Overheating sbc - Page 6 - Chevelle Tech
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post #76 of 148 (permalink) Old May 1st, 19, 7:57 AM Thread Starter
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Gerrett
 
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@MaLiBu 64

I did notice that the ported seemed to give me a better consistently in gear. It would drop to 600 and still sounded very strong.
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post #77 of 148 (permalink) Old May 1st, 19, 8:32 AM
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Re: Overheating sbc

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Originally Posted by Mrfresh352 View Post
@MaLiBu 64

I did notice that the ported seemed to give me a better consistently in gear. It would drop to 600 and still sounded very strong.

Either try the can I posted part nr of or run ported and limit the mech advance to 10-14 deg and run more initial. With correct tuning it shouldnt drop more than 100-150 rpm. Have you tried to adjust the idle mixture screws?

I have limited mech advance on heis with a small screw. But some says its not the correct way to limit the mech advance on a hei. This adjustements may improve driveability and it timing is way of help cooling but think your overheating problem has to do with something else.




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post #78 of 148 (permalink) Old May 1st, 19, 8:58 AM
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Re: Overheating sbc

I would do a full flush on the engine using a pressure like a garden hose to get all the scale out of the block. Then start from scratch again with a 50/50 mix. Boil your thermostat and watch to make sure it's opening. Are you running electric fans or clutch?
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post #79 of 148 (permalink) Old May 1st, 19, 10:32 AM
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Quote:
Originally Posted by Mrfresh352 View Post
Quote:
Originally Posted by Reelysalty View Post
What kind of carb
do you have w/a
left side fuel entry ?
I get this every time someone sees my carb lol. I think everyone but me is on a hydra jet, double pumper or eldebroke. This is a holley 4160 I think. No fuel float adjustments either.
“Edlebroke”, hahaha, got that right

I have a 670 VS Holley Blue Ultra FS, like new.

I wonder about timing light broken unless p/u dropped and cracked.

You gotta have a dial back. I like Actron about $ 100, You’ve spent $ 100 in aggravations
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post #80 of 148 (permalink) Old May 1st, 19, 11:34 AM
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Run a hose from the water pump to the intake, willing to bet it fixes your issues.
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1974 chevelle with 73 laguna nose sbc 357 Brodix IK180 heads Comp Cams XE274H Edelbrock RPM airgap 650 AED double pumper, M20 muncie, Truetrac with 3.73s
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post #81 of 148 (permalink) Old May 1st, 19, 4:13 PM Thread Starter
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Gerrett
 
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Run a hose from the water pump to the intake, willing to bet it fixes your issues.
I thought about this but all the research I could dig up said that doing the bypass hose only worked on BBC. Something about a SBC didnt circulate in a desirable direction.

If this is wrong I’ll defiantly add it.
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post #82 of 148 (permalink) Old May 1st, 19, 4:16 PM Thread Starter
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@Reelysalty

The light worked fine last month before I changed my distributor, the old one was just a no name brand hei, but using my actron it worked fine. it’s the light or my distributor isn’t grounded correctly.

My tach in the car was also acting funny when I would try and hold the rpm at 3600. It just shut off and then turned back on. Are there other negative terminals I need to add to the distributor?
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post #83 of 148 (permalink) Old May 1st, 19, 4:27 PM Thread Starter
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Quote:
Originally Posted by ZEN357 View Post
I would do a full flush on the engine using a pressure like a garden hose to get all the scale out of the block. Then start from scratch again with a 50/50 mix. Boil your thermostat and watch to make sure it's opening. Are you running electric fans or clutch?
Running a clutch fan. And I have done a flush. Take a look at the photo I posted, on photos I see others post here the thermostat housing is level with the inlet to the radiator. On mine it higher. Idk how much pressure the water pump produces but it seems off to me.
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post #84 of 148 (permalink) Old May 1st, 19, 5:03 PM
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Quote:
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@Reelysalty

The light worked fine last month before I changed my distributor, the old one was just a no name brand hei, but using my actron it worked fine. it’s the light or my distributor isn’t grounded correctly.

My tach in the car was also acting funny when I would try and hold the rpm at 3600. It just shut off and then turned back on. Are there other negative terminals I need to add to the distributor?
Maybe your distributer is acting up. I would highly recommend a MSD RTR 8360. Your dial back light should display rpm. This is a big advantage to Actron IMO.

Do you have a 6v points style ignition or converted to 12v ?

If you have modern ignition only 3 wires. One to ground, one to pos coil, one to neg coil. If you have modern ignition on stock 6v resistance wire, you’re headed for trouble.

Not directly related to overheating, but might explain some other problems.

Keep us posted !
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post #85 of 148 (permalink) Old May 1st, 19, 5:15 PM
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Quote:
Originally Posted by Mrfresh352 View Post
Quote:
Originally Posted by JF74chevelle View Post
Run a hose from the water pump to the intake, willing to bet it fixes your issues.
I thought about this but all the research I could dig up said that doing the bypass hose only worked on BBC. Something about a SBC didnt circulate in a desirable direction.

