quick way to tell 150 from 165 franklin?
- Thread starter tjbell
- Start date
Larry Lowenkron
Member
165's have "dimples" on the valve covers due to the higher lift for the valves. However I suppose you could put 165 covers on a 150, though I haven't seen that. Also Intake tube to the carb zone are bigger on the 165. 165 has an MA 4.5 carb versus the MA 3SPA on the 150. Of course as a last resort, one can always look at the data plate 
There is a legal STC for putting 165 valve train on 150s so the dimples dont always mean a 165. Many have been done without the STC so log books dont mean too much. The carb and intake tubes are an indication also, but again, I have read on the Stinson Forum that some 165s were put into planes with 150 intake systems. The case casting numbers are the most accurate but there are normal and heavy case 150s and light and heavy case 165s. Now that I have confused the issue, I would say that the carb is probably the best indicator, but if it is a 165 make sure it is a heavy case. As Larry L. can verify, I once bought a 165 with half heavy case and the other half was still the light case. It had been that way since 1953. I dont have the case numbers close so maybe someone else can supply them for you. Good Luck. Grant.
Larry Lowenkron
Member
I really wonder how many 150 engines have actually had the 165 valvetrain installed. For a quick visual check I still say the dimples valve covers are the fastest way to see that if It is a 165. Again if you really want to know what it is and check the data plate and the casting numbers on tne bottom front of the case. When we looked at the engine Grant referred to I think we saw the case casting number on one side and did not look at the other side. I mean who would've thought that anybody would have mixed a light case and a heavy case!? Oops I guess they did, And we've missed it!