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Sat Feb 20, 2010 9:14 pm

I rebuilt my sons motor and bought brand new stock carbs for it. The motor was a 1700 cc type 4, But they sent me bigger pistons so now its a 1800 cc. The carbs I bought are twin solexes. I think they are 34's. I bought them from CB, they are not empi's. I think the main jets are too small by the way it running, I get that assumption from reading tomilisons weber carb manual. I cant afford the bently manual yet, can anyone tell me what size the jets are supposed to be on a stock 1800 cc motor? I'm pretty sure they have the same carbs.
Also I went back to a vacuum advance distributer with pertronix pointless ignition. It ran so much better after I did that.

Sat Feb 20, 2010 9:45 pm

you can fined Mikuni s/p? jets at a motorcycle shop they fit the pict may fit the duals, I ran a 132.5 on a 1776 T1, altitude and exhaust are also things to take into account when jetting.

Mon Feb 22, 2010 4:12 pm

WayneN wrote: I rebuilt my sons motor and bought brand new stock carbs for it. The motor was a 1700 cc type 4, But they sent me bigger pistons so now its a 1800 cc. The carbs I bought are twin solexes. I think they are 34's. I bought them from CB, they are not empi's. I think the main jets are too small by the way it running, I get that assumption from reading tomilisons weber carb manual.

If you have fresh piston rings and new engine friction, do not assume that the carbs are jetted too lean. The original stock carbs were PDSIT 2/3 carbs with a central idling circuit. Do your replacement carbs have a central idling circuit built into the left carb? If not, the stock jetting for the 1800 factory engine may not be what is called for.

Your best indication of jetting is going to be your spark plug insulator colors after a highway run. Generalized misbehavior can be cleaned up with correctly synchronized airflow and mixture adjustments.
Colin

Tue Feb 23, 2010 9:39 am

This is what I bought. I was thinking that being a kit, it would need to be jetted. I did sync them and they work pretty good they just hesitate slightly.

Tue Feb 23, 2010 9:59 am

Is the hesitation happening as you come off idle? Or while cruising and accelerate? Also need to know your location as in altitude, what are the jets you have now, idle, main and air correction. One other item, what is the timing advance at idle and what is the idle rpm? Have you verified the total advance and what is it at what rpm?

Tue Feb 23, 2010 11:00 am

busman78 wrote: Is the hesitation happening as you come off idle? Or while cruising and accelerate? Also need to know your location as in altitude, what are the jets you have now, idle, main and air correction. One other item, what is the timing advance at idle and what is the idle rpm? Have you verified the total advance and what is it at what rpm?

Hesitation is off idle. Altitude is just below 5000 ft. Advance is 30* at 3500 rpm (28* total advance plus 2* for altitude) I dont know where I got this number but it seems to work pretty well for my other 2 VW's. Idle rpm is 800 and the advance is about 5 to 8 degrees. I dont know what size jets I have. I will have to take apart one of them.

Tue Feb 23, 2010 12:13 pm

Bump the initial advance to a fixed 8 degrees, not a 5 to 8, if you are at 5 that is too low. You also might try bringing the idle to 850 or 900, especially if you do not have a equalizing tube between the manifolds.

I have the Weber ICT's but on a 2.0L, have 57 Idle, 140 Main, 180 AC idle advance is 10*, total advance is 30 all in by 3,100 rpm.

Wed Feb 24, 2010 8:20 am

Thanks for the specs, I used to have weber ict's and the rebuild kit cost me $60.00 and the accelerator diaphragm ripped after a week. Somehow they filled the crankcase up with gas so I just replaced the whole carb setup. I also wanted a choke. When I say 5* to 8* I mean it jumps around a little bit. I have a large hose connecting the two carbs together and it tees off to the brake booster.

Wed Feb 24, 2010 9:08 am

Jumps why? Should be steady. Appears to me that your initial timing is at 5* which is too low. Are both carbs feeding the vac advance? If so block the the main line, if the timing steadies then one or both are advancing the distributor. You should have zero vac from the ported outlet on the carbs. If there is a vac being drawn at idle then the throttle plate of one or both is open too much. The low and/or bouncy timing will cause hesitation coming off idle. Throttle plate(s) open too much at idle will also cause hesitation for you are already into to progression circuit.

Wed Feb 24, 2010 11:03 am

The vacuum advance is connected to the left side only. I would say it is 8* at idle. If i raise the idle to 900 it would be around 10*.

Wed Feb 24, 2010 11:45 am

You do not want to raise the timing by increasing the idle, first raise the idle with the vac disconnected, balance the two carbs, verify the timing is still 8*, connect the vac and it should still be 8*. Test run it to see if that helped. To increase timing is the same, vac disconnected, increase timing, the idle will go up, reset to the prefered idle setting, which includes balancing the carbs and then reconnect the vac, timing should remain the same.

Having a vac gauge is really handy, you can verify that the ported vac signal is zero at idle and that the vac signal is ample to operate the distributor.