1.9 liter rebuild (need help)

[victrolakid]

My father is the original owner of a 1972 Opel Gt and it was just give to me as a present for my 19th birthday. the car that my dad gave me looks great, but there was some sort of major mechanical problem, and I wasnt getting any compression in the third cylinder so I took it to the mechanic, and they said that I need a complete rebuild. So here is were i start my my questions, First, I am having major problems finding a machine shop that will redo my engine. I am in the San Fernando valley So-Cal , if anyone knows of any reputable machinist that would do a 72 opel in that area could you please let me know. my next question is as long as i am having the motor rebuilt and it is all going to be apart what kind of preformance mods can I make, that wont cost me to much money, as I am young and dont want this project to put me in a huge debt. If somone that is more knowledgable than me on this forum could please help me I would truly appreciate it.
Sincerely
Sterling "A complete novice at this point"

[wrench459]

First off WELCOME to the site glad to have you onboard.
Theres a major car show this weekend so don't be surprized if there very little feedback from your post.

[opelwasp]

For less than the cost of a complete rebuild, why don't you just call Opel GT Source and get a good used 2.0L? All the accessories will bolt right on.

[victrolakid]

Well the thing is, my dad is the original owner,and he wants me to keep it all original for all intents and purposes. he said that I can change the internal parts like i am thinking about getting a cam, 2.0 valves, and new lifters. I have another opel gt that has a 2.0 in it but I am thinking that I am better going with the rebuild because then it will be like a new engine Vs. swapping the 2.0 liter into my dads car and then it wont be stock and i dont know the condition of my 2.0. But I would like to know what kinda preformance parts can go into the 1.9 as long as I am rebuilding it and it will be apart. I would like to thank you for your thoughts.

[RallyBob]

But I would like to know what kinda preformance parts can go into the 1.9 as long as I am rebuilding it and it will be apart. I would like to thank you for your thoughts.

The sky's the limit...or at least your wallet is.

You can always bore the 1.9 out for new pistons....at least .020" to straighten the bores. For the same money, .040" overbore will net you 1938 cc's (stock is 1897 cc's). While you're at it, you might as well install flat-top pistons in there, same as was used by the factory on all pre-1971 engines and rated at 9.0:1. The compression ratio will increase, higher than your 1972 engine (rated at 7.6:1). Opels have thick cylinders, so another option is to order some Opel 2.0 litre pistons and punch the block out 2 mm's (.080") to increase the displacement to 1979 cc's. Compression is also increased with these pistons.

The real key to making any good power in an Opel is really the headwork and the camshaft. Although that said, you need the complimentary components (intake work, carburetor, exhaust, and ignition) to fully realize the power gains the headwork can offer. Without going 'crazy', you can easily fit 2.0 intake valves into the Opel 1.9 head. This works better than fitting the intakes and exhaust valves from the 2.0, as the 1.9 head has imbalanced airflow in stock form (high exhaust flow). Alternatively, you could fit the larger 2.2 intake valves and the 2.0 exhaust valves and improve the power potential a bit more. There's an article on how to perform 'do it yourself' porting here somewhere that some schmuck wrote I think.... You can read the condensed version above, or the longer, dragged-out original version here.

For a street engine, it's probably wisest to stick with hydraulic lifters, and maybe install a mild performance cam that can utilize the stock valvetrain parts (for simplicity and cost savings).

The best bang-for-the buck IMO, is porting the intake manifold and fitting a Weber 32/36 DGV if there's not already one on the car. Do a search as there's a bunch of photos and info on this procedure on these forums. I'd scan through the 'performance' section carefully, there are a lot of good ideas here.

If you can procure a 1975 Opel 'Sprint' exhaust manifold, and have a custom 2" exhaust system bent up, you'll have excellent results for a street engine. Good torque, good power, and economy retained. Bigger is NOT better in this case. Most headers out there are junk, so unless you stumble onto a custom small-tube 4-1 equal length header for cheap, resist the temptation to buy any commercially available headers out there.

