30MPG is the Goal

[Paul]

Originally Posted by wrench459 Lets see If I got this right 1.5 head stock on a 93 mm block (dished pistons) rough and I mean rough compression guess would be around a little under 11:1 You might in my opinion might what to retard the cam timing to lower the pressures down to keep from detonation or a special cam to take advantage of the higher ratios.

I'd have to go back and re-calculate... but I don't believe a 1.5 head (un-milled) on dished 7:6 to 1 pistons would yield 11:1. I think its closer to the 8.5 - 9 :1 range...

[Paul]

Originally Posted by hrcollinsjr If I were starting from scratch on this engine I believe I would try some of the high tech coatings for the piston tops and for sure the combustion chamber. Harold

I'm with Harold on this one... with fresh pistons, I'd send them to Swain and have the moly coating on skirts and the cermic on the tops.... ~~~$35 each IIRC

[Gary]

Good tip. I'll do that with the stroker engine I'll be building for my GT.

I'm avoiding touching the lower end on this one as it was running well. It's my Summer DD and just had an oil leak (stream) from the front of it and that's what started this adventure.

[Gary]

Originally Posted by Paul I'd have to go back and re-calculate... but I don't believe a 1.5 head (un-milled) on dished 7:6 to 1 pistons would yield 11:1. I think its closer to the 8.5 - 9 :1 range...

That's what I have been going by: http://www.opelgt.com/forums/13188-post4.html

[RallyBob]

Originally Posted by Gary That's what I have been going by: http://www.opelgt.com/forums/13188-post4.html

Yup, dished pistons with a 1.5 head don't yield too high a compression ratio...about 8.8:1. Even with flat-tops you're under 11:1!

No problem with pump gas, and the chamber/piston design is pretty efficient as far as 'squish' goes. Should be able to run 87 octane with that combo quite easily, as long as you don't add too much total ignition timing. I'd deburr the chamber edges to be safe.

I ran 89 octane with a stock hydraulic cam and 9.8:1 (flat-tops with milled 1.9H head), and it was great. It would *barely* ping with 87 so I bumped it a few octane points. I'm referring to the same shortblock I loaned you for your *Labatt's blue* wagon Gary.

Bob

[Gary]

Originally Posted by Gary Good point, Dan. I was working on it this past weekend and had a brain lock with the advance/retard setting (clockwise = advance?) so I just stopped and came in and worked on the site. I won't get back to it until the weekend so we have time to debate this. Tomorrow's another day.

Getting back to the advance/retard issue and my brain lock.

I modified a cam gear by drilling out new dowel pin holes to RallyBob's specs. The first pic shows the cam gear in a rough position for TDC on no. 1 cylinder. The second (mark is ~ 1/2 tooth to the left) was taken after I rotated the gear to the first new dowel hole. The third (mark ~ 1/2 tooth to the right of original) was taken after I rotated it to the second new dowel hole) The last pic shows what it looks like when the timing is one tooth off.

My initial thinking is that the third pic with the mark to the right would advance the cam timing. Then I started over analyzing it and finally looked over at my GT and thoughts of Penelope Cruz popped in and the day was history.

I'm also attempting to make a simple tool that can be used to check valve timing when #1 is firing.

[jeff denton]

If the head was on a block and #1 piston was at TDC (actual, not guessed) and a timing chain was installed AND the right side had no slack, then YES, the farther the mark goes to the right on your neat little gauge the more the cam is advanced. If your looking at the original dimple on the sprocket, then apparently your gauge is timing it to #4? I'm not sure Bob's drilling method is the same as mine, but if so, that dimple can only be used when the pin is in the original hole! If his method is different then my answer may be backwards...
Anyway, think of it this way: if the cam is ahead of the crankshaft, it is advanced. If the cam is behind the crankshaft, it is retarded.
Aw, crap, I can't use that kind of language. Sorry. I meant mentally handicapped.
The simple tool is that little clock on the magnetic base, but move it up to number one cylinder. Then mark off all your flywheel teeth and use it as a huge degree wheel. There's lots of room next to the teeth to write things like "TDC" and "BDC" and "IO" for intake open and "IC" for intake closed. It will all become crystal clear! Once you "get it" you don't need timing marks any more.
I gotta get back outside for a minute. My kids are very worried about the moon. I think the power company up there is having a brownout or something.

[wrench459]

Until you cc the piston,head,measure the compressed thickness of the head gasket you wont have a clue of the true ratio.
And just where is TDC don't forget about dwell time.

[Gary]

Thanks, Jeff. That is what my initial thought was before the brain missed a shift. It's amazing how easy it is for the mind to complicate things.

[jeff denton]

Come to think of it, you may have me confused, too. I need a close up picture of the upper sprocket. To see what method of advancement you are using.
That's why I say, "Forget that timing mark!" when you are degreeing a cam. All it will do is confuse you. It is crankshaft position compared to valve position, period. Marks have nothing to do with it.
I think my previous answer was wrong. I think maybe you are comparing valve timing to the timing mark? Kind of a backwards way to do it, but it could be made to work. Your crankshaft is not in the equation at the moment.

[Gary]

Originally Posted by jeff denton Come to think of it, you may have me confused, too. I need a close up picture of the upper sprocket. To see what method of advancement you are using. That's why I say, "Forget that timing mark!" when you are degreeing a cam. All it will do is confuse you. It is crankshaft position compared to valve position, period. Marks have nothing to do with it. I think my previous answer was wrong. I think maybe you are comparing valve timing to the timing mark? Kind of a backwards way to do it, but it could be made to work. Your crankshaft is not in the equation at the moment.

