Dwell angle specs:Lycoming GT engine?

I have a Lycoming GT engine, 226 cu in 8 cyl in-line engine. It was used in the 1928 Auburn model 77. It also was used in the '28 Gardner model 75 which I own. Is there any spec for the dwell on the points? The only info I have is the gap setting of .018" to .022". I think the dwell angle would be a more precise way to set them, if someone has calculated what it should be. I'm not sure of the specs to set the timing either. Do I need a 6 volt dwell meter and timing light?

Any help would be appreciated.<!-- google_ad_section_end -->

Ooops! I gave erroneous info on the engine model. It is not GT, it is the Lycoming 4HM. I just found a Dykes that shows 10 dgrees AT for the Auburn version, but it says 1" AT for the Gardner, and the same engine was used in the Elcar which shows TDC for timing. Is there a way to calculate the 1" into degrees? These engines were obviously set up a bit differently by the various car manufacturers.

You should be able to calculate how many degrees the inch represents by measuring the circumference of the flywheel. 1"/circumference" times 360 degrees will give you the number of degrees of timing.

There was a change of distributer from 1926 to 1927. Earlier Remy 648B had 8 lobe cam, and both sets of points opened at the same time. Later 958A distributer had a four lobe cam, and not only did the points need to open 45 degrees apart , but the open gap should be the same at 22 thou. (Stated the gap had to be kept between 18-24 thou). Obviously the dwell angle would be different for the four lobe cam. (I am not sure how this works without a seond coil, but only one is shown. If you want to use a dwell angle meter, just use an external 12 volt battery for power. If you check the distributer model I can give you all the information from National manual on it.

If you can gather a Rickardo squish head from an Auburn 115 , 120, or 125, the car will be faster than with the very low compression head of the 4HM. Even so, the 4HM still gave very useful performance. Ivan Saxton

Thanks Ivan. It is a Delco Remy 658B distributor. It has the 8 lobe cam, so the points need to be synchronized.

Dear John,

I have a page out of a Radco reference that you may be interested in. What it shows is the 1" past top dead center applies to a 1927 model and that the 1928 model 75 is timed at top dead center. It also indicates a method of timing and syncronizing the points.