Projects Old school cool 248 Gmc

First time I've heard of that alteration on a Chev or GMC. They cooled well as designed ...

 

I think it is more about preventing cavitation at high rpms. There is things people say about dwell time but in a closed system I am a sceptic

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The only heating problem I ever had on a Chevy or GMC six was with my 270. I put a fancy dampener on it and could not get pulleys to align so the fan cleared the belts. I put an electric fan on it and had heating issues. Had a stock dampener rebuilt and put the stock fan back on. Still there today.

I wonder if half of the fins were gone and the pump did half the work if there would be half the engine power loss from running the pump?

 

Not half, but there would be less power used to turn the water pump with half the fins gone

 

When I ran stock water pumps at Bonneville I did it to them, trying to find HP where ever I could...

 

I bought a military 302 that the guy had completely rebuilt and done this to. Paid scrap price since it was ruined. Good head at least.

 

I have been working on my Mallory dual points. Put it on the dist machine and at first my spark was weak, suspected my AC delco finned coil. Moved to a old mopar coil and no change. Had 3 great sparks and 3 poor, figured out the poor spark was though 3 resistor plugs, changed to all ngk race plugs and the spark was great. Set the dwell this morning to 29 deg on each set and tested rpm. it would cut out at 3k rpms with the AC delco finned coil and run past 6k with the old mopar coil. AC delco tests 8 ohms on the primary windings so I guess it is failing. Ordered a Bosch 00012 coil from Amazon and set of stuff for wires from Brillman. I will see how the curve is tomorrow. Defeated the vac brake per Bubba GMC.

 

Here are some pictures, not the best dist machine but it works. Sun's are hard to find.

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Cleaned up my water pump and painted it before installing it. Figured out the Mallory dist advance.

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Finished my water pump build. Had to clearance the impeller side of the shaft and had to use 2 gaskets. Determined we need to start by cutting .25 off the 292 balancer.

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Using the stock water pump with the 3/8" belt pulley, I had to make a 3/8" spacer behind the pump to line up the 292 damper from Tom Langdon. He had already pre cut the damper snout. I was hoping it would have been closer but it worked out better on the fan placement and shroud kit we bought for a circle track radiator from Speedway. Looking Good..

 

That clearance problem is somewhat common with these pumps. I've had to use the double gasket trick myself with some re manufactured pumps fresh off the UPS truck.

 

Cut about .230 off the damper snout. Test fit tomorrow. Jimmy Six I have more cut off the back of the damper than you do so it should fit closer to stock. Still want to degree the damper.

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I used a tape strip from Summit. Had to cut it narrower. Was made for a V8 so I marked it in 1/3’s instead of 1/4’s. JD

 

Not a lot going on. Machinist buddy doesn't like getting up as early and has camping on the brain so gone weekends. I am returning to working at the plant so it will limit my work more. BXOv-2 kit came in. Otherwise working in a timing pointer. not pretty but I tried. I wanted to degree the balancer but will likely go to a tape.

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The hamber "Truckedup" who originally built my Jimmy 302 kept the pointer very simple but it works.

 

I was going to use a nail but I found a old sbc pointer

 

I've always used a bent wire attached to one of the cover fasteners. I had a few originals that used 2 of the screws but when I went to big dampers they wouldn't fit. Glad your moving along...

 

What a great thread. I have been absent for a while and just now read all of it. Hoping to get back on the lakester in my avatar this next winter. Had planned a GMC from the beginning. Have one sitting in the shop. @jimmy six hopefully see you on the Salt this year? Its either that or the HAMB drags for me.

 

I hope this is just the start of a few builds. My Gramps old truck won't ever be hot bit it could be cool at the dirt drags or something. I would love to build a super charged gasser at some point but I have so many projects it will have to wait. I want to go watch at speed week some year. Second Kid on the way means not this year.

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Not much progress, put the 3/8 bolts in the front cover and installed the pan. Side note if you try and build baffles put them well below the top of the stock vertical baffles or they will hit and require you to remove them and be frustrated so you give up.

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The Salt is a must do if you are into inlines. So many cool variations and technology. I plan on running a blown class with a turbo.

 

Thanks Tman, but my salt days are over unless spectating. Sacrificed too many pickups and trailer bottoms to come back with a car. I’m great full for El Mirage and I’m very close to ending my driving there. One must know his limitations as Clint Eastwood said once..

Ned are the cap screws on the second main the originals?

 

Yes I reused all the main bolts

 

Not to totally hijack this thread, but we are changing class with our 302

 

Yeah baby....... great move....

 

Removed the second head plug to move the sender and allow coolant to flow through the intake bottom for carb heat. Took a torch to get it out. Now it is on to exterior block cleaning and masking for paint.


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You are going to run coolant out of one of those holes up to the water neck, right? Lot of people don't, Back two cylinders need that water flow.

 

I was going to run the farthest back hole in a piece of copper tubing though the bottom of my Nicson intake then to the thermostat housing and the plug I removed today, will be the new gauge location. At least that is what JD was saying I should put the sensor. Planning on drilling my intake at both ends of the exhaust heat passage for a 3/8 npt and just block the exhaust inlet with a plate.

 

Did some painting today.

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