i am perplexed and annoyed to the point where if someone offered me 500 bucks for my truck i probley would take it. lol

story is like this

360 v8 1970 f250
stock exhaust manifolds
new 2 1/4 inch pipes flowmastewr mufflers all out the back
ford carb brand new
new cap and rotor from a 85 mustang ( big cap)
new 8 mm wires
new vacumn advance
new alternator
new coil
new sparkplugs gapped at 42
new vacumn lines

2 weeks ago while trying to get my truck to run better i put on a autolite carb, my timing wasnt set right so when i let off the throttle i got two of the biggest back fires i have ever heard, in turn the rumble started as i blew the old mufflers into shrapmetal.
so on the drive home i relize she is running a little rough, you know kind of sounds like a harley when she is ideling, other wise has plenty power. before this she ran okay but had some problems. so i stop at oreilys and order a new carb ( $105.99 ) because i tired of playing with old ones, i then called the local muffler shop and ordered up some new pipes and flowmaster mufflers to be put on the following day ( $350.02 )
so monday i got it back from muffler shop and new pipes sound nice but still running rough. yesterday i installed the new carb. still running rough. today i installed new spark plugs, still running rough, i tried resetting the timing by ear and still runs a little rough.
while outside shoveling snow i had my truck warming up in the garage with the big door open and i was watching the tailpipes billowing out exhaust in the cold air , once in a while i would notice a smoke ring coming out of the passenger side pipe. the driver side wasnt doing this, sometimes there be two or three in a row then for a few seconds none, then i would see them again.
i walked over and felt the exhaust as it blew out, the driver side was blowing warm and the passenger side was cold, even when i drove the 4 miles from my garage to my house the driver side was still alot warmer then the passenger side.
so does anyone have any ideas what the heck is a matter with my truck to make it run rough and blow smoke rings.
i checked all the vacumn lines and plugs, and none of the sparkplugs were much different from the rest when i changed them today. she has good power though when i am on the freeway but i want her to run smooth again. help me if you can. i am open to suggestions

 

I forget, have you done a compression test yet? This is going to be the best way to go right now. Make sure your rings and valves are doing there job before you blame the top end stuff. Its probably going to be tough to narrow down if the compression checks good. Is the cam stock? Was it degreed on install. I'm sorry if you have mentioned this stuff before. I tend to forget things.

 

ratsmoker i havent meationed that before, but as far as i know the cam is stock and i dont know about degreed either. if you remember though from earlier threads i have meantioned i couldnt get this engine timed well, at 6 i might as well get out and push. i have to time it 14-20 to get any power out of it. i havent done a compression check yet, i planned on doing that though but i am hoping that comes up good, what is a good level to be looking for. the easiest way i know to fix this problem is to switch enignes with you and let it be your problem lol

 

LOL! Amount of pressure really isn't important unless you are getting very low presure with a very small cam. You want to look for problem cylinders. If cylinder 1 - 7 are getting 140psi and number 8 gets 85 psi then you have a problem. You can even figure out if the problem is a valve not seating or bad rings without taking the heads off. If you put a teaspoon of oil into the bad cylinder and the pressure comes up then it is rings. If it stays the same then you have a bad valve.

It also sounds as if your balancer is starting to slip. I used to wonder why my engine liked som much timing. It actually has power at 6BTDC now. I obviously run more though.

 

you didnt by chance get #2and #4 crossed when you replaced the cap (only reason i ask is cuz i did it, truck idled like crap ran okay but sounded horrible made power just fine just sounded awful hope this helps

 

nope didnt cross any wires, i replaced the cap and rotor about 2 weeks before i turned my mufflers into pipe bombs. this problem developed after that event. it was running fine before this event. i thought it was a blown powervalve but nope, i thought it was a blown vacumn line nope, i am afraid to check the compression, this might lead to big dollars and downtime and much feared actual work. i am sure the dampner needs replaced was trying to hold off til this summer when i tear the whole thing down to the frame and rebuild it for a year or so lol.

 

what would account for one pipe hot one pipe cold ?

 

Isn't there some sort of baffle or valve in the passenger side exhaust manifold. It's closed when cold to force exhaust through the cross over in the intake manifold and is supposed to open when warm. Now I've never seen this valve except in shop manuals. Anyone else?

 

no compresion do to a big hole in a piston or a nice sized piece of valve missing

 

I had a friend who had the same problem in chevy motor when he sold it the guy who bought it tore the motor down guess what a craked piston...(almost all the way split)...Just a thought...

 

i am thinking it might be a valve, this engine was just rebuilt 3 years ago. but they didnt do a valve job. dont know why they didnt, wasnt my truck then. looks like i gotta start working some overtime after i check the compression.

 

do the test....maybe pull the heads and check it out......let us know how it goes......

 

i will do that, i hate to pull the heads, i know i will have to either way. kinda wish i still had that other set of heads so i could just do a switch out. i still might do that, i know a parts yard where i could get some heads real cheap and have them done then just switch them. i am just afraid if i do this i might get a case of mightaswells, i am sure you all know what that is

 

lol yea...if it just the valve swap em or just get a new setup..and then put it back together and hold off on the mightaswells and then when you can do them thats what i gota do on my latest project 69'

 

goes to show when you do something might as well do it right ......(rebuild)