1968 2.0L Engine Tuning

[911Lguy]

Thanks for the heads up on oil filters. Here is a link to one persons analysis and opinion whcih seems to be informed by some thoughtful testing (Opinions and Recommendations - Oil Filters Revealed - MiniMopar Resources).

As we say in our business ... the data speaks!

[Jay Laifman]

Anyone ever find a replacement for this sealing ring?

901 331 283.

[roblav]

A few thoughts:
- Bosch W3DPO are too cold. W5 is the more correct heat range. I agree with using NGK.

- SWB rear wheel bearings generally do not wear out. They are a much better design than the LWP version, which I've had a couple go.

- The 68 911L in US version came with 40IDAP type carbs. When I ran a 68 engine in my 67 car, it always backfired. I removed the IDAP carbs and installed the 67 Normal IDA3C type and the backfiring stopped.

- I would leave the vacuum unit attached. That should retard the timing at closed throttle situations. You should check and verify that your distributor is actually changing the mechanical as well as vacuum controlled timing!

- Difficult hot start "driver" solution on these cars is by holding the throttle down almost all the way while cranking. Never press the throttle more than once! I ran these cars in CA and FL heat for years with the normal Bendix fuel pump and fuel line system.

- Fram oil filters are about the worst there out there. I tend to use Wix.

Beautiful car and color!

[1QuickS]

Comments regarding Weber IDA vs. IDAP carburetors: IDAPs differed from IDAs only by the addition of a vacuum port on the bottom mounting flange. Progression circuit hole sizes and geometry relative to throttle shaft axis are exactly the same for both types as is the size of the idle air bleeds. The remaining components are selectable and therefore not a fundamental design difference. There is a design variation from the earliest IDA Webers to all Webers manufactured after around January 1967 (rough timeline guesstimate based upon my experience) which typically results in running issues; the throttle shaft bearings in the outer journals of the throttle bodies were revised to include Teflon sleeves which allowed for early throttle shaft/throttle body clearances. These wear related clearances allowed uncontrolled air leakage resulting in erratic idle, progression and deceleration operation.

Engine running issues should not be attributed to the type variation of these carbs however, IDTP carbs are another topic.

[roblav]

Thanks for the clarification Paul. Agree that there are other variables as to why my engine ran much better on the IDA3C rather than IDAP's. That was way back in 1985. The engine I took them from was a 901/05, so I suspect I had the earlier type.

[ThomasTe]

Originally Posted by 911Lguy

Grady and Other Contributors –

Most replacment axle parts were fairly easy to source, but the rear axle sealing ring (PET P/N 901-331-283-00, #16 in the diagram) is NLA from Porsche, Pelican and the other usual suspects. In addition, I have not found a local seal supplier whom can source this item despite several enquiries. Any suggestions?

Here are the critical dimensions for the seal:
OD = 37 mm
ID = 30 mm
Thickness = 3.5 - 4 mm
Height = 7 mm
The edges appear to have a 1 – 2 mm radius. I am assuming the material is Buna-N rubber. In the picture below, you can see that the seal on the left was mostly OK, but the seal on the right came out in pieces so they need replacment.

Will this seal be useable instead of nla 901.331.283.00? (For Nadella drive shafts).

https://www.bearing-king.co.uk/bearing/30x37x4mm-r23-tc-double-lip-nitrile-rotary-shaft-oil-seal-with-garter-spring/6364

Or maybe one of these:

4mm: https://www.123bearing.eu/seal-OAS-30X37X4-NBR.php

7mm: https://www.123bearing.eu/seal-OAS-30X37X7-NBR.php