TheSamba.com :: View topic - need help tuning mystery motor in 75 automatic

Wed Oct 21, 2009 11:34 am

Hi all.
Im helping a friend with his 75 automatic westy and we ran into a few snags. He recently purchased a rebuilt motor that had actually been rebuilt 15 years ago and put in storage, then sold along with another bus so the paper work and story with it was a bit shady.

The engine case is an AW 1800 however it has hydrolic lifters and 2.0 heads so we're assuming it also has a 2.0 crank, rods, pistons and jugs. Basicly a 2.0 in an 1800 case.

Being what it is we put in a single vacuum distributor from a F.I. 2.0 and a New Weber carb.

Questions ???

1. Were should the timing be set? 7.5 BTDC or 5 ATDC
2. What distributor would be best? The original one for the automatic, one year only or the current single vacuum.

After we istalled and broke it in, it runs and idles very smooth but seems to lack power on hills. 60-65 easy on flat roads but drops to 30-35 or lower on hills.

Any insight on this would be greatly appriciated

Wed Oct 21, 2009 12:01 pm

For a single vac advance distributor, the timing should be set at 7.5BTDC at idle then when you get it running you want to set at like 27 BTDC at 2000 rpm. What is the timing at now? Does the distributor advance properly? Either could bog you down on hills.

I think that the stock distributors that had an advance and retard connections were primarily for the dual carbs. I might be wrong but I can't see how automatic plays into the equation. The engine/ignition system doesn't care if its turning a flywheel or a torque converter. I am sure I will be corrected if this is not the case.

Wed Oct 21, 2009 12:12 pm

If it were me, I would hook up the timing light and remove the vacuum hose(s) and then rev the engine up until all of the centrifical advance it has is all in at ~ 3500 RPMs. Make that point to be 28º BTDC on the timing scale.

Then let it loaf back to idle, tighten the distributor clamp and set the idle speed to about 850-950 RPMs. Note where the initial timing falls at idle speed but don't change it. It shoudl be roughly about 7.5º BTDC.

Then take it for a ride and see how it performs.

Some dual carbs would be a good investment.

Wed Oct 21, 2009 3:36 pm

kevin77westy wrote:
I think that the stock distributors that had an advance and retard connections were primarily for the dual carbs. I might be wrong but I can't see how automatic plays into the equation. The engine/ignition system doesn't care if its turning a flywheel or a torque converter. I am sure I will be corrected if this is not the case.

The vacuum retard was an emissions thing. All the distributors are doing roughly the same thing moving down the highway. Time it for full mechanical advance and move on. I'd be looking at the carb...

Wed Oct 21, 2009 7:54 pm

Kickdown might not be working. It is an electric kickdown and the sending unit is on the gas pedal.

When you say it drops down to a lower speed do the rpms drop down also or is there some slipping in the trans.

Wed Oct 21, 2009 8:35 pm

Depending on what you call a hill 30-35 might be normal. These things were never known for their power. They will typically only be able to hold highway speed on a 4-5% grade. Pennsylvania has lots of grades steeper than that.

Thu Oct 22, 2009 6:45 am

Thankyou for all the responses. My friend lives 1.5 hours from me so I didn't get back out here until today. We're taking it into town so I'll drive it and check the timing as suggested. The timing is set @7.5 BTDC currently. I do know that the trans shifts smooth and I did't feel any slipping but I know nothing about the electric kickdown.

I'll have a better idea of how it"s performing after our trip to town.

Thu Oct 22, 2009 6:54 am

jcooksvws@aol.com wrote: Thankyou for all the responses. My friend lives 1.5 hours from me so I didn't get back out here until today. We're taking it into town so I'll drive it and check the timing as suggested. The timing is set @7.5 BTDC currently. I do know that the trans shifts smooth and I did't feel any slipping but I know nothing about the electric kickdown.

I'll have a better idea of how it"s performing after our trip to town.

When you put the pedal to the metal does the trans kick down into a lower gear?

Thu Oct 22, 2009 9:05 am

We just returned from our trip and I found that it seems to be a carb tuning issue. It shifts down when you floor it but it feels as though it's starving for fuel at different ranges. It tried to diesel when I shut it down after the trip so it may also be in the timing. I'm a F.I. guy and don't fool with carbs much so I'm not sure what the next step should be other than rechecking the timing.

Are there different jets for the carb that would help or maybe an adjustment to the flash pump?

Thu Oct 22, 2009 9:25 am

Dieseling doesn't tell you much. These carbs usually do not have idle cut off so dieseling is pretty normal. If the idle is high that will make dieseling worse.

Jets are available, but I wouldn't recommend playing with the jetting unless you have an exhaust analyzer available, and have exhausted all other possibilities.

Have you checked your fuel delivery. If the pump doesn't move enough fuel at the correct pressure you will have poor power during full throttle operation.

Check out this thread, it has pretty good coverage of progressive problems and some solutions. Unfortunately way too often progressives don't come out of the box ready to run.

http://www.thesamba.com/vw/forum/viewtopic.php?t=217070

Thu Oct 22, 2009 9:46 am

The bus is running the stock mechanical fuel pump mounted on the side of the motor but we left the electric pump ( not the F.I. pump) mounted just in case. I'll give that a shot first since I don't have a fuel pressure gauge with me.

Fri Oct 23, 2009 5:31 pm

Well the electric fuel pump made no difference. The carb also seems to be in tune so were starting to look at the transmission. It seems as though it doesn't shift down on a hill as early as it should and loses too much speed to recover.

We found a part that came with all the F.I. stuff that does't look familiar.

Is this part of the automatic kickdown system and "T" into the vacuum line to the tranmission?

Thu Oct 29, 2009 3:09 am

i think that might be part of the decel valve
im not sure