TheSamba.com :: View topic

Tue Jul 07, 2009 1:16 pm

Thanks keith, I've been away from the computer all day....

By the way, my latest "master chart" of everything for upright engines, I made a couple of minor changes to it recently and it's here. It's MS Word doc file though:

https://www.thesamba.com/vw/archives/info/glutamodo/temp/CarbBaseFlangeNumbersA.doc

-Andy

Tue Jul 07, 2009 1:43 pm

Perfect! And thanks.

Keith,

You kindly offered me advice that got my Solex going without a rebuild. I'm actually looking forward to having a problem bad enough that I need to pay you to help me. :D

Tue Jul 07, 2009 3:34 pm

glutamodo wrote: Thanks keith, I've been away from the computer all day....

By the way, my latest "master chart" of everything for upright engines, I made a couple of minor changes to it recently and it's here. It's MS Word doc file though:

https://www.thesamba.com/vw/archives/info/glutamodo/temp/CarbBaseFlangeNumbersA.doc

-Andy

:shock:

That's pretty awesome.

Thu Jul 09, 2009 8:52 pm

Here's a cut and paste from a different thread that I incorrectly posted in the wrong place.

I hate to piggyback a thread, but my question is related to the same problem. I have a 74 super with AH engine code. It has a 34 pict 3 carb (Bocar) and an 034 distributor that has just recently been added. The Muir book says I should time it at 5 degrees ATDC . Old volks says a 74 Cali is 5 ATDC. A Federal 74 is 7.5 BTDC.

My issue is that my car has a blocked off EGR, but I believe has been owned in SC since it was new. I recently switched to an 034 dizzy from an 009. I had the 009 pretty well tuned considering the setup. It was at 7.5 BTDC. I have the 034 now, and I am trying to set it to 7.5 as well, but am I completely wrong? My quick setup seemed a little rough and it is overheating. I'm dialing it in a more precisely now, but I am wondering if I'm headed in the wrong direction. Someone please help, I have a roadtrip planned for Saturday.

Thanks in advance,
McCay

Edit: I just got back from a test drive with the timing set at 7.5 BTDC. It seems to run pretty well. We'll find out if it overheats when I drive out and back to work tomorrow. How do I tell I tell if the Bocar was meant for an SVDA or a DVDA? I'm assuming from this thread that if it was meant for DVDA then I could benefit from the pop rivet.

Thu Jul 09, 2009 8:54 pm

Another question was that when I was adjusting the carb after setting the timing I couldn't seem to lean it out. Regardless of how much I turn the screw it didn't seem to make a difference. Should I wind it all the way in and then back it out?

Thu Jul 09, 2009 9:01 pm

Czarlxxvii wrote: Here's a cut and paste from a different thread that I incorrectly posted in the wrong place.

I hate to piggyback a thread, but my question is related to the same problem. I have a 74 super with AH engine code. It has a 34 pict 3 carb (Bocar) and an 034 distributor that has just recently been added. The Muir book says I should time it at 5 degrees ATDC . Old volks says a 74 Cali is 5 ATDC. A Federal 74 is 7.5 BTDC.

My issue is that my car has a blocked off EGR, but I believe has been owned in SC since it was new. I recently switched to an 034 dizzy from an 009. I had the 009 pretty well tuned considering the setup. It was at 7.5 BTDC. I have the 034 now, and I am trying to set it to 7.5 as well, but am I completely wrong? My quick setup seemed a little rough and it is overheating. I'm dialing it in a more precisely now, but I am wondering if I'm headed in the wrong direction. Someone please help, I have a roadtrip planned for Saturday.

Thanks in advance,
McCay

Edit: I just got back from a test drive with the timing set at 7.5 BTDC. It seems to run pretty well. We'll find out if it overheats when I drive out and back to work tomorrow. How do I tell I tell if the Bocar was meant for an SVDA or a DVDA? I'm assuming from this thread that if it was meant for DVDA then I could benefit from the pop rivet.

Bocar's all have the smaller hole in the throttle plate BUT still have the fitting for the DVDA... I guess they are supposed to be an "all purpose fit" but who can tell... As long as you have unused vac ports plugged and the advance for your SVDA going to the correct port on the LH side of the carb you should be fine.

And that your not using the screw ON THE THROTTLE ARM to try and set idle...

Czarlxxvii wrote: Another question was that when I was adjusting the carb after setting the timing I couldn't seem to lean it out. Regardless of how much I turn the screw it didn't seem to make a difference. Should I wind it all the way in and then back it out?

This to me reeks of either a poorly tuned engine over all ( valve adjustment, plugs, point gap etc no vacuum leaks on intake or base of carb )

OR perhaps even too high of fuel pressure syndrome... making the carb hard to tune, small mixture screw useless in trying to tune the carb at idle. But as always there are several things you could have going wrong at once.

