Engine Troubles...

[RHGuyettejr]

So my motor has been running rough, actually ever since I bought it, and I was suspecting it is due to poor valve adjustment, I haven't pulled the valve covers yet, but I did check the firing order and it is correct, I also checked the timing today and it is at 5* initial timing (about 650rpm) and the shop manual I have calls for 4*, but it has never detonated or showed symptoms of being too advanced, I know some people can get as much as 10-12* out of a sbc, but I figured I would stick with what the manual said until I get the issue diagnosed. I bought plugs today but of course I trusted the guy at the counter to get me the right ones and they are not even close so Im planning on doing plugs and wires tomorrow night. Anyhow the distributor cap is pretty small and looks like it could still be points, the guy I purchased it from said the motor was rebuilt about 1000 miles ago (whatever the distance from NC to NH is), and I don't for the life of me know why he wouldn't put electronic ignition on it. Anyway another worry is that he said the dipstick broke and he couldn't get it out of the tube so it was still in there, I pulled the tube today and looked in the block and couldn't see it, so now I have to drop the oil pan to look for a piece of dipstick that may or may not be there.

Anyway sorry for the rant, ill post a video clip of the truck running, I know this has been posted before so forgive me if you have seen it just figured it would be easier to post all in one place.

Thanks for any suggestions.

1969 C20 Cold Start - YouTube

[Lattimer]

650 idle is too low, should be more like 850. I would also check fuel pressure and manifold vacuum to see what you have. 5 degrees is probably not enough timing. The factory spe con my 327 says 4-6, I'm running 12 and it runs sooooo much better. A vacuum gauge can be your best friend, it will really show you what you have going on.

The way it starts sounds like the choke isn't working right either unless it has been sitting there for over a month. A properly rebuild engine should pop right off without you pumping it full of gas like that.

Otherwise, if any of the parts are old, start with a general tune up and work from there.

[RHGuyettejr]

Yeah in this video it had sat for a few months... I've been starting it more regularly. Actually it is still manual choke as far as I know, and I completely forgot to choke it when I started it. I'll do an electrical tune up, i checked the carb today and it was clean and operating correctly. I can bump up the idle a little as well. Thanks for reply.
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[RHGuyettejr]

Also not to sound dumb, but is there a port on the intake manifold to hook up a vacuum gauge? I've never tested vacuum before.
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[68gmsee]

A good tuneup would be the first thing to do. This way you know what's been done. I never like to take someone else's word for it. Get new wires if they look old or are original, new high quality points (not cheap ones), cap and rotor. Adjust the points to specs and as mentioned up the idle a tad.

The vacuum can be checked on any vacuum port on manifold vacuum (lower part of carb or manifold itself). Maximum vacuum is best. I like to see my engines (minus radical cams) between 17-22 on a vacuum gauge at recommended idle rpms. I adjust idle air screws on carb, idle rpms and timing for maximum vacuum.

[Lattimer]

Originally Posted by RHGuyettejr

Also not to sound dumb, but is there a port on the intake manifold to hook up a vacuum gauge? I've never tested vacuum before.
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There should be a capped port on the carb you can use, if not, there should be one behind the carb on the manifold. Don't use the vacuum advance port.

Don't worry about sounding dumb.......we have all been there. I've had my truck for 2-1/2 months, and its the first carbureted engine I have ever worked on. I have learned a tremendous amount in a short period of time.

[Lattimer]

Originally Posted by RHGuyettejr

Yeah in this video it had sat for a few months... I've been starting it more regularly. Actually it is still manual choke as far as I know, and I completely forgot to choke it when I started it. I'll do an electrical tune up, i checked the carb today and it was clean and operating correctly. I can bump up the idle a little as well. Thanks for reply.
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Gotcha. Didn't see you pull a choke so I was assuming its automatic.

They start better with the choke....LOL

[Lattimer]

Originally Posted by 68gmsee

A good tuneup would be the first thing to do. This way you know what's been done. I never like to take someone else's word for it. Get new wires if they look old or are original, new high quality points (not cheap ones), cap and rotor. Adjust the points to specs and as mentioned up the idle a tad.

The vacuum can be checked on any vacuum port on manifold vacuum (lower part of carb or manifold itself). Maximum vacuum is best. I like to see my engines (minus radical cams) between 17-22 on a vacuum gauge at recommended idle rpms. I adjust idle air screws on carb, idle rpms and timing for maximum vacuum.

