050 Timing Spec

[Jim Chambers]

Have '69 912 with "050" distributor. Assume 3 degrees ATDC is no longer correct. What is the proper spec?

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[ScotMcLean]

Hi again! I also run the 050 and recently had mine tuned. The sticker on the motor mount says 5ATDC but all the manuals state 3BTDC. I took it to my seasoned mechanic that knows the 912 pretty well and he thought 3BTDC sounded right, looked it up, & confirmed it. Just to be sure, he set it to 5ATC, ran it, and then re-set it to 3BTDC, ran it again, and found the 3BTDC to be much better. Good luck with your new P-car!

[josh912]

3BTDC is WRONG!!!!! On the 050 5ATDC is correct. If you set the 050 at 3BTDC you get 28 deg. high speed advance, instead of 33, which is factory spec. The 050 has a shorter advance curve and therefore needs a higher static advance to achieve the proper high speed advance. So disregard all of the factory specs as they are for the original distributor and not the 050. I consulted Harry Pellows (the Maestro) on this and he confirmed it. Good luck!

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Joshua Harrison
1968 912 Coupe

[ScotMcLean]

Thanks - I'll take another look. Harry would certainly know. Since I got it back from the shop, however, it runs smooth & even. I'll have it set at 5ATDC and drive it myself.

[Duke]

Hello Jim: I have used the 050 since 1983. The setting that came with it called for a static setting of 5BTDC. You should also check the advance at 3000rpm. This should be 33-35BTDC. These settings will give you the best performance. The "Sears Magic Dial" timing light is the one to use. Best wishes from Redding. Duke, 69 912.

[Jim Schott]

Originally posted by josh912:
3BTDC is WRONG!!!!! On the 050 5ATDC is correct. If you set the 050 at 3BTDC you get 28 deg. high speed advance, instead of 33, which is factory spec. The 050 has a shorter advance curve and therefore needs a higher static advance to achieve the proper high speed advance. So disregard all of the factory specs as they are for the original distributor and not the 050. I consulted Harry Pellows (the Maestro) on this and he confirmed it. Good luck!

Josh912 - advance means the spark fires earlier. If you set the static at 5 ATDC, the 28 degrees of advance for an 050 will only give you 23 BTDC at max advance. If you set the static at 5 BTDC, then you achieve the desired 33 BTDC at max advance. All of the above is based upon my understanding that the 050 offers a maximum mechanical advance of 28 degrees. However, considering the quality of today's gas, slightly retarding the static setting from 5 BTDC may be called for.


JAS

[josh912]

Your absoulutely right Jim! I got my ATDC's and BTDC's messed up and it is as you say, 5 BTDC and 33 BTDC.

As far as retarding it, their is a big performance increase if you bring it up to 5BTDC, and it also has 33 degrees high speed advance which is what the car came stock. I have 10.5:1 compression on my 912 and haven't experienced any pinging with this timing, except with Texico and 76 gas. In the heat of California Shell, Chevron, and Mobil run great!


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Joshua Harrison
1968 912 Coupe