I have a 63 GT Hawk, R1. When I got the car it had a miss in it, but it ran down the road but you could hear the miss in the exhaust plus it ran rough. Well I started with a compression test and it was 155psi in all 8 cylinders. I changed the plugs and wires, ran the same. I then removed the distributor and replaced both set of points condenser and cap no change. I found there was no ground going to the engine so I fixed that, no change. I removed the carb and rebuilt it, no change. removed intake installed new gaskets, no change. I replaced the carb with a used Holley and now it starts but dies. I then replaced the distributor with another one. Replaced the coil. Any help you can give me. I don't know what to do next. I would buy a new carb if that would fix it but I hate to spend that much and be right where I am now. Thanks tman1912
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Without a Scope or Engine Analyzer computer, the Old School way to determine poor Intake or Exhaust Valve seating, or Worn Rings is to pressurize each Cylinder using a 14 mm thread Air Hose quick disconnect fitting at TDC compression stroke (both valves closed) and listen for escaping air at the Tail pipes, Carb. or Oil Filler which will tell it ALL!
It sounds like you may have an Exhaust Valve too tight, hanging up or with a burned or excessively worn Seat.StudeRich
Second Generation Stude Driver,
Proud '54 Starliner Owner
SDC Member Since 1967
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I agree with Rich that you might have a slow to close valve. A compression check at cranking speed will show good, but at speed, the valve is too slow to close and give good power. Try a can of Sea Foam in the oil, and another can in the gas. I had sticking hydraulic lifters on a car in the 80's, so I drove 5 miles for a can of Sea Foam, and before I got home the engine sounded like new. I had even dropped the pan and replaced the rod bearings trying to fix the clack. It did sound like a rod bearing rather than a sticking valve or tappet.
A vacuum gauge may show a slow to close valve.
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Originally posted by tman1912 View PostHi, yes I did adjust the valves, I forgot to put on the list. Good idea, thanks
I'm assuming that one cylinder is misfiring at all rpm, and all the time. Pull the spark plugs and look at them. Broken plug, bad plug wire, loose plug wire, cracked distributor cap?
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Not sure if you know whether the engine sat without running before you bought it. I have heard of engines that sat for a period of time, having weak valve springs on the cylinders that the valve was held open. It makes sense, as the spring would be compressed and held there for as long as the engine sat idle. Just one more thing that you might check. It is also logical that a weak spring would produce a good compression check, but not work well at much rpm. Good Luck with getting it figured out.Tom Senecal Not enough money or years to build all of the Studebakers that I think I can.
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We've been through this before, but the first thing to do is replace all the ignition components; points, condensor, rotor, cap, spark plugs. and spark plug wires. This has fixed many a mysteru miss. They can look OK, but they won't carry a load.
jack vinesPackardV8
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He mentioned that he changed all of the ignition comonents, and the the entire distributor. As somebody mentioned, if he could nail it down to which cylinder it is, he could swap wires, plugs etc. I wonder if there is any possibility that one runner on the intake could be plugged with something. Not knowing any history, it may have sat with the carb off long enough for hornets, or a critter to get into the intake?Tom Senecal Not enough money or years to build all of the Studebakers that I think I can.
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Make sure the #5 and #7 spark plugs wires are not running parallel. Those cylinders are next to each other in the firing order, and if the wires run parallel it can cause a mis-fire. Route one of the wires thru the front 'bracket' (loop?) that attaches to the valve cover nut, and the other thru the bracket that attaches to the rear valve cover nut. The wire routing will look a little odd because #3 and #5 wires will cross, but this is the way they are supposed to be routed.
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