The Ford Barn

39topless · 10-14-2015, 11:21 PM

I need some advice on where to look now for the root cause of my engine running like a slug up hill in a sand storm. My engine is a 39' 221 V8 that's stock except for finned heads and 2X2 carbs with a "super" type intake. Fuel is supplied by a Holley electric pump and regulator set at 2.5 psi. Ignition is a stock helmet type distributor with "tube type" coil and adapter. Symptoms: It starts ok and idles ok but with a slight hitch in the rhythm. There are spotty black deposits on garage floor below exhaust pipe. On acceleration, it cuts out, occasional back fire thru exhaust, and slugs down the road as if running on 6-7 cylinders, choke or no choke. It is one gutless SOB.
My unsuccessful remedies to this engine illness include the purchase and installation of: Rebuilt carbs (97s) by Uncle Max, rebuilt distributor by Bubba (recently rechecked by Bubba), two new coils and a new coil wire, three new condensers (NAPA RR174), new set of spark plugs, replaced inline fuel filter and flushed gas line.
Tests and procedures include: check for vacuum leaks (found none), checked spark plug wires and coil wire for spark on cranking (adequate blue color), checked accelerator pumps in carbs for gas flow (ok), compression check (lowest=80 all others 90-110#) with all plugs out and carbs open. Removal of plugs revealed two with lots of carbon deposits and all others clean.
Questions: Will a bad valve always reveal itself in a compression check? What should I check, and or, try next? Thank you.
Phil

Mark's 37 · 10-14-2015, 11:27 PM

An easy test for valve sealing is to attach a vacuum gauge and watch the needle at idle. If the needle fluctuates that indicates a possible valve problem, if it is steady the valves are probably ok.

Mike in AZ · 10-14-2015, 11:48 PM

2.5 psi checked by gauge??....Mike

Ken/Alabama · 10-15-2015, 02:42 AM

Did you bypass the resistor under the dash when you installed the round coil?

Terry,OH · 10-15-2015, 05:38 AM

2.5 psi checked by gauge??...

Ol' Ron · 10-15-2015, 07:45 AM

Sponsored Links (Register now to hide all advertisements)

ompression test.

fordhistory · 10-15-2015, 08:16 AM

That's a good point Ken made. If you installed a modern coil, that coil may have an internal resistor. In other words, all coils need a resistor. You can buy a modern coil which needs a resistor somewhere in the coil wiring, or you can buy one which already has a resistor built inside of it. If you have stock wiring, which has a resistor up under the dash, AND are using a modern coil with an internal resistor, you will have too much voltage drop at the coil and the coil will not produce enough spark. The engine would probably start and idle ok, but under load it would run like, well, you know....

fordhistory · 10-15-2015, 08:28 AM

The other thing you could check is for an exhaust restriction. The easiest way to do that is to hook up a vacuum gauge and start the engine. The vacuum should be normal (between 17-21), but will soon drop to between 0 and 5. Or, rev up engine to about 2500 rpm and watch the needle. If it begins to drop a lot, you probably have an exhaust restriction. A plugged/restricted exhaust will definitely give you the symptoms you are talking about.

wbedwards · 10-15-2015, 09:17 AM

I had similar symptoms with my 59 and here is the diagnosis progression:
http://fordbarn.com/forum/showthread...55#post1172755

I Can't put a finger on the exact cure but seemed to be several small things the worst being the firewall grounds and the resistance in my primary wiring through the resistor. Every thing I did made it run a little better but the missing stopped with a new coil which you have already done and cleaning up the wiring connections. My primary was giving my coil only 5.8 volts and book says minimum of 8.5. Now I am up to 9.8. I wish I had checked this first

39topless · 10-15-2015, 10:08 AM

Quote:

Originally Posted by Mike in AZ

2.5 psi checked by gauge??....Mike

yes, thanks

39topless · 10-15-2015, 10:10 AM

Quote:

Originally Posted by Ken/Alabama

Did you bypass the resistor under the dash when you installed the round coil?

Yes, the former owner that installed the newer style coil did that. Thanks

39topless · 10-15-2015, 10:32 AM

Quote:

Originally Posted by Ol' Ron

ompression test.

Ron, did you mean "compression" test? Can't find anything regarding an ompression test. I did do a compression test with all the plugs out and the carbs wide open. Results were: #1=90, #2=100, #3=80, #4=97, #5=97, #6=105, #7=100, and #8=110. Thanks

deuce_roadster · 10-15-2015, 11:34 AM

Plug wires shorting inside conduits? Plug wires loose in the caps? How new are they? Maybe replace the 2 that go to the cylinders that are sooty. Did Bubba supply new inner caps?

