Need help-New build overheating

[jerry]

Fresh 440 in 68 Coronet. New 26" rad from US rad, shroud, 4 blade fan (clutch fan wont fit), 180 tstat, half and half on antifreeze.
I can drive the car around the block for 15 minutes-stays around 190.
Took it on highway for first time and after 5 minutes at 60 mph I was at 220. Pulled in parking lot for carshow and started steaming at 235. Took backroads home (after cool down) and heated up again after 20 minutes of easy driving. Checked and tstat was open. My antifreeze (Peak) looks strange - has brown sludgy bubbles, but not caked up. Had new water pump installed with motor rebuild. Timing is set by ear and starts instantly, but could that cause that much heat?
Appreciate any thoughts.

 

[67 B-body]

does the lower hose have a spring in it to prevent sucking closed?

 

[68383]

In addition to the fresh build, did you put on new hoses, thermostat, etc.?

I'm putting a 522 in mine and changed all that stuff to ensure I don't get any crap in my new engine.

 

[70rr-brian]

Did you take the plugs out and inspect them? Perhaps it is running lean which could cause overheating. 4 blade fan seems odd to me but admittedly I don't know about every fan. Brown bubbles is just weird if everything is new. Maybe head gasket? Do a compression check for grins and giggles.

 

[Big Jim]

Lean mixture, weak/sloppy timing chain will cause overheatng. Was timing set replaced during build (seen it happen to cut corners)-cam installled properly? Not knocking you, just asking. Brown stuff sounds like water jackets not boiled out with block prep. Just some random thoughts...

 

[jerry]

First - nospring in lower hose. Makes sense during hi rpm ride down hiway, but not while babying it all the way home.
All new hoses and 2 new tstats. Carb is a known "good" 700 holley. Smells a little rich if anything. We are pulling plugs and water pump tomorrow.

 

[jerry]

Also- new mopar water pump installed w/engine build. When we checked tstat opening, while motor was still hot, we could feel the water boiling up thru the upper hose. Can I have a huge air bubble that is not clearing out?
If so, what is a good way to eliminate?
Thanks

 

[70rr-brian]

Also- new mopar water pump installed w/engine build. When we checked tstat opening, while motor was still hot, we could feel the water boiling up thru the upper hose. Can I have a huge air bubble that is not clearing out?
If so, what is a good way to eliminate?
Thanks

Try just idling the car for a while (5mins or so) at operating temperature with the cap off. If there is air in the system it should come out and you should see a drop in coolant level in the radiator.

 

[Cranky]

Is the block and heads something that you had used before the build? How was the block cleaned for the build?

 

[twinscrew698]

First - nospring in lower hose. Makes sense during hi rpm ride down hiway, but not while babying it all the way home.
All new hoses and 2 new tstats. Carb is a known "good" 700 holley. Smells a little rich if anything. We are pulling plugs and water pump tomorrow.

Take a piece of stainless welding rod and wrap it around a piece of PVC and insert it in the bottom hose as i am sure that it is collapsing!
It will run warmer than normal as being a fresh rebuild too!And also drill a 1/16 hole in the thermostat will help rid of any small air pockets!

 

[bigmanjbmopar]

Heater hoses hooked up? was there old water from the heater box mixing in with the new making it look brown? My new build started off cool until we started tweaking timing then it got way hot, at the time all we had for a fan was a 16" electric pusher, added a 19" flex fan no shroud inside and adjusted timing again and all is good..If your block was not cleaned throughout then some rust may have come loose from you water passages I would flush it all out and then have the radiator flushed as well.

 

[jerry]

Thanks for these suggestions. Will apply them all today and get back.
Where are you in Cincy Brian? I'm in Eastgate.
The motor was built before I got the car and not installed. It was done by a reputable shop. We will lose the rest of the antifreeze today and I will flush it and go with straight water for a while.
The heater hoses are in and were clean when installed.
Included photo of car.

 

[67 B-body]

nice looking ride!

 

[70rr-brian]

Thanks for these suggestions. Will apply them all today and get back.
Where are you in Cincy Brian? I'm in Eastgate.
The motor was built before I got the car and not installed. It was done by a reputable shop. We will lose the rest of the antifreeze today and I will flush it and go with straight water for a while.
The heater hoses are in and were clean when installed.
Included photo of car.

Hey Jerry...I am actually in NKY. I say Cincy cause its easier. I live near the airport.

 

[Big Jim]

Damn- pic made me drool so much got to go change my shirt now....nice ride and good luck!

 

[Cranky]

Nice ride!!

 

[detmatt1]

Sweet car, love the `68's! Hope you get the overheating issue worked out.

 

[jerry]

Thanks - Monday we switched lower hose, tstat, and timed it (we were actually just a hair retarded). Wouldn't cool down still. Then we said the hell with the tstat and THEN the air bubble emerged. Drove it home and didn't even hit 170 without it.
Will replace 180 tstat now.
Thank you all for your help.

 

[70rr-brian]

Good deal. Glad you got it figured out.

Maybe we can get together sometime so I can check out that sweet ride. I am taking the RR to Tennessee for the winter on Sept 27th. If not this year maybe next summer.

 

[moperformance]

I was wondering what the Bee would look like Blue! Thanks for the pic
Bill