JBugs Video Series

VW Super Beetle Carburetor Tuning:

Video Overview:

In this video we will cover VW Carburetor tuning. With the engine for our 1971 Super Beetle project started and through its initial break in run, we can take a quick look inside the valve covers, fix some minor issues and then continue breaking in the engine. While the engine is running we’ll tune the 38EGAS carburetor for the larger 1800cc displacement and after we’ve run the engine for another 15 minutes, we’ll drain the oil, and check the valve adjustment.

Video Tips:

Ultimate Guide to VW Carburetor Tuning


Today we're diving into the nitty-gritty of tuning your VW carburetor and performing essential engine maintenance. We've got your back with detailed steps, so let's get those bugs purring smoothly!

Tools Needed:

-12mm Wrench
-13mm Wrench
-3mm Allen Wrench
-5mm Allen Wrench
-3/8" Ratchet
-10mm Socket
-1/2" Ratchet
-30mm Socket
-Adjustable Wrench
-Needle Nose Pliers
-Wire Brush
-Small Flat Head Screwdriver
-Medium Flat Head Screwdriver
-Large Flat Head Screwdriver

Chemicals Used:

-Copper RTV
-Parts Cleaner

Step 1 - Post-Run Check: Valve Covers and Rocker Assemblies

After the engine cools a bit, start by removing the valve covers to inspect the internals. If you find loose rocker assembly bolts, like we did, no worries! Simply reinstall and tighten them. Double-check all end bolts, then reinstall the valve covers, even if they leak a bit — we'll be pulling them off again soon.

Carburetor Tuning Pic 1 Carburetor Tuning Pic 2

Step 2 - Carburetor Tuning: Fine-Tuning for Optimal Performance

While the engine is running, grab your timing light for an easy visual on carburetor adjustments affecting RPM. Whether you prefer tuning by ear or using the light, start by setting the idle mixture screws for the best lean idle. Turn them in until stumbling starts, then quarter-turn out at a time. Continue until the RPM increases, making the engine run smoother. Once set, adjust the idle screw at the carb linkage until you hit the sweet spot of 850 to 900 RPM.

Carburetor Tuning Pic 4 Carburetor Tuning Pic 5 Carburetor Tuning Pic 6 Carburetor Tuning Pic 7

Step 3 - Timing Check: Ensure Precise Ignition

Loosen the distributor clamp and hook up a timing light. Advanced to 30 degrees, point it at the crank pulley, and rev the engine to 3000 RPM. Look for top dead center while slowly moving the distributor. Once found, set the timing, and tighten the distributor clamp.

Carburetor Tuning Pic 8

Step 4 - Final Run and Diagnosis: Identifying a Lean Condition

Complete a final 10-minute break-in run, avoiding prolonged idling to prevent uneven wear. If you notice hesitation or backfiring during rapid throttle acceleration, it's a sign of a lean running engine. Consider installing larger main and idle jets to address this.

Step 5 - Oil Change and Sump Maintenance: Keep It Clean

After the run, let the engine cool and drain the oil by slightly pulling off the sump plate. Look for debris and clean the oil pick-up screen. Install a new sump plate gasket, followed by the plate, and refill with oil. Check and adjust the valves, coat new valve cover gaskets with copper RTV silicone, and reinstall.

Carburetor Tuning Pic 9 Carburetor Tuning Pic 10 Carburetor Tuning Pic 11 Carburetor Tuning Pic 12

Step 6 - Wrap-Up: Clean Up and Get Ready for the Road

Clean up any oil leaks, and you're good to go! Follow these steps for a smoothly tuned VW carburetor and a healthy engine. Enjoy the ride, and keep those bugs rolling!