1970 Chrysler 70hp, miss at WOT

[K Hultgre]

I have recently acquired a 1970 Chrysler 70hp on a Ex-El, Delray (Canadian made)from a relation. According to them the motor has a problem at WOT (miss only noticiable when sitting in the jump seats). Two mechanics could not locate the problem so the price was right.<br /><br />From the information I could glean from them the miss is not a "bang" or a jerking of the motor so it does not sound like a lower unit (lube is clean).<br /><br />If anyone knows of problematic areas to watch for in the future and or hints where to start looking it would be appreciated.<br /><br />one thing I found while running it in the driveway for 10min the throttle will not go to WOT while in neutral (good and bad) and wondered if that is normal?<br /><br />-kevin

 

[eurolarva]

Re: 1970 Chrysler 70hp, miss at WOT

cant help on the miss but chryslers will only let you crack the throttle when in neutral. Best rpms in neutral is only around 1000 rpms.

 

[K Hultgre]

Re: 1970 Chrysler 70hp, miss at WOT

Thanks E, that's what I was thinking.<br /><br />When I ran the engine to moniter the head temp (close to spark plugs). I could put my fingers on it for a couple seconds before burning. The exhaust mfld and other side of block I could keep my hand on for many minuets.<br />After about 5 minuets something started to chirp. Fearing overtemp I shut it down even though it has a good stream of water out the pee hole. Any one know why it would start chirping ?

 

[K Hultgre]

Re: 1970 Chrysler 70hp, miss at WOT

Finally was able to water test. The engine is bucking only under WOT. It does this approx 1x every 1-2min. Immediately decided it was the lower unit clutch dog. Had a friend drive for me while I did some trouble shooting. If I push on the shift linkage (where cable attaches) I can get another 1/8" of movement. If I hold that in place while under WOT the lower unit does not act up.<br />After the lake test I pulled the shift cable and shot some JB-80 down it (unable to completely pull apart) and reinstalled. Shifts easier but still have the 1/8" slack. I checked the remote and found the slack comes from the Neutral button(shaft)/shift gear assy. Upon further investigation the Neutral button (shaft) has a roll pin that engages a slot in the shift gear and it appears the shift gear is a little worn in that slotted area. If I put the neutral button (shaft)/roll pin in the shift gear by hand it will engage deeper in the gear and then there is no slop.<br /><br />Questions,<br />1.)do you think the 1/8" extra movement is substiantial enough to make it jump out of gear?<br />2.)has anyone attempted to repair the control box? I was thinking about installing a larger pin in the Neutral button (shaft) then very carefully opening the slot in the shift gear until it is a perfect fit. <br /><br />Items 19 and 20 (i think)<br /><br /> http://www.mercruiserparts.com/Show...8.png&inbr=1813&bnbr=100&bdesc=REMOTE+CONTROL

 

[eurolarva]

Re: 1970 Chrysler 70hp, miss at WOT

That jump is probably the sign of the clutch and gear faces becoming rounded. There should be enough movement with the shifter to engage the gears without having to go all the way. The smaller chryslers have an adjustment nut in the motor leg that would allow you to get more forward motion on the forward gear. I dont see this with your motor. I noticed that part number 20 is no longer availible. I am not sure where you are in Minneapolis but libraries like Ridgedale or Brookdale should have a copy of the syloc or clymor manual for your motor. There is an adjustment procedure outlined in there that I am having problems understanding without having a motor to work with. I live in brooklyn park and work in plymouth. If either of these locations is close to you you can copy the pages out of my clymor manual.

 

[K Hultgre]

Re: 1970 Chrysler 70hp, miss at WOT

Euro,<br />That was my fist thought until I found the extra 1/8" movement, then thought that might translate into something substantial on the clutch dog to gear interface.<br />There is an adjustment on the vertical shift shaft (nylock nut located under the bottom carb). But am weary of making adjustments fearing losing reverse.<br />I work in EdenPrarie and reside in Mound. Thanks for the offer, I may take you up on it but will first check Ridgedale, Chanhassen, and the Mound libraries since they can be on my way home.