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Topic Review (Newest First)
03-12-2012 07:24 PM
Pre-Tuner I found one without the hex head on it so the sending unit would sit in the coolant as far as it could. So far so good.

Thanks for the help everyone
03-11-2012 08:30 AM
boothboy Just check with a good hardware store and your auto parts store as to who has the fitting that will work for you. They each will have a different supplier. Shouldn't be a problem.
03-10-2012 08:46 PM
Pre-Tuner I thought about that, but I've had troubles with those in the past. I wasn't sure if it would allow it to stick in the coolant path enough either, but it's definitely worth a shot.
03-10-2012 08:29 PM
boothboy Why don't you just install a brass pipe bushing in your manifold and use your original sending unit?
03-10-2012 08:04 PM
Pre-Tuner Hot rodding is so much fun
Hot rodding is so much fun
Hot rodding is so much fun

That's what I have to keep telling myself.

New problem, the old school sending unit is the wrong resistance. The gauge goes all the way up.

Any ideas what might have a different resistance? I believe I was told there were only two, but I could be talking out my *****.

I thought about buying an adapter fitting and using my old gauge, but there is no way the sending unit would sit in the coolant enough to work properly.
03-07-2012 09:51 PM
Pre-Tuner Steam holes are drilled and I have a 3200 stall converter.

I put the new sending unit in, but I have to find a connector for it now. They give the plastic housing for the connector but not the terminal?
03-07-2012 02:54 PM
stich626 u drill steam holes in those heads?
03-07-2012 01:38 PM
Barry Templin
Originally Posted by blwn31
Since you replaced the sending unit I would tend to believe the temp gauge. The heads will run hotter than the intake, that's why I like to take the temp from the intake near the thermostat. One thing I have done to my engine, is drill a small hole (1/16th) in the thermostat to keep a good supply of hot water moving up to the thermostat. I've found this keeps the engine temps more stable instead of the big swings I used to see. Difference for me is, the engine being all aluminum, it was sucking so much heat out of the cylinders, I felt the engine was getting to hot before the thermostat would open. Once I put the bypass hole in, everything became normal.

My son had this same problem on a 383 stroker w/450 HP. It was his torque converter that wasn't high enough. He ended up with a 2600-2800 stahl on the converter and the overheating stopped. Barry
03-04-2012 11:06 PM
blwn31 All you're trying to do is move warm water up to the thermostat so the as to not get the heads overly hot and large temp swings. I just keeps the entire motor at a more stable temp. You can try 2 holes, see if you like the results??? I personally didn't.

03-04-2012 10:59 PM
Pre-Tuner Well damn. So much for the theory if one is good two must be real good.

03-04-2012 10:56 PM
blwn31 You don't need two 1/8" holes. You will move a ton of water through a quarter inch combined hole. The thermostat probably won't ever open. Get another thermostat, drill one 1/16th to 1/8th inch hole. When I originally did mine I drilled two 1/8th inch holes 180 degrees apart. I have since downsized to one 3/32nd inch hole. My temps are nice and stable now with no spikes.

03-04-2012 08:53 PM
Pre-Tuner Did some work today. I removed the thermostat, drilled two 1/8" holes, and reassembled. I also confirmed that it is a 195 thermostat and that the cap is 16lbs.

I also attempted to move the sending unit into the manifold. The sending unit I pulled out of the head is 3/8" pipe thread, but the holes in the manifold are 1/2". My Dad said to get a sending unit for a car from the 60's or 70's. Can anyone confirm this is correct or that the resistance is the same?
03-02-2012 06:40 AM
Adam65 Not sure how electric senders are made, but if this is a mechanical gauge-make sure the bulb that sticks into the head is not contacting the actual aluminum casting inside the water jacket. That will make it read all kinds of funny. If so, get a longer guage fitting to keep that from happening...
03-01-2012 10:12 PM
bentwings I have my temp sending unit on the rear of the Edelbrock RPM heads. I have alway felt that the temp spikes were because the alum soaks up the heat faster than iron. Also at the rear of the heads is supposed to be the hottest part of cooling system.

I also have a sender at the thermostat housing but it turns out it is wired differently so I have not used it.

The thought that there is steam forming around the exhaust is interesting. I have a regular coolant loss problem that I have been chasing for 3 years. All the minor leaks have been fixed and I have a larger coolant recovery system. I think the higher pressure cap may really be the answer. Ceartainly worth a try as crusing season is knocking on the door.
03-01-2012 06:51 PM
Pre-Tuner It's a new AC Delco radiator, but it does have the plastic tanks. I'll have to check the cap rating to be sure of what I have on there now.

Also, I belived I checked the coolant passages in the gaskets when I built it and they matched the holes in the block and head. I'm not sure if I've seen a 400 head gasket that didn't match, but I could be wrong.
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