Detroit 6-71 ilding

Busted Knuckle · October 22, 2009, 06:53:48 AM

Quote from: cody on October 22, 2009, 06:24:52 AM
Probably needs new plug wires lol.

Uhmmm more likely moisture in the distributor cap, or bad plugs! But plug wires could be the culprit too!

BK

lostagain · October 22, 2009, 07:17:37 AM

Some of you guys need to refer to the service manual, the tune up chapter, before you start talking about things you don't know anything about. Loping is caused by the buffer screw not being far enough in. You need to turn it in a little to eliminate loping but not too much that it would increase idle speed. Idle speed is a different adjustment.

3, 4 years ago, I didn't know anything about Detroits, but I wouldn't have gone on a thread like this one and start writing things that maybe I guessed or had heard from the neighbour's uncle who knew a back yard mechanic...

I have gotten a lot of good info from this board over the years, but you have to sift through so much BS and opinions and useless posts like above from guys who have apparently all day to blabber about things they don't know about.

So stay away unless you know for sure, and waist other members time and confuse them.

This is why I don't post very often.

Sorry about the rant, but I had to get it off my chest.

JC

cody · October 22, 2009, 07:19:53 AM

Now quit beating around the bush and say what you mean

lostagain · October 22, 2009, 07:22:34 AM

I am not referring to Cody or BK.

zubzub · October 22, 2009, 07:54:28 AM

So... for those that know.
1.What is the down side of having the buffer idle switch off a tad?
2.Is the buffer really that far off if once warm everything is hunky dory?
3. when I look into the manual the tuning is done on a warm engine so a little lope seems possible without being a problem, hence my queries.

John Z · October 22, 2009, 08:22:35 AM

Jeez Lostagain, i think you mite be talking about my post being a waist of time. I want too apologize for righting that post and waisting all the time you took two reed it. I guess if i had studied my owners manual i could have found out about the buffer screw. Of course if we all would do a hole lot more research on our questions, then their wood bee no kneed for this bored at all.

lostagain · October 22, 2009, 08:34:30 AM

From my limited experience and knowledge:

Back in the Seventies, most 2 stroke DDs that we drove loped at idle just after starting. This is why that "lope" still puts a smile on my face when I hear it. (I'd love to have it on my cell phone as a ring tone). I don't think it hurts anything. I find with the Jakes switch that replaces the buffer screw, it has to be adjusted a little farther in so the Jakes come on. If the switch (buffer screw) is backed out so it lopes, it is too far out for the Jakes to come on. That is my experience with my 4-71. YMMV.

JC

thejumpsuitman · October 22, 2009, 03:18:01 PM

Great, thanks for making it evident that the loping is not uncommon. Interesting that a particular maladjustment can be so common that it can make some think it is normal.

So at what point would the loping become problematic? Or could this potentially cause any problems? Obviously it only lopes at idle, so any related problems would only occur at that time.

gus · October 22, 2009, 03:45:19 PM

I'm sure TomC and JC know what they are talking about but, as my ole grandpappy always said, if it ain't broke don't fix it.

This has to rate way down there with the very minor problems.

So, mine will stay as is until it develops something more serious than this before a mechanic puts a wrench to it.

TomC · October 22, 2009, 10:23:20 PM

A loping engine will NOT hurt anything. Only if you have an automatic and it lopes all the time causing lurching in the vehicle. Good Luck, TomC

wal1809 · October 23, 2009, 03:50:11 AM

Mine does the same thing for couple of minutes then it quits.

luvrbus · October 23, 2009, 05:01:49 AM

Like others have said set your buffer,idle speed and starting aid with a rack adjustment and the problem will go away

good luck

thejumpsuitman · October 23, 2009, 06:06:56 AM

Thanks everyone for the responses. I am learning something every day.

johns4104s · October 24, 2009, 07:46:47 PM

Lostagain.

had heard from the neighbour's uncle who knew a back yard mechanic...

The thee 671 engines I have one was rebuilt and set up by a DD in Lufkin Texas, the second had the head replaced and the rack run by one of the top DD mechanics in the Costa Mesa are ( I blew a head gasket and a great busnut who happend to have an Eagle ) he lined the guy up for me. The third was set up by Huggy Bear.
All three lop when fist start up, but idle right on the money when warm.

I do not profess to know much about engines but the above guys can clean any mechanic out there.s clock.(with the exception of Huggy as he is no longer with us).

John

4104GA · October 25, 2009, 08:02:32 PM

WOW Now I know why my old 671 lopes after start up for a few minutes and then idles smooth. Thanks all