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| Mechanical Mechanical – General Tips, Problems, and Solutions, not related to the specific systems above |
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#26 (permalink) |
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Old Opeler
Join Date: Jun 2003
Location: New Zealand
Posts: 5,686
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Acetone ...
http://www.opelgt.com/forums/general...tone-fuel.html .. and the grooves in the head! http://www.opelgt.com/forums/general...n-chamber.html though it might be better to put the groove in the piston top - rather than 'hack' into a 1.5L head ... :O
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GTJim Opel Owner since last Century! Copyright © 2000-2009 J D Henry All Rights Reserved Last edited by GTJIM; 01-31-2008 at 07:57 PM. |
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#27 (permalink) | |
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Living in the past
Join Date: Oct 2005
Location: Chesapeake, Virginia
Posts: 1,368
Real Name: Lloyd
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#28 (permalink) | |
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1450 Seeker...
Join Date: Jun 2003
Location: Cape Cod, Mass
Posts: 631
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If you are able to justify the fuel savings over say, 47 years, you may want to look into having a camshaft designed according to the Atkinson Cycle
Atkinson cycle - Wikipedia, the free encyclopedia
Mileage may vary.
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Keep it Blitzed |
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#29 (permalink) | |
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2200 Post Club
Join Date: Jan 2003
Location: Chapel Hill, TN
Posts: 2,253
Real Name: Harold Collins
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Harold |
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#30 (permalink) |
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Living in the past
Join Date: Oct 2005
Location: Chesapeake, Virginia
Posts: 1,368
Real Name: Lloyd
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I don't know if your thinking incorrectly, I can only speak about what has worked for me. Every Opel that I have ever owned has had the dist. locked and the advance reworked to put it in quicker on a stick shift car and slower on the automatic. My wife drove a 75 FI Manta with an automatic that was getting 22-23 MPH before the dist. modification and with no other modifications made it went to 25-27 MPG. You have to have a dist. machine and play with the springs and weights in order to achieve the right curve and you have to time the car at TDC by static timing it, with the engine off.
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#31 (permalink) |
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2200 Post Club
Join Date: Jan 2003
Location: Chapel Hill, TN
Posts: 2,253
Real Name: Harold Collins
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Vacuum advance
I did a quick google search on vacuum advance helping fuel economy and came up with this:
Vacuum, Timing and Fuel Economy: in Non-Computer Assisted Engines -------------------------------------------------------------------------------- Publication:Lousiana State University Date:1993 GOALS: To understand the relationship between vacuum and ignition timing and to identify the cause of reduced fuel economy. OBJECTIVES: For non-computer assisted and some partially computer assisted vehicles, the student will: 1. Learn to identify the ignition system's vacuum sensing device. 2. Acquire the knowledge in order to test for a faulty vacuum sensing device. 3. Calibrate, for optimum fuel economy, a vacuum sensing device (when possible). LESSON/INFORMATION: Ignition timing is the single, most critical adjustment for a gasoline engine. Assuming the engine is in good mechanical condition, there are no vacuum leaks, and the fuel mixture is correct, then the ignition timing can affect the net power yield from the fuel. Improper timing can significantly change a vehicle's mpg. Three types of timing are used for gasoline engines. They are: 1. Static timing; 2. Mechanical (centrifugal) timing; and 3. Pneumatic (vacuum) timing - mechanical. Each has a specific purpose. 1. Static timing establishes a physical relationship between engine crankshaft position and the distributor. This is fixed and should not change. Basic and initial are terms also associated in the static timing. 2. Since fuel burns at a relatively fixed rate (i.e., time to burn is in milliseconds), then the faster the engine runs the earlier the fuel must be ignited so that the millisecond time frame will remain constant. Thus, mechanical timing advances are used. A device, usually a centrifugally activated weight control balanced by a spring, advances the timing proportionate to engine RPM's. The faster the engine runs, the more timing advances. This is true up to approximately 2,700 to 3,500 RPM's. Mechanical timing is critical to acceleration and power response in a gasoline engine. This timing is added to the static timing. 