1971 Chrysler 105 hp

[Abuelo Joe]

My first post, new member. I have a 1971 Chrysler Sport Fury w/ 105hp motor. Purchased new and been in family since then. Has not been in water for 5 years. When last winterized the engine ran ruff at low end of rpm range; started and idled fine, ran great at top rpm range. Prepped boat and put in lake two weeks ago. Same problem. Took to marina where they diagnosed a "ignition pack" problem. They could not get replacement parts for this old boat. I found aftermarket (CDI) product, bought and delivered to mechanic. THE PROBLEM remains. Mechanic states he now believes problem is the stator. He cannot order thru his distributor. I have completed several hours of research on this device and potential problems but cannot find any after market parts. Mechanic states no identification on stator. I am able to find re-purposed stators that MAY work but cannot be sure part is correct. Any thoughts on issue and where to source this part (and others) for this engine. Thanks for your interest.

 

[Nordin]

First of all do a compression test.

Have you clean the carbs?
As it has been sit for several years, change the fuelpump diaphragm.

Your engine have a battery feed CD ignition with beltdriven distributor.
As you stated it runs good at high RPMs but rough at low.
The stators purpose is only to charge the battery and the ignition system use the battery voltage to create spark.

I do not think the issue is the stator.
You can check the stator by check the voltage at the rectifier AC side. At idle you should have about 11-12VAC. Throttle up to 1500-2000 RPM and the voltage should rise to about 13,5-14 VDC. If nothing happens the sator is bad.

Clean the carbs, set and clean the points to 010 in and start from there.

You says you have change the CD module to a aftermarket CDI box 115-3301 I believe. Your factory Motorola or Delta CD box is not bad.

 

[Abuelo Joe]

Nordin, thank you for the sanity check. Marina mechanic received a replacement stator from me this AM that I found on eBay. I assume I will learn that stator is not the problem. I will move him to your suggested next steps. Have a great day.

 

[Abuelo Joe]

Update! Mechanic installed owner supplied stator. Same issue. Owner has purchased replacement oem "rectifier". I should have tomorrow. Mechanic states issue is electrical and that voltage is dropping in mid range rpm's...runs fine at low and high end, misses in the middle. starts and idles fine. Marina is ready to give up as they have no other resources other than trial and error to diagnose problem which they state is unusual.

 

[Abuelo Joe]

After long searches found and replaced the rectifier and voltage regulator. Engine performance the same...starts and idles great, runs poorly at mid-range, great at higher rpms. Mechanic convinced issue is electrical. Process of elimination of major components has failed. I will pick up boat today as marina has given up. Any additional thoughts will be appreciated.

 

[Nordin]

Check the spark at all plugs at mid-range with a timing light.
I think you will be able to see if it have spark missing.

Can you explain how it act in mid-range.

Have you set the spark advance at WOT?
Should be 30 dgr BTDC.

 

[Abuelo Joe]

Engines starts/idelesnormal. Operates up to about 1500 rpm normally, runs rough/misses (does not stall) up to about 2500 rpm, 2500 to top end runs normal (screams as it always has). Mechanic states he will continue to work on engine starting with timing issues you outlined per my request. I just ordered the service & parts manuals. I was introduced to another Chrysler owner who also has a 105 hp. He has replaced the Chrysler power head with a Force power head which he says has simplified the engine and improved reliability significantly. I will review the forums on this approach. Thanks for your interest.

 

[Arawak]

How rough? Frank told me once when I commented that mine ran a bit rough in the mid range that "it's a Chrysler, they all do".

 

[Abuelo Joe]

Very rough; must ease thru in order to prevent stalling to get to cruise speed. This issue is recent and engine used to run fine. And yes, it is a Chrysler and we have had many different problems with it over the years but has not been run much in the past 10 as we have a newer/larger craft.