1.9 to 2.0 upgrade

[Bud K]

I am rebuilding my '71 1.9 GT engine with 2.0 pistons, 2.0 valves, and a 'Combination' solid lifter camshaft all from OGTS. I want a streetable, autocross car to run on pump gas. My machinist wants to know if I want to deck the head/block to get more compression. I saw the articles about the problems with camshaft timing and would be willing to tackle that issue. So, here are my questions.

How much decking of the block/head should go for?
How much compression would be reasonable?
Where do I find an affordable, adjustable camshaft gear so I can do some tinkering and maintain low end torque?

Bud K

[hrcollinsjr]

Originally Posted by Bud K My machinist wants to know if I want to deck the head/block to get more compression. I saw the articles about the problems with camshaft timing and would be willing to tackle that issue. So, here are my questions. How much decking of the block/head should go for? How much compression would be reasonable? Where do I find an affordable, adjustable camshaft gear so I can do some tinkering and maintain low end torque? Bud K

If want to deck the block as much as possible you will need to install the pistons to see how far down in the block they are. The machinist will probably make a recommendation has to how much clearance to leave. If you rev the engine fairly high, rod stretch may come into play or the thickness of the head gasket if your really looking for max. gains in compression. Do a search for head milling especially angle milling of the head. When all of this is done you'll need to check valve to piston clearance, just in case, and possibly cut or modify the valve reliefs already in the piston tops. Do your searching on this site for Opel specific info. There should be lots of info already here discussing these topics already.

HTH,
Harold

[anastosmotors]

When you deck your block or cylinder head your valve timing change
I use an adjustable cam sprocket to degree my cams. (Kent Performance Cams Ltd)
You can mill your cylinder head no more than 70 thousands.
Pete

[hrcollinsjr]

I wouldn't recommend trying to get the maximum compression from a street engine that you want to be reliable. The closer you are to the limits of compression and clearances the more you had BETTER know what you are doing because there is a LOT less room for error. Not saying that you can't study up on it and with a good machinist make it work but how much hp do you stand to gain? What IF you're calculations are off a few thousandths and you tear something up. With a racing engine you push the envelope if you want to be competitive and when you go too far you step back and analyze what you did wrong and try again. I don't have that kind of money so I build something relatively safe.

Harold

[wrench459]

Originally Posted by Bud K How much decking of the block/head should go for? How much compression would be reasonable? Where do I find an affordable, adjustable camshaft gear so I can do some tinkering and maintain low end torque? Bud K

With the 95mm pistons you should be in the high 9's
BUT that all depends on the deck height of the block and the head cc's along with the headgasket thickness.

I would use a custom cam grind where you can order the advance ground in ahead of time. Then a simple chevy offset bushing to dial it in. Yes I'm cheap!