3. The third timing, pneumatic (vacuum) - mechanical, provides an extra measure of timing over and above static and any mechanical advance. The vacuum advance extends the burn cycle even longer so that all the heat energy may be absorbed by the pistons resulting in more power yield per measure of fuel and more mpg. The sensing device is a spring offset, vacuum activated diaphragm. This diaphragm receives its vacuum signal from the carburetor or intake manifold. In many vehicles this signal is modified by the transmission gear selector position, by coolant temperature sensor(s), by vehicle speed sensor, or by combinations of the above. Early computer assisted vehicles retained the vacuum advance system but employed the computer to modify the signal to the diaphragm, thereby optimizing the system performance. Total advance is the combination of initial, centrifugal, and vacuum. Vacuum advances are sensitive devices. By design, vacuum advances are spring offset to give zero advance. Only when a strong enough vacuum signal is present will it advance the ignition timing. The higher the vacuum signal, the greater the timing advance. High vacuum signals are indicative of low engine loads at a closed or nearly closed throttle position. At idle, when the throttle is almost completely closed, vacuum is highest; however, during idle, no vacuum signal is present at the vacuum advance. This is accomplished by tapping the vacuum for the advance system above the throttle plate. Excessive vacuum advance results in part throttle ping and a loss in mpg. Insufficient vacuum advance results in poor part-throttle response and a loss in mpg. Notice both insufficient as well as excessive vacuum advance results in a driveability problem and a reduction in mpg. Many drivers try to correct the part-throttle ping by purchasing higher octane fuels. This may fix the ping problem but mpg will still be reduced (See Fuel Octane Selection Guide.) Some technicians attempt to fix poor part-throttle response by advancing or retarding the static timing. This may correct the part-throttle problem, but basic, wide open, and near wide open throttle positions will have excessively advanced or retarded timing. This could result in an extremely hot combustion chamber temperature and long term, severe engine damage may result. Worn cylinders, cracked piston rings, burned valves, worn valve guides, damaged piston ring lands, or holes in pistons are some of the possible long term engine damages that may occur with excessively advanced static timing. Again, owners may compensate for the pinging noises by purchasing higher octane fuel. The result is the same, lower mpg and wasted energy. (See Fuel Octane Selection Guide.) High combustion chamber deposits, low fuel economy, or poor power output can occur with retarded engine timing. The correction for each of these problems is a complete, systematic, diagnostic approach using the manufacturer's recommended procedures and specifications. Static timing must first be set properly. Mechanical advance may then be checked and finally the vacuum advance checked. If the distributor fails any test, it should be removed for repair, recalibration, or be replaced. Prior to disconnecting a distributor's vacuum advance system, always check hose routing, system sensors, and soundness of the hoses and connections. Ultrasonic vacuum detectors or propane detectors are good diagnostic devices for locating leaking vacuum lines and connections. Improper hose routing, by- passing system sensors, failed system sensors, and/or leaking hoses account for significant numbers of malfunctioning or poor operating vacuum advance systems. It is important to remember that even a slightly mistuned engine will deliver poor fuel economy. Optimum fuel economy may only be achieved when timing is optimized. |
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#32 (permalink) | |
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Cam-in-head?
Join Date: Mar 2003
Location: Rochester, MN
Posts: 177
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-Kurt |
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#35 (permalink) |
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Member
Join Date: Mar 2005
Location: Utah
Posts: 191
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Earlier in this thread a member posted this website from northern tool.
Gastester Digital Exhaust Gas Analyzer | Automotive Diagnostics | Northern Tool + Equipment Another member I know is having issues passing emissions on a 73 GT and I was wondering if this inexpensive tool would help in tuning her car to pass emissions?? Any help would be appreciated. Last edited by neuropel; 02-03-2008 at 11:00 AM. Reason: Fixed link |
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#36 (permalink) | |
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2200 Post Club
Join Date: Jan 2003
Location: Chapel Hill, TN
Posts: 2,253
Real Name: Harold Collins
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I would do similar for the GT. Hopefully they have electronic ignition, set the timing to factory specs and hook up the vacuum retard, see if it will idle with the PCV hose pulled from the valve cover, add the octane booster, and remove the filter. There are some fuel additives that you can buy that promise you will pass or your money back. Personally, any state that makes you test a '73 car is just wanting money. Move to TN and don't talk about how much better the place was that you moved from and we'll be glad to have you. ![]() HTH, Harold |
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#37 (permalink) | ||
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Site Admin
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I may have him make up one for my GT while he is at it... While the intakes off, I'll put in the F.I. hose fitting and a GT oil pressure sending unit. While this is all apart, I may replace the fuel line from the gas tank. With F.I. in the future plans, should I use 5/16 or 3/8? Same diameter for the return line? |
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#38 (permalink) | |
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1000 Post Club
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The head your using is a 1.5 right? stock valves,ported? Then theres the bottom end what size pistons,stroke Oh questions ..that needs to be answered 1/4 inch return line should be fine .. do you have a fuel well in the tank? Its all about the total combination.
