MJAKS462

I flipped around some plug wires on my cutlass last fall and I had some nasty backfiring. I am about ready to start it up but I am not sure how to find the #1 on the Hei cap ? Does that make any sense ?

captjim

http://www.oldsmobility.com/tuneup.htm

Depends, though, you did not state the year. You can remove the #1 plug, disable the ignition, and "bump the engine over until you feel/hear compression on that cylinder and rotate the engine until the mark on the balancer was at zero. Then, look at the rotor and see which position it is at.

joe_padavano

What he said. Since you don't know if the distributor is in the original position, just get No. 1 to the compression stroke, and start there, especially given the fine print on that link above:

Chumley

Important to make sure the #1 cylinder is on compression stroke. If you use the timing marks alone, it could be #6 cylinder at TDC compression stroke.

oldsdroptop

In my limited experiece with the newer style HEI's (I usually run the older type points type caps with a crane undercap pointless ignition) But if I remember correctly the #1 plug wire sets in the loom the 1st post just to the left of where the power wire, tach wire and the 4 prong plug goes in. I'm not sure if all the top snap in wire holder has a #1 listed on that post, but I thought it did. Then just follow the fring order on theintake manifold. Check it just like Joe and the guys told ya. But if the dist is setting about right the box those 3 different sets of wires go in is facing the drivers fender (close but you'd have to check it with a timing light and go by what the light says sometimes I get lucky). Oldsdroptop

MJAKS462

You guys dont know who you are talking to , all three of these responses might as well be in Chinese.
I cant even work on a lawnmower without screwing it up.but lack of funds forces me to do this myself.
Tell me if this is correct : Pulll the cap off , pull #1 spark plug ( #1 is closest to front of car on driver side ? ), turn engine over until #1 cyl comes up inside block so I can feel it , from there what do I do , No timing light , dont know what balance at zero means ,It is a 72 Cutlass but has a 78 403 in it .
Should the rotor be facing the #1 cyl . ? what if it is not ?
Thanks so much , Please have patience I am a good learner

joe_padavano

No problem, but you basically understand it. Remove the distributor cap and No. 1 plug. Simply checking when the plug is at Top Dead Center is not sufficient, since in a four stroke engine it comes to the top twice, once on the compression stroke and once on the exhaust stroke. You need to be sure it is on the compression stroke. One way to do this is to hold your thumb over the spark plug hole while someone bumps the starter. You will feel the compression. Unfortunately, you will also feel some compression on the exhaust stroke but it will be much lower, so just be sensitive to that. When you start to feel compression, look at the timing tab on the front cover (driver's side of the front cover, behind the balancer). Continue to bump the starter until the mark on the balancer is at the zero mark on the tab (or at least close to it). The terminal in the cap that the rotor is now pointing to is the No. 1 terminal.

MJAKS462

Thanks guys. I actually found pics that I took when I got the car and it ran decent. I had a pic of the wires and I could see which one was hooked up to the #1 and its location on the cap. Unfortunatly all the wires are in Correct order so something else must be causing backfires. Dont bother responding yet , I have the carb off right now so I wont be able to really figure this out yet. I will come back to this post when I am ready to start it back up., Thanks so much , John

stan 65 cutlass

finger in #1 spark plug, watch the rotor, when it blows remember where the rotor points, make it #1 plug wire,watch the rotation,should be counter clock wise, i know, too many cooks

oldsdroptop

I went throught this exact same scenario with my 71 455 and spent a butt load of money. I installed a new gas tank with fresh fuel, new intake carb, completely rebuilt the C heads. Still back fired at idle. I thought okay now there's only 1 thing left. I tore off the front timing cover and discovered the timing chain (which was non factory and less than 5K miles on it had jumped 1 tooth. How. I have no idea. I thought only the factory aluminun/plastic upper timing sprockets were prone to this. WRONG. This was an aftermarket set and the motor had been previously rebuilt. So I'm not saying this is for sure your problem. But I sure wouldn't rule it out. Good luck. Oldsdroptop

MJAKS462

Thanks drop top , I will keep that in mind