New member - Need help

[vapg7]

Well, i just found my answer. Need to use the cars starter...i'll check it out this evening and see what the actual compression is

[smiley]

Hello, bingo..Let us know...mike

[vapg7]

I've done it right this time: 148, 151, 150, and 149. I'm glad to see she wont need a new motor anytime soon.

So, my next step is to tune the carburetor (32/36 weber) with a vacuum gage that's gonna arrive tomorrow. Like measuring the compression, this will be my first time trying to tune a carburetor so any tips will be appreciated.

[smiley]

Hello, well, check the timing first, with the vaccuum line dis-connected. I think 5 btdc is stock, but I would try between 8-10. If it pings, then back it down. Go for highest idle speed with the mixture screw, then back down the idle to normal idle speed. Or richen it (screw out) until no noticable changes are happening, then turn back in, till you notice a slight change, or drop in the idle.That is the lean drop method.before that, have you already checked your vavle clearence (valve adjustment). If not, do that first...mike

[vapg7]

Hi, the timing was done a couple of weeks ago and i set it to what the manual calls for; 8. I played around with the carburetor before i read your post so I already "tuned" it a little and I've also replaced the blown muffler. I bought a used 20r engine for $50 bucks and stole the exhaust manifold from it and replaced...now she's quiet and hopefully with no exhaust leaks. I had heard that the leak could contribute to backfiring so i wanted to eliminate that as a possible cause.

I have not checked the valve clearance and nor do i have a clue how to do it but I'll start reading my 20r repair manual to figure that out. I know the valve open and close but how do they affect the engine if they are not at the right clearance? Anyway, before I crack into my engine I'm gonna practice on the extra one i bought and make sure I don't screw anything up with the one that's in it.

Good news are that I can now drive her around without being too loud, having too much backfiring (if any), and without getting intoxicated by the exhaust leak She handles a little rough and brakes need to be looked at but that's another monster that I'll be tackling next.

VIC

[smiley]

Hello, sounds like it's coming along. Having an exhaust leak will cause a back-fire (sometimes) because it allows extra air to be sucked up into system, making it lean. Also a lean idle mixture can cause the same thing. When you say "back-fire" do you mean in the exhaust system, or in the intake? Like a "sneeze"thru the carb. Setting the valve clearance is important because it allows the camshaft to perform as designed.to much clearance will be noisy, andshortens the duration the valves are open. too tight, and the valves could stay open when the shouldn't be. that can cause a burned valve. The manual will say to put at TDC and adjust 4 of them, then turn over (180 or 360 I can't remember)and adjust the other 4. I like to adjust individually, making sure the rocker arms are on the base circle, opposite the lobe.This is a personal prefference, some advise not to do it this way because it is important to check it the same way every time (and it takes longer).I do it my way so I don't forget one.I also like to set them at 7 and 11 though, instead of the stock specs (8-12?) again, a personal thing to get the most duration from the cam, and to insure they won't be noisy.Make sure the drag is appropriate, being pretty heavy. Easy to get the feeler gauges twisted and whatever, causing a bad reading...Mike

[vapg7]

Hello, sounds like it's coming along. Having an exhaust leak will cause a back-fire (sometimes) because it allows extra air to be sucked up into system, making it lean. Also a lean idle mixture can cause the same thing. When you say "back-fire" do you mean in the exhaust system, or in the intake? Like a "sneeze"thru the carb. Setting the valve clearance is important because it allows the camshaft to perform as designed.to much clearance will be noisy, andshortens the duration the valves are open. too tight, and the valves could stay open when the shouldn't be. that can cause a burned valve. The manual will say to put at TDC and adjust 4 of them, then turn over (180 or 360 I can't remember)and adjust the other 4. I like to adjust individually, making sure the rocker arms are on the base circle, opposite the lobe.This is a personal prefference, some advise not to do it this way because it is important to check it the same way every time (and it takes longer).I do it my way so I don't forget one.I also like to set them at 7 and 11 though, instead of the stock specs (8-12?) again, a personal thing to get the most duration from the cam, and to insure they won't be noisy.Make sure the drag is appropriate, being pretty heavy. Easy to get the feeler gauges twisted and whatever, causing a bad reading...Mike

Mike,

The backfiring is through the exhaust. I adjusted the valves over the weekend and it ran much smother, it helped out a lot actually. A day after after setting the valve clearances I decided to install the A/C compressor belt that was missing and it ran a little funny after that...would this cause timing to be retarded a little? Before installing this belt it ran fine and after it I was getting a random backfire every now and then...I'm gonna check the timing again just to be safe. I got a nifty "engine analyzer" this weekend so I'll be adjusting the dwell angle so make sure it's right. I had her running smooth for a while until I installed that belt, and the A/C didn't blow cold so it might not even work.

