Chrysler 120HP 1974 Exhaust Port Cover

[Ghatz]

Hi.
I have a 1974 120HP Chrysler engine and when I removed the cowling yesterday, the exhaust port cover is corroded near one of the bolts.
Is this "normal" for the cover to corrode?
I haven't dismantled it yet, and wondering whether there are any tricks I should be aware of?
Also, when re-assembling with a replacement cover, how tight should the bolts be?
Any help would be greatly appreciated.
Thank you,
George.

 

[Frank Acampora]

Re: Chrysler 120HP 1974 Exhaust Port Cover

Yes, on an engine that old and especially if it has been used in salt water there usually will be significant corrosion. In fact, salt water use will likely perforate the cover. They usually snap at leat one bolt when the cover is removed. So, a little penetrant for about a week before and then some heat during bolt removal will help. An impact gun as long as it is not set too high will usually do better than a hand wrench.

Reassembling, the bolts are 1/4 -20 and take a torque of 70 inch pounds.

Snapped bolts can be drilled out carefully. They usually go crooked anyway so the holes can be drilled deeper and re-tapped.

For drilling out bolts, I take them to level with the block. Then I put the new cover on with some of the bolts. I hammer in a 5/16 roll pin into the hole to be drilled and use it as a guide for a 3/16 drill.

If the snapped bolts have enough protruding from the block, you can grab them with a vice-gip--the branded tool, not generic- -clamp it on as tight as you can get, heat the block and twist them out. This sometimes works.

 

[Ghatz]

Re: Chrysler 120HP 1974 Exhaust Port Cover

Thanks Frank.

I'll give it a go. I'm hoping it doesn't become too much of a problem.

Would you know what type of gasket it has behind the cover?

Thanks,
George

 

[Frank Acampora]

Re: Chrysler 120HP 1974 Exhaust Port Cover

It is a simple fiber gasket. There are two of them with a stainless plate sandwiched between. They cost about 10 bucks apiece. Since Chrysler and Force changed the bolt pattern a couple of times, you would be best off sourcing--locally if you can-- if not locally, contact franzmarine@aol.com. Regular suppliers usually don't go back that far. Of course, if you have time on your hands you could always fabricate the gasket. Me? I simply don't have the patience for that particular one even though I make many others.

 

[Ghatz]

Re: Chrysler 120HP 1974 Exhaust Port Cover

Thanks again Frank.

Chrysler parts are getting very difficult to find in Australia and there is only one outboard service centre that stocks minimal parts. Whenever you need something specific, the first thing they try to do is to sell you another complete engine.

My Chrysler has been very reliable and doesn't give me any trouble except for a flat spot when first accelating where it makes the whole boat shudder. Once you slowly accelerate through the shudder, the motor is absolutely fine. I'm assuming it's a carb adjustment - the engine is the twin carb model - but have never tried to adjust them in fear of making them worse!

If I can't find the gaskets locally, Ill contact Franz marine.

I'm also hoping I don't break any of the bolts on removal as it will be a much easier job if I don't. Hope you don't mind me asking, however is there anything I should use on the threads of the bolts when re-assembling, like never seize?

Thanks again,
George

 

[Frank Acampora]

Re: Chrysler 120HP 1974 Exhaust Port Cover

I use anti-seize but I am strictly a fresh water boater. Some of the guys on the forum say that never seize in salt water becomes ever seize. I don't know. I have seen good results with water pump bolts sealed with RTV silicone and I know of several people that use Vaseline Petroleum jelly.

If you do use anti-seize compound be certain to use the nickel compound or a compound specific for aluminum. Those containing copper set up a galvanic reaction between the bolts and the aluminum casting, causing worse problems than using none at all

 

[Ghatz]

Re: Chrysler 120HP 1974 Exhaust Port Cover

Thanks again Frank.

I'll attempt to remove the cover over the next week or so.

Will report back on how successful or otherwise I have been.

Cheers,
George

 

[dropbear68]

Re: Chrysler 120HP 1974 Exhaust Port Cover

If you can Id have the inside of the cover blasted, retap all the bolt holes, a bit dose of red oxide primer on the inside wont hurt, vaseline on the bolts is a good idea, any gaskets you could dose with hylomar and then use a quality RTV to set them down, if you dont have a Chrysler Manual go find one, Ill look in mine and give the torque settings for the bolts, Id replace the bolts with new stainless bolts there available through specialty fastener shops, cost a few bob more but start with fresh bolts things last longer, you can never use too much vaso on things, I have used Cat never seize compound on my prop shaft left over from my dozer days I found it went yucky and the prop was hard to shift, Shell make a great marine grease.