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fresh rebuilt Engine overheating.
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Author:  wjajr [ Mon Jul 16, 2018 1:35 pm ]
Post subject:  fresh rebuilt Engine overheating.
67 Dart, 225, Holley 390, 40 over in fresh cut bore 9.6:1 compression, Oregon cam grind #346, fresh valve job + oversized valves, ported head, headers, two inch pipes to back bumper, 2400rpm stall, 3.55:1 rear.

Only change is 40 pistons, new cam, and valves that now seat, all new bearings, new water pump, and rebuilt transmission, other than that nothing else was changed.

After a long idle session at 1000 rpm, and a few trips around neighborhood at 20-25mph less than a mile pushes temp gauge pointer to right edge of "P" and inside of normal line. I discovered this problem while checking and topping of transmission. Static timing set at 12*, vacuum advance kicks in at 1200 rpm, governor weights seem to be moving freely.

Engine shut down without any dieseling when key turned to off. I could hear boiling coolant and steam being discharged into over flow tank to level of 2". After about 10 minutes it stopped boiling.

I have a 195* thermostat installed; the right way. Engine previously overheated without thermostat during brake-in, and after intake center line was moved to 99* from 104*. All new hoses, fan belt not slipping, can't hear any ping or pre-ignition, radiator is clean and flowing as far as I know

Should I make idle mixture richer, advance static timing, is engine still just too tight, or something else.
Author:  Dart270 [ Mon Jul 16, 2018 2:06 pm ]
Post subject:  Re: fresh rebuilt Engine overheating.
Weird. A tight motor will make more heat, that's for sure.

What fan are you using? I assume the radiator is holding pressure (15-16 psi cap)? Maybe try a 180 tstat to see if that changes anything? 50/50 coolant/water mix? Do you have an IR temp gun to point at things (tstat housing or rad top tank, for example), or a reliable temp gauge with numbers (temps) on it? Did you use the same temp sensor from your old head, or a different one? That could make your temp gauge read higher or lower than before.

Lou
Author:  69a100 [ Mon Jul 16, 2018 2:53 pm ]
Post subject:  Re: fresh rebuilt Engine overheating.
I'm not familiar with that cam grind, but sounds close to the same thing I want and have planned to build, I'm sure that thing breathes tons better with a ported head and bigger valves? Same as my plan! Is your exhaust really just 2" all the way? Sounds like there's back pressure that could be causing problems? I'd go to 2 1/4" if it where me. Outside of being a new tight motor making more friction, and the 195* stat, I don't know? Good Luck
Author:  sandy in BC [ Mon Jul 16, 2018 3:16 pm ]
Post subject:  Re: fresh rebuilt Engine overheating.
Run an 180 thermostat and drop the timing a couple of degrees till it breaks in.

……..and then see if it overheats.

New motor ……= lots of heat
Author:  DusterIdiot [ Mon Jul 16, 2018 4:53 pm ]
Post subject:  Re: fresh rebuilt Engine overheating.
Just out of curiosity, has the head "burped" yet?

:lol:

So far every slant I've built has either had to have the T-stat drilled with a 1/8" hole to bypass the "pill" so it will purge the air pocket in the head, or break the
engine in without the T-stat and run the loop without the radiator cap and fill the radiator as needed during break in... on late peanut plug heads we get to cheat
a bit since you can pull the CCEGR temp sensor in the head while filling the cooling system and purge it that way as well (once full, you teflon tape the threads and
reinstall the sensor or a plug).

If there is still an air/steam pocket in the head it won't open the pill on a stat and will drive the temp sensor to H until you get water moving through there...once it does you'll
get over flow at the open radiator neck, or big time in the overflow reservoir, then you know after it cools down you can install a good T-stat and go.

If you've already had this happen disregard, and go to a 180 degree stat, carry extra coolant and get that first 100 mile break in done.
Author:  wjajr [ Tue Jul 17, 2018 6:36 am ]
Post subject:  Re: fresh rebuilt Engine overheating.
50/50 mix, same 16 psi cap as before, coolant emitted from 1/8" plug top of head adjacent to upper radiator hose neck, same gauge & sending unit. Head appears to be full.

I looked up model of new water pump: AC Delco 252600.

At time of thermostat install, car was on steep incline nose up such that head would expel all air when stat opened, in addition one of heater core supply hose was pulled to aid in venting while refilling cooling system. Engine was run with radiator cap off and large funnel inserted in radiator which allows coolant level to rise above cap, burp and not make a mess. Ran engine until it took all coolant, and air bubbles ceased to be seen.

I have an inferred temperature gun but did not use it, the thing was hot, hoses were rock hard under pressure and too hot to handle. Something is a miss, as it also ran hot without thermostat installed. Could it be water pump is not pumping? I did not see the usual agitation of coolant in radiator once stat opens, but it was full to top of neck and may have been circulating.

