Ignition problems
Hotshot
Joined: Jun 2015
Posts: 12,871
Likes: 2,445
It should not be that hard to start. I can reach in and bump the key on the CJ (304 w/ factory DS2) and it fires right up.
Lead Driver
Joined: Nov 2013
Posts: 7,178
Likes: 1,174
Some recent history may help, too.
Has the truck been running nicely with this carb and intake, and this problem is something new out of the blue? If those parts are new, did it run okay with the stock configuration?
Was this a derelict project dragged out of a salt mine, and this is the first time running in years?
Something in between?
Has the truck been running nicely with this carb and intake, and this problem is something new out of the blue? If those parts are new, did it run okay with the stock configuration?
Was this a derelict project dragged out of a salt mine, and this is the first time running in years?
Something in between?
FTE Legend
Joined: Nov 2015
Posts: 30,935
Likes: 4,123
From: Angier, NC
I cants see what his 300 six would be any different than mine.
He went and changed the dist. and it is worst now. I would pop the old one back in and see if it returns back the way it was for testing.
We also dont know what plugs are in the motor as the plugs can have a big outcome on how the motor runs.
But what do I know when I chased my azz when my truck was bucking under load and I did everything but plugs up to that point.
As soon s I pulled #3 plug I knew I found the problem.
Dave ----
FTE Legend
Joined: Nov 2015
Posts: 30,935
Likes: 4,123
From: Angier, NC
Some recent history may help, too.
Has the truck been running nicely with this carb and intake, and this problem is something new out of the blue? If those parts are new, did it run okay with the stock configuration?
Was this a derelict project dragged out of a salt mine, and this is the first time running in years?
Something in between?
Has the truck been running nicely with this carb and intake, and this problem is something new out of the blue? If those parts are new, did it run okay with the stock configuration?
Was this a derelict project dragged out of a salt mine, and this is the first time running in years?
Something in between?
I posted why it could be running rich power valve blown if it back fired up the carb.
Dave ----
Thread Starter
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Trailering
Joined: Jun 2024
Posts: 17
Likes: 2
Thanks for your help guys, I believe I got it pretty good, but still a small issue. Just put new autolite plugs in gapped at .044, and got out the timing light again and the distributor is tuned better, if not perfect (10°) It starts easier now, but my only issue is it idles sorta rough, and it “bucks” from idle to about 1,500rpm, then after that it is pretty smooth. Any ideas? Carb is tuned right and when I drove it, it didn’t backfire once (which is new as it always use to backfire a little bit) it didn’t want to die, and it feels as if I gained a lot of power.
Lead Driver
Joined: Nov 2013
Posts: 7,178
Likes: 1,174
One quick comment:
Which type of plugs did you install? Iridium or platinum or unobtanium or something like that? We’ve had several instances of guys finding out the hard way that these old engines run better with ordinary plugs. Of course, the kid behind the counter is more than happy to suggest the expensive version instead.
Which type of plugs did you install? Iridium or platinum or unobtanium or something like that? We’ve had several instances of guys finding out the hard way that these old engines run better with ordinary plugs. Of course, the kid behind the counter is more than happy to suggest the expensive version instead.
Thread Starter
|
Trailering
Joined: Jun 2024
Posts: 17
Likes: 2
One quick comment:
Which type of plugs did you install? Iridium or platinum or unobtanium or something like that? We’ve had several instances of guys finding out the hard way that these old engines run better with ordinary plugs. Of course, the kid behind the counter is more than happy to suggest the expensive version instead.
Which type of plugs did you install? Iridium or platinum or unobtanium or something like that? We’ve had several instances of guys finding out the hard way that these old engines run better with ordinary plugs. Of course, the kid behind the counter is more than happy to suggest the expensive version instead.
FTE Legend
Joined: Nov 2015
Posts: 30,935
Likes: 4,123
From: Angier, NC
One quick comment:
Which type of plugs did you install? Iridium or platinum or unobtanium or something like that? We’ve had several instances of guys finding out the hard way that these old engines run better with ordinary plugs. Of course, the kid behind the counter is more than happy to suggest the expensive version instead.
Which type of plugs did you install? Iridium or platinum or unobtanium or something like that? We’ve had several instances of guys finding out the hard way that these old engines run better with ordinary plugs. Of course, the kid behind the counter is more than happy to suggest the expensive version instead.
Also when setting the timing the vacuum hose was off and plugged right?
Did you check if the mechanical & vacuum advance was working as it should?
Set timing no hose then bring the RPM up to 2500 / 3000 and note what the timing is. It should be more than set point timing. When back to idle did the timing come back to set point?
Now hook up the vacuum and do the same test to 2500 / 3000 RPM and note the timing, it should be higher than with out the vacuum. Did it come back to set point?
Did you do a compression test and if so what were the readings? If a valve was not sealing a compression test would show this.
If you want to get real crazy you could do a leak down test but a compression test will show a lot and is easier to do.
With out going back over all posts what year truck and make carb on the motor? How did you set the mixture, vacuum gauge / tach or by ear and how good is your ear
Dave ----
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FTE Legend
Joined: Nov 2015
Posts: 30,935
Likes: 4,123
From: Angier, NC
Just a thought a flat cam may not show bad compression and either will a leak down test.
Poor running, low on power as that hole is not helping to give power and you can get popping out the cab as the gases go out the exh if the valve cant open.