Ken/Alabama · 10-15-2015, 11:54 AM

Are you sure there's not a crossed plug wire at one of the inner caps?

FlatheadTed · 10-15-2015, 01:37 PM

Has the car ever run any good since you owned it ?? .try a jump wire direct to coil from the battery .try another fuel pump (stock ) by pass the valve .Check the valve timing by watching one valve through the plug hole .lift the manifold and check all the valve action and the horse shoe retainers .Ted

39topless · 10-15-2015, 04:33 PM

Just started down the great list of suggestions from above and now the water pump is leaking bad. Will need to fix that first (can't run the #*^^>@ engine!!). Just placed order for new ones with C & G. Will give update later. Thank you all for the responses.
Phil

39topless · 10-15-2015, 04:36 PM

Quote:

Originally Posted by FlatheadTed

Has the car ever run any good since you owned it ?? .try a jump wire direct to coil from the battery .try another fuel pump (stock ) by pass the valve .Check the valve timing by watching one valve through the plug hole .lift the manifold and check all the valve action and the horse shoe retainers .Ted

No Ted, the car has never run real well since I've owned it. I'm going to correct that (with a little help from my friends). Thanks.

FlatheadTed · 10-15-2015, 06:11 PM

Phil I like the line .ALHFMF ,seen a car that had a valve retainers up in the spring ,showed compression but missed etc. on running ,Ted

39topless · 10-15-2015, 06:45 PM

Quote:

Originally Posted by FlatheadTed

Phil I like the line .ALHFMF ,seen a car that had a valve retainers up in the spring ,showed compression but missed etc. on running ,Ted

At this point, I'm thinking it must be something internal. I will remove the intake, give it a crank and see what's up. This I can do while waiting for the new water pump to arrive. Thanks for the suggestion.
Phil

scooder · 10-16-2015, 01:41 AM

You say no vacuum leaks, it's possible that there's a vacuum leak from manifold to the valve chamber, the inside of the port. I've had this once.
Can't find it the usual way of spraying stuff around the manifold, only see it when the intake is removed, mine had a section of gasket gone from the inside of the port. Mine had the all the plugs clean bar one that was carboned up, it was the one from the bad gasket part. Theyll pull air from the valve chamber into the cylinder.
Yours had six clean plugs, two dirty ones. Sounds similar, definitely worth a look if all the other stuff is good.
Martin.

10-15-2015, 09:17 AM	#9
wbedwards Senior Member Join Date: Jan 2015 Location: Birmingham, Al. Posts: 339	Re: Need advice to fix rough running engine. I had similar symptoms with my 59 and here is the diagnosis progression: http://fordbarn.com/forum/showthread...55#post1172755 I Can't put a finger on the exact cure but seemed to be several small things the worst being the firewall grounds and the resistance in my primary wiring through the resistor. Every thing I did made it run a little better but the missing stopped with a new coil which you have already done and cleaning up the wiring connections. My primary was giving my coil only 5.8 volts and book says minimum of 8.5. Now I am up to 9.8. I wish I had checked this first

10-15-2015, 11:34 AM	#13
deuce_roadster Senior Member Join Date: Oct 2011 Location: Shelton, WA Posts: 3,971	Re: Need advice to fix rough running engine. Plug wires shorting inside conduits? Plug wires loose in the caps? How new are they? Maybe replace the 2 that go to the cylinders that are sooty. Did Bubba supply new inner caps?

10-15-2015, 11:54 AM	#14
Ken/Alabama Senior Member Join Date: May 2010 Location: Alabama Posts: 3,395	Re: Need advice to fix rough running engine. Are you sure there's not a crossed plug wire at one of the inner caps?

10-15-2015, 01:37 PM	#15
FlatheadTed Senior Member Join Date: May 2010 Location: Auckland Posts: 4,745	Re: Need advice to fix rough running engine. Has the car ever run any good since you owned it ?? .try a jump wire direct to coil from the battery .try another fuel pump (stock ) by pass the valve .Check the valve timing by watching one valve through the plug hole .lift the manifold and check all the valve action and the horse shoe retainers .Ted __________________ http://www.flatheadted.com Flathead Ted brake Floaters ,

10-15-2015, 04:33 PM	#16
39topless Senior Member Join Date: Sep 2013 Posts: 1,027	Re: Need advice to fix rough running engine. Just started down the great list of suggestions from above and now the water pump is leaking bad. Will need to fix that first (can't run the #*^^>@ engine!!). Just placed order for new ones with C & G. Will give update later. Thank you all for the responses. Phil

