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Compression in my J13 engine


Rusty Dawg

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Rusty Dawg says this is a J13 in the title of the thread. I'm thinking the J-Series and the E-Series temp sender are different. I have a J-Series temp sender in my E-1 and it appears to me to read backward. I might see if I can contact Andy in Kansas and see if he can shed some light. He has a group of these 320's.

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35 minutes ago, difrangia said:

Rusty Dawg says this is a J13 in the title of the thread. I'm thinking the J-Series and the E-Series temp sender are different. I have a J-Series temp sender in my E-1 and it appears to me to read backward. I might see if I can contact Andy in Kansas and see if he can shed some light. He has a group of these 320's.

The sending unit is gauge specific, not block specific. The E1 and J15 sender fit the same in the block with the same retaining nut. But the 320 gauge doesn't read properly with a 520/521 sender. I've got a J15 but was able to get my hands on a 320 sender to get my gauge working properly.

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That's what I was trying to say. I did a good study on fuel gages/senders a few years back and learned that there are a number of ohm ranges and some rise in resistance and some fall as the tank empties. I'm figuring that the temperature systems also use different parameters from one system to another. I believe that Ted H. also posted that there might also be a small screw on the gage to calibrate/adjust to fine tune the gage reading.

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Moses, You can check your sender and narrow it down to the gage being why it never reads full. with the float all the way up, the sender should have a resistance value of 90 ohms. With float all the way down should read 0 ohms. Mine never reads over half full and I have the new Classic Instruments tubular sender, so I'm chalking it up to the gage.

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2 hours ago, difrangia said:

Moses, You can check your sender and narrow it down to the gage being why it never reads full. with the float all the way up, the sender should have a resistance value of 90 ohms. With float all the way down should read 0 ohms. Mine never reads over half full and I have the new Classic Instruments tubular sender, so I'm chalking it up to the gage.

Great advice, thanks. I'd say mine goes up to 90%+ or so but maybe that's just the way it's supposed to be. I'm always a little dissatisfied I want to see it tippy top. 

 

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Howdy,

 

I decided to run my engine longer that just a few minutes and noticed the temp gauge starts above 212 and after 4 minutes or so it dropped below the 140 degree mark.  I kept checking the temp at the block to make sure it didn't go too high.  The temp gauge rose a bit, but never seemed to get above 140 after 15 minutes.  The temp at the block read anywhere between 119 and 143.  I installed a 180 degree thermostat.  Fuel gauge still reads "E" regardless if in the off or on key position.

 

I wanted to start a new thread regarding initial starting issues, but I will just ask here.  My engine will re-start after 10-20 minutes of sitting, but if left overnight I have to prime it every time with carb cleaner to get her going and then she runs on her own.  My carb has be rebuilt.  Am I losing vacuum(fuel) somewhere between the inlet to the fuel pump and the carb inlet?  I have tried the choke and pumping the carb, but to no avail.

 

Thanks,

Roman

Edited by Rusty Dawg
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You're saying the gauge reads 212F but takes 4 min to get down to 140F???????

 

Or

 

You're saying it turns on at 212F but immediately drops to cold and then takes 4 minutes to rise to 140F?

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Maybe I don't understand but your temp gauge sounds right to me and the rising then dropping reflects your thermostat opening. 

 

With your carb issue is your glass bowl filling up and staying full over night? I'd check all your fuel lines for leaks and maybe put a new diaphragm in your fuel pump. Do maybe your fuel lines empty out over night?

 

 

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9 minutes ago, Rusty Dawg said:

the gauge takes 4 minutes or so to get down below 140 and then it goes up to 140.  It does not go to 140 when started.

 

When you start it cold don't you think the engine is like 30F or what ever it is outside????? How can the gauge tell you it's above 140F if the car sat outside in the snow all night????

 

This is why I asked if this was a positive ground. If this was changed to negative ground but has positive ground gauges would they start at 212F instead of zero and read downward?????????

 

 

In addition the gas gauge seems to be reading backwards also. Alarms should be going off.

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9 minutes ago, 320 Newb said:

Maybe I don't understand but your temp gauge sounds right to me and the rising then dropping reflects your thermostat opening. 

 

With your carb issue is your glass bowl filling up and staying full over night? I'd check all your fuel lines for leaks and maybe put a new diaphragm in your fuel pump. Do maybe your fuel lines empty out over night?

 

 

I will take a look at the bowl tomorrow.  I think there is a leak in the fuel pump as well and might look to rebuild it if I can find the parts.  As for the the thermostat opening, I can't image that the engine temp will rise that quickly in just 4 minutes with outside temps in the high 50's, but who knows.  I am curious why I can't seem to get the engine above 140 though per the temp gauge.

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6 minutes ago, datzenmike said:

 

When you start it cold don't you think the engine is like 30F or what ever it is outside????? How can the gauge tell you it's above 140F if the car sat outside in the snow all night????