Right. I was just doing a bench check to see what affect the new dowel pin holes would have on the timing mark. New "dimples" were made for each new dowel hole.

I marked a pulley for TDC using an dial indicator on the piston. Next I need to get the stock hydraulic cam specs.
(Note to self: the engine part (6.0) for the FSM did not upload)

Not sure if they are in the FSM or not. Anyone have them handy?

[Paul]

Gary

There's a thread out there where I posted a drawing of the various advance/retard possibilities with the 2 new dowl locations... but you know all about the search feature

.... that's strange I can't find it... I repost it from work...

[namba209]

Originally Posted by Gary (Note to self: the engine part (6.0) for the FSM did not upload) Not sure if they are in the FSM or not. Anyone have them handy?

Gary, I've got the 73 GT FSM on a disc. If your ISP can handle it I can send the whole PDF file to you, or copy the disc and snail mail it to you.

[Tru-Craft]

Gary, sounds like the engine will be OK, tranny should be a manual.
Rolling friction is also important.
Wheel bearings good? Lower viscosity grease.
Synthetic oils, low viscosity.
Check U-joints, torque tube condition, rear axle for friction/damage.
Straight aluminum wheels,narrow tires/high pressure.
Brake drag? Rotors/drums true? Caliper pistons retracting.
Suspension/tie rods in good shape.
Wheel alignment, keep toe-in to a minimum.
Weight reduction, insulation out, A/C out, Passenger & rear seats out, rear glass out, no spare tire/can of fix a flat instead, no tools (join AAA)........Sub-Way

K&N air filter, free flow exhaust, pertronics, lean 32-36 Weber.
Vacuum gauge in the car dash is helpful also.
All cheap ways to get closer to 35MPG.
Lyle

[Gary]

Originally Posted by namba209 Gary, I've got the 73 GT FSM on a disc. If your ISP can handle it I can send the whole PDF file to you, or copy the disc and snail mail it to you.

Ron - The entire FSM is already in the downloads section. I broke it down into chapters for ease of search and viewing. I missed adding the engine chapter.

Originally Posted by Tru-Craft Gary, sounds like the engine will be OK, tranny should be a manual. Rolling friction is also important. Wheel bearings good? Lower viscosity grease. Synthetic oils, low viscosity. Check U-joints, torque tube condition, rear axle for friction/damage. Straight aluminum wheels,narrow tires/high pressure. Brake drag? Rotors/drums true? Caliper pistons retracting. Suspension/tie rods in good shape. Wheel alignment, keep toe-in to a minimum. Weight reduction, insulation out, A/C out, Passenger & rear seats out, rear glass out, no spare tire/can of fix a flat instead, no tools (join AAA)........Sub-Way K&N air filter, free flow exhaust, pertronics, lean 32-36 Weber. Vacuum gauge in the car dash is helpful also. All cheap ways to get closer to 35MPG. Lyle

Good points Lyle. I gave my "Subway" comments in the first post. I'm getting lazy while sitting in traffic now so it's going to stay an automatic. I will be rebuilding a spare front end with new parts after the engine and exhaust are done. Might do a F.I. conversion. Geeze, at the rate I'm going it may not be ready until the Nationals.

Meanwhile, once the weather breaks, I think I'll spoil myself and switch the plates over to the Senator and drive that while I'm working on the wagon. I'm putting too many miles on my Tacoma.

Thanks for all the comments and ideas.

[namba209]

Originally Posted by Gary Ron - The entire FSM is already in the downloads section. I broke it down into chapters for ease of search and viewing. I missed adding the engine chapter.

I've seen that Gary. But I have the disc Wayne Torman generated some years ago. I tried to just copy Group 6, but ended up with the whole FSM in a new file on the computer. I figured, if you want to load Group 6, I could send you the whole thing on a disc and you could or should be able to extricate what you wanted for the site.

[hrcollinsjr]

To be honest with you I don't see where 35 mpg will be much of a challenge. If the car is mechanically sound, tuned properly, tires chosen for economy not performance, and the driver does their part it should approach 35 mpg anyway.

I think you should be seeing how close you can get to 40 mpg. Of course you might have to put the manual transmission in for that goal.

JM2CW,

Harold

[Gary]

Originally Posted by namba209 I've seen that Gary. But I have the disc Wayne Torman generated some years ago. I tried to just copy Group 6, but ended up with the whole FSM in a new file on the computer. I figured, if you want to load Group 6, I could send you the whole thing on a disc and you could or should be able to extricate what you wanted for the site.

Ron - I have that file. The entire FSM is here: Opel File Downloads - File Downloads - Opel Community Forums
The same FSM scan broken down by section is here: Opel File Downloads - Factory Service Manual - Opel Community Forums

I used a program to break up the original PDF file into the individual chapters. I have Group 6 already, just forgot to upload it when I uploaded the rest.

[Gary]

Originally Posted by hrcollinsjr To be honest with you I don't see where 35 mpg will be much of a challenge. If the car is mechanically sound, tuned properly, tires chosen for economy not performance, and the driver does their part it should approach 35 mpg anyway. I think you should be seeing how close you can get to 40 mpg. Of course you might have to put the manual transmission in for that goal. JM2CW, Harold

Well, I was getting between 20 and 24 MPG with this wagon before so a 50%+ improvement would be a good start.

[jeff denton]

The Opel auto trans is basically a Powerglide, isn't it? Same torque converter? If so this is probably the most often messed with converter in the world.
So maybe a torque converter can be custom built/modified to help achieve the goal here. I'd guess you want it to let the engine freewheel at idle better. And lock up completely at higher rpm.
Can this be done? I don't have