overheating (?) issues
Printed From: TheAMCForum.com
Category: The Garage
Forum Name: AMC V8 Engine Repair and Modifications
Forum Description: AMC-made V8 engine mechanical, ignition and fuel from basic repair to high-perf modifications
URL: https://theamcforum.com/forum/forum_posts.asp?TID=89111
Printed Date: Apr/23/2024 at 5:44pm
Software Version: Web Wiz Forums 12.03 - http://www.webwizforums.com
Topic: overheating (?) issues
Posted By: tdkask
Subject: overheating (?) issues
Date Posted: Aug/12/2017 at 7:07pm
|
New member here. Posting for some help. I have a 360 in my '80 CJ7 and I'm having some issues I can't sort out. I'm here asking for ideas or experiences. The engine was pulled from a '74 J10 and is stamped for a .060 over rebuild, but I don't know anything about any work done to the heads or whether the pistons are stock. I ran the engine for quite some time with the stock 2 bbl carb and intake, and had really no issues. But I wasn't that impressed for it being a 360, of course. FWIW, it has an aluminum 3-core radiator. So during a recent series of upgrades on the Jeep I swapped in a CompCams 260H cam and lifters, a Edelbrock Performer intake, Patriot shortie headers, and an Edelbrok 1406 carb. I'm having issues with it overheating and not staying running. Basically the engine starts heating up, fuel stops flowing into the carb, and it shuts off. My pre-filter just after pump is clear, and I can literally watch the fuel inflow decrease to a stop as the engine gets warm. First, I assumed the carb is getting too hot. I added a 3/8" phenolic spacer. The carb still seems to be getting a little hot and it all seems to be little change. Next, I swapped in a Holley DP I had, and still no change. I am running the stock mechanical pump, clear pre-filter, and stock filter with "regulator" and return line. My next steps are to address cooling issues (fan shroud, relocate PS and trans coolers) and a much taller (1"?) spacer. I just don't know what else could be causing the issues other than overheating, which causes percolating in bowls, and therefore back pressure on fuel system? As soon as the engine cools off the fuel comes back into the clear filter. When it's not hot yet, it idles great, and runs like a bat out of heck. Has anyone had these issues before? Will warm carb actually push the gas out of carb and cause back-pressure on the pump? Any other ideas where to look? Thanks for any help. I'm out of good ideas and getting very frustrated. I appreciate it. |
Replies:
Posted By: one bad rambler
Date Posted: Aug/12/2017 at 7:18pm
|
Have you tried running the car from a remote tank/gas can from the stock pump? -------------  68 AMX 390 4 Speed,68 American,64 American 2 Door Wagon Altered Wheelbase,78 Concord Build 360,727,8.8
|
Posted By: tdkask
Date Posted: Aug/12/2017 at 7:40pm
|
Why would you ask this? I haven't... but the fuel cell and fuel lines are also all new, so shouldn't be a clog. Fuel cell is vented. And it happens as it gets warm, stops as soon as it cools off. |
Posted By: tdkask
Date Posted: Aug/12/2017 at 7:45pm
| With thermostat removed, does water forced into the heater core loop circulate through entire engine water jacket? I was thinking of splicing in there with water hose and forcing cold water through to see if this proves that it's just a cooling issue? I suspect that a really hot carb would cook the gas and cause the issue? |
Posted By: tdkask
Date Posted: Aug/12/2017 at 8:41pm
|
One thing I just considered, the new intake (maybe?) has the exhaust crossover? If so, I might try to block that off. Also, a bigger spacer? |
Posted By: Someassemblyrqd
Date Posted: Aug/12/2017 at 10:33pm
|
Did you pressurize the water system to get all air pockets out? What,s the operating temp climb to when it craps out? Have you checked float bowl for proper height? Timing? Work one issue at a time. I,m sure others will chime. Accept all inputs. There,s a wealth of knowledge in this Forum. Greg ------------- Greg E. |
Posted By: thedowell
Date Posted: Aug/12/2017 at 10:43pm
|
The Intake you are using has an Exhaust crossover that runs under the carb. This has a tendency to overheat the carb. I had the same issue. Because I don't drive my car in the winter, I removed the intake and welded the cross over shut and my problem went away. If you plan on driving in cold weather you might try restricting the flow through the cross over. or using a bigger spacer to get more distance between carb and intake. Others have gone to the Air Gap intake with good success. ------------- 67 Rogue convertable |
Posted By: tdkask
Date Posted: Aug/13/2017 at 8:29am
|
An air gap isn't in the budget at this point. Also, there's only a couple weeks of cold-ish weather here in S. GA. However, I don't have the ability to weld aluminum. I wonder if that steel putty stuff would work? Or maybe some kind of block off between heads and intake? I'll be getting a much taller spacer in today and addressing the cooling. Got to get some improvement here. I'm missing out on all the fun. |
Posted By: scott
Date Posted: Aug/13/2017 at 10:47am
| I see you are running the stock style fuel filter with a return line. Try plugging the return line, or replacing the filter with one that does not have a return line. |
Posted By: tdkask
Date Posted: Aug/13/2017 at 11:20am
|
scott wrote:Posted By: scott
Date Posted: Aug/13/2017 at 12:07pm
| How hot is it getting when it overheats?? Pegging the gauge?? |
Posted By: mmaher94087
Date Posted: Aug/13/2017 at 12:30pm
|
Run the engine with the fuel cap open. This sounds strangely like a non-vented cap problem. ------------- Mike |
Posted By: farna
Date Posted: Aug/13/2017 at 3:31pm
|
You can use a piece of thin sheet metal to block off the exhaust crossmember -- one on each side. Could be non-vented fuel cap... ------------- Frank Swygert |
Posted By: mmaher94087
Date Posted: Aug/23/2017 at 6:56pm
|
Any update? ------------- Mike |
Posted By: tdkask
Date Posted: Aug/23/2017 at 7:35pm
|
Sorry for the lack of responses or updates. It is boiling the carb at about 195 or so. I have since blocked off the exhaust crossover and replaced the 3/8" phenolic spacer with a ¾" hard rubber spacer. I've also moved the radiator a little closer to the fan (now 1/2" between them) and relocated the trans cooler. I'm not sure how much difference the spacer has made, as I can now keep my hand on the intake. Carb stays reasonable, and not as hot as intake. Also, temps never reach 190° either. Seems to be resolved. I haven't had a chance to really test though. I just got it all back together today and need a thermostat gasket before driving. |
Posted By: gd5052
Date Posted: Aug/24/2017 at 9:44am
Posted By: gd5052
Date Posted: Aug/24/2017 at 9:45am
| 060 overbore isn't helping matters |