I seem to have an engine miss around 1000 - 1200 rpm, runs a bit rough ? car idles perfectly and comes alive when you get on it, but cruising at city driving speed, say 45 MPH seems to miss or run rough

any thoughts out there ? Maybe even 1500, I'll take it out today and get a better idea of RPM ranges

 

Without knowing all the particulars such as when the spark plugs were changed and what brand. Original carburetor and distributor or what modifications it's a bit difficult. Right off the top of my head thinking of a stock 440 I would check to see if the vacuum advance is working correctly or if you have a flat spot in the carb which usually occurs at the rpms you're talking about.

 

Thanks !! I have only had the car for a week so lots of unknowns, I thought about Plugs, Wires and maybe a Vacuum issue, I did not think about the carb ?? That might be it since the car idles perfectly and at higher rpm's screams

The motor is very stock so hopefully i can track it down quickly

 

Well, I MIGHT have found it, will know tomorrow, Darn Choke plate was flopping around a little, the Vacuum pot is missing that ran the choke so it was kinda "Rigged" :-) and get this, both idle adjust needles are missing, grrrr

 

Keep us posted

 

All minor stuff. Glad you found the potential problem.

 

Right, so far mostly minor stuff thankfully and I have those parts on the way, the Biggest issue is the speedo's not working, I have a speedo on the way but not looking forward to pulling the dash. I have put the cart before the horse and not verified its the speedo cable which I think I will do tomorrow

Thanks !

 

I would check to see if the cable is spinning for sure. If it's not spinning check to see if the gear in the tranny is even there and not torn up. Speedo heads on those rarely go bad. If the cable is ripped up it's usually caused by the housing having a bur or two

 

Good Info, Thanks !!!

 

Hi RacerHog / Kusvaz101, I didn't drive it yesterday so dont know if its the floppy choke plate or not, The exhaust does seem to have more than expected fuel smell, I wonder if the missing low idle adjust needles have anything to do with that and the rough running, waiting on those to show up. I did score a set of NIB MOPAR 34P plugs. Im also looking to put on a new set of wires in the future. I noticed something "disturbing" yesterday, I'm not able to crawl under a car like I used to :-) My shop used to have a lift in it but its gone darn it, ( previous owner divorce fallout ) Might have to get one but will take a little convincing from the "Boss" :-)

 

Im pretty sure you will find the spark plugs black when you remove them......
Do those spark plugs cross to the Champion RJ12YC ?????

 

Yes, they cross. The MOPAR 34P's are rebranded J-11Y's Thanks

The car ran MUCH better yesterday, at 2000 rpm, not sure if its the choke plate work or the VP Racing additive but heading in the right direction. I kinda think its the choke plate fix. Looking forward to getting the low idle speed needles

 

Got to have those for sure...

 

Every original cast iron set of big block heads Ive gone through have needed valve guide work. A bad guide will seal sometimes but at times allow the valve to not seat causing a miss. I’d start with a compression test.

 

Thanks Iowan ! I will keep that in mind. I remember putting a fresh set of 906 heads on my V code car and it was a HUGE difference.