Fri Jul 10, 2009 9:43 am

keifernet wrote:

Bocar's all have the smaller hole in the throttle plate BUT still have the fitting for the DVDA... I guess they are supposed to be an "all purpose fit" but who can tell... As long as you have unused vac ports plugged and the advance for your SVDA going to the correct port on the LH side of the carb you should be fine.

And that your not using the screw ON THE THROTTLE ARM to try and set idle...

The vac ports are plugged and I'm not using the screw on the throttle arm.

keifernet wrote:
This to me reeks of either a poorly tuned engine over all ( valve adjustment, plugs, point gap etc no vacuum leaks on intake or base of carb )

OR perhaps even too high of fuel pressure syndrome... making the carb hard to tune, small mixture screw useless in trying to tune the carb at idle. But as always there are several things you could have going wrong at once.

I think the engine is turned well, but I'm still a noob so I could be wrong. The points are gapped at .016 and the dwell is dead on 50 degrees. The engine had just been rebuilt when I got the car in april. I adjusted the valves after about 200 miles. They were set at .006. I've probably driven it 500-600 miles since then. They may have tightened up though since the engine is still green. The plugs are new from the rebuild, and all the extra vac holes are plugged. What confused me is that the carb had no issues whatsoever with the 009 dizzy. It dialed right in when I timed it after the first valve adjustment. (Keith, can I get on the list for a Solex?)

After some more research, I'm even more confused about whether I should be at 7.5 BTDC or 5 ATDC. I'm assuming (big assumption on my part) that if it runs decently at 7.5 BTDC then it would run like crap at 5 ATDC.? [/quote]

Fri Jul 10, 2009 10:21 am

Czarlxxvii wrote: keifernet wrote:

Bocar's all have the smaller hole in the throttle plate BUT still have the fitting for the DVDA... I guess they are supposed to be an "all purpose fit" but who can tell... As long as you have unused vac ports plugged and the advance for your SVDA going to the correct port on the LH side of the carb you should be fine.

And that your not using the screw ON THE THROTTLE ARM to try and set idle...

The vac ports are plugged and I'm not using the screw on the throttle arm.

keifernet wrote:
This to me reeks of either a poorly tuned engine over all ( valve adjustment, plugs, point gap etc no vacuum leaks on intake or base of carb )

OR perhaps even too high of fuel pressure syndrome... making the carb hard to tune, small mixture screw useless in trying to tune the carb at idle. But as always there are several things you could have going wrong at once.

I think the engine is turned well, but I'm still a noob so I could be wrong. The points are gapped at .016 and the dwell is dead on 50 degrees. The engine had just been rebuilt when I got the car in april. I adjusted the valves after about 200 miles. They were set at .006. I've probably driven it 500-600 miles since then. They may have tightened up though since the engine is still green. The plugs are new from the rebuild, and all the extra vac holes are plugged. What confused me is that the carb had no issues whatsoever with the 009 dizzy. It dialed right in when I timed it after the first valve adjustment. (Keith, can I get on the list for a Solex?)

After some more research, I'm even more confused about whether I should be at 7.5 BTDC or 5 ATDC. I'm assuming (big assumption on my part) that if it runs decently at 7.5 BTDC then it would run like crap at 5 ATDC.?

Correct, the only distributor that times retarded to 5 ATDC is the DVDA.... your SVDA "034" should time to 7.5 BTDC hose off at idle and should also stay at 7.5 at idle after you plug the hose back on. Should go to approx 30 revved up hose off and over to around 40 hose on (in the driveway under "no load" you will see it go that far if you have a degree pulley that is...it will not go that far when the car is driven/under load though)

Fri Jul 10, 2009 11:30 am

Thanks for the help. I guess I need to play around with the carb to see what's up with it. It seems to be running well with the car, just a bit rich.

Fri Jul 10, 2009 11:35 am

Czarlxxvii wrote: Thanks for the help. I guess I need to play around with the carb to see what's up with it. It seems to be running well with the car, just a bit rich.

As I eluded to in an earlier post... get a gauge and check the fuel pressure.

Fri Jul 10, 2009 12:50 pm

keifernet wrote:

As I eluded to in an earlier post... get a gauge and check the fuel pressure.

I read right over that. Sorry :(

Wed Jul 22, 2009 2:58 am

Czar,

You can easily make a fuel pressure tester with some hose, a "T" fitting, and a $1.98 fuel pressure gauge from Autozone. Remind me and I'll send you a picture of the one I made.

Have you done the COMPLETE tune/reset of that Bocar? By that I mean the whole setting of the screw on the throttle arm, and setup of the two side screws to their "factory" setting? There's a decent writeup for that on this website as well as the vwresource site.

