Carb question

[SRSANDS]

Hey guys I put a used weber 32/36 dgv on my L motor. It starts right up and idles great. When I throttle it up it there is a flat spot where it cuts out and then once past a point throttles back on. What would you say is the issue. The accel pump seems to be working fine I have a good amount of fuel spray into the primary. The plugs are black? Let me know if you have any suggestions. Im not to knowledgeble about carbs. Also when installing the carb I placed a gasket on the mani then the spacer then another gasket then the carb. Does this sound right? All the gaskets I made out of gasket paper and didnt get the holes perfectly cut smoothly does it matter? I have two of these spacers didnt know what one to use both look the same except one has a small notch on on the side of one of the holes? Which one do I use and whats the notch for?

 

One more thing.....If I hold the secondary butterfly with a screw driver while throttling up the flat spot seems to go away? Let me know please what you think. THANKS!!!!!

[Cuts metal like mad]

sounds like the secondary jet a bit small, maybe one or two sizes up, the jets from the factory are for L16 to L20b and are more or less a general base jet sizing to get you started. Most people don't even get into the secondary jet to even notice the flat spot.

 

Could also be timing... I had the same thing on my truck, it was timing. It still bogs a little when the secondary is opened but not bad, mostly only when opening the secondary on a cold motor.

[SRSANDS]

Thanks for the info......this flat spot is at initial acceleration just as you puch the pedal down so im not sure. As far as timing goes the car idles great and has smooth acceleration other than that flat spot. Each of the jets that you can access from the outside of the carb primary and secondary are as far as I can tell say 50 or .50? I dont know enough about carbs to mess with jets. I know its probably a simple procedure but I suppose I gotta pay a carb shop 125 bucks to dial it in

Edited October 19, 2008 by SRSANDS

[banzai510(hainz)]

weber DGV there might be a hestitant when inbetween the 1st and 2nd barrel opening. YOu lose some vacuum due to the mechanical secondary openingup to fast if you just punch it.

Try easing smoothin on exelleration ans should be OK

 

Here is where a stock carn shines on smotthness as it uses vaccum to open up the 2nd barrel and only take what it needs

[SRSANDS]

Hey thanks I was waiting for the L motor god to chime in.....I havent had the chance to actually drive my car yet so im not sure how its going to operate under load. Thought it was the timing like stated above but I messed with that and no change. Since you chimed in I need to ask why the pointer on the pulley is so far away from the five white marks. If I turn the dizzy to bring the pointer towards the marks it runs like dog @&*%. Its ok on the last little mark but better more advanced???? Whys is this? I have a ei dizz installed off a L20. It fires up and idles nice...revs good also. Is something off? Would it fire and idle as good as it does if so?

[Cuts metal like mad]

with the EI dizzy you should be at about 12* btdc... you should also have your plugs gapped to about .041 +/-

[datzenmike]

Mechanical advance weights or even the vacuum advance may be stuck with 10 degrees advance already dialed in. Take the cap off and the hose to the carb and suck on the end. The plate below the rotor should twist in a clockwise direction and return when you let off. Try turning counter clockwise and see if it loosens up. Compare it to the L20B dizzy you have and see if it moves through the same range.

[SRSANDS]

I took the cap off the matchbox dizzy and blew into the vac tube and yes the lower plate does advance clockwise as I do so....not sure I understand the reasoning as to why you had me do this:p

[datzenmike]

Applying vacuum tests the vacuum advance. Seems like it's working, does it return all the way back without sticking?

[yello620]

What size L motor did you install this on? L16 L18 L20? How many turns out is your idle mixture screw? And how many turns is your idle screw from making its initial contact? Have you read the tuning page at racetep.com?

 

Jason

[SRSANDS]

Yes the plate seems to stick a bit....how can I free it up? As far as the second question the idle mixture screw sets about 2.5 turns out from all the way in

[SRSANDS]

Sorry I installed it on the L16.....think its all carb problems.....

[twindragon6]

Thanks for the info......this flat spot is at initial acceleration just as you puch the pedal down so im not sure. As far as timing goes the car idles great and has smooth acceleration other than that flat spot. Each of the jets that you can access from the outside of the carb primary and secondary are as far as I can tell say 50 or .50? I dont know enough about carbs to mess with jets. I know its probably a simple procedure but I suppose I gotta pay a carb shop 125 bucks to dial it in

 

Sounds like a manifold vacuum leak, is your carb on tight? (11 FT LBS(132IN LBS of torque to the manifold)) Some do it yourself gasket paper leaks like no tomorrow through the material itself. Could be that combined with a mixture that's too rich (black plugs do to higher mix/idle to keep the thing running smoothly). Does it idle down the road smoothly without pedal or does it surge and jerk?

Edited September 21, 2009 by twindragon6