an series timing woes?

[jinx]

trying to find what timing my t4 AN engine should be set at? got it running at 7.5 deg btdc i think but lack of markings makes it hard to be shure!

starts ok ish but ticksover realy high when warm then runs on when the ignition is switched off!

[raygreenwood]

This sounds like a vacuum leak. Also...am I right to assume this is twin carbs? If so...check to make sure that the idle cut-off valves in each carb are operating and getting power. They cut off teh flow of fuel when the ignition turns off to prevent run on. Ray

[jinx]

no its a timing problem now iv checked the rest! not sure what it should be timed at tho! ?

[raygreenwood]

7.5 should be fine. In general...if your idle cut-off jet is working properly...it should not be possibel to run on...no matter what the timing. Ray

[Wally]

7.5 should be fine. In general...if your idle cut-off jet is working properly...it should not be possibel to run on...no matter what the timing. Ray

Yeah, I agree with Ray.
Mine is an AN engine as well.
Most - no, make that ALL - 412 engines have at least the idle timing mark visable through a big black plug on top of the magnesium airflow-housing.

Some even have a timing mark for max advance (without vacuum), which is around 27 degrees BTDC..

Do NOT set timing accidently at the max advance mark. Strangely enough, it is even possible to let it run at idle (somewhat) at that mark if you really try....

[jinx]

been on to pelician and it appears that im setting my 7.5 deg the wrong side of the TDC mark!
might explaine a bit!

[raygreenwood]

Dang....also what am I saying...for some odd reason....I almost thought this was a type 3. 7.5 is for type 3. I have found that most type 4's with stock cams....do better at about 950 rpm and 10-12 before top dead center at idle. Just be sure to check your total advance. Ray