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Discussion Starter · #1 ·
I've been busier than ever and instead of scattering various threads about, If it's ok With you all I decided to put up a newer thread that included some of the getting back to regular gas and a roller install that is coming right up. To be honest I do use the threads as a reference to myself and it allows me to look back and see where I could have done something different or where I found such a great idea.

A quick summary of the last couple of days include the removal and replacement of the back glass. I found and procured a fresh billet cam that has me pretty happy, ok alot of luck on that one. I welded in the plate for the passenger side retractor seat belt and did some interior finish work. I also removed the stock fan and shroud without removing the radiator and installed an electric one from I believe an early Honda. I also did the remote battery mount and tried it all out.

I was told that tomorrow or the next day the cam may ship so I'll be doing this a bit quicker than expected.

If this is ok with you all I'd like to keep up on the documentation, if it is, then I'll work on some pics of the most recent mods and I suppose if the old thread is salvaged they could be merged?
 

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Discussion Starter · #2 ·
One item that has been eating my lunch for me is a better distributor. I've been hunting a 75 for a few weeks and just now was told it shipped. Ok I've heard it before so I'm not going to hold my breath waiting. I was digging through all the posts of altered distributor advance but none were very clear of how this was done or on which particular model or year of distributor. I found a very good pic in RallyBobs turbo postings that show a lower bracket that none of the early styles had. It was this bracket that was used to limit the advance. I have been looking for a way to get there in a few steps and didn't really find too much. Before I go back into fall back and punt mode I'll try an odd idea or two on one that I already consider not the best and then I'll hold my breath and hope it really did ship this time.
 

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Discussion Starter · #3 ·
I've been thinking alot lately of where this whole project is headed. Another summer is about gone and it's hard to judge if I'm closer to it really being drivable or further away. I've pretty much hit my limit of how much money time and effort I'll put into a losing cause. I'm starting to look at the car with disguest and that is not what I had in mind at all when I got it. Almost all of the nitpicky stuff is done and it should be all good but maybe I'm just too worn out. If I had the motivation I could put the other motor in it and just call it good but I just don't have it in me to tackle that. I have no idea of even if I ever get the parts I seem to need if it will help make it more drivable or if it's just money into the pit. If anybody has any ideas where to go I'm still listening.
 

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Dave, it's time to walk away....for a week or so that is. You obviously need a break....we all get that way at times with our projects. But that's just what they are, projects. Projects keep us Gear Heads sane. Every car I have ever "finished" got sold. Then it was on to something else. I couldn't stand to be with out a toy. I think that I have dragged the work out on my GT just because of this. I really don't want something else, so I just keep on coming up with new stuff to do to the GT. It probably never will be finished. This site has also done alot to keep me interested in the Opel. Reading about others with similar problems and solutions helps keep it fresh.

Is it a money pit? Without a doubt. All old cars are. I am very afraid to add up my receipts. I know I could have bought a nice used modern sports car, such as a Miata, for equal money, and I haven't even touched the body and paint yet. But could you even remember how many Miatas you passed on the road today? How about 'Vettes? You don't even notice them. Can't say that about the Opel!

Bestus,
James

time to get off my soap box!
 

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Discussion Starter · #5 ·
All right I'm asking for some help on which distributor to use and or modify. I'm posting some of these numbers from memory so I can only hope I'm right. twin DCOM webers jetted 138 mains F64 emulsions 160 air carriers 53F21 idles on a magnalesti manifold. A lightly ported head with stock intakes and 2.0 exhaust valves. 11:1 compression Venolias with all the edges broke except for the piston top outside edges. I was thinking rollers and using a fresh billet cam that is advertised 292 but is 248 at .050 and has .455 lift given the 1:157 roller ratios. I'm at my wits end and could use some help. Bob Does this sound like it could run on 91 octane or am I just dreaming?
 

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Any year distributor is okay Dave, as long as it is modified with the appropriate advance. It doesn't have to be a 1975 distributor. With 91 octane I think you'll be limited to around 32-34 degrees of total timing, but you can still run a lot more initial timing because of the overlap of that camshaft. Throttle response will be much better, and it will be more driveable and will start better.

Case in point: A full race engine with a .528" lift, 266 @ .050" duration, 106 lobe sep. camshaft can be totally driveable and even streetable.....IF the distributor is set up for it. If not, it will be a cantankerous pig that is hard starting, fouls plugs, and has lousy response. But I once 'test drove' my friend's racecar on the street with this same camshaft, and it was fully driveable.

Bob
 

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Discussion Starter · #7 ·
I was looking at the modifications to limit the advance in the turbo for Carlisle thread and the bracket where the screws were placed is not on any of the distributors I have. Was this added or is it just a type that I don't have?
 

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There are at least three or four distinct types of Bosch distributors:
1) the early "twin can" unit with two vacuum cans ( you pictured one )
last digit of the part number stamped on the body 0 xxx xxx 001?
2) the 1969 and 1970 models for the hi-comp motors with lots more advance
last digits on part # 005 through 007
3) the 1971 through 1974 lo-comp motors with less mechanical advance
last digits on part # 011 and 012
4) the elusive 1975 "injection" model with no vacuum can
part # 0 231 170 140

Have a look at what stops the distributor cam when it is fully advanced in which ever type(s) you have and modify it to reduce the full movement down to a total of 12 to 13 distributor degrees ( that gives 24 to 26 crankshaft degrees ). Remove the vacuum can altogether and clamp the two plates under the points together imovably.