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Tinkering is my name..fun is the game |
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#39 (permalink) | |
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Site Admin
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Std. bore, low comp pistons. (PO had the engine rebuilt by "the most reputable rebuilder in NJ" ) ![]() I put a '75 tank in it last year. |
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#40 (permalink) | |||
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Project 1450 supporter...
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Bob |
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#41 (permalink) | |
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Site Admin
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I read somewhere that the new ethanol mix in gas is not friendly to rubber hoses when the car is not used regularly and sits for long periods so I'll be going with hard lines. I won't be driving on salted roads so I guess aluminum tubing would be ok. |
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#42 (permalink) |
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6,000 Post Club
Join Date: Aug 2002
Location: Imperial Beach, CA South of San Diego
Posts: 6,054
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Just as info for you Gary, I've got a high pressure pump (70 psi) feeding the fuel rail on Willit? The surge tank overflow, pump bypass and bleed, and the fuel rail all dump into a #4 (3/16" ID) stainless line back to the tank and it works just fine.
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Ron 72 GT 3.4L V-6/T-5/ZF posi - almost done - Just need AC installed. ![]() 75 Chevy monza 5.7L/TH350/Auburn 3.08 posi - Next |
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#43 (permalink) |
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Site Admin
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Thanks, Ron. BTW, the first season of John from Cincinnati is going to be repeated on HBO starting March 31. Maybe this run will generate enough ratings for a second season and bring the production $$$ back to Imperial Beach.
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#44 (permalink) |
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6,000 Post Club
Join Date: Aug 2002
Location: Imperial Beach, CA South of San Diego
Posts: 6,054
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Could be Gary, but the motel they used next to the taco stand is being sold, so I guess all the work the players did was for naught. I would like to see a sequel, just to see who John tries to help next go around. Maybe some of the druggies that are on the beach. It appears to be a thriving business at the men's room by the pier. I do know the Sheriff's Office liked them being here, the officers got extra pay and the department picked up some loot too, for traffic control. If you remember the huge circular antenna array, what we call the elephant cage, that's where Willit? spent 8 years after I blew the third engine in it. It belongs to the Navy Seals now, they use it for a training facility. The township of Coronado wants it, so they can build a golf course. We don't have enuff of them, yet. Only 125 in San Diego county, not counting the 4-5 on military installations. Yeah, bring back John From Cincinnatti, we need the income to fix up this burg.
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Ron 72 GT 3.4L V-6/T-5/ZF posi - almost done - Just need AC installed. ![]() 75 Chevy monza 5.7L/TH350/Auburn 3.08 posi - Next |
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#45 (permalink) |
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Site Admin
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Yeah, that antenna array played a special part in it. We will probably never know what it was.
A TV show that actually made you think, what a novelty! And it was canceled after 10 weeks.... I just read where one ton of birdseed is going to be delivered to HBO as a Jericho type of protest. Hijacked my own thread.... I'll split it if this sub-topic continues.. Last edited by Gary; 02-16-2008 at 07:45 PM. |
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#46 (permalink) |
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6,000 Post Club
Join Date: Aug 2002
Location: Imperial Beach, CA South of San Diego
Posts: 6,054
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I'll do a quick and dirty here. The antenna array was used by the Naval Security Group, part of the Command I was a Legal Officer for. From what I've been told and from what I know, from working on the Blackbird, there's no frequency that can't be accessed from that array. They had groups of Sailors sitting at computers, listening and typing stuff as it came in, lotsa secret stuff you understand. Now they use the satellites to listen in on stuff and send out secret stuff to the various Commands worldwide. As far as JFC and the array, mayhap that was how he communicated with his "father". They sure showed it a bunch of times in the latter episodes.
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Ron 72 GT 3.4L V-6/T-5/ZF posi - almost done - Just need AC installed. ![]() 75 Chevy monza 5.7L/TH350/Auburn 3.08 posi - Next |
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#47 (permalink) | |
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Living in the past
Join Date: Oct 2005
Location: Chesapeake, Virginia
Posts: 1,368
Real Name: Lloyd
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35 Mpg
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#48 (permalink) |
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1000 Post Club
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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.
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Tinkering is my name..fun is the game |
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#49 (permalink) |
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Site Admin
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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.
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#50 (permalink) | |
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2200 Post Club
Join Date: Jan 2003
Location: Chapel Hill, TN
Posts: 2,253
Real Name: Harold Collins
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Harold |
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