Agree. First thing I did with my truck was rip all the old stuff off and start over. Plugs, wires, and rebuild my HEI. I had a reason though----5 wires were melted on the headers

[cdowns]

crap gas goes bad quick now// so i'd first get good gas then change gas filters/ then clean and set the points prior to anything


checking for bad vaccume hoses as well as noises while it is running

valves rarely if ever need to b reset and it is a great way to really screw somthin up and should b a last restort type thing

[RHGuyettejr]

Yeah I totally agree with doing the easy stuff first. I got the right plugs and I'm going to do the tuneup tomorrow. I just worry the guy said he put "New" heads on and I don't know if he just threw some used junk on there or what.. guess time will tell.

Thanks again guys.
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[RHGuyettejr]

Ok so I got to work on the truck today, installed new plugs and wires, and got a chance to put new headlights in. I also discovered there was a very large vacuum leak in the manifold from a vac line that used to go to the cruise control, I capped it for now. The truck seems to run better at higher (above 1000) rpm, but still sounds pretty crappy at idle. There is a video of a walk around below and it is idling at temp, and I do my best to rev it to about 1krpm, it smooths out much better, but still has a problem. I may tinker with advancing the timing. Also I found the pcv valve was getting hit by the lifter (i could feel it) so I spaced it out and I am going to buy the appropriate one, as well as the appropriate plug for the manifold. I also pulled the distributor cap and the rotor and such looked to be new. ( I know that doesn't mean anything). Also how do I set the points? if this is a points distributor, I attached pics below and it is unlike the distributors I have worked on, maybe it has had an electronic conversion done to it? the rotor doesn't look like it belongs in a points style distributor but I am unfamiliar with old motors so any input is welcome. I attached the pics below.

Walkaround video
http://www.youtube.com/watch?v=0cdA5...ature=youtu.be





Thanks again guys.

[GMtrucknut!!]

That is the original style points rotor, you really need to have someone set the dwell . Then I would set the idle at around 750. Check for any vaccum leaks at the base of the carb I usually set the timing at 8 btdc.

[steves1967]

Nope, you still have points in it! I dont want to sound rude, so please dont take it that way, but if you are unsure of whether or not its points or electronic it might help to find a local shop that can help you with maintenance just until you get a better feel for working on the truck. The PCV valve wasnt getting hit by the lifter either- maybe by the rocker arm but even that is doubtful- are you sure it wasnt just the check valve opening and closing?

[RHGuyettejr]

Alright thanks, is the dwell something I could handle doing myself? pretty mechanically inclined, just not something I have done before.

Thanks again.

[trevrolet65]

Looks like points to me, dizy looks like the one on my sons 65. If that thing is missing, try pulling a plug wire then put it back one at a time and listen for a change. If there is no change, thats the cylinder missing. If they all idle down then they're hitting. But be carefull, it's not fun getting shocked, believe me.

[GMtrucknut!!]

THe dwell is the degrees that the points are closed as the distributor rotates which is set by lifting the little window on your cap and inserting the proper allen wrench .Either adjust the screw clockwise or counter clockwise to achieve the proper results. You will need a dwell meter which can be purchased at most quality auto parts stores. The dwell on a v8 engine should be set at 30 degrees . Have fun with it ,learning to tune an engine is a lost art !!

[RHGuyettejr]

Originally Posted by steves1967

Nope, you still have points in it! I dont want to sound rude, so please dont take it that way, but if you are unsure of whether or not its points or electronic it might help to find a local shop that can help you with maintenance just until you get a better feel for working on the truck. The PCV valve wasnt getting hit by the lifter either- maybe by the rocker arm but even that is doubtful- are you sure it wasnt just the check valve opening and closing?

Yeah sorry, I was of thinking about something else, and yea it was rubbing on the rocker arm... I pulled it and it was worn on the bottom, when I spaced it out the ticking went away, I could still feel the valve working as it should. Dont worry about sounding rude, it's just something I have never done and I always like to learn new procedures. I have replaced a lot of electronic ignition components, I know they make electronic conversions that just modify the inside of the dist. and I was just making sure it hadn't had one of those installed, I have never dealt with points and condenser setups. I just didn't know if the setup was somewhat simple, or a bit more rigorous.