Just carefully consider the changes necessary and cogitate on this modification till the new cam arrives - you may need a bit of a rest from GT trauma for a week or so!
 

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I'm sorry I didn't think to take pics of mine when I modified it. I spent a week or so with a couple of distributors tore down on my bench, just playing with them. I finally riveted a small piece of metal in the slot to limit the total movement of the weight. I then coated this stop with JB Weld as an added safety. I was then able to grind this stop back with my Dremal tool and fine tune it until I got the total advance where I wanted it. If I remember correctly, it's about 38 total, with 12 at idle. Also remember to use the 2 light springs, as Rally Bob suggested in some old threads.

Jc
 

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N61WP said:
Also remember to use the 2 light springs, as Rally Bob suggested in some old threads.

Jc
In truth the 'light' springs have more initial tension than the OEM mix-n-match of one light spring and one heavy spring. This is because the 'heavy' spring has a larger free loop, and it has almost no initial tension, that being taken care of by the 'light' spring almost entirely. This allows the weights to fly out fairly quickly. This is fine with stock timing, but if you have, say 15 degrees initial, they fly out too fast, and the engine will ping. It also tends to 'hunt' for an idle speed, since the higher idle necessitated by the hotter cam will tend to just be on that borderline where the mechanical advance begins to kick in. So I run the two 'light' springs, but if I'm in doubt as to their tension, I will remove a loop or two to increase tension and to delay the onset of the mechanical advance.

RE the distributor in the Carlisle thread, it is typical of all 1971-1975 distributors, the early (pre-'71) types are physically different in terms of advance mechanism. Travis modified one of these early distributors and posted pics here some time ago, so I'm sure a search might turn up the pictures he posted with the alternative method of modifying the advance for the early-type distributors.

HTH,
Bob
 

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Discussion Starter · #12 ·
Ok I understand this a bit better, depending on the year distributor you have or choose to use it can be limited in two ways that I've come across. On the earlier style it's best to use a small nut and bolt to limit the total advance. I took a pic of a 69 type that had a total of 32-36 total mechanical advance. With the green bolt in the pic added I can limit the space between it and the spring post by some 35 percent to get down to around 22 degrees of total advance. I can bring my initial timing up a bit to around 10 or 12 then.

On the other hand with a 75 type I am a little more limited as to initial timing. with it I'm looking at around 8 degrees initial and 25 mechanical.

I think it's somewhat clearer, thanks.
 

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With that cam you're ordering, I'd shoot for 15-18 degrees initial timing and 32-34 total. The nice part about the threaded 'stops' is that they are adjustable once you've established the upper and lower thresholds for timing.....you want as much initial timing as you can get for response and still have it hot start and not ping off idle, and you want as close as you can get to 35-36 degrees total timing (as I mentioned you won't get this much with your local gas) for maximum power without pinging.

HTH
 

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if you are not great at modifing things (like me) pull the distrib and go to the welding shop and have about half the advance area welded shut. Put it back ad see what the total advance is now. Then just pull it and file the weld back till you get to the 34 or 36 or whatever Bob said is best for your set up.

sure it takes a while but the weld is sturdy and then you don't have to worry about the distrib any more.

c
 

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Discussion Starter · #15 ·
After I welded in the stop I was checking it with a degree wheel and adjusting it. I have it set at 22 but going lower is really easy. I just reset it to right around 16-18 degrees. That should be a good place to start.
 

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Discussion Starter · #16 ·
My mechanical advance is set. I pop riveted the breaker plates together as close as I could get to what was it's static start point. I finished this little bit of fun by installing the Crane optics and shutter. The first pic is looking down into it and the second is all finished. I'll try this one first but I also have a 75 that should arrive on Wednesday.
 

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Discussion Starter · #17 ·
While I'm playing with the timing in anticipation of doing the Rollers. I was thinking it might be nice to do another front pulley just for this motor. Marked at #1 #2 #3 #4 tdc and again at 15 and 35 degree advance marks. I was just thinking that it might make timing and doing the valves alittle easier. Maybe do TDCs in red and timing in white?
 

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Dave, there are timing tapes that can be placed around a crank pulley and glued in place, i've seen them but can't recall where. Maybe a major catalog sales outlet like J.C Whitney, Jegs , or NAPA, or some of the others. Just an idea. :D
 

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Discussion Starter · #19 ·
this was kinda what I had in mind to do that might make things easier. Red is TDCs and white is 15 and 35 degree marks for timing.
 

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namba209 said:
Dave, there are timing tapes that can be placed around a crank pulley and glued in place, i've seen them but can't recall where. Maybe a major catalog sales outlet like J.C Whitney, Jegs , or NAPA, or some of the others. Just an idea. :D
I wish this were this easy Ron, but unless the pulleys are the exact same diameter, the timing tapes don't correspond. Not to mention, on a Chevy or other comparable domestic engine there is usually a harmonic dampener that the tape is affixed to....the Opel engines do not have this large surface to apply the timing tape to (even the 2.4 has a different sized harmonic dampener).

What David has done is the same way most racing/performance Opel engines are done. I like to notch the edge of the pulley with a file to indicate the timing marks, going from 0-40 degrees. I mark all of the notches with white paint, except for 0 and 35 (I use orange and yellow, but any contrasting color works fine.) This way, timing is easily checked and you *know* right away if you are advanced or retarded (the timing anyway!) just by referencing the colored marks.

HTH,
Bob
 
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