Engine Help on dead cylinder

luisjluis1

Member
Dec 4, 2020
33
4
18
18
Columbia, Mo
Have you put copper spark plugs in it yet?
Just took the plug off cylinder #5 which is the next one in time with cylinder #1. It would obviously be off time but still would fire. It worked, I got #1 to run for the first time since I bought the car. On the way to get a new electrical system! :) Anyone have a good distrutor coil combo I should buy? Thanks.
 
  • Sponsors(?)


KRUISR

5 Year Member
Apr 16, 2015
679
226
63
50
Anyone have a good distrutor coil combo I should buy?

OEM system.

If you are so removed from an stock wiring system, maybe an older Duraspark unit with vacuum advance and use an MSD, Crane, Holley ignition box (much like the pre-EFI cars used.
Regarding aftermarket non-TFI units, take a chance if you like, many have had issues with MSD distributors and everything works when they go back to stock.
 

92mustang74

Member
Apr 26, 2020
10
3
13
75
virginia
10-1 compression doesn't mean much to my old mind, but 130-140-150 LB does. Getting spark just means that it has an ignition source, you also need fuel and air. If the intake runners are blocked or the valves are not opening, especially the intake valve, there would be no vacuum created which could account for dry ports. What is strange it is on both sides of the engine. My next step would be pull a valve cover and see if the valves are opening and closing. Another quick thing you can do is pull a spark plug in a cylinder that is not firing, remove the coil wire place your finger over the spark plug hole and have someone turn the key. You should feel the compression build up then a pop which you will feel on your finger, just like when you are setting it up to find TDC. No pop no air entering the cylinder = valves-lifters-rocker arms-cam etc. If you did a rebuild this should not be.. wish I was there to work on it....

Only one other thing I can think of that happened to me 60 years ago. Replaced a starter on a boat that had a 312 ford engine, for some reason the starter was rotating in the wrong direction and the motor would not start, only found out what was wrong by checking firing order at the distributor looking at a Motors Manual, it was turning in the wrong direction. Might check that, battery polarity wrong?? This is a tough one!
 

KRUISR

5 Year Member
Apr 16, 2015
679
226
63
50
Not that this is the issue, but I had an 83 with a V6 that would start and run like a bag of :poo:. When you put it in gear it would stall. Back into park and would restart. Changed the engine (with another V6 at the time) and the shop checked into the old motor. Cam had snapped in middle. The back half of the cam was not turning at all. So it was running on 2 cylinders - no wonder is stalled in drive.

I would agree that valves not opening would definitely explain alot, but to have 4 cylinders spread over the entire length of the engine seems extremely unlikely (I could see 1 or 2, but 4 is a stretch.

Another quick thing you can do is pull a spark plug in a cylinder that is not firing, remove the coil wire place your finger over the spark plug hole and have someone turn the key. You should feel the compression build up then a pop which you will feel on your finger, just like when you are setting it up to find TDC.
This would be a good, free test to do on the 4 dead cylinders.
 

luisjluis1

Member
Dec 4, 2020
33
4
18
18
Columbia, Mo
I bought a coil and OEM dizzy out of an 85. I can't be at the car until Monday night but once I install that ill let everyone know if anything changes. Thanks, everyone! I'm new to this community and you have really helped me out a lot.
 

luisjluis1

Member
Dec 4, 2020
33
4
18
18
Columbia, Mo
I got the coil and dizzy out of an 85 stang. Is that all I need for my ignition system. Seen things about resistors and ignition boxes, do I need all that?
 

29FORD

New Member
Nov 4, 2020
11
0
1
62
newfoundland,Canada
Luis , I am a retired automotive mechanic, 35 years at this stuff, dont know it all but a little. you need three tools and less parts. a previous poster suggested a Vacuum Guage, get one and learn how to read it. Second acquire a good thread in Compression Tester and diagnose readings. Fuel pressure Gauge , a carb takes less pressure than EFI so make sure on correct pressure, No need on buying/exchanging parts while frustrating the fun out of this.
 

luisjluis1

Member
Dec 4, 2020
33
4
18
18
Columbia, Mo
Luis , I am a retired automotive mechanic, 35 years at this stuff, dont know it all but a little. you need three tools and less parts. a previous poster suggested a Vacuum Guage, get one and learn how to read it. Second acquire a good thread in Compression Tester and diagnose readings. Fuel pressure Gauge , a carb takes less pressure than EFI so make sure on correct pressure, No need on buying/exchanging parts while frustrating the fun out of this.
Thanks. I did a compression test and that went well. I pulled vacuum and that was a steady 17in. Haven’t yet checked fuel pressure but the pump I got was rated at 35gph at 7psi. Since ignition is totally out of the question could this be an air/fuel ratio giving me trouble? Could it be valves not opening properly?
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
19,646
6,567
193
polk county florida
If the valves were not operating properly it would show up on the vacuum and compression tests.
What makes you sure it's not an ignition problem?
 

29FORD

New Member
Nov 4, 2020
11
0
1
62
newfoundland,Canada
Thanks. I did a compression test and that went well. I pulled vacuum and that was a steady 17in. Haven’t yet checked fuel pressure but the pump I got was rated at 35gph at 7psi. Since ignition is totally out of the question could this be an air/fuel ratio giving me trouble? Could it be valves not opening properly?
start from basics, rotate engine until TDC On compression stroke on Cylinder one, timing pointer on Harmonic balancer should be on Zero or there about, remove plugs and push tissue into plug hole, rotate engine and when tissue blows you are TDC, Then rotor button should be aligned with number one tower on distributor cap. basics I know but has to be checked.
 

luisjluis1

Member
Dec 4, 2020
33
4
18
18
Columbia, Mo
start from basics, rotate engine until TDC On compression stroke on Cylinder one, timing pointer on Harmonic balancer should be on Zero or there about, remove plugs and push tissue into plug hole, rotate engine and when tissue blows you are TDC, Then rotor button should be aligned with number one tower on distributor cap. basics I know but has to be checked.
Will do, Thanks.
 

jrichker

StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
27,399
2,732
234
75
Dublin GA
lowendmac.com
Hello

jrichker, Thanks for posting chart, VERY HELPFULL!​

I have a question. Now that his car is running a carb, should the vacuum gauge be connected to manifold vacuum, OR ported vacuum, I’m assuming (ported vacuum). In addition if you could clear the “FOG FACTOR” for me, ……

Depending on the carb, I’m assuming you know when you are on PORTED vacuum when the gage reads 0 (at idle) and will see gauge move when the idle is increased?

And when you are connected to MANIFOLD vacuum, the gauge will be giving you a constant reading (at idle and or increased idle)?
Thank you in advance for your help.
The vacuum gauge is always connected to the manifold vacuum. That takes anything done by the carb out of the vacuum equation.
 
  • Like
  • Agree
Reactions: 3 users

90sickfox

Wasn't a pretty sight...and I've got big hands
SN Certified Technician
Mar 2, 2015
5,901
5,005
203
43
Are you using the correct firing order ?..there are 2 for a 5.0.
 
  • Like
Reactions: 1 user
Feb 26, 2018
16
13
13
46
Are you sure you got the right distributor for your engine? If it's a HEI style GM distributor it Maybe firing the wrong cylinders at the wrong time because of the wrong ignition module. Look at the part number on the module and cross it. Check application. Make sure it's for a HO firing order.