new motor runs hot - Team Camaro Tech
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post #1 of 9 (permalink) Old Jul 14th, 00, 01:47 PM Thread Starter
Join Date: May 2000
Posts: 67

I just installed a 383 into my 69 camaro. The 383 is making about 430 hp with the edelbrock system. The car originally had ac, but I got rid of it all and put in a big block heater box to give me some more clearance.

The problem is the car is now running at 215-220 in stop an go traffic on a St. Louis 95 degree day. Is this too high? Should I change the cap? Add an electric fan?

The car came with a 7psi radiator cap when I bought it and it currently has a 180 degree thermostat. All hoses are new, the timing is 10 btdc, and the heater core is new. I have a flex fan.

Thanks in advance for the help.

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post #2 of 9 (permalink) Old Jul 14th, 00, 01:48 PM Thread Starter
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I forgot to mention I put a Weiand Aluminum Water Pump on with the new motor.

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post #3 of 9 (permalink) Old Jul 14th, 00, 02:14 PM
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what is your compression ratio?.... my .040 over 383 is 9.4 to 1 [was a 302 Z-28] runs about 190 no problem stock radiator I run 38 deg total timing ... is yours too lean? look in the radiator and make sure you have good water flow. if that looks ok then look towards the fan..... I'm using the stock fan and clutch

keepin' it original 69Z
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post #4 of 9 (permalink) Old Jul 14th, 00, 03:48 PM
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Location: Fortuna, CA
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Here is what I have learned from this site, the chevelle site and some first hand experence....

HP makes heat! If your motor will idle in the 210 deg range all day your doing good!

Next you need good cooling parts: Radiator & cap, shroud & fan (not a flex style), waterpump, hoses and thermostat.

Coolant and timing play a big factor. Water absorbs heat better than antifreeze but there are thing in antifreeze that prevent corossion and it acts as a lube for the waterpump. A 50/50 mix is the most you want but during summers heat 70% water is going to work better. If your timing is not set properly (too retarded) it will also create more heat.

So with all that in mind start looking at the hardware first. Is each piece doing what it is designed to do? Does the shroud cover the entire core? Do you have the right size core? Isolate the part or parts that are failing!
Hardware passes the test, coolant is 70/30 check your timing 10 inital might not be enough 14 inital might just drop 10-20deg from your temp at idle. Check your total timing because adding 4 at idle if you already have 38 total might not be a good idea! If this is the case a recurve is in order.

If things are cool (pun intended) when the car is moving but tends to heat up at idle think airflow or timing. Don't run without a thermostat and keep in mind a 160deg stat may open too soon and start the coolant moving before it can pull the heat from the block. You might want to experiment with several different temps to see how they react to your combo.

There is always a chance that an external heat sorce might be creating all the heat. An auto trans with the incorrect converter can heat up and transfer heat back to the engine. A mis adjusted TV cable will cause slipage and heat!

Well did I say enough? Too much? There have been so many posts on this, did I miss anything?

Good Luck, and excuse the spelling!

Camaros Limited Nor-Cal
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post #5 of 9 (permalink) Old Jul 14th, 00, 04:47 PM
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change that cap first, i run a 13lb cap on my 450hp small block, 2000 cfm electric fan. i don't think 7 lb is enough. higher pressure=higher boiling point

67 RS
355, SUPER T10 4 SPD
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post #6 of 9 (permalink) Old Jul 14th, 00, 06:21 PM
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Hi rlrr, how many miles do you have on this new motor? It's always been my experience that motors breaking in will run warmer. My 327 puked anti-freeze and ran about 205-215 degrees while I was breaking it in. Thats cruising in traffic. On the hiway it wasn't so high. Now the car runs at 180 when it's 90 degrees outside. Just a thought before you spend money on more parts. I hope it's that easy for ya.

67 SS 396,4-sp
67 RS 327,4-sp
72 RS 350/350
69 4X4 suburban 350,4-sp
73 3/4 ton 454/400
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post #7 of 9 (permalink) Old Jul 15th, 00, 05:03 AM Thread Starter
Join Date: May 2000
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Thanks to everyone for all of the quick and detailed responses. Here's where I'm at so far.

The car runs 180 on the highway and anytime I can get some airflow over the radiator. It only heats up when sitting in traffic.

I called a friend of mine who owns a radiator shop. He said my stock 3 row shouldbe capable of cooling my 383 (with 9.6 to 1 compression). He thought the radiator is probably clogged and weak. I am going to take it to him today to have him test it.

I also discovered my fan should be a little deeper into the shroud. I am going to get a new spacer and install it.

I will keep you updated.
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post #8 of 9 (permalink) Old Jul 15th, 00, 11:13 AM
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definatly an airflow problem. Your fans fins should be about half way out of the shroud, You may need an aux. fan if it doesn't stay cool at idle.
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post #9 of 9 (permalink) Old Aug 3rd, 00, 03:41 AM
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Location: Stuart, Florida
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I am going through the same problem right now. Just put a 10.2:1 355 and six speed in a 92'. Car runs about 205 to 210 in traffic. Runs about 190 (day) while cruising. I am running a two core aluminum radiaitor and a full shroud with a flex fan.

I was told the same thing about a new motor. Cutting in the rings creates friction. I guess I will wait and see.

One question I did have, is anyone running one of the "black magic" style 2800 cfm fans. I was wondering if they are worth the $$.

1992 Firebird 355/Six Speed
1991 RS 350 / Blown (As in Broke)
1987 Toyota Pickup 383 / 500 + HP

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