Chrysler '79 70 hp 3 carb tuning

[tnstreamy]

I have downloaded the FAQ for tuning carbs in and have followed the proceedure as presented and I'm missing something.
The cam is lined up on the indicator line on center of roller carbs b-fly valve closed on all three... go to WOT the cam doesn't get near opening the B-fly on any carb. It appears it's about 3/8 " away from the mark I put on the cam for opening the B-flys?
I've adjusted the ball connector one way for low idle the other for near WOBfly it's either one or the other.
I can get WO B-fly or low idle?? no the bottom carb is leaking out gas~!!!
Help!!!!

 

[Frank Acampora]

Re: Chrysler '79 70 hp 3 carb tuning

Did you read my post: Synchronizing carbs and timing? It is all explained in there. The initial mak is just for setting the carbs closed Thr roller will NOT be on that mark with the engine properly set and idling correctly. Again, search and read MY post.

And before you do anything else, correct the leaking carb. Take it off, clean it, check the inlet needle and seat, and check the float level.

 

[tnstreamy]

Re: Chrysler '79 70 hp 3 carb tuning

Frank thanks for the response.
It was your post I downloaded and was going by, it made the most sense of any I had seen.

I did fix the leaky carb.
I also switched my cables just to see if one was different. They look the same with the same length and travel but one seem to adjust on the ends better for the carb to be in low idle and almost get to FT.
The control is a one handle Chrysler type with pull button for throttle only.
I finally figured out the throttle cable arm needs to be facing forward at 3oclock to get throttle in F & R, and the shifter just has to move enough to get the gears. However the bracket that holds the throttle cable in place in the middle of the control box isn't allowing much adjustment, by threading in the cable to the arm 1/4" and trying too secure the cables holder bracket it doesn't line up. If I adjust the cable in more the threads hit the front of the control casing? I know it must be simple adjustments and that's my next job.
Since I switched the cables yesterday and secure the throttle cable best I could and I now get a better idle, but the motor is stumbling and doesn't sound like all are hitting correctly? I tried the slow speed adj screw 1/8" adjustments but not noticing mutch diff.
I guess Spark plugs are my next purchase. which plugs are best for the old girl '79 70hp Chrysler?

I have no idea how to adjust this distributor 30degrees at WOT it has the one arm with a screw adjustment that is on the throttle linkage tower.

thx again for taking the time to help a fellow boater.
S

 

[Frank Acampora]

Re: Chrysler '79 70 hp 3 carb tuning

Hmmm! Maybe I need to modify that post.

At the control box, the cable should be about 1/2 way into the circular "pin" with a 10-32 nut securing it from backing out. Then, the cable sheath should be secured into the pivot in the center of the box, NOT one of the legs. Be sure the groove in the ferrule is snapped in properly. Only the gearshift cable is secured in the leg if it is a hidden box (almost square)or the box case if it a surface mount (Rectangular.)

BTW: There are two legs or two holes in the box to allow flipping it over for use on the opposite side of the boat. Same thing with the holes in the shift lever. And the control handle may be adjusted infinitely on its splined shaft.

The adjustment at the engine should have a large spring loaded (cylinder) end for the throttle. It is screwed onto the cable so that in neutral about 1/4 inch of the spring loaded center is pulled out. This allows shifting before the throttle starts to advance. If both cable ends are the same and only about one inch long, then the throttle cable has the incorrect end. Adjustment will be difficult.

At the engine, you should be sure that the groove in the ferrule at the cable end is secured in the clamp. NOW, you should be able to correctly adjust the carb opening at full throttle and still have correct cam position at idle. NOTE that changing the idle speed with the stop screw will change the position of the mark on the cam.

The distributor is first adjusted to top dead center. With the flywheel at top dead center, the pulley on the distributor should have the curved groove matching the curve of the flywheel with the center straight line pointing straight at the flywheel. To change pulley position loosen the two 9/16 head bolts and loosen the distributor so the belt can be moved. After setting the pulley, pull out the distributor ONLY until the belt will deflect about 3/16 inch when pushed in the center with an .010 feeler gauge and tighten the bolts. Timing belt too loose and timing will flutter a bit. Too tight and the engine will bind going into and coming out of gear. Now the distributor matches the flywheel position.

Timing can be done static on these engines by turning the flywheel by hand with the ignition on. Be sure all the plugs are out and grounded so the damn thing doesn't fire and put you in the nine finger club.

The distributor is held in position by two black plastic pieces joined by a threaded rod. You loosen the locknut and turn the threaded rod to open or close the gap between the plastic pieces, thereby retarding or advancing timing.

Once you have set the cam and roller on the throttle, when the engine is correctly set-up and idling, the marks on the cam will NOT touch the roller but will be slightly below it.

Hope that helps a little more.

 

[tnstreamy]

Re: Chrysler '79 70 hp 3 carb tuning

Frank that was more indepth on the cables and shifter linkage and just what I was looking for. I installed new spark plugs major difference!
After tinkering with all the possible throttle cable arrangements in the C-box, I had to fashion a clip of sorts that holds the throttle cable in the middle swivle bracket. With the screw end into the circular "pin" as far as it would go and the cable end hit the C-box case and the cable notch still wouldn't line up ?? this seemed to advance the idle also. I bent some 16ga copper wire and fastened it into the notch and bracket which ends up about a 3/8 inch apart. I'll have piece milled for it if I have too this winter.
So end result She is now idling better, and I was able to follow the carb adjustment you posted, 1/8 movement out seemed the best. Idle still may be a little high...As for timing it fires on the second rotation,,, boom so I probably shouldn't mess with that, if it aint broke..thanks for the warning 'bout the nine finger club!!
You say there is a different end for the shifter from the throttle, on the motor side? This may be my problem mine are the same. Both are spring loaded screw on ball clamps, about an 1" in length..

I do think you should update the "carb timing" post with the cable addition, noone seems to cover cables like they're a no brainer. Well when your starting out it's all unknown.