Dying 350 Chevy. Need advice.

[samt]

Well my 350 Chevy, mystery motor I bought cheap is dying. It's has never liked to rev past 4000, lately it's done some popping if you reved it too fast. Well it is rattling when you let off the throttle and doing extra backfiring, seems to come from cylinder 8 under the valve cover. I haven't torn in, but suspect I have some bad valves or cam. Probably why I burnt up an exhaust hose right there. Anyways I found a whole 350 that runs, but a guy snapped a main bolt on the rear main. It has 882 heads. I'm thinking about putting those heads on my block (4bolt, target master) and going with a new cam. I'd like to run one of the $100 jegs or summit cams. What do yall suggest. I'd like more than my current 175hp I have now.

 

[81 Checkmate]

Merc guy here...but Proly a worn down lobe on the cam. The burnt up exhaust hose is due to no cooling water in the exhaust. Is the Target master the mystery motor? If so proly needs new cam bearings in the block to go along with the new cam. Summit cam would be ok....just go with a truck cam grind, dont want a lopy car cam in a boat. 882 heads are ok...... just check for flatness..

 

[samt]

Yes the mystery motor is a target master. It "was" a good running motor, but was less powerful than the OMC 200 305 in the boat before.
Hopefully I have time tonight to pop a valve cover and atleast see if the cam went and what the heads on it are. I was planning to swap the cam this last winter, but moving and changing jobs got in the way!

 

[samt]

Oh yea , I may have burn a hose the first time out this summer. I forgot to tighten the water pump hose and it blew off while I was cruising a 4,000 rpm. Almost sunk the thing. That water pump on the drive pushes a lot of water when your at full speed across the lake.

 

[81 Checkmate]

You could just go for it and throw in the a new cam and lfters with the 882 heads and run it till it pukes. Heck you could do that in a weekend. Then rebuild the one with the snaped main cap bolt over the winter and then swap motors.

 

[bruceb58]

Have you measured compression or done a cylinder leak down test yet? Thinking you need to put a cam in right away is putting the cart before the horse.

Your exhaust hose burnt up because of your water pump issue, not the cam. Even if you did have a worn cam, that would not cause an exhaust hose to heat up.

 

[samt]

I investigated today. Compresssion is 135-140. plugs are all black fouled (delco R45TS) all look the same besides a few that were a little wet. Everything under the valve covers looks good. I did the redneck check for bad rodbearing on cylinder 8 (didnt feel anything then or when I was listning with my screwdriver the otherday) I should have checked the timing I guess. I guess when the new hose comes in I will put new plugs in and check the timing.
Could I be getting detonation from the fouled plugs that sounds like something coming apart under the valve cover? maybe timing a little to advanced? I'm running a GM HEI distributor, its got the vac advance. I shoved it in because it was in great shape and my marine one needed some $$$ put in it. Maybe if I plug the vac advance off some of my issues will go away? I know it isn't marine, and I see alot of debate on if the vac advance is worth a crap on a boat, most say no, I guess if I plug it it becomes a normal one.

May be a good Idea to get that motor and build me a more beefy one over the winter. wifes not really into spending money on the boat, but its getting time. We have enjoyed it for a summer and a half now, there is some bastardized stuff on it I need to take care of too, like the distributor

 

[bruceb58]

First thing you do is get rid of that distributor. Besides the fact that it isn't safe to run in a boat, the advance curve is completely wrong.

 

[Bondo]

wifes not really into spending money on the boat,
there is some bastardized stuff on it I need to take care of too,

Ayuh,...... Sounds like the best way out is to unload the barge ya got, 'n convince the wife to up-grade to a much less bastardized boat,.......

 

[samt]

Ayuh,...... Sounds like the best way out is to unload the barge ya got, 'n convince the wife to up-grade to a much less bastardized boat,.......

That's definetly a good option, I'm building a new shop this winter and will be looking for a newer or a new boat once it can live in a insulated shop. I figure if you park it inside and do proper maintenance a new one would last the rest of my life.
I've had a lot of fun with this one, but the previous owner not doing maintenance (had a OMC oil filter on it still, he said he had never changed the oil) coupled with the worn out OMC drive has been a nightmare. I feel like it's always on the verge of being trash, so I'm not willing to spend much on it, hence shoving my old hei distributor.
But it does have a trailer that would make me a good light duty car hauler and people pay a lot for functional OMC parts.

 

[samt]

All that said, my uncle has a late 70's 18' VIP ski boat that's in better shape, lived in his barn since new. Merc drive with a 4cylinder "mercruiser 470". Local lake went dry and he parked it 5years ago. He said the water pump is out. I can probably get it for free. Will that be another money pit? He is one of those guys that made us drip dry on the back before we could get in.

 

[Bondo]

I can probably get it for free. Will that be another money pit?

Ayuh,..... Probably,..... The ole 470 is the one Merc ya Don't want,....

 

[samt]

Well I will add that to my list of free items not to accept.

Anything OMC at the top! (I say that, but I really need a parts boat)
Weimaraner puppy second
Maybe the Merc 470
Not sure what's next.

 

[Bondo]

my list of free items not to accept.
Not sure what's next.

Ayuh,..... A Cold is at the top of My list,......

Junk I can scrap,....

 

[samt]

Well I got my exhaust hose fixed and put the marine Mallory dizzy back in. My tick is gone. But engine won't rev good. Gets rough at 2500, starts backfiring at 3500. I set timing at 8*. I can rev a little higher if I advance it a lot.
Think my points are shot? They may be 1981 model for all I know. Anyone have a part number I can use at my local parts store?

 

[samt]

Also just noticed that my fuel pump is done, it's pumping fuel out the vent line. I had the air cleaner off so it wasn't going down the carb at this time.