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Bruiser! 78 620 KC project

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Allot has happened since the end of April and Bruiser has gotten quite a bit of use.


You may have noticed in the "Swamp Thing" thread that the truck started running VERY POORLY on our trip to Shelton at the end of June. 


I found that one of the SU floats had sunk but was able to make trackside repairs to get back home to Lynnwood.


I figured since one was down - the other was not likely far behind so I ordered a pair of new floats from Z Therapy upon my return.  They arrived later that week.




Here is a new composite float vs an old brass one:




In the process of swapping them out I found a few very interesting things:


1)  After a week of driving, some of the sealant I had used to back up my float repair had unsurprisingly failed and was found floating around in the fuel bowl.




2)  The fuel was actually getting in the float via a crack, not a failed seam as I had originally thought.  (who knows, maybe both?)




3)  BOTH floats had taken on fuel - not just the one I repaired.  The 2nd one didn't have much but you could still hear it rattle inside the float.


4)  When I repaired the float in Shelton, when I scraped off the solder covering the factory hole in the top of the float, the fuel inside came squirting out like a punctured can of pop!  It was actually pressurized!!!  How in the heck can fuel get in there against the internal pressure?


After the repair, I knew the chances were pretty good that I hadn't seen the last of this issue.  I pulled out all the old sealant I could see from the float bowl but come on...  With my luck?


On the 2nd drive with the repaired truck - on the way home from the grocery store with my wife, the truck suddenly lost power and forced me to stumble into the nearest parking lot I could find.  I removed the fuel line from the float bowl to the carb and it was clear.  Then I removed the nozzle from the bottom of the SU carb and found this jammed in there:




Reassembled everything and was back on the road with full power:


Hopefully that will be the end of it!





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Now the next bit of excitement - A couple weeks ago, Corey and I were idling in the parking lot at work making our way to the exit so we could get on the road to head home and all the sudden *BANG! WHIRR WHIRR WHIRR WHIRR*


Oh crap!  What is it now?!


I backed into a nearby parking spot, turned off the truck and got out to look what happened.  I started looking under the truck at the rear when Corey yells "found it!".  He was up front and noticed the engine fan was sticking out from below the core support - nearly touching the ground.  What the?!


I popped the hood and confirmed that the fan had left it's moorings and tried run for freedom out the bottom of the truck. 


With the fan now in - hand - and finding the mounting ring fully in tact and the fan only slightly damaged by some rubbing of the spinning water pump, I disconnected the upper radiator hose and removed the fan shroud.  I was surprised at this point to find the fan mounting screws still fully installed in the fan clutch.  I was not surprised at this point to find that the dislodged fan had stricken the radiator and caused a leak.  : (


I reinstalled the fan, topped off the radiator, and got ready to head home - figuring I'd have to pay close attention to the temp gauge.




We made it home no problem and hardly lost a drop of additional coolant.  Even under pressure, the hole isn't enough to create a stream, just a drip.  Still - the radiator would need replacing and I'm embarrassed to fully realize what happened at this point.  There are 12 holes in the mounting ring on the fan.  Four are intended for mounting and are just larger than the bolt diameter.  The other 8 are for??? and - as I just discovered - are big enough to slip over a bolt head. 


Despite my efforts to get it right, with the fan shroud disconnected but in place around the fan (I thought it had to be?), barely enough space for my man hands between the fan and the radiator, and no visual of the actual screw holes in the fan and clutch, I must have installed the bolts in the wrong fan holes so for the last 3 months, it was either not bolted down at all, or just barely under the corners of the bolt heads.  *sigh*



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I ordered a new radiator and the leak turned out to be so minimal - we were able to still drive the truck a few days while waiting for it to arrive.


To say thank you for its dependable service - I rubbed down the whole truck with TR3.  Never has it looked so good!  And now all the panels look really nice together.  Some of them looked like a slightly different color to their neighbor due to different levels of oxidation.







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Finally, the radiator arrived!




Complete with giant puncture hole in the box - inches from the "FRAGILE" sticker.  Thanks.  No - really!  : (


I got the radiator from Rock Auto.




I assumed I'd be getting a Champion aluminum radiator or something like that bout was surprised to find there isn't an offering for the 620 (that is bolt in) so I ended up with one of the plastic tank - aluminum core - aftermarket radiators.  I was worried at first but that is now all the new OEM radiators are built so...


Fortunately, the box damage did not extend to the radiator itself:




So I drained the old radiator and got ready for the swap.




Out with the old




In with the new




Would you believe it is 100% bolt in?!




The only thing that did not match the factory fitment was a missing hoop to catch the radiator overflow line on the side of the radiator.  It even has the little bracket to mount the electrical box near the distributor.  I was both amazed and impressed.


Here you can see the damage to the stock radiator.






I would like to have repaired it or replaced it with another stock radiator




but now that this aftermarket one is in...  I'm glad I switched.  I can't believe how much cooler the truck runs now.  I don't have a gauge with numbers but in terms of sweep on the gauge, it runs at least ten degrees (geometry) cooler.


Very happy with that.


Still need to due some work on the SU tuning and possibly timing, and the engine makes quite a racket at idle.  Timing chain rattle?  It didn't do it before the head swap, but now does it constantly.  I'll try to share a video next time I think of it.



Edited by carterb
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