I'll never pay for a tuneup again
Success!
Around 2 p.m. today Dad called me at the worst possible time. He wanted to talk about our stupid skiing trip to stupid Wisconsin and stupid Michigan that we're doing in lieu of glorious Montana. I had a hard time concentrating on what he was saying about where we should get a hotel near Mt. Bohemia because when he called I had my hands full with a tach/dwell meter. It was the last step before declaring my Ghia's motor finely tuned.
I asked Dad to let me call back in half an hour or so and got back to hooking up the tach/dwell. Once warmed up the motor was idling at 900-950 rpms, so I turned the volume screw in about one full turn to make it 6 total turns from bottom. Any more turns than that and the idle would drop and make the mixture slightly lean. I turned the bypass screw in until the idle dropped to 850, double-checked the timing with the strobe and happily verified it was at 5 degrees ATDC (After Top Dead Center).
A simple procedure, non? Thing is I'd been working at the whole thing since 8 this morning. Last night between 10:30 and 12:30 I was getting bloody knuckles wrestling the intake manifold off the cylinder heads after removing the sheet metal trim that runs along the bottom rear of the engine bay (it was oily and dirty!) All this week I was spending 1/2 an hour here and there with other preparations: removed the carburetor over lunch Tuesday, dismantled it and cleaned the small parts on the shop table in the basement that night, cleaned the carburetor body Thursday evening and finally reassembled the carburetor Friday evening with the rebuild kit ordered through Cip1.
The engine bay stripped of manifold ends, carburetor, bottom-rear trim, air cleaner and heater hoses
This morning I ran to my local Ace Hardware for, well, hardware: spare 10mm, fine-thread bolts to replace the rusted-out ones holding the heat riser tube and spare 13mm nuts. I also got a gallon of some Castrol super cleaner/degreaser stuff and muffler repair putty to patch the heater boxes (a later project). I then went to Sears and picked up the timing light and tach/dwell/ohm meter. Those two pieces of equipment cost just under $60, or the labor charge from VW Man for adjusting the timing and idle. In other words, they more than pay for themselves the first time you use them.
When I got home I took to cleaning the manifold ends and engine bay trim pieces with the Castrol degreaser stuff. Worked great! Just dipped an abraisive brush into a bowl of the stuff and scrubbed. Rinse with water and the gunk comes off practically by itself. Once the cleaning of those parts was done I started getting excited: time to put it all back together again!
Clean manifold ends on garage floor and brand new red boots and clips on bumper
Freshly-cleaned, albeit rusty, bottom-rear engine bay trim
My disassembly and reassembly of the carburetor didn't present any obvious causes for my tuning issues. To recap, I couldn't get my car to idle unless I had the throttle positioning screw turned in about 4 or so turns from where it was just touching the fast idle cam (I later determined 7 turns was overstating it). This screw is only supposed to be 1/4 turn in, so something was certainly amiss. I adjusted the volume and bypass screws as best I could and the car idled and drove OK, but I knew the carburetor needed to be looked at and rebuilt.
VW Man said I needed a new distributor because the vacuum unit wasn't working right. At the time, it was looking like a $300-$400 job in parts and labor if I had them do it: brand new carburetor and brand new distributor. Then the snow flew and I was able to sit on it. Now we're at the end of about the warmest January on record and I got back to tinkering with the Ghia.
At first I thought the fuel cutoff valve was faulty, but I tested that part and it worked just fine. My current theory is there was a leak or clog in the carburetor's vacuum signaling system. My distributor is a dual vacuum distributor, so the carburetor needs to send information out two ports about how much air is going through it so the sparks will fire at the right time. I used a can of compressed air to blast out all the passages in the carburetor and replaced all the diaphragms and gaskets. So, if that was a problem, it isn't now.
The rebuilt carburetor. Not spotless on the outside, but good enough.
The next clue came when I finally had it all back together again. After all that work I started it up, it idled high just as it should for a cold engine and then idled slower and slower as it warmed and the throttle moved down the ratchets of the fast idle cam. I was ready to tear my hair out when the motor warmed up fully and died. It wouldn't idle with the throttle arm screw only 1/4 turn in. Crap!
I adjusted the volume and bypass screws in the basement per the instructions: 2 1/2 turns out for volume and 3 or 4 out for bypass (guessing on that one). After the engine died I started counting the number of extra turns out on the volume screw before it got to a point where it idled. Eventually, I was back to Square 1: throttle position screw 4 turns in and volume screw 8 turns out. OK, calm down, time to use that timing light you just got.
The timing light's pretty neat, and ultimately really easy to use: red clip to positive battery terminal, black to car frame and sensor clipped around #1 spark plug wire. Just pull the trigger with it pointed at the crankshaft pulley and you see the paint marks! And, what do you know: about 7 degrees BTDC (B is for before!) Ah ha! At idle the spark plugs were firing way too soon, so no wonder it was dying.
I loosened the distributor nut, started rotating it back to 5 degrees ATDC and sure enough the idle picked up speed. Cautiously and nervously I turned the throttle position screw back out. I was ecstatic when I saw light between the end of the screw and the fast idle cam and the motor was still idling! I turned it in 1/4 turn from touching the cam and then played around with the volume and bypass screws.
In the end, I had to keep the volume screw out a full 6 turns. I'd heard about how this can happen, and apparently it's to be expected with a 30+ year old carburetor. It's just not as perfect as it used to be so you can't have the volume screw at the standard 2 1/2 turns out. Oh well.