Thanks.

[RHGuyettejr]

Originally Posted by GMtrucknut!!

THe dwell is the degrees that the points are closed as the distributor rotates which is set by lifting the little window on your cap and inserting the proper allen wrench .Either adjust the screw clockwise or counter clockwise to achieve the proper results. You will need a dwell meter which can be purchased at most quality auto parts stores. The dwell on a v8 engine should be set at 30 degrees . Have fun with it ,learning to tune an engine is a lost art !!

Alright, thanks man, maybe I will go pick one up tomorrow and see if I can get it to run a bit better. Always looking to learn something new.

[trevrolet65]

Originally Posted by trevrolet65

Looks like points to me, dizy looks like the one on my sons 65. If that thing is missing, try pulling a plug wire then put it back one at a time and listen for a change. If there is no change, thats the cylinder missing. If they all idle down then they're hitting. But be carefull, it's not fun getting shocked, believe me.

Realy, I would make sure you hitting on all 8 before investing money into it. Sounds like that thing was missing in the video. I could be wrong, but running on 7 cylinders will full you if you have'nt had much experience. I had one running on six, still cherp the tires, just a thought.

[RHGuyettejr]

Originally Posted by trevrolet65

Realy, I would make sure you hitting on all 8 before investing money into it. Sounds like that thing was missing in the video. I could be wrong, but running on 7 cylinders will full you if you have'nt had much experience. I had one running on six, still cherp the tires, just a thought.

I agree with you, in person it sounded like it was missing, however it would come in cycles, seemed as though it would start to recover, then it would start missing again. it did get better when i plugged the manifold leak, however the only difference it seemed to make was decreasing idle speed.

[scrappy]

Definately get a vaccum gauge & dwell meter as mentioned before, those tools are imperative to tuning a carbourated engine with points ignition. The points gap should be around .019"(I think old timers used to use a match book to set the points gap). On the distributor shaft you'll see a hexagon shape(thats 8 sides right?) where it makes contact with the block on the points housing/frame. Also, make sure there's lube behind the block where it makes contact with the distributor shaft. Spin your engine over by hand until the high part of the distributor shaft is opening the points. Set the gap, put everything back together & than start the engine. Open the window on the cap & set your dwell as mentioned before. This picture is of a mallory points distributor but the concept is the same. Hope this helps.

[RHGuyettejr]

So i just went out and pulled one plug at a time to see what cylinders are firing, it started out great as when plugs 2,4 &6 where pulled the motor idled down, but plug 8 was pulled with no change, to my surprise plugs 1,3,5 &7 revealed no change as well? now I have driven this truck and it has nuts, I never suspected that it was missing on so many cylinders, so I checked it again to make myself feel better, still no change. However spark was getting to the #1 cylinder because I could hear it arc when I put the wire close to the plug, I could not see it though. Cylinder 3 seemed to actually make the motor run better while unplugged, and i could only hear it arc maybe every 3 cycles to the plug when I put it close. cylinders 5 & 7 I could not hear for sure, and 8 I i did not think to do this test on, but it is easy enough. The firing order is correct as it has been checked over twice to verify. Obviously the spark not getting to the plug is either a cap, condenser, or points issue, but what about the others that where getting spark? Guess i should start with making sure the dist. is set right points and dwell, then move on to compression / vacuum tests after that.

Thanks guys

[unclesalty]

I just went through the same sort of stuff over the summer with my '69... Don't take for granted that just because your plugs, wires etc are new, they're good, because some brands are rough as far as quality issues go. I had trouble with some of the new plugs, they wouldn't work proper right out of the box. A dwell meter is a great investment if you are keeping the points distributor, my 350 idles great, starts great now. I also had a plug wire burned and shorted to the exhaust. After you have verified the points, plugs, wires and valves, take a flash lite and have a look down the quadrajets primaries, make sure your not dribbling gas, that would fit the poor idle @ low rpm, etc.
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[Aaron Burkemper]

If you have the time, money, and inclination I would replace the points distributor with an HEI unit. Around here the are about $20 at the boneyard. It is so much more simple to maintain. JMHO. Enjoy the learning process in the mean time. I love the sense of satisfaction when I learn something new and get it to work!

[trevrolet65]

I 'd run a compression check on the cylinders missing
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