Number five is NOT alive...

[fishead]

So the other day a buddy was over and helped me tune the carb up a bit.  Starts real good now, but idles pretty rough.  Today having gorgeous weather, I washed her, then did a compression test.  I first warmed up the engine, and pulled out all the plugs.

7 of the cylinders tested between 150 and 160.  Awesome. #5 on the other hand was 15.  Not so good.  I poured about an ounce of 10W30 down the plug hole, and it went up to 30psi.  On the advice of another friend, we got her running again, put it in gear, held down the brakes and revved it up a bit.  No coughing out the carb, or farting out the tail pipe, but it was definitely rough sounding under load. 

What do you guys think?  Got this truck from wife's grandpa.  He had recently blown the heads, and got new ones.  He had a tough time getting it to run, and said something about having to adjust the valves a long way from where they were supposed to be.  Buddy said to go to #5 and back both valves off a full turn then test again.  Not sure how to adjust valves, going to have to buy a book on engines I guess.

Let me know if you guys have any advice.

Thanks,

Chris.

[VileZambonie]

A cylinder leakage test using a dual leakdown gauge and compressed air will reveal the source of the problem however it does sound like your valves are adjusted incorrectly and #5 is too tight on at least one of the valves. Adjusting the valves is pretty easy and if you are going to buy a book just follow the procedure. If you need help just ask and we'll give you some pointers.

[1976Scottsdale]

A cylinder leakage test using a dual leakdown gauge and compressed air will reveal the source of the problem however it does sound like your valves are adjusted incorrectly and #5 is too tight on at least one of the valves. Adjusting the valves is pretty easy and if you are going to buy a book just follow the procedure. If you need help just ask and we'll give you some pointers.

Not to come off as rude to any member here, but let us all be civil about our own valve adjustment methods versus those of other members.  I guess I would just go to oreilly's and get a box of those Lisle brand rocker stoppers and pull the valve cover, put them in and back the rocker nuts off one at a time until they tap and then tighten(removing the socket occassionaly to ensure its not binding the rocker) until the valve is quiet again and the go something like a quarter to half turn more making sure you don't kill the engine or start hearing air comong back up the intake.

[VileZambonie]

A cylinder leakage test using a dual leakdown gauge and compressed air will reveal the source of the problem however it does sound like your valves are adjusted incorrectly and #5 is too tight on at least one of the valves. Adjusting the valves is pretty easy and if you are going to buy a book just follow the procedure. If you need help just ask and we'll give you some pointers.

Not to come off as rude to any member here, but let us all be civil about our own valve adjustment methods versus those of other members.  I guess I would just go to oreilly's and get a box of those Lisle brand rocker stoppers and pull the valve cover, put them in and back the rocker nuts off one at a time until they tap and then tighten(removing the socket occassionaly to ensure its not binding the rocker) until the valve is quiet again and the go something like a quarter to half turn more making sure you don't kill the engine or start hearing air comong back up the intake.

How was my post uncivil or rude? 

Fishead - do your inital adjustment without the engine running. If you develop a ticker and want to quiet it down it's ok to do it running but unecessary and messy. The best method is to adjust to zero lash on the base circle of the cam and increase lifter preload - typically 3/4 to 1 full turn of the nut with a hydraulic flat tappet cam. If you are using any other rockers than stock you will have to be a little more precise.

[fishead]

Thanks for all the advice guys.

I told my wife that I wanted to work on the truck tomorrow (Monday is a Stat holiday in BC) and she got all cold.  Any advice on this would be MUCH appreciated.  Seems she wanted me to put down laminate flooring in another room.  You know how blissfully you can forget the projects you don't want to do?

Seeing as how all the other cylinders seem to have good compression, I am going to start with backing off the valves on number 5.  If I can't get the compression up, I will assume the problem is in the bottom end, and go from there. 

Thanks for all the helpful advice.

Chris.

[static22]

One more thing to consider is if they rockers are too tight you are running a risk of flattening the lobe on the cam so be careful driving it. That may get you out of the flooring as well. Just did that for the fifth time last week.

[camdenoilchange]

I agree with Vile. with every cam swap or motor build i've done, i set the valves before i even start it. by setting the valves on the compression stroke at tdc, it takes all the guessing and mess out of the picture. no offense to other members, this is the best way in my opinion.

Fishead--good luck with your issue. hopefully it will be a simple fix and no internal damage has been done. let us know if you have any more questions.

[fishead]

So I finally got a few minutes to spend on my truck this afternoon.  I pulled off the Valve Cover, and backed the #5 valves off one full turn each, then did a compression test.  Because this was a qualitative test, and not quantitative, I didn't bother warming it up, or taking out all the spark plugs.  I cranked her over a few times, and got like 5 to 10 PSI.

Grandpa said that the heads are new (rebuilt) but he is pretty sure there is something wrong with the block.

I think I am going to pull off the head(s) just because I have never done anything like that before on anything bigger then a lawn mower.  I am really looking forwards to the adventure.  Crazy, huh?  My goals for the truck though, are to find an '87 to '95 TBI parts truck.  I am a robotics technician, and would really like to do the conversion to electronic control rather then old-skool carb.

Thanks for your help guys.  If (when?) I do pull the head off I will let you know what I find.

Chris.

[VileZambonie]

Loosen the rockers all the way and run your shop air into the spark plug hole. Listen in the exhaust pipe, the intake, the crankcase, and the radiator for air. Wherever the air is going is where your problem lies.