The International Cessna^® 170 Association

Is the crank flange bolt count and the Starter mount/Accessories the only differences in a Cont. 300-A & 300-D?
I am near TBO and want to continue flying while an A&P friend does a major on another engine. He works as A&P part time and needs time for the project. I've found a complete "A" engine that is not as high time as my "D". Are there any internal differences that can't be updated to "D" specs? I am guessing it can be tagged as a "D" if brought up to those specs.
Any thoughts would be appreciated.

Yes they are the only differences.

Sixracer wrote: I am guessing it can be tagged as a "D" if brought up to those specs.

I wouldn't guess. You would follow TCM M75-6, Rev. 1 found here. http://www.cessna170.org/forums/viewtop ... =29&t=2303

What are you going to do for a crank?

Bruce,
I was thinking of buying one. Then sell off all the parts I don't use. Tonight at my race car shop my A&P buddy came up with a great idea. My engine had a complete set of cylinders on it about 285 hours ago (because of an AD) . He said just buy a case and perpare it and put my new cylinders with new pistons & new cam on it. That might work even better.
Hey,Hey -- there I might even figure out how to put a Big Block Stroker in that little case... HA! ;~)

There are not too many "part time A&Ps" that I'd trust to rebuild my engine.

In fact....there are none.

(I paid my personal way through college and flight training as an assemblyman at an aircraft engine shop that specialized in large radials and Continentals for cropdusters and utility companies. I am comfortable making component changes and most repairs on this engine, but I would not undertake to completely re-build one on my own without other supervision and assistance by someone who does this engine work regularly and is properly equipped to inspect and NDT the components. Engine rebuilding/conversion from one model to another is not always the dirt-simple task of stuffing cylinders on and fire'n 'er up. It's not like doing a head job on a four-bolt 350 Chevy, either. Lots of everyday-on-the-job-A&Ps are not sufficiently experienced to reliably build up one of these "simple" old O-300's without errors. Errors that can be costly. I'd find someone who ...having rebuilt scores of Continentals....has done more than a half-dozen of these specific engines to perform such a conversion, IMO.)

I admit that I am picky.

gahorn wrote:There are not too many "part time A&Ps" that I'd trust to rebuild my engine.

I agree George which is why Leroy and I rebuilt mine and the part time A&P (who had built many engines over 40 years) agreed we'd done a better job than he would have and signed off the books.

These engines are not rocket science as I'm sure you will agree. And I also agree there is nothing better than first hand experience to help insure the job is done right. An A&P license doesn't make you an engine builder either. One of the problems I see with very qualified engine builders of other types is they want to use the latest greatest techniques and practices rather than the tried a true approved methods of 40 years ago.

I agree with the “Part time” concerns, but this is a personal friend(he will fly with me, too) of mine that I have done work for many times in the last 42 years of my race engine machining and building business. The cap put on his income by SS is what makes him “Part time” & semi retired from the aircraft field. Yep he is in that age group that is penalized. He, like me, chose to get his SS early. You know the deal…. while there is some $$$ still there in SS.!!!
What I do everyday in machining & building race engines is way more demanding of accuracy and holding tolerances than any specs I’ve seen in any of the aircraft work I’ve looked at. With His experience, he was doing aircraft engines before I entered college and engineering school, and my capabilities we will make this project fly. (Pun intended)
I am concerned with TBO and the condition of my engine because I had a valve stick and what I saw when he and I fixed it. When they put the cylinders on they (whomever did the work) only replaced the cylinders. No new pistons. It looked like the rings had been replaced and the cylinders are the later ones with the 30degree intake valve seat angle. I got the yellow tags for all 6 of them in the logs and paperwork when I bought the plane. It did look like there were new springs and valves installed. Part of the problem with the stuck guide was the new valves and tight guides and the lead varnish deposits. I “honed” the varnish out of the guides & kept them in spec. Yep, I hone instead of reaming and have the dial bore gauge to measure the guide ID to .0001.
Now for what really bothers me.! The ring lands on the piston are at the outer limits of wear and the pins and pin bushing wear did not appear to be addressed when the cylinders were installed. The pins and pin bushings are also at the top of the wear limit.
This winter I plan on new Paint, Interior and engine work. I also plan on updating the windows ( I have done a search here & will have questions about them) and putting on some small curved wing tips as well as gap seals. In my spare time I’m working on adapters to put the refreshed engine on my dyno for break in and tune up. When all that is done I will send the prop to be checked and have it pitched right for good cruise.
I must close by saying: Thanks to all the good people on this forum I feel I am going to get my old bird all freshened up and back in the sky without making any bad mistakes. So, please don’t get tired of my Questions…. I wouldn’t ask them if I didn’t appreciate and respect the depth of the knowledge pool here.
Adger Smith
Adger Smith Performance Engines
2802 W 7th St
Texarkana, TX 75501
adgersperf@aol.com

I've held back making comments to this thread because much like the MMO thread in the end it comes down to personal desires and expectations. As well just as vast as the knowledge base is here, the experience base can be quite vast as well. The only problem is; often those that respond to questions don't know which end of the spectrum they are addressing.
Your engine will only be as good as the work and the processes undertaken. From your last post, I probably don't have to mention that. Yes it's a simple engine and so some might say its a simple rebuild. I tend to lean towards using the modern NDT methods and inspection equipment.
A concern might be new cylinders on a high time bottom end just for the very reason you have concerns about your rods. Some may express there's little wear, but its likely it hasn't been measured or appreciated when new tops are installed.
Another thing to consider are the subtle change in material properties which occur over time and environment. For that reason alone, I'm in the check everything with the latest techniques camp.
Big rocks, open water, vast timber and VFR on top motivated me to have my engine done by the best in my area. Yes I could have done it myself but I'm not a gambler or at least not a serious gambler, yet.

c170b53 wrote:Yes I could have done it myself but I'm not a gambler or at least not a serious gambler, yet.

Jim, I would say you gambled that someone else would do it right. And that is pretty serious.

We are all gamblers all the time. You just have to know when to hold em and know when to fold em. Isn't this a key in life?

Knowledge is the key to knowing when to hold or fold. I tend to be pretty up front with my experience and knowledge in order to encourage or educate and help others as others have been pretty free with their knowledge and experience helping me.

Could many of my comments here get someone in trouble, sure could. I'm gambling however that I'll help much more than hurt or I wouldn't offer the advise. Hard to believe but I have held back on occasion.

Absolutely it's all about spreading knowledge, sharing experiences and even expressing opinions.