A good ignition is also paramount. There are the inexpensive ones such as the Pertronix which work quite well but don't 'add' any power to the engine. They just eliminate misfires and produce a better running engine. A Crane XR-700 is a nice step up, and from there a Crane XR-3000 is better yet. Or even a full blown Compufire DIS-IX ignition if you want to spend the money. But don't expect miracles from an ignition, there are other places to spend your money to make power.

Now for the 'reality check'. It will not be cheap. Even if you assemble it yourself, and get good prices on the parts, expect to spend $1500-$3000 depending on your decisions. And as far as power, yes, it's a bit depressing to see the final numbers! A good running 1972 Opel should make about 47-55 hp to the rear wheels (they were rated at 75 hp at the crank). With 2.0 pistons, some head milling, bigger valves, a modest cam, intake porting, Weber carb, better ignition and exhaust, you can make 75-85 HP at the rear wheels depending on the variables chosen and the tuning. Doesn't sound like much for the money, huh? BUT, it's the percentage that counts, and if you can improve the power from 50 hp to 75 hp, hey...that's 50% more power! The car will be a LOT faster because of it.

HTH,
Bob

[victrolakid]

Bob that is a lot of info, and I appreciate it. The info you provided does lead me to ask the following questins, first about what kinda price difference would I be looking at between having machined to the 1.9 vs. 2.0 , next question is are new flathead pistons expensive, and lastly if I do bore the engine out 2.0 what other than the pistons would I have to change and would it be a costly proposition to change the parts to make the engine a 2.0

[Gordy]

I had my 1.9 bored to accommodate the 2.0 pistons. I needed new pistons anyway since my rings had cracked and wore down the piston grooves. They are not cheap, but the price is the same for 1.9 oversized or 2.0 pistons. Look to spend $400 from OGTS for the set of 4 with rings.
I must say that in 37 years of Opel ownership, my 1970 GT with the 2.0 with sbc valves and all the add ons (Bob L. intake, 38 Weber, Cam Techniques cam, header) and the Getrag 5 speed is by far the best driving Opel I have ever driven. You can drive on the expressway at 80 mph and be turning only 3500 rpm. It makes me do the math in my head as I'm driving and the engine is not even breathing hard yet, just what the top end would really be!? I'm thinking 140mph at about 6200 rpm.
2nd gear is a killer and will take you up to 50 mph in a blink and 3rd gear can be used to city drive at 30 mph or hit 80 from the toll booth.

[Paul]

Bob that is a lot of info, and I appreciate it. The info you provided does lead me to ask the following questins, first about what kinda price difference would I be looking at between having machined to the 1.9 vs. 2.0 , next question is are new flathead pistons expensive, and lastly if I do bore the engine out 2.0 what other than the pistons would I have to change and would it be a costly proposition to change the parts to make the engine a 2.0

If you purchase 2.0 pistons from OGTS, then you will have to buy a head gasket that is properly sized for the extra bore too. OGTS can sell you that as well. I suggest you give them a call, they sell everything you need and give great advice for free.

The real trick is having the machine shop do the work correctly for an Opel engine and not the way they'd do it for Chevy's and Ford's. Print out the How-to articles RallyBob has written and take it with you to the machine shop....

GL

[GTJIM]

Welcome to the site - plenty of info here ... just click on the OpelGTcom Lite on the left hand side of the Home page and you will see an index for the site.

Here is a link to one of the most informative ... and entertainin ... engine rebuild threads here:

http://www.opelgt.com/forums/6a-engi...e-rebuild.html

You don't need to use Chevy pistons which require modifications if you use +.040" 1.9 pistons or 2.0 Opel pistons from OGTS:

Opel GT Source --- Welcome

[victrolakid]

First off I want to thank everyone that has helped me out with their suggestions. Second is another question, the question is this car is a automatic, so i am wondering if I do the preformance mods, will I be limited by the transmission.
Thanks again.
Sterling

[GTJIM]

We have just been 'discussing' GTs with auto transmisions.