Most of the time the motor will idle ok, unless the cam is really bad but will show up at higher RPM with the cam valve timing overlap.
Only really way I know to check is pull the valve cover and measure each rocker movement. If the cam is really bad you may see it when running?
Just something to think about.
Dave ----
Poor running, low on power as that hole is not helping to give power and you can get popping out the cab as the gases go out the exh if the valve cant open.
Most of the time the motor will idle ok, unless the cam is really bad but will show up at higher RPM with the cam valve timing overlap.
Only really way I know to check is pull the valve cover and measure each rocker movement. If the cam is really bad you may see it when running?
Just something to think about.
Dave ----
Thread Starter
|
Trailering
Joined: Jun 2024
Posts: 17
Likes: 2
Just a thought a flat cam may not show bad compression and either will a leak down test.
Poor running, low on power as that hole is not helping to give power and you can get popping out the cab as the gases go out the exh if the valve cant open.
Most of the time the motor will idle ok, unless the cam is really bad but will show up at higher RPM with the cam valve timing overlap.
Only really way I know to check is pull the valve cover and measure each rocker movement. If the cam is really bad you may see it when running?
Just something to think about.
Dave ----
Poor running, low on power as that hole is not helping to give power and you can get popping out the cab as the gases go out the exh if the valve cant open.
Most of the time the motor will idle ok, unless the cam is really bad but will show up at higher RPM with the cam valve timing overlap.
Only really way I know to check is pull the valve cover and measure each rocker movement. If the cam is really bad you may see it when running?
Just something to think about.
Dave ----
Moderator
Joined: Jan 2001
Posts: 56,992
Likes: 2,741
From: Virginia
Drove it to school this morning and it idled rough and drove rough (bucked) anywhere from idle to 1,500 or so, then drove smooth after that. Gonna limp it home and park it till I get new exhaust valves in it. I determined it’s the exhaust valves because when I got here I poured water on each of the headers and the front two headers were not nearly as hot as the other four were, so I’m assuming the front two exhaust valves are bent, and need replacing. A buddy of mine has an ‘81 f250 with the 300-six and he had to replace an exhaust valve, and his had the same issue of rough idling and “bucking” like mine has, so everything is pointing to bent exhaust valves.
Lead Driver
Joined: Nov 2013
Posts: 7,178
Likes: 1,174
Drove it to school this morning and it idled rough and drove rough (bucked) anywhere from idle to 1,500 or so, then drove smooth after that. Gonna limp it home and park it till I get new exhaust valves in it. I determined it’s the exhaust valves because when I got here I poured water on each of the headers and the front two headers were not nearly as hot as the other four were, so I’m assuming the front two exhaust valves are bent, and need replacing. A buddy of mine has an ‘81 f250 with the 300-six and he had to replace an exhaust valve, and his had the same issue of rough idling and “bucking” like mine has, so everything is pointing to bent exhaust valves.
When troubleshooting, a good rule of thumb is to avoid running around in circles like a chicken with its head cut off.
To get to the bottom of the issue, I've been authorized to break out the forum tranquilizer dart gun. This short educational video explains the process:
It's important to understand this is for your own good. Do NOT pull out the dart. When you regain consciousness, we can take our time and figure out exactly what is happening. Before committing my efforts towards replacing the exhaust valves, I'd want to run some detailed tests (compression, rocker arm lash, etc.) to be positive. Replacing valves is WAY too much work to try on a hunch.
Thread Starter
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Trailering
Joined: Jun 2024
Posts: 17
Likes: 2
Before I dive into the valve project and troubleshooting, I may have found a solution. A buddy’s dad suggested my carb float is stuck, which makes a lot of sense, considering 1. My old spark plugs were black, which is a sign of it running rich. 2. When I drove home today I had said buddy follow me to my house and he said there was a strong smell of gas, which tells me it’s running very rich. 3. My fuel economy has been out the window for a few days, meaning it’s rich. 4. I did just rebuild my carb and I’m pretty sure I got all the adjustments right but I’m not 100% on that, maybe I messed something up in there and that’s causing it to run so rich.
FTE Legend
Joined: Nov 2015
Posts: 30,935
Likes: 4,123
From: Angier, NC
Before I dive into the valve project and troubleshooting, I may have found a solution. A buddy’s dad suggested my carb float is stuck, which makes a lot of sense, considering 1. My old spark plugs were black, which is a sign of it running rich. 2. When I drove home today I had said buddy follow me to my house and he said there was a strong smell of gas, which tells me it’s running very rich. 3. My fuel economy has been out the window for a few days, meaning it’s rich. 4. I did just rebuild my carb and I’m pretty sure I got all the adjustments right but I’m not 100% on that, maybe I messed something up in there and that’s causing it to run so rich.
Dave ----
Thread Starter
|
Trailering
Joined: Jun 2024
Posts: 17
Likes: 2
Before I dive into the valve project and troubleshooting, I may have found a solution. A buddy’s dad suggested my carb float is stuck, which makes a lot of sense, considering 1. My old spark plugs were black, which is a sign of it running rich. 2. When I drove home today I had said buddy follow me to my house and he said there was a strong smell of gas, which tells me it’s running very rich. 3. My fuel economy has been out the window for a few days, meaning it’s rich. 4. I did just rebuild my carb and I’m pretty sure I got all the adjustments right but I’m not 100% on that, maybe I messed something up in there and that’s causing it to run so rich.