If this is wrong I’ll defiantly add it.
My engine was doing this exact thing when I plugged my heater lines and didn’t connect the intake to water pump, once I installed my new heater with the lines to the intake and water pump it was fixed. I don’t think a timing issue is causing it to over heat this badly.
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1974 chevelle with 73 laguna nose sbc 357 Brodix IK180 heads Comp Cams XE274H Edelbrock RPM airgap 650 AED double pumper, M20 muncie, Truetrac with 3.73s
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post #86 of 148 (permalink) Old May 1st, 19, 6:07 PM
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[QUOTE=JF74chevelle;

My engine was doing this exact thing when I plugged my heater lines and didn’t connect the intake to water pump, once I installed my new heater with the lines to the intake and water pump it was fixed. I don’t think a timing issue is causing it to over heat this badly.[/QUOTE]

If this were the case, all older V8 Chevys would overheat as heater control cut off heater core circulation ??? Back in the day, we would turn on heat to circulate water thru core to cool hot engine in July !

Now calling you out, just trying to understand.
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post #87 of 148 (permalink) Old May 1st, 19, 6:23 PM
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[QUOTE=Reelysalty;11072076]
Quote:
Originally Posted by JF74chevelle;

My engine was doing this exact thing when I plugged my heater lines and didn’t connect the intake to water pump, once I installed my new heater with the lines to the intake and water pump it was fixed. I don’t think a timing issue is causing it to over heat this badly.[/QUOTE

If this were the case, all older V8 Chevys would overheat as heater control cut off heater core circulation ??? Back in the day, we would turn on heat to circulate water thru core to cool hot engine in July !

Now calling you out, just trying to understand.
I don’t really know what to say. I changed one thing and one thing only and it fixed the issue and never did it again so that is telling me it was the fix. He can give it a shot without messing with the distributor or anything, maybe it cures it maybe not, but it cured my similar problem.
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post #88 of 148 (permalink) Old May 1st, 19, 6:45 PM
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post #89 of 148 (permalink) Old May 1st, 19, 8:36 PM
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Timing light mistake, not Actron as I stated...this is it, INNOVA.
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post #90 of 148 (permalink) Old May 1st, 19, 9:33 PM
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Re: Overheating sbc

Quote:
Originally Posted by Mrfresh352 View Post
I thought about this but all the research I could dig up said that doing the bypass hose only worked on BBC. Something about a SBC didnt circulate in a desirable direction.

If this is wrong Iíll defiantly add it.
Your small block already has a built in bypass that bypasses through the water pump. L79 and LT1 both had an additional bypass between the pump and manifold. Both were Chevy's highest performance small blocks. I never really knew why, but it came from the factory that way, so I guess some engineer thought they needed it. My guess? To help stave off pump cavitation at high RPMs. See attachment, one leg of your water pump should have 4 holes in it. 2 for bolts, one for regular flow and one for bypass.

Both small and big blocks circulate coolant in the same way. Big blocks do not have the built in bypass and were equipped with a bypass hose from the pump to the manifold.

I doubt your overheating issue is caused by timing, but it is something you will eventually want to get right. You should start by verifying the correct location of your timing mark on your harmonic balancer by using a TDC piston stop tool and the procedure to locate and mark true TDC on your harmonic balancer. Most of these engines run best with 18 initial and 36 all in timing with the vacuum advance disconnected and plugged. After your timing is dialed in set the carb fuel idle adjustments for best vacuum reading or best rpm. Then set your idle speed to your taste or spec and connect the vacuum advance. You can play with your curve once you get your cooling issue under control.

Your symptoms show signs of an improperly functioning thermostat. It's not opening at the correct time. Your cooling system appears to be up to the task of cooling at idle or your temps would never come down from 240 once you got to that point at idle. It's possible that you were sucking some air from the leaks you discovered with the compression test. It's also possible to get a steam pocket, both might hinder thermostat operation by isolating coolant from the thermostat in the form of an air pocket. The air would end up stopping at the highest point, the thermostat. For that reason, and initial fill and to get past having to burp the system, thermostats with jiggle valves or some sort of bypass were invented. Most cheese variety thermostats won't have this feature, so we drill a 3/16 hole as a bypass to help eliminate these issues.

So, throw a new $10.00 thermostat in there with a bypass hole added. Then tune her up. Your best temp range to avoid excessive cylinder wear is above 180 degrees for a street car. If you run a 160 and your cooling system is capable of running that low continuously, your best bet would be to install a 180 degree thermostat to help get into the correct operating range for longer engine life. If you live in a cold area, just run a 1/8 hole in the stat as a bypass, in your case it's just there to pass air.
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