Help with rough running I-6

[DHregdovic]

My I-6 started running a little rough 2 weeks ago. It would occasionally hesitate/miss (under load) - not always though. It idled like normal though. Last week it started doing it all the time even during idle. It has almost no power and even idles roughly now. At times you can hear a slight exhaust backfire also. I checked the compression: 1-143, 2-150, 3-130, 4-145, 5-149, 6-146. Although these numbers are not great they are about the same as when I checked it last year and it ran fine.

Possibly jumped a timing gear tooth? But then again it was intermittent at first and a timing gear would be sudden.

I put an hei in last year and relatively new cap, rotor, and wires.

Any ideas?

[Longhorn Man]

Check your fuel and air filters, douche it with some gum-out, and if still spittin and farting, try messing with the carb screws. Sounds like a sick carb to me.

[Willy Prost]

This could be coming from the Department of Redundancy Department but, is timing and dwell (if you have points/condenser distributer) at specification? OOps, I just reread your post, you don't have points.

I mention this because last year I was experiencing the same symptoms. I was thinking "Oh no! Valve job time." The engine has a lot of miles on it. When I checked the timing to see where it was, I found out that the distributer had worked its way to being 15 degrees off!!! I was amazed that it ran at all. Reset timing and it runs fine.

[DHregdovic]

Thanx for the input guys. I will clean the K&N and replace the fuel filter tonight. I did the filter a few thousand miles ago but maybe I over oiled. I'll let you know.

[Gordo]

Double check your tune-up parts and check for vaccum leaks. Don't worry about the timing gears jumping, this is a gear drivin cam, not a chain, if it sheared teeth off the stock fiber cam gear, it wouldn't run at all.

[Tim Christian]

replace your intake and exaust manifoid gasket both of them the one that goes on the block also the one were the intake and exaust manifoid bolts together and the doughnut to.

[DHregdovic]

Well no luck on the air filter or the fuel filter - changed both with the same results. I did find a bolt loose - one of the ones that bolts the intake/exhaust together. I'm now thinking that maybe the gasket seal was broken. I did tighten it and it still runs the same. Maybe my tomorrow project should be to put new manifold gaskets on.

[sakohntr]

I recently acquired a parts truck with an inline 6. Inside the glovebox were some tune-up parts for it. There yours if you PM me your mailing address. I have no use for them. If you need other hard parts i have them as well. bruce minn

[Southpa]

I'm betting something is amiss in the distributor area, have a look inside the cap for any busted or burned contacts, check the plugs for fouling, check the wires etc. The symptoms you described are very similar to what I went thru with my 350, I found the center contact in the cap was broken. Must have been a real light show inside, lol.

[Slammed67]

Loose or cracked vacuum hoses? Distributor advance froze up? My brother had similar symptoms (lack of power) and he found that his mechanical advance was froze up.

[DHregdovic]

I've got it narrowed down pretty good now. It was not the manifold gaskets either. I still kinda thought it was an electrical problem so I thought of putting my timing light on the wire for each cylinder - guess what I found... Cylinders 2 and 3 are only firing maybe 1/3 of what they are supposed to be. I guess I found my miss.

Cap and rotor still look good. I'll try putting some new plugs in 1st and if that doesn't do it I guess it's cap and rotor time. Amazing being I changed all of those at the same time - maybe 2,000 miles ago. Gotta love those cheap parts.

Anyway - Thanx alot for all the previous replies. They really helped me...