They are tough little gearboxes and will take considerably more power than the 1.9L motor puts out - but you must not use too 'hot' a camshaft.
Just like any auto trans they rely upon low end torque and soak up a bit of power.

So the best route to take is increasing the engine displacement to increase low end torque. That means a 2.0L motor with a 'combination' or 'torquer' cam unless you can afford to go to a 2.2L motor ... or a 2.4L

The Master Rebuild Kits are still available and the trans can be upgraded to be made even stronger as it was used in 6 & 8 cylinder Holdens plus Rover V8's. These had 4 or 5 clutches in the low gear and an extra pinion in the planetry gear set.

Don't worry too much about keeping the motor 'original' as GTs never had 'numbers matching motors' - though it is possibleto find out from the Factory what the original engine number was. There is no tie-up between the VIN number and the engine number other than they were from the same period of production.

[victrolakid]

I have another question for all of you knowledgable people, if I go to sell the vehicle several years down the road would be worth more being done to the original 1.9 specs or would it be worth more boring it out to the 2.0 and putting on the hige preformance parts?

[deaner]

As mentioned before, You want torque. And there is nothing like a bigger Engine. You can build your 1.9 to be a very respectable performer. Being an automatic you don't want too big of a cam. You want to keep it drivable. Do a little research on what works and doesn't for your driving conditions. And plan it out. Everone has given you great advice. Listen to them and use what works for you.

Where in So. Cal. are you? I know some good machine shop's, mostly in San Diego County. It's best to find a machine that will work with you. Go in armed with info and spec's. (you can find it all here in the archives). Just use the search feature. HTH

[victrolakid]

I am in Los Angeles county in the san fernado valley so I am thinking that san diego county would be kinda far. Also I really do appreciate all of the good info that everyone has helped me to get. Deaner, I am thinking about boring my engine out to the 2.0, but you are saying that the 1.9 can be a respectable preformer, what kind of mods would I need to get the preformance out of the 1.9, and is it worth the price to bore it out or would i be better off price wise to just rebuild the 1.9 with the preformance parts that you will hopefully tell me about.

[opeletti75]

welcome to the sight you can also lighten and balance the flywheel and clutch asembly to help it along and a electric fan helps as well or the five blade fan is lighter too

[deaner]

welcome to the sight you can also lighten and balance the flywheel and clutch asembly to help it along and a electric fan helps as well or the five blade fan is lighter too

Remember he has an automatic trans.

[RallyBob]

First off I want to thank everyone that has helped me out with their suggestions. Second is another question, the question is this car is a automatic, so i am wondering if I do the preformance mods, will I be limited by the transmission.
Thanks again.
Sterling

It limits the cam choices for sure, unless you use a high stall torque converter. But it is a strong transmission as Jim mentioned, so no worries there. When you get to that point when you are trying to decide on a camshaft, let us know and you can be pointed in the right direction.

[deaner]

The sky's the limit...or at least your wallet is.

You can always bore the 1.9 out for new pistons....at least .020" to straighten the bores. For the same money, .040" overbore will net you 1938 cc's (stock is 1897 cc's).

HTH,
Bob

Bob, what was the size of your C&R 2.0 forged piston set to increase the 1.9 Opels? I have that setup in my Manta, they were Venolias.

[RallyBob]

Bob, what was the size of your C&R 2.0 forged piston set's, that were sold to increase the 1.9 Opels? I have that set up in my Manta, They were Venolia Pistons.

Those were 3.75"/95.25 mm.

Bob

[victrolakid]

Bob just a question, at what point do I start looking for the cam shaft, and can i still ligten the flywheel or is that not do-able because it is an automatic? If I do decide to bore the engine out what pistons do you recomend? Also I am still really in need of a good machinist close to the san fernado valley, so if anyone could help me with that it would really be appreciated.