Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 09-09-2012, 06:08 PM   #1
newshirt
Senior Member
 
newshirt's Avatar
 
Join Date: Jan 2011
Location: Colorado Springs
Posts: 868
Default Chug, chug, chug like a John Deere

When under load, my car makes a distinct chug, chug, chug sound like a John Deere Model A. It's the sharp sound of compression or exhaust -- like a two-cylinder tractor. It's most noticeable from 25 - 40 mph when coming up to speed. I think the sound is becoming more distinct and more noticable -- enough to alarm me. Retarding the spark significantly or reducing throttle lessens the sound, but then there's little power for acceleration. Changing manifold gasket didn't help. Reducing spark gap may have helped slightly, but not much. I don't like the sound, so I reduce throttle or spark to avoid it, and it seems like I'm having to do that a lot more than I used to.

Compression at 7,600' elevation: 70, 48, 62, 40.
Compression with four shots of motor oil in each cylinder: 80, 60, 75, 50

Car has lots of power, clears every hill, 60 mph top speed at 7,000' elevation, never burns oil, light tan 3X plugs after 3,000 miles, no obvious manifold cracks.

But what is that chug sound?
__________________
Ray White

Last edited by newshirt; 09-09-2012 at 06:14 PM.
newshirt is offline   Reply With Quote
Old 09-09-2012, 06:39 PM   #2
Karl
Senior Member
 
Karl's Avatar
 
Join Date: May 2010
Location: Manawatu, New Zealand
Posts: 1,416
Default Re: Chug, chug, chug like a John Deere

Seems like quite a variation in compression readings between cylinders ? Head Gasket . other things to think of re noise would Timing incorrect or alternatively manifold leak but you have looked at that -Karl
Karl is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 09-09-2012, 06:44 PM   #3
Logan
Senior Member
 
Logan's Avatar
 
Join Date: May 2010
Location: Fort Worth, Texas
Posts: 1,055
Default Re: Chug, chug, chug like a John Deere

In my opinion, your compression differences are way to big. I would start with figuring out why your compression is not right. I'm not saying this will be the fix to your noise, but it way help
__________________
Cowtown A's
Logan is offline   Reply With Quote
Old 09-09-2012, 06:53 PM   #4
Bob-A
Senior Member
 
Bob-A's Avatar
 
Join Date: May 2010
Location: Central FL, USA
Posts: 1,136
Default Re: Chug, chug, chug like a John Deere

I had a very similar problem with my newly "restored" '29 roadster. Found the valves way out of ajustment.

Bob-A
Bob-A is offline   Reply With Quote
Old 09-09-2012, 07:47 PM   #5
Greg Jones
Senior Member
 
Greg Jones's Avatar
 
Join Date: Jul 2010
Location: Aiken, South Carolina
Posts: 695
Default Re: Chug, chug, chug like a John Deere

Where do you regularly position the spark lever for highway driving? Do you just advance to the bottom and leave it there? Do you have a high(er) compression head? When I lived in Parker it took me a while to learn proper spark adjustment on those Colorado hills (beautiful!) Not saying you are doing anything wrong, just wondering if you pull back on the spark advance when negotiating a long hill, that sort of thing. I beat the hell out of an A engine with too much advance and detonation that I was not smart enough to listen to. I sure know that sound now!
Greg Jones is offline   Reply With Quote
Old 09-09-2012, 07:59 PM   #6
newshirt
Senior Member
 
newshirt's Avatar
 
Join Date: Jan 2011
Location: Colorado Springs
Posts: 868
Default Re: Chug, chug, chug like a John Deere

Sponsored Links (Register now to hide all advertisements)
Quote:
Originally Posted by Greg Jones View Post
Where do you regularly position the spark lever for highway driving? Do you just advance to the bottom and leave it there? Do you have a high(er) compression head?
Snyder 5.5 HC head.

I drive with spark advance at 1/2 quadrant most of the time, and rarely go full. The points open at 1-2 clicks down. Big hills require full retard.
__________________
Ray White
newshirt is offline   Reply With Quote
Old 09-09-2012, 08:09 PM   #7
Tom Wesenberg
Senior Member
 
Tom Wesenberg's Avatar
 
Join Date: May 2010
Location: Mpls, MN
Posts: 27,582
Default Re: Chug, chug, chug like a John Deere

If you have slow closing valves Sea-Foam in the oil and in the gas should help. First I'd bring each piston to TDC on the firing sroke and apply air pressure, then see if it's coming out the car, oil filler, or tail pipe. If it hold air pressure OK, then it's probably slow to close valves and that should show up by using a vcuum guage on the intake.
Tom Wesenberg is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 07:45 AM.