Carburetored type IV engine problem diagnosis., Engine idling problem. |
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Carburetored type IV engine problem diagnosis., Engine idling problem. |
Keith914 |
Oct 21 2016, 07:00 PM
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#1
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Member Group: Members Posts: 248 Joined: 29-April 16 From: Laguna Beach, California 92651 Member No.: 19,948 Region Association: Southern California |
Just completed very careful cleaning, installing, adjusting, balancing two Weber carbs on my recently rebuilt '72 1.7 type IV 914 engine upgraded to 2.4 L. Carbs are real Webers (Spain), and we're working well earlier. Balancing and setting idle at 1,100 rpm was done on cold engine - nice smooth idle and solid response to accelerator action. The carbs are 44's, idle jets are 55's, main jets are145's and the air jets are 200's. Sea level ambient condition.
Engine starts immediately and runs very well and continues to run very well above about 2,000 rpm. But once engine is approaching and then at normal operating temp - 190 F, it will not run smoothly below about 2,000 rpm, and at idle accelerator position, engine drops below 1,000 rpm and stumbles to stalling sometimes with pre ignition sounds as it stalls! Timing is set at 32 degrees at 3,000 rpm, and distributor is new with new Pertronix electronic unit, and no vacuum mechanism. Welcome any diagnosis suggestions. |
porschetub |
Oct 24 2016, 02:22 PM
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#2
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Advanced Member Group: Members Posts: 4,725 Joined: 25-July 15 From: New Zealand Member No.: 18,995 Region Association: None |
That fuel pressure is very high,that would cause the stalling,try to regulate it back to 3 psi,I think Jake Raby mentions he uses 2.5 psi. which ever pressure you use it will improve.
Choose a quality low pressure regulator not the cheap crappy one the VW shops sell. You can never tune carbs with high fuel pressure as you will have fuel spilling over from the fuel bowls down the throats,raw fuel doesn't burn well. These are large carbs for a 1.7 what size venturies are you running? . Good luck. |
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