Joe

Fri Sep 25, 2009 9:58 pm

thanks for the carb tip! my 79 cab with carb runs and idles good!i jumped from the computer to the garage.........thanks g bags

Fri Apr 23, 2010 7:20 pm

keifernet wrote: Gariack wrote: Anyone know the diameter of the different size holes in the throttle plate on the 34 pict carbs.

The DVDA is approx 5/32" and SVDA is 1/8".

Hard to believe that difference does anything but trust me... it makes a big difference in the way the carb runs/tunes when your using a DVDA flange # German carb meant to be timed at 5 ATDC with an SVDA timed at 7.5 or an 009 timed at 10 BTDC.

I find the pop rivet easier than taking the plate out and soldering the hole shut, grinding it flush and re drilling it but that's a personal choice. It can also be "undone" in a matter of minutes if someone wants to go back to a DVDA and does not alter the carb in any other way.
Sorry to bring this old thread back, but my 34Pict3 and SVDA combination is stumbling and I think it's because the carb is meant for a DVDA. I'm going to try the rivet trick. What size rivet is the right one? Also, I assume I've got to remove the center of the rivet after installation?

Sat Apr 24, 2010 7:02 am

It could be that, or just general wear on the throttle shaft causing issues. Have you looked up your carb's base-flange number on the chart posted earlier in this thread? If you don't have one, then you'll just have to take it off and look at the throttle butterfly and see what size the hole is now, again, refer to pictures earlier in this thread.

-Andy

Sun May 02, 2010 7:27 am

Keith rebushed the throttle shafts a couple years ago, they're good. The carb base number (281-1) indicates it's meant for a DVDA. Turns out there already was a rivet in the throttle plate but the center pin had not been knocked out. This morning I pulled the carb and knocked out that pin, warmed up the engine, tuned the carb, and BINGO, no more stumble!! What a difference!

Thu Jul 21, 2011 7:35 am

I want to query plugging the hole in the throttle plate.

Mine is fully plugged with a rivet, no hole at all. I got it this way and it worked.

Car is a 1971 DP 1600 with a 34 pict 3 carb (1972) and a SVDA 1974 dizzy.

I hear with DVDA dizzys there must be a hole in the throttle plate but that for SVDA dizzys there need not be. Can someone clarify this for me and tell me if I am fine or if I DO need to drill a small hole in that rivet - and if so, how big?

Thu Jul 21, 2011 11:22 am

The purpose of the hole is to allow a small amount of air past the throttle butterfly, this allows the adjusment of the air bypass and volume screws to be in proper range for the initial timing of 7.5BTDC or 5ATDC. The DVDA particularly needs more air past since it's timed so far back. The SVDA less so - if yours is running OK and you get a decent adjustment from those screws on the side, then I'd call it good and not mess with it further.
-Andy

Thu Jul 21, 2011 11:48 am

glutamodo wrote: The purpose of the hole is to allow a small amount of air past the throttle butterfly, this allows the adjusment of the air bypass and volume screws to be in proper range for the initial timing of 7.5BTDC or 5ATDC. The DVDA particularly needs more air past since it's timed so far back. The SVDA less so - if yours is running OK and you get a decent adjustment from those screws on the side, then I'd call it good and not mess with it further.
-Andy

But his isn't running well at all. I'd by all means drill a small hole as a bypass. You are looking at the size of a pop rivet stud. A 1/8" pop rivet here in the USA has a .074 stud on it. That's bigger than 1/16 but smaller than 5/64. That hole size generally works on these cars to help the idle and dead spot.

Dave

Thu Jul 21, 2011 12:25 pm

djkeev wrote: glutamodo wrote: The purpose of the hole is to allow a small amount of air past the throttle butterfly, this allows the adjusment of the air bypass and volume screws to be in proper range for the initial timing of 7.5BTDC or 5ATDC. The DVDA particularly needs more air past since it's timed so far back. The SVDA less so - if yours is running OK and you get a decent adjustment from those screws on the side, then I'd call it good and not mess with it further.
-Andy

But his isn't running well at all. I'd by all means drill a small hole as a bypass. You are looking at the size of a pop rivet stud. A 1/8" pop rivet here in the USA has a .074 stud on it. That's bigger than 1/16 but smaller than 5/64. That hole size generally works on these cars to help the idle and dead spot.

Dave
Hmm, well I should perhaps update you on my car! Since installing a new float valve with .5mm washer and replacing the manifold boots and gaskets, my engine WILL now run and idle on the lowest step of the cam - but still very rough. If I can't sort the smooth idle with the bypass and volume screws I can try drilling that hole. My drill doesnt hold that small a bit unfortunately :D