned. And beware of using a solid lifter cam with hydraulic lifters, as the ramp-up is much steeper. The opposite might work, but why would you? Pistons are interchangeable, and it's VERY desirable to get the flat-top pistons. I believe that the difference in advertised horsepower was 102 HP down to 76 HP. Even factoring in advertising exaggeration, you're looking at a 25% increase with just HC pistons. So long as the rest of the engine is up to snuff. It won't help to have the flat-top pistons if your cam is worn flat, or you have burnt valves, or the carb is flooding (spelled Solex), or .... I believe the heads are interchangeable, and you can even use a later ('72 and later) head gasket with the two extra (12 in total) bolts. Preference seems to use the '71 head, which has the 4 bearing cam but is less prone to cracking than the later flame hardened valve seats (get stelite seat inserts installed). There are a couple TERRIFIC threads on the topic of engine performance. Try: http://opelgt.com/forums/showthread....&threadid=2305 and have a "search" around. HTH

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