I'll dial back timing to 10 or so where ever it will idle. Timing got moved back to zero during one test drive, and engine did not like that at all, stalled with a backfire through carb when turning into driveway, and quit like the key was turned to off. It started right back up. I had inadvertently rotated distributor retarding timing while installing vacuum hose to vacuum advance pod, and didn't notice the timing change; it was kid'ah hot down in there for the old hand.
Author:  wjajr [ Tue Jul 17, 2018 7:22 am ]
Post subject:  Re: fresh rebuilt Engine overheating.
Just started engine, dropped timing back to +8* from 11*. Ran at idle of 1000 rpm for short time perhaps 10 minutes, temp gauge pointer came up to right side of "E" where it has always stood when warmed up, and while under way. Shut engine down, head went to 230 degrees its full length, thermostat/upper hose housing same temp. Radiator top tank had like readings.

More when I return from state inspection.
Author:  wjajr [ Tue Jul 17, 2018 10:32 am ]
Post subject:  Re: fresh rebuilt Engine overheating.
Got the sticker, no problem, went for a spin where engine did not over heat on way to inspection, rolling on 65 miles. It did not over heat, speeds varied between 35 & 45mph than up to 55 mph at end of ride, just one mile in town driving. Temp gauge would move needle left when thermostat opened, and after the first 20 miles mostly stood straight up and centered.

Time it took to stop, retrieve my mail from RFD box while idling, jump back in and get rolling, temp gauge headed to right. Pulled into garage, shut it down with a bit of back-spin. Checked temperatures of top of tank, top of head between valve cover and manifold, thermostat housing all read 240* no percolating or steam sounds this time.

Engine not happy with 8* initial advance which is setting for 65 mile ride, hesitates and occasionally sneezes back through carb at low rpm opening throttle, once engine cools down I'll reset timing to 12*
Author:  Dart270 [ Tue Jul 17, 2018 10:41 am ]
Post subject:  Re: fresh rebuilt Engine overheating.
Sounds like it might be getting better? I doubt that timing is the problem, so setting to 12 initial is good for the next step.

Lou
Author:  wjajr [ Tue Jul 17, 2018 1:05 pm ]
Post subject:  Re: fresh rebuilt Engine overheating.
I'm wondering if pump is pumping. Engine never overheated in previous 9 years no mater how long it idled since I've owned this car.

Would pulling feed hose, from pump to heater core, place said hose in bucket and start engine be best way to test pumping?
Author:  '67 Dart 270 [ Tue Jul 17, 2018 1:53 pm ]
Post subject:  Re: fresh rebuilt Engine overheating.
New builds produce a lot of heat, but they cool down pretty well after break in. Sounds like your build is settling in.

brian
Author:  emsvitil [ Tue Jul 17, 2018 10:41 pm ]
Post subject:  Re: fresh rebuilt Engine overheating.
Have you tested the thermostat? (temp and movement)
Author:  wjajr [ Wed Jul 18, 2018 4:48 am ]
Post subject:  Re: fresh rebuilt Engine overheating.
I did not test new stat. However observed movement of temp gauge needle indicates it is opening and closing maintaining normal temperature while under way driven above 30 mph. At one and only light during yesterday's brake-in drive engine started to heat up, 2000 rpm while sitting in traffic cooled it down close to normal. Large air flow seems to be what is needed at the moment.

I'm going to drive car more today and tomorrow, adding perhaps an additional 100- 130 of two lane easy highway miles.
Author:  emsvitil [ Wed Jul 18, 2018 5:53 am ]
Post subject:  Re: fresh rebuilt Engine overheating.
Clogged tubes in radiator ?????

Do you have an IR gun?
Author:  wjajr [ Thu Jul 19, 2018 11:51 am ]
Post subject:  Re: fresh rebuilt Engine overheating.
Quote:
Clogged tubes in radiator ?????
I don't think so, it did not over heat before engine pull. Radiator has just 25,000 miles/ten years on it, and coolant was clean when drained. When radiator was out I flushed it with hose, it took all the hose could deliver running freely from top and or bottom tank.
Quote:
Do you have an IR gun?
Yes. After car had been parked for five minutes, hood closed, top of head is 240* after today's long ride. Hood open another five minutes top of head dropped to 228*. After heat soak, engine starts right up, temperature gauge drops back very quickly to straight up and down in no time. Pump must be pumping, and radiator flowing.

I just got back from a ride down river to Belfast, and back. Engine now has 190 miles on it. It runs much better than before rebuild, now idles down in gear to 750 rpm when stopped without having to feather throttle to keep it running. Still heats up when idling in park at 1000 rpm, but not as fast as it did a few days ago.

All during trip, temperature remained normal while under way.
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