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Old 11-07-2010, 12:00 PM
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RicardoJM RicardoJM is offline
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Default Aisan DD38/38 Carburetor Rebuild

Red72FJ40 (Pete) started a carb thread and via the forum, we were able to determine that his accelerator pump was not working as it should. After some e-mail/pm exchange we decided to do a rebuild of the carb. Pete ordered a Keyster kit from cruiseroutfitters.



It took a while for our schedules to align and few weeks ago I met Pete and picked up the carb. Pete's FJ40 is a 1972 and is running an F engine.


Prior to removing the carb we checked the timing, vacuum and compression. As we were warming the truck up for the diagnostics, it idles smooth and does not smoke at all. The engine is a bit dirty and oily, but not any worse than other old F engines. Overall, the engine really appears to be in good "run it" shape.

The timing was spot on the BB and vacuum was just over 14 and under 15 with very little waver. Longmont is a bit lower altitude than Denver. The FSM for an F engine indicates that compression between 128 to 150. Adjusted for 5,000 feet altitude ; an F engine with compression between 110 and 129 is within spec. The compression numbers on Petes engine ranged from 122 to 129, nice and tight.
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Old 11-07-2010, 12:03 PM
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Default Teardown and Inspection

The carb is DD38/38 Aisan with a 1972 build date. It has been worked on at some time in the past. This will the fourth Aisan carb rebuild that I have done and as with all the others, photos and notes are important to keep things straight. Here are some photos of the carb before tearing it down.








In the second photo above, you can see the throttle positioner linkage has been previously removed. I was concerned about this, but after some doing some research, I have come to understand the carb will be ok with out it. Coolerman has some detailed photos (Fig. 5 and Fig. 9) of his DD38/38 before and after having it rebuild by JimC. This thread has additional insight on what the TP does.

Another concern was the brass nozel that funnels the fuel spray into the primary barrel. On this carb, the brass nozzel appears to have been cut off. Upon cleaning it out, it works just fine.



The next concern was the amount of white grit pebbles that had worked their way into the fuel inlet. They were all throughut the screen, inlet and the finer particles made their way into the float bowl.







In short order the carb was torndown and ready for cleaning.



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Old 11-07-2010, 12:05 PM
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Default Cleaning and Rebuild

The cleaning and rebuild were uneventfull. Coming out of the carb dip, everything was very clean and new looking.





The carb kit came with replacement jets for everything but the seconary slow jet. This is the second time that I have used this exact kit and each time it came with only one slow jet.




On this carb I did not change the float adjustment to the specification (4.1 mm) from the FSM. Fact is the float level was perfect when we removed the carb from the truck and on all my other rebuilds where I have adjusted the float to specification - it has ended up with the fuel level being too high and needed to be re-adjusted. In Pete's carb, the fuel level was spot on.



The new power valve, jets and clean fuel bowl look much better than before.



The jets sizes are:
  • Primary Slow Jet - 50
  • Secondary Slow Jet - 80
  • Power Valve - 60
  • Primary - 114
  • Secondary - 180
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Old 11-07-2010, 12:06 PM
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Default Installation and Fine Tuning

Yesterday morning we installed the carb. It looks a bit too clean for the rest of the engine bay.



I did not bench test the accelerator pump at home and the brass discharge nozzle was plugged. In short order we pulled the air horn and got it cleaned up. The engine fired right up; full choke and two pumps.

We were having issues dialing in the idle and vacuum adjustements. The adjustements were not having the effect they should. The idle was not consistent, bumping around between 500 and 700 and missing. The vacuum was very low, around 10. The slow idle adjustment would kill the engine.

We went about double checking items. We swapped out the coil to distributor wire and found not change. We checked the power to the idle cutoff solenoid and solenoid operation - they were just fine. We sprayed starter fluid around the carb, manifold and vacuum connections and could not find any vacuum leaks. I was certain we had a vaccum issue, but really stumped that we could not find it. It turns out that our issue was with a vacuum connection to the distributor. Pete's truck has a vacuum retard distributor and the vacuum connection was direct to manifold vaccum. Once we removed this connection and capped it at the manifold - our lean drop adjustments worked just like they should. Vaccum is steady between 13 and 14.

Overall, we are very pleased with the results. We took the truck out for a test drive and it is running nice.
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Old 11-07-2010, 03:44 PM
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I see a good retirement business for you, Ricardo...
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Old 11-07-2010, 11:09 PM
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Thanks for sharing your new expertise Ricardo!
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Old 11-08-2010, 09:01 AM
Red72FJ40 Red72FJ40 is offline
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Big SHOUT OUT to Ricardo. You rock, man. Thanks for all your help and expertise, and for posting this thread for others. I took the Cruiser for a cruise yesterday, and it runs great!

Thanks again.

Pete
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Old 11-08-2010, 09:17 AM
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Quote:
Originally Posted by nattybumppo View Post
i See A Good Retirement Business For You, Ricardo...
X2
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Old 11-08-2010, 02:00 PM
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Ricardo,

Just let me know when you want to tackle/learn Weber carbs
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Old 11-08-2010, 02:12 PM
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Quote:
Originally Posted by Red72FJ40 View Post
Big SHOUT OUT to Ricardo. You rock, man. Thanks for all your help and expertise, and for posting this thread for others. I took the Cruiser for a cruise yesterday, and it runs great!

Thanks again.

Pete
I really enjoyed being able to give hand. Many here have helped me along and it is nice to be able to pass some of it along. I'm looking forward to you getting to a club meeting and/or run when your schedule allows.

Quote:
Originally Posted by corsair23 View Post
Ricardo,

Just let me know when you want to tackle/learn Weber carbs
I have a 32/36 DGAV and the Weber carb manual. I'm still having to hunt down a bracket for the accelerator cable and air filter - but I do intend to put it in my truck and give it a whirl. It might not be a replacement for my Aisan, but I am curious enough to give it a try.
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