What to do if Your Head or Block is Milled? (was "what to do with a decked head?")

[wrench459]

Paul I messed up big time with the small stem valves head
and I'm tryng to find a solution
Thanks for your input

[jeff denton]

Rally Bob's recommendation is to angle mill the head .080" on the spark plug side, zero or minimal on the manifold side. The quench area is not affected, only the volume of the chamber, and the timing of the camshaft. To affect the quench area you mill the block to give a maximum of .005" of piston sticking up above the deck. This is to increase CR, but I know the reason you are asking. This might work, it's worth a try. Yes you must spot face the bolt holes. No big deal. Be sure to grind some more room around the chain as mentioned before, you will appreciate this later, believe me!
The dimension of the head, from the deck to the valve cover, is unpublished and we need to keep it that way, OK? It comes up every time we discuss this. This is not just me asking, it was asked of me by several of the best known Opel racers. You know, the famous ones, er, the ones you see on TV sometimes.
I hope this will fix your head. If not, the bigger gasket will, but then we'll have to talk you into going to the bigger bore to match! And the 2.2 stroke... oh and longer stronger rods... and the light flywheel... where does it stop?

[imamachine]

Ugh, several months ago I bought a rebuilt short block and an old head with "bigger" valves and a "reground" cam. I'm planning on reusing the timing chain. My problem is that I have no idea how much of the block was milled, I had the head decked and I don't know how much came off at that point or how much may have been taken off previously, and I don't know anything about the cam. My head hurts after reading the 5 pages of previous posts...can I bolt this thing back together or is that just a bad idea? Where do I start?

[hrcollinsjr]

I'm planning on reusing the timing chain.

Timing chains are CHEAP! Unless that thing has almost no miles on it I would think about a new one. I lectured a student on the evils of trying to save a dollar by using the old timing chain set in a Ford. After his had jumped time. I did the same thing later on an Opel because I wasn't going to keep it that long. That darn car ran and revved sooo well! I was lucky when it broke, I was able to coast all the way into my parking spot in front of my apartment.

NEW CHAIN, $20+/- ?

Harold

[hrcollinsjr]

Ugh, several months ago I bought a rebuilt short block and an old head with "bigger" valves and a "reground" cam. I'm planning on reusing the timing chain.

If the pistons are dished, the lower compression ones, then I don't think that you will be satisfied with the performance of the bigger valves and "reground" cam. I know I still haven't answered your initial question about determining how much has been taken off of the block & head surfaces.

Harold

[Tru-Craft]

After reading this for a million times..
Whats ya'lls thoughts on angle milling?
Whats the compressed dia. of a stock 1.9 headgasket?
The same question for the 2.0 gasket this I really need to know that one.
Can you angle mill the head .040
and then flat mill to get the quench back flat?
I don't like spot facing the head bolts holes in the head.

Take a look at this thread.
http://www.opelgt.com/forums/opel-en...-1-9-head.html
Lyle

[Paul]

I'm planning on reusing the timing chain.

Bad idea... new ones are available from many sources.. OGTS, RockAuto.com, Parts America, Napa... etc

. My problem is that I have no idea how much of the block was milled, I had the head decked and I don't know how much came off at that point or how much may have been taken off previously, and I don't know anything about the cam. My head hurts after reading the 5 pages of previous posts...can I bolt this thing back together or is that just a bad idea? Where do I start?

Since you don't have any hard information about whats been done prior, about the only thing you can do is assemble the engine with a new chain, old head gasket and go through the process of checking the valve to piston clearance and degreeing the cam. This will tell everything you need to know. I know it takes a little time and can be a PITA if you are just learing how to do it and have to buy/borrow a few special tools. But you'll be more than happy that you took the time to do it right the first time... Believe me, the cost of just throwing it together and having to tear it back down will more than pay for the tools to do it right.... And you get to keep the tools for next time!!!

[jeff denton]

What you've got is a modified engine. Without knowing just exactly how it's been modified, to assemble it you have to check everything. Everything as in piston height, valve clearance, valve timing.
It's just the basic engine building/blueprinting procedure.

[imamachine]

10-4, thanks everyone for the numerous replies.

[P.J. Romano]

Here it is. Adjustable sprocket from Kent Cams, U.K. Perfect match to my angle-milled cylinder head.
Expensive? Yes.
Could I do it without? Probably.
Does it make me happy? Hell, yes! Can't wipe-off stupid smile the whole day.
Opelitis, the worst form...

[hrcollinsjr]

Adjustable sprocket from Kent Cams, U.K. Perfect match to my angle-milled cylinder head.
Expensive? Yes.
Could I do it without? Probably.

P.J. you can add to your list of things to do, the limits of how much you can retard or advance your cam timing without having clearance issues. It's always something isn't it? It does look purty though.

Harold

P.S. A friend said he threw his in the river after failing to tighten the bolts enough and he destroyed an engine. Wish I had been there when he threw his little tantrum.

[RallyBob]

Wow, I just re-read this entire thread. I miss the days when we got into technical discussions like this without butting heads! Just an exchange of ideas, and people helping other people....

[asdasc]

This is such a great thread.

By the way, I really mean it when I say that this is the year I assemble all those parts in the garage, and make a motor. I have already spent 99% of the money, I just need to put it all together.

Wish me luck.

[tekenaar]

Here's the Dealer Opel Team cam timing method, which Jeff recently 'rediscovered' on his own. Note there are two additional dowel holes, which allows for three total possible cam timing positions. I added the two other timing marks on the outer perimeter for easier identification. Hope this clears things up a bit for those who wanted to know a bit more about this method.

Bob

. . . looking in on this thread, but I know for a fact that Toyota had been using this idea on their stock, chain-driven, SOHC engines at least since the early '70s, specifically to allow for chain stretch cam timing adjustments when rebuilding the engine. It's covered, complete with pics, in their FSMs even . . . from personal experiences with a '71 Corona Wagon (18RC) and an '80 Cressida Sedan (4/5-ME) . . .