quote:

Still can't believe I got a complete carb for the VW, with electric choke and gasket, postpaid, for $68! Gotta love those 3rd world prices...

Just because you are in Florida and get cheap parts for your van does not give you the privilege of rubbing it in. Hard to believe parts for this old Rochester are so expensive. I may have to cut your frig case to a 6 pack!!!!

Ok this has been going on since last year. Is any member going to suggest that it is a Quadra-jet, so in 2050 someone can find this information in our archives?

I think that's a great idea.
Tere

Geez Kevin, I thought Quatra was cool!!!!! Funny I never noticed I misspelled it...

quote:

Originally posted by Duane88:
Geez Kevin, I thought Quatra was cool!!!!! Funny I never noticed I misspelled it...

If you never noticed the misspelling, how could you notice it was cool?

quote:

Originally posted by Duane88:

So I guess I never had use of the 4 barrel part of the carb. Hope I can find a replacement motor.

Great. Get registered and I'll dig out my fire suit and helmet, we will head to Salt Lake and do some high speed runs.

quote:

Originally posted by Kevin:

quote:

Originally posted by Duane88:
Geez Kevin, I thought Quatra was cool!!!!! Funny I never noticed I misspelled it...

If you never noticed the misspelling, how could you notice it was cool?

I thought it was cool (no time frame), but I never noticed the misspelling. .Pay attention Kevin...

I feel better. Thanks for fixing.
Tere

Benebob, I am not sure what would blow-up first. Nose Engine, run out of fuel, or the tires.lol

Maybe we can get Mwrench to come over and time us!!!!!

Well I still have not installed the Rochester. Today is in the high 30's might get it done. The Hot Rod test guy never called me to check the Quatra out. Oh well!!

Looky Benebob has a supporting badge!!!

Ok, Quadra Jet is back in the nose all is operative and my dead spot is gone. Starts better too, although it did die shortly after the first start.

I did open a new can of worms!! It now floods easily and backfires until it starts, the ported Vacuum switch that operates my new secondary lockout motor does not open, the check valve between the pvs and the distributor is screwed too. I think someone set the timing to work without the pvs and a screwed check valve. Two man job to change timing and I have never checked it.

I ordered a pvs, but they do not specify at what temperature they open, I have a 180F stat so I will check that for opening before I install it. My wile loves it when I use the cooking stuff to check things. I want it to open at 170F or less, I guess.

They do not have a replacement check valve with four ports like the one I have, I did find a 3 port one at Rock Auto, O'Reiley does not even have that. I will finger through Steve's P3xxx handbook, hope I can find that vacuum circuit. Maybe I can modify it to work with a three port. It did run the AIR stuff too.

BTW Steve the PVS was $30 bucks I bet you could have bought a whole VW van vacuum system for that.....lol

Geez I love this old machine.....

If we look at the older pre EPA carb setups, we see a much more simple vacuum system, often a single hose from the ported vacuum source in the carb to the vacuum advance on the distributor.

The advent of the emissions concerns pushed the factory tuners to lean mixtures and retarded timing. This reduced hydrocarbon emissions. Many of the devices found in the late 70's cars and 80's trucks were designed to prevent or delay the onset of the vacuum advance until the engine was off choke (warm and lean) and in high gear. They also reduced the compression ratios which really cut power.

In addition, they added politically correct AIR pumps to introduce more air into the exhaust. Since the regs of the day specified ppm (not grams per mile) to measure emissions, the popular saying became "the solution to pollution is dilution."

As for performance, the engines ran better, had better throttle response and made more power when they had high compression, richer mixtures and full advance.

Since most of the vacuum switches and delay valves are no longer working and/or leaking air, the net result now is poorer performance, poor fuel economy and ironically, increased emissions.

Without major teardown or turbocharging, there is nothing we can do about compression ratio and loss of power.

However, by returnng to pre EPA tuning we can achieve better performance. If we look at factory specs for most engines in the 60's and 70's we see idle timing set at 8 to 10 degrees BTDC (before top dead center) or more. In addition, the distributor had centrifugal advance weights and springs to increase advance as rpm went up, typically about 10-15 more degrees. Finally there was the vacuum advance diaphragm which added another 8 or 10 degrees advance for total advance around 35 degrees.

Later engines called for 0 to 4 degrees advance at idle, less centrifugal advance, and delayed or blocked the vacuum signal for the vacuum advance. EGR (exhaust gas recirculation) leaned/diluted the mixture by introducing oxygen poor exhaust gases into the intake stream, resulting in poorer performance and lower combustion temperatures, to reduce NOx emissions.

So, for best results, be sure you have no vacuum leaks. Set the choke rich enough to run without backfire when cold. Find the carb port that produces vacuum just off idle and run it straight to the distributor. Set the idle timing to around 10 degrees. Be sure the advance weights in the distributor are not rusted stuck. Disconnect/remove the EGR valve (ports are prob blocked with carbon and corrosion anyway) and the AIR pumps. Finally, adjust the idle mixture for best idle.

Run as much advance as the engine will take without knocking. On my carb 454 I ran 10-12 degrees BTDC at idle.

The advent of fuel injection allowed mixture and timing to be varied on the fly per the computer program, allowing pre EPA timing and advance to be used when conditions were right.

Good luck with your tuning.

quote:

Good luck with your tuning.

Well Professor, the information I needed as usual!!!

EGR and AIR stuff is long gone. So 10 degrees advance, check advance weights in Stribbie, run vacuum advance direct to carburetor. That leaves only the secondary 4 barrel lockout running to the PVC. Check for vacuum leaks. Adjust idle mixture and speed cold engine and run temperature...adjust choke to eliminate cold engine backfire..

Thank you my Hero~~~~!!!!!

My nearly new Q-jet is still available. By now you could have had it mounted and running, 300 hour running take off from new engine. For an extra $10 donation to the site I will include the marine flame arrestor!