VIC

[smiley]

hello, the A/C won't retard the timing. what can happen is the compresser can come on at idle (if set to do so with the controller, which is under a cover on the heater box) That can bring the idle down pretty low. The system is probably low or empty on refrigerant, if not cold, and the compresser turns on. if you want A/C, it is best to convert to R134 instead of paying a huge price to fill with R12.Let me know if you want some advice on doing that. On the back-fire try screwing the idle mixture screw out,about 1/2 to 1 turn out, and see if that cures that. If not, could be that carb is not able to get any richer,or a vaccuum leak,or possibly the check valve in the air-injection system.Lots of things to check out.I don't recall the year your car is, but it may not even have points. Later cars have electronic ignition.sounds like it's coming along..mike

[vapg7]

Mike,
I'm not too worried about the A/C for now, I just wanted to see if it would work. I did notice the rpm drop when I pushed the A/C button so it may just be empty on the refrigerant. I'll take you up on the conversion info later as the backfiring issues came back and need address that first. I feel like I'm back to the beginning but at least now i have all the tools to tweak this thing.

The car is a '77 LB with a 20R and weber carb. Below is the picture of the distributor and I believe it does have points (according to the owners manual):


I'll try your suggestion with the carb, vacuum leak, and valve but I'd like your input/help with my findings yesterday. I purchased this engine analyzer to help me adjust the dwell angle (http://www.amazon.com/Actron-CP7677-Aut ... 651&sr=8-1) and after hooking it up to the ignition coil it gave me angles between 67 and 70 degrees. Now, i followed the instructions on the instruments manual and i feel this is a correct reading which means its way off since the dwell angle should be 52 according to the engine manual. Then I proceed to adjust the angle by twisting the knob on top of the distributor but after twisting it all the way down it only brought it to 65 degrees. How else can I adjust the points to bring the angle down? I didn't get to mess around much with the distributor but I'll try to figure something out tonight.

Thanks for the help.

VIC

[smiley]

Hello, when you adjusted the knob, you didn't change dwell. You changed the timing. Set the octane adjuster (the knob)in the middle, and forget it for now.It has points, so set the dwell at the factory spec. This is done by opening or closing the points gap.Same as setting the points gap.Can use remote starter and adjust while cranking,or move a little bit, start, and re-check. Can double-check your work by using feeler gauge and setting -checking gap (with key in off position,and point rubbing block on highest point on cam) .018 is good.After you have done this, go back and re-check the timing.forgot to mention the back-fire can be caused by holes in the exhaust system, too.May want to start a new thread about this, as it's really not an introduction, at this point. Make sure the cylinder count selection is set to 4cyl, or you will get the wrong readings...and, by setting the points gap properly, the dwell will be very close to spot-on. In fact it may be better to go buy a new set of points, and condensor, to make sure they are in good shape.May want to concider the Pertronix set-up to eliminate them all together, that is the way to go..it is normal for the idle to drop with the AC on, probably more if it was full. Might want to unplug the compressor. if it is low the refrigerant wont cycle the oil in the system, and could kill the compressor.

[vapg7]

got her all straightened up after I corrected my mistakes...thanks for the help and i'll be sure to make new threads in their respective categories next time...sorry it got so out of hand

[smiley]

Hello, so, runs good with no back-fire now?...mike

[vapg7]

Hello, so, runs good with no back-fire now?...mike

No more backfire...but got something else that's annoying me now...thanks for all the help

[neil reid]

Hello, so, runs good with no back-fire now?...mike

No more backfire...but got something else that's annoying me now...thanks for all the help

I'd say join the club, but you already have!



Neil

[vapg7]

Hello, so, runs good with no back-fire now?...mike

No more backfire...but got something else that's annoying me now...thanks for all the help

I'd say join the club, but you already have!



Neil