1973 Questions for all other cars Timing dwell testing

GERRY_H

MEMBER
1973 ALL OTHER MAKES ALL OTHER MODELS

Engine Performance problem
1973 Questions for all other cars 4 cyl Two Wheel Drive Manual lots miles

Actually it's my Allis Chalmers loader/tractor. A mod. 615 ind. The wife says I love that tractor more than her.
The engine (an A.C. 160 power crater industrial), is running rough.
In trying to check the dwell (spec'ed for 24 BTDC) - (note: it has a oem 4 cyl. 'Gas' engine w/all Delco ignition components).
I could not adjust a reading below 29-to-30 degrees dwell no matter what rotation of the distributer?

I was checking the dwell with a new Actron DMM auto service meter (w/dwell). First time i've used it. Can only assume it is accurate, (having it tested now).
Assuming meter is correct (i.E. Little to no adjustment range of timing dwell - rough running), what in the world could be causing that sort of symptom?

Thanks Rob Harris

2 Replies

MHPAUTOS

MECHANIC
31,938 POSTS

When it is running how much dwell variation do you have at around 1200 rpm?

Mark (mhpautos)

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Thursday, August 19th, 2010 AT 9:59 PM

GERRY_H

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Specs. [Allis Chalmer 615i tractor w/oem bucket loader. Gas eng. Model w/160ci 4cyl. AC Power Crater engine. Electrical sys. All Delco Remy.]

Hi Mark,
I'm back. (Lost my PWord).

Checked it through full range 1000 to 1900 rpms - results odd? All ranges gave same readout (bounced) 29 to 30 degrees dwell.
As mentioned - this is a 'new' Actron automotive type test DMM, i've never used before - it could be the problem. Haven't tested yet with a timing lite. (So. Fl. We've had pretty steady rain lately, and the tractor is outside). I'm not complaining, we needed the rain ;-)

I did have a break to discover a little contamination in the fuel sys. Have the carb. Off right now to clean - it a pretty simple task.
By the way - a timing chain can be ruled out - this eng. Uses helical gears in a cluster w/ a cam gear drive.

Q: could ign. Points some how cause a lack of response to manual (distributor) timing adjustments?

Checking point gap from 0 to max. Opening, seems to imply that dist. Shaft lobes are OK.

Clue: When manually turning the dist. From full CW to full CCW, (w/engine running). - At the two (full) 'extremes' of dist. Rotation the engine would load noticeably and drop a hundred or so rpms - but, no audible engine changes could be heard throughout the mid-portion of rotating the distributor.

That indicates something - I think :-D