10-14-2015, 11:21 PM	#1
39topless Senior Member Join Date: Sep 2013 Posts: 1,027	Need advice to fix rough running engine. I need some advice on where to look now for the root cause of my engine running like a slug up hill in a sand storm. My engine is a 39' 221 V8 that's stock except for finned heads and 2X2 carbs with a "super" type intake. Fuel is supplied by a Holley electric pump and regulator set at 2.5 psi. Ignition is a stock helmet type distributor with "tube type" coil and adapter. Symptoms: It starts ok and idles ok but with a slight hitch in the rhythm. There are spotty black deposits on garage floor below exhaust pipe. On acceleration, it cuts out, occasional back fire thru exhaust, and slugs down the road as if running on 6-7 cylinders, choke or no choke. It is one gutless SOB. My unsuccessful remedies to this engine illness include the purchase and installation of: Rebuilt carbs (97s) by Uncle Max, rebuilt distributor by Bubba (recently rechecked by Bubba), two new coils and a new coil wire, three new condensers (NAPA RR174), new set of spark plugs, replaced inline fuel filter and flushed gas line. Tests and procedures include: check for vacuum leaks (found none), checked spark plug wires and coil wire for spark on cranking (adequate blue color), checked accelerator pumps in carbs for gas flow (ok), compression check (lowest=80 all others 90-110#) with all plugs out and carbs open. Removal of plugs revealed two with lots of carbon deposits and all others clean. Questions: Will a bad valve always reveal itself in a compression check? What should I check, and or, try next? Thank you. Phil

10-14-2015, 11:27 PM	#2
Mark's 37 Senior Member Join Date: Jul 2015 Location: Aptos, Ca Posts: 355	Re: Need advice to fix rough running engine. An easy test for valve sealing is to attach a vacuum gauge and watch the needle at idle. If the needle fluctuates that indicates a possible valve problem, if it is steady the valves are probably ok.

10-14-2015, 11:48 PM	#3
Mike in AZ Senior Member Join Date: May 2010 Location: Waddell, AZ Posts: 2,540	Re: Need advice to fix rough running engine. 2.5 psi checked by gauge??....Mike

10-15-2015, 02:42 AM	#4
Ken/Alabama Senior Member Join Date: May 2010 Location: Alabama Posts: 3,395	Re: Need advice to fix rough running engine. Did you bypass the resistor under the dash when you installed the round coil?

10-15-2015, 05:38 AM	#5
Terry,OH Senior Member Join Date: May 2010 Posts: 5,187	Re: Need advice to fix rough running engine. 2.5 psi checked by gauge??...

10-15-2015, 07:45 AM	#6
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,985	Re: Need advice to fix rough running engine. Sponsored Links (Register now to hide all advertisements) ompression test.

10-15-2015, 08:16 AM	#7
fordhistory Member Join Date: May 2011 Posts: 99	Re: Need advice to fix rough running engine. That's a good point Ken made. If you installed a modern coil, that coil may have an internal resistor. In other words, all coils need a resistor. You can buy a modern coil which needs a resistor somewhere in the coil wiring, or you can buy one which already has a resistor built inside of it. If you have stock wiring, which has a resistor up under the dash, AND are using a modern coil with an internal resistor, you will have too much voltage drop at the coil and the coil will not produce enough spark. The engine would probably start and idle ok, but under load it would run like, well, you know....

10-15-2015, 08:28 AM	#8
fordhistory Member Join Date: May 2011 Posts: 99	Re: Need advice to fix rough running engine. The other thing you could check is for an exhaust restriction. The easiest way to do that is to hook up a vacuum gauge and start the engine. The vacuum should be normal (between 17-21), but will soon drop to between 0 and 5. Or, rev up engine to about 2500 rpm and watch the needle. If it begins to drop a lot, you probably have an exhaust restriction. A plugged/restricted exhaust will definitely give you the symptoms you are talking about.

10-15-2015, 06:11 PM	#18
FlatheadTed Senior Member Join Date: May 2010 Location: Auckland Posts: 4,745	Re: Need advice to fix rough running engine. Phil I like the line .ALHFMF ,seen a car that had a valve retainers up in the spring ,showed compression but missed etc. on running ,Ted __________________ http://www.flatheadted.com Flathead Ted brake Floaters ,

10-16-2015, 01:41 AM	#20
scooder Senior Member Join Date: Jul 2010 Posts: 2,595	Re: Need advice to fix rough running engine. You say no vacuum leaks, it's possible that there's a vacuum leak from manifold to the valve chamber, the inside of the port. I've had this once. Can't find it the usual way of spraying stuff around the manifold, only see it when the intake is removed, mine had a section of gasket gone from the inside of the port. Mine had the all the plugs clean bar one that was carboned up, it was the one from the bad gasket part. Theyll pull air from the valve chamber into the cylinder. Yours had six clean plugs, two dirty ones. Sounds similar, definitely worth a look if all the other stuff is good. Martin.