351m problem driving me nuts
New User
Joined: Aug 2008
Posts: 2
Likes: 0
your problem is most likely all in your carb.....has to do with the amount of fuel that you are dumping in a motor that cant get the air to match.....either change your jet size or install a high rise intake with a racing cam
More Turbo
Joined: Mar 2002
Posts: 606
Likes: 3
From: Colstrip, MT
Since the problem is solved - danlee, you mentioned a heat riser valve on the exhaust manifold. Is this valve installed at the outlet of the exhaust manifold? I don't seem to find one on my 400( 78 F-150 with stock engine), but headers have been installed. I remember the old style on a 59 ford with a visible coil spring on the exhaust manifold.
I was just wondering if this might help solve a long-term overheating problem?
I was just wondering if this might help solve a long-term overheating problem?
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Since the problem is solved - danlee, you mentioned a heat riser valve on the exhaust manifold. Is this valve installed at the outlet of the exhaust manifold? I don't seem to find one on my 400( 78 F-150 with stock engine), but headers have been installed. I remember the old style on a 59 ford with a visible coil spring on the exhaust manifold.
I was just wondering if this might help solve a long-term overheating problem?
I was just wondering if this might help solve a long-term overheating problem?
I think that the modern version of the heat riser valve is a vacuum cylinder that is operated by a temperate sensitive valve. The exhaust flow valve opens when the motor gets warm.
If you have eliminated this valve, then you should have no problem, but it may take a little longer for your motor to run efficiently in cold weather.
Removing this valve will not affect normal operation at full temperature.
Blocking the exhaust crossover in the intake manifold will keep the manifold cooler. This will help make more power, but at the cost of fuel mileage.
None of this should apply to the engine operating temperature.
Look at your Fan, Shroud, Tstat, Belt slippage or Radiator blockage for cooling problems.
More Turbo
Joined: Mar 2002
Posts: 606
Likes: 3
From: Colstrip, MT
Thanks for the reply, Dan. The list of items replaced in the cooling system with new is quite long. Basically everything has been replaced, including the engine(stock rebuild - Oh, TMI, where were you when this engine was rebuilt?) New radiator for a 460 engine, new robertshaw 180 deg thermostat, new heavy duty fan clutch, new water pump, new fan shroud(Dennis Carpenter), new radiator hoses, new fan belts, new EGR with a 135 deg F. cut in temp, timing set at 10 BTDC, etc.
By overheating, I mean about 220 deg F.
I know this subject has been beat to death, but after three years, I'm still fighting it.....
By overheating, I mean about 220 deg F.
I know this subject has been beat to death, but after three years, I'm still fighting it.....
Senior User
Joined: Jul 2008
Posts: 157
Likes: 0
From: Mariposa, CA
There are only a couple of causes for this problem. if there is gas dripping from the booster nozzles at idle, the float level is either too high or a stuck needle seat, or the float has become saturated with gas or leaked into it(brass only) and sunk. these are the most common. It could be that your idle mixture screws are adjusted wrong. If your carb is not dripping from the boosters at idle, your problem sound like its in the idle circuit. Also I just looked at both my 351M & 400 neither have a heat riser on the exhaust manifold. it is probably boiling the gas out if its getting that hot. i hear alot of talk about removing the valley pans also, it is designed to keep the hot oil off the bottom of the intake. since yours has so few of miles it should still have it.
Hope this info helps.
RW
Hope this info helps.
RW
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Thanks for the reply, Dan. The list of items replaced in the cooling system with new is quite long. Basically everything has been replaced, including the engine(stock rebuild - Oh, TMI, where were you when this engine was rebuilt?) New radiator for a 460 engine, new robertshaw 180 deg thermostat, new heavy duty fan clutch, new water pump, new fan shroud(Dennis Carpenter), new radiator hoses, new fan belts, new EGR with a 135 deg F. cut in temp, timing set at 10 BTDC, etc.
By overheating, I mean about 220 deg F.
I know this subject has been beat to death, but after three years, I'm still fighting it.....
By overheating, I mean about 220 deg F.
I know this subject has been beat to death, but after three years, I'm still fighting it.....
Low speed overheating and cool cruising indicates an air flow problem. Overheating at highway speeds indicates a water flow or load problem.
Maybe the head gaskets were installed wrong!
More Turbo
Joined: Mar 2002
Posts: 606
Likes: 3
From: Colstrip, MT
Low speed, idle is no problem. So, airflow is ok?
Overheating occurs under load - long hills, or pulling a 18' camp trailer. Outside temperature makes a big difference also. It just seems like it can't remove the heat fast enough. All the changes made above did help the overheating problem, but I just dread pulling the camp trailer 100 miles beacuse it involves constant stops to cool down the engine.
I actually had them pull the heads after the engine was installed, to verify the gaskets were installed correctly. They were.
I am leaving at midnight tonight, so I can pull the trailer up the hill while it is cool. Thanks for the suggestions.
Overheating occurs under load - long hills, or pulling a 18' camp trailer. Outside temperature makes a big difference also. It just seems like it can't remove the heat fast enough. All the changes made above did help the overheating problem, but I just dread pulling the camp trailer 100 miles beacuse it involves constant stops to cool down the engine.
I actually had them pull the heads after the engine was installed, to verify the gaskets were installed correctly. They were.
I am leaving at midnight tonight, so I can pull the trailer up the hill while it is cool. Thanks for the suggestions.
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Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Check your pulleys. Do you have the right pulleys? A crank pulley that's too small or a WP pulley that's too large will slow the water pump, resulting in reduced water flow. Did you use your old pulleys on that rebuilt motor or some pulleys that came with it?
New User
Joined: Sep 2008
Posts: 1
Likes: 0
Oil filter
The Low oil Pressure could be caused by one of two things, The Old filter. (Try a K&N filter fixed my problem with low oil pressure when the engine is hot) The other could be the cam bearing. You could have an Intake Leak, the Al intakes don't like the metal intake gasket. I use two sets of Fel-Pro 1240 with the metal gasket in-between, You might need to have the intake machined to do this. Try visiting http://www.fowlerautomotive.com/Intake_Manifold_Machining.html he sell some information the helped me a lot when I was having head to Intake problems. Also the heads tend to warp around the exhaust crossovers to the outsides of the head and this can cause internal exhaust and vacuum leaks. Try checking this with a strait edge. I hope this helps 
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Moderator
Joined: Nov 2007
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From: Denver Metro Area, CO
too?
Freshman User
Joined: Jul 2007
Posts: 43
Likes: 0
ANYTHING over a 600cfm carb in a 351m is TOO MUCH FUEL. you have to tune down your carb and that still might be too much fuel! you have somethin like a 750 edelbrock you say? how is it tuned because i think tuned down thats still too much fuel intake for the modified.