 

This is why I asked if this was a positive ground. If this was changed to negative ground but has positive ground gauges would they start at 212F instead of zero and read downward?????????

No snow here fortunately😀

 

When I ran my truck tonight it was around 58 degrees.  As for your question regarding negative ground versus positive ground, I am still trying to wrap my brain around it.  Logic tells me that something is backwards.

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15 hours ago, 320 Newb said:

Maybe I don't understand but your temp gauge sounds right to me and the rising then dropping reflects your thermostat opening. 

 

With your carb issue is your glass bowl filling up and staying full over night? I'd check all your fuel lines for leaks and maybe put a new diaphragm in your fuel pump. Do maybe your fuel lines empty out over night?

 

 

Having checked the glass on the bowl this AM, it was just under half full.  I cleaned the tank and ran new fuel lines along with a filter all the way to the carb and see no leaks.  I am looking at trying to find a rebuild kit for the fuel pump since that seems to be the only thing that it could be. 

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Once fuel is in the carburetor bowl it can't siphon back into the tank. It simply can't jump up hill one inch and into the inlet through the needle valve.

 

If there was a loose hose clamp or a crack in the hose or line between the pump and the carburetor it would leak under pressure when running,

 

If there was a leak anywhere between the tank and the pump air could possibly leak in and the gas would siphon back into the tank, though slowly. In any case, there would be more than enough gas in the float chamber for starting the engine, and once started it would draw fuel from the tank and fill the line.

 

 

Next time you go out to start the truck in the morning, have a look at the level of gas in the carburetor. It should be where it was the night before... about the half way mark. Again... this more than enough gas to start the cold engine and if you started driving would go a block or two.

 

 

 

 

I hate to keep coming back to the temperature gauge but not getting the answer I want. With the ignition off the gauge reads 212F correct? When you turn the ignition on without starting it.... withing 10 seconds what does the gauge read?

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datzenmike,

 

I decided to try and take a little longer in turning the engine over while pumping the carb and I was actually able to start her without using carb cleaner.  It took a few times to keep her going, but I was eventually able to get her running.  I was told that there are some carburetors that take more priming than others and that this may be the case with mine.

 

As for the temp gauge, the temp reads just above the 212 mark with the ignition off and after 10 seconds it's still in the same spot.  After 4 minutes or so it works its way down to under the 140 marker.  It then climbs back up to the 150 or so area and bounces around from there down to the 140 level.  I determined that my truck is negative ground.  The person that rebuilt my generator requested that I remove the gauge and bring it to him to see if it's a polarity issue. 

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  • 4 weeks later...
41 minutes ago, Rusty Dawg said:

Well I finally got her going on the road, but unfortunately after a few rides with the family I noticed that the oil has water in it now.  Gonna just pull the entire engine out and do it right. 

 

Stand by....

FullSizeRender.MOV

 

When you replace the headgasket use one from Moss Motors for an MGA. It's high quality and hasn't been sitting on a shelf for 40 years. 

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On 2/12/2021 at 12:59 PM, 320 Newb said:

As someone who just replaced head gasket I agree, drive it and watch for symptoms. And maybe check your compression periodically. The first symptom with my blown head gasket was exhaust blowing coolant out the radiator overflow.

 

If I would have just read your response a little closer I would have known I had a blown gasket since I couldn't understand why my truck would blow out so much coolant out the overflow hose every time I ran it the past 2 months or so.  You mention exhaust, but would this also be a precursor to a blown head gasket?  Also, would some white smoke out the exhaust be a sign of a blown head gasket as well?  I went from super happy to super sad in a matter of 25 minutes🤮

Edited by Rusty Dawg
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Can anyone tell me if an L series (L13) engine might bolt up to my original transmission?  Might be an option as opposed to trying to locate parts for my J13, unless I just decide to replace the gasket which in that case I would purchase the head gasket on Moss Motors for a 63-80 MGB engine part #387-505.

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No. Two completely different engine series and bolt patterns.

 

Compression and cylinder firing pressures far exceeds the cooling systems ability to contain it.  Compression builds pressure above the rad cap's 13 PSI and expels coolant till it's so low it over heats.

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Very well.  I think I'll stick with my J engine in that case.  I will drain the fluids and replace with fresh oil and water with a flush to run it a while and get the moisture outta there until I get to remove the head or entire engine.

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56 minutes ago, datzenmike said:

No. Two completely different engine series and bolt patterns.

 

Compression and cylinder firing pressures far exceeds the cooling systems ability to contain it.  Compression builds pressure above the rad cap's 13 PSI and expels coolant till it's so low it over heats.

Are you saying that I need a different cap or that in fact this is happening due to a blown gasket?

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Not at all, only that the compression is pushing the water out past the rad cap.

 

If there is water in your oil, most likely the head gasket is blown into the water jacket. Some coolant  is bound to get in the cylinder and work it's way down past the piston and into the oil pan.

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