New 73 Merc Comet Owner

73 is low compression ... 87 should be fine unless it is carboned-up. Only step up in octane if it pings under a load or diesels (keeps running) after you try to shut it off. Dieseling can also be fixed with a carb adjustment some times.

As you raise octane, fuel burns slower (contrary to what most people will believe...) .If you run more octane than a motor calls for, the slower burning creates more carbon deposits inside, and ultimately, the higher octane fuel "creates it's own need".

My 351 is perfectly happy with 89, and it is a pretty rowdy motor. I do drop to 87 while highway driving, and keep my foot out of the last 1/3 of the throttle.

 

Pinging

You got my attention on that Ping under a load. I thought about this and now Im wondering about this sound that comes from the engine. at first i thought it was an exhaust leak. but it very well could be a ping. it only does it when i put my foot in it. im still running 87 but with the lead additive. i have not ran out the tank of gas yet. i guess i need to isolate the problem.

 

Bead Blasting

I have another area of concern. Bead blasting some of the trim that is made of that metal potting. i wanted to have the trim rechromed but i thought maybe i could do it my self by having all the trim bead blasted to start with. just not sure if that would be to harsh on that type of material. any ideas???

 

Boomerang Pieces

I think you guys call them boomerang pieces. anyways the trim around the qtr glass, or side glass. those are really ate up with pitting and the chrome is coming off. i thought i could bead blast them. any thoughts on this??

 

If it is pinging ... three ways to correct it ...
1) Back the timing down a bit ... but that usually means a bit less power
2) Raise the octane in the gas.
3) Have the carbon knocked out of the motor. There are chemical treatments to do this.

Ping does damage, mainly to the rod bearings ... it is like smacking the piston with a hammer.

If you have about half a tank in it now ... put some 92 octane in it. That would average out to somewhere in between. If it is pinging, you should notice a big change. I would run 89 octane in it next and see stays away. Likely, this is the simplest solution, and driving the car for a while may clean up the chambers a bit too. Shell advertises that their gas has additives that can help clean them ... don't know if it is really effective or not personally.

 

Ok, but it could still be a leak at the headers or is that a completely different sound? keep in mind i have not gotten under the hood and listened to it with someone else jamming on the gas. the ping that your talking about should be coming from the top of the engine..correct?

 

If it is pinging, that is definitely as far in the engine as a noise gets. You will not hear pinging if someone is revving the car in neutral... the motor needs to be under a heavy load.

If it is an exhaust leak, you will hear it with the car revved in neutral ... a lot of times they sound like an old mechanical alarm clock ticking.

 

Welcome from Virginia

 

Turn Signal Cam

What a disaster, so i pulled the steering wheel replaced the cam, thought everything went nice and smooth.....nope, wrong. now not only does the right turn signal not cancel (original problem) but now the turn signal dash lights dont work and the right turn signals (outside of car) does not work. I replaced everything just as the instructions called out. whats weird is that the right turn signal worked before they just wouldnt cancel. booooooooooooo. so now i got to pull the steering wheel back off and check that all the little electrical connections are working. of course as always im up for any suggestions you gear heads may have out there.

 

You'd be money and time ahead to just replace the entire switch.

 

Well it ended up just being the little contacts were stuck...i used contact cleaner to get all the goop out of there and that took care of it..the lights not cancelling was a different story. i had to modify the cam because the lobes were not catching correctly..she's good as gold now....for the time being anyways..i didnt know you could change the whole thing out..how much would that set me back?