Only one thing left! Just got to hook up the tach/dwell and find out if my idle is right and- yep, that's when Dad called. :)
Around 2 p.m. today Dad called me at the worst possible time. He wanted to talk about our stupid skiing trip to stupid Wisconsin and stupid Michigan that we're doing in lieu of glorious Montana. I had a hard time concentrating on what he was saying about where we should get a hotel near Mt. Bohemia because when he called I had my hands full with a tach/dwell meter. It was the last step before declaring my Ghia's motor finely tuned.
I asked Dad to let me call back in half an hour or so and got back to hooking up the tach/dwell. Once warmed up the motor was idling at 900-950 rpms, so I turned the volume screw in about one full turn to make it 6 total turns from bottom. Any more turns than that and the idle would drop and make the mixture slightly lean. I turned the bypass screw in until the idle dropped to 850, double-checked the timing with the strobe and happily verified it was at 5 degrees ATDC (After Top Dead Center).
A simple procedure, non? Thing is I'd been working at the whole thing since 8 this morning. Last night between 10:30 and 12:30 I was getting bloody knuckles wrestling the intake manifold off the cylinder heads after removing the sheet metal trim that runs along the bottom rear of the engine bay (it was oily and dirty!) All this week I was spending 1/2 an hour here and there with other preparations: removed the carburetor over lunch Tuesday, dismantled it and cleaned the small parts on the shop table in the basement that night, cleaned the carburetor body Thursday evening and finally reassembled the carburetor Friday evening with the rebuild kit ordered through Cip1.
The engine bay stripped of manifold ends, carburetor, bottom-rear trim, air cleaner and heater hoses
This morning I ran to my local Ace Hardware for, well, hardware: spare 10mm, fine-thread bolts to replace the rusted-out ones holding the heat riser tube and spare 13mm nuts. I also got a gallon of some Castrol super cleaner/degreaser stuff and muffler repair putty to patch the heater boxes (a later project). I then went to Sears and picked up the timing light and tach/dwell/ohm meter. Those two pieces of equipment cost just under $60, or the labor charge from VW Man for adjusting the timing and idle. In other words, they more than pay for themselves the first time you use them.
When I got home I took to cleaning the manifold ends and engine bay trim pieces with the Castrol degreaser stuff. Worked great! Just dipped an abraisive brush into a bowl of the stuff and scrubbed. Rinse with water and the gunk comes off practically by itself. Once the cleaning of those parts was done I started getting excited: time to put it all back together again!
Clean manifold ends on garage floor and brand new red boots and clips on bumper
Freshly-cleaned, albeit rusty, bottom-rear engine bay trim
My disassembly and reassembly of the carburetor didn't present any obvious causes for my tuning issues. To recap, I couldn't get my car to idle unless I had the throttle positioning screw turned in about 4 or so turns from where it was just touching the fast idle cam (I later determined 7 turns was overstating it). This screw is only supposed to be 1/4 turn in, so something was certainly amiss. I adjusted the volume and bypass screws as best I could and the car idled and drove OK, but I knew the carburetor needed to be looked at and rebuilt.
VW Man said I needed a new distributor because the vacuum unit wasn't working right. At the time, it was looking like a $300-$400 job in parts and labor if I had them do it: brand new carburetor and brand new distributor. Then the snow flew and I was able to sit on it. Now we're at the end of about the warmest January on record and I got back to tinkering with the Ghia.
At first I thought the fuel cutoff valve was faulty, but I tested that part and it worked just fine. My current theory is there was a leak or clog in the carburetor's vacuum signaling system. My distributor is a dual vacuum distributor, so the carburetor needs to send information out two ports about how much air is going through it so the sparks will fire at the right time. I used a can of compressed air to blast out all the passages in the carburetor and replaced all the diaphragms and gaskets. So, if that was a problem, it isn't now.
The rebuilt carburetor. Not spotless on the outside, but good enough.
The next clue came when I finally had it all back together again. After all that work I started it up, it idled high just as it should for a cold engine and then idled slower and slower as it warmed and the throttle moved down the ratchets of the fast idle cam. I was ready to tear my hair out when the motor warmed up fully and died. It wouldn't idle with the throttle arm screw only 1/4 turn in. Crap!
I adjusted the volume and bypass screws in the basement per the instructions: 2 1/2 turns out for volume and 3 or 4 out for bypass (guessing on that one). After the engine died I started counting the number of extra turns out on the volume screw before it got to a point where it idled. Eventually, I was back to Square 1: throttle position screw 4 turns in and volume screw 8 turns out. OK, calm down, time to use that timing light you just got.
The timing light's pretty neat, and ultimately really easy to use: red clip to positive battery terminal, black to car frame and sensor clipped around #1 spark plug wire. Just pull the trigger with it pointed at the crankshaft pulley and you see the paint marks! And, what do you know: about 7 degrees BTDC (B is for before!) Ah ha! At idle the spark plugs were firing way too soon, so no wonder it was dying.
I loosened the distributor nut, started rotating it back to 5 degrees ATDC and sure enough the idle picked up speed. Cautiously and nervously I turned the throttle position screw back out. I was ecstatic when I saw light between the end of the screw and the fast idle cam and the motor was still idling! I turned it in 1/4 turn from touching the cam and then played around with the volume and bypass screws.
In the end, I had to keep the volume screw out a full 6 turns. I'd heard about how this can happen, and apparently it's to be expected with a 30+ year old carburetor. It's just not as perfect as it used to be so you can't have the volume screw at the standard 2 1/2 turns out. Oh well.
Only one thing left! Just got to hook up the tach/dwell and find out if my idle is right and- yep, that's when Dad called. :)
posted by Chris Druckenmiller at 1:53 PM
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