VW 1600 bogging and/or flat spots. Please Help

[andrewvwclassic]

Dual kads can be overkill on an engine. you have heard mention go fast parts and those can be just another accessory that can make an engine less reliable. one would have to know your entire engine setup to help you find what your looking for. dont look for many to tell you not to run cads here though you will find most people reccomending dual carbs of some nature. I personally find them to be a weakness for a street motor. the cross linkages sometimes need adjusting and you will need to synchronize them periodically. I would go with a webber progressive and svda setup for the street. the svda should work well with a progressive. one turn adjustment and jet changes are more convenient for a street engine I would rather be driving my car than tuning carbs.

[garyt]

Just in case anyone is still reading this, I'm a bit surprised that the advice didn't include suggesting, with the original setup, that you drive around and try different settings with the distributor. This is the only way I can sort out my timing. I have a route that is in the country and go up and down a few hills and repeat this adjustment over and over. I get a big tank of petrol so I can take the time, and use a ratchet with an extension to tighten and loosen the distributor nut. Obviously doing this you have to be careful of the fan, and you need to be away from traffic. The car should be pretty warmed up too. You start to get the feel of the motor after a while.

[Jrbrass]

I finally found a shop that specializes in VW Sand Rails. Right away, they told me to go back to my two Dual 40mm carbs. They explained to me about the jetting process and that I should have never gone with the Pic 30 carb. Well, I picked it up from the shop and all I can say is wow. What a difference. It runs so much better, no hesitation at all from start to finish. No hesitation accelerating from first and down shifting and picking it back up from second. Now my Sand Rail gets up and moves, I didn't realize it then, but it was a dog with no power with the pic 30 carb. Putting the two dual 40mm carbs, it practically took out the oversized cam. Anyone that is having a problem or needs a great shop with great mechanics, I would recommend Montz Auto Renditions in Phoenix, Arizona. After they were through with it, it was like getting a whole new Sand Rail.

[Jrbrass]

Alright, I contacted Doug's Bugs and Bunnies in Mesa AZ concerning my problem. They immediately gave me a 140 main jet and a 60 idle jet. I put them in and now the hesitation is practically gone. Wow, what a difference. Now I can at least drive it around in the nice weather and enjoy it. Going to take it in to them in about a week or so to have them fine tune it. So, the main jet I took out was a standard 120, put in a 140. The standard idle jet was a 50, put in a 60. I wanted to post this in case it helps someone else down the line. Thank you all for all your help and suggestions.

[Jrbrass]

[Aussiebug]

[drs1023]

Don't assume what lift you have onto the camshaft. Can youmeasure the lift on the cam? You can almost nail it by measuring the total travel of an intake and/ or exhaust valve- try just one first as dual pattern VW cams are not so common. Set (by magnet) a dial indicator on a fully closed valve. Temporarily close the lash to zero so there's no slop. Zero the indicatorand open that valve fully & slowly noting the highest reading.
Now call a reputable camshaft company and give them this info along with your rocker ratio. Then you will be a little more knowledgable as to whether the twin 40's are adequate.

[Jrbrass]

Different VW repair shop is telling me to get rid of my 30pict and put the two Dual 40's mm back on. That the Dual 40's can and will solve the problem. I'm going to try changing the jets first as suggested here in the forum, but if it doesn't work would you guys go back to the two Dual 40's setup due to the oversize cam?

[Jrbrass]

Thanks for all your replies, it's very much appreciated. Love all the VW people wanting to help, what a great group. OK, took off the brand new 30/31 pict carb out of frustration. Wanted to see what size main jet was in it. Pulled it out and it only had a 120 in it. So, sounds like from you all I need a larger size main jet. Would you step it up to a 125, 127.5 or a 130. Not sure what size the other jets are, is the size stamped on them as well? So, seeing my main jet is only a 120, what combination size of jets should I use. Please use the proper term for the jets, I'm a newbie. Will be trying to get the jets you guys recommend on Monday. Once again, that all of you for caring.

[Aussiebug]

[Glenn]

[ashman40]

This thread is an interesting read.

Two points I wanted to make...
1) The 30/31 carb uses venturi vacuum for distributor advance. This is weak vacuum and will not work with most SVDA distributors. You need to use an earlier SVA (SVSA) distributor like the 205T if you want to use vacuum advance.

2) The venturi vacuum used by the 205T is less prone to problems with a loppy cam. Cams with big overlap cause issues with intake vacuum and ported vacuum. The 30/31 and 205T combo uses venturi vacuum which is based on the volume/speed of the air through the venturi. Higher rpms means more airflow and more vacuum. As long as the engine is running above idle there is venturi vacuum that varies with engine rpms.

So you can either make the 009 you have work better, or look in the classifieds for a 205T/M/K distributor and hook it up to your carb.
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[sb001]

[drs1023]

This entire conversation reminds me of when I first started messing with VW's back in the early 70's. The engines look so simple that I thought any go-fast item could just be bolted on or added in. I have run the entire scale of mixing and matching parts to save a buck, make it go faster, or get better fuel mileage. What I found out is that VW engineers were a lot smarter than I originally thought. Yep - lots of add-ons are out there which will make your engine purr, scream, hiss, spit, cough, etc., and your mixture of parts seems like a perfect combination.

Fix your timing and carburetor adjustment first. And to Go-Bug-N - spot on! Put the engine as close to factory set-up as you can with what you have before letting any mechanic talk you into more parts. Step by step you can adjust for cam lift and separation, electronic ignition (which I love), re-jetting carb(s), etc. If you can "hear" that the cam is not for street use, then it may have been just thrown in without hi-performance lifters to match, valves may not be ground to accept more fuel quickly (3-angle grinds help), etc. I have run Bosch 009's - I even have a complete back up with electronic ignition in my on-board tool box in case I am stranded by the side of the road - but I don't run it as an everyday unit.

[Go_Bug_n]

When all else fails, put the motor back to what it was when it first rolled off the VW dealer's lot. That way, you KNOW it won't hiccup or bog. Many troubles are caused by PO's who bought go-fast crap from EMPI and JC Whitney and put them on.

Just my opinion, the VW engine is a rather sensitive thing. Anything from the smallest vacuum leak to mongrelized carb and 009 combos will make life miserable for everyday street driving.

sb001 has a superb posting and a chart of carb and distributor combos! Maybe you might be able to keep the aftermarket cam but, again, I'd suggest you get the motor back to pure stock if you want a drama-free engine. The only genuine improvement would be a Pertronix electronic ignition. Now THAT has proven to be a huge improvement in my experience.

[Jrbrass]

So, if I am reading all the comments right, sounds like adjust my timing to 30 or 32 advance first (already tried adjusting carb), then adjust the accelerator pump, maybe a slightly larger main jet. If I adjust the timing to 30 or 32 degrees advance, will that be too hot? I just got a advance timing light, so turn the knob to 30 or 32, then rev it up, turn dist where the line lines up with the crack of the crank case, right? If it is already set to 10 degrees, then I just need to go 20 more? I really don't have a tach, this can be done by ear, right? Sorry, too early not thinking clearly. Thank you all for your help, very much appreciated.

[glutamodo]

[camaroboi13]

[Brian]

Just get a 010 or 019 and call it done.
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[dcnjoe60]