Slant Six Forum :: Twiggy - Long Rod Aluminum Block Engine Build-up

What about the method of scoring the rear cam journal to increase top end oiling? is there a depth of cut that should be observed?

...drilled an oil passage from the oil ring in the piston to improve piston pin oiling. Is there a size for that oiling passage that you suggest?

In an iron block, what size would you suggest opening the oil passages up to? How about the passages down to the cam and the mains? I noted the cam bearing modification.

What about the method of scoring the rear cam journal to increase top end oiling? is there a depth of cut that should be observed?

...Now, should I do both mods, or just one? Drill the cam to match, or go with the groove?
CJ

Is this the Blue Printed oil pumps I here about? (refering to porting them)

Also, is there a good way to get the plug( 3/8 sq head) out of a CI block? Oppsite of the freeze plugs.

Doug, this what you're showing us with reconstruction and modification of the water pump scroll area gets me thinking (if you thought you smelt something burning, that's why): From a fair number of cooling system and pump experts over the years now, I've heard/read that in a centrifugal pump setup like the SL6 water pump, the tighter you can get the clearance between the OD of the impeller and the ID of its scroll, the more efficient becomes the pumping action. This makes sense to me; we've got a 3Â½" impeller splashin' around in a much larger cavity, so there are bound to be stray currents of water just recirculating from one side of the impeller to the other â€” much like a radiator fan without a fan shroud is less efficient than a radiator fan with a shroud, because the shroud stops air recirculating around the fan blades. Have you ever thought about building up the walls of the scroll to bring them closer to the impeller? What would you use if you were going to do so â€” welded metal, or block filler?

Author:	dakight [ Thu Oct 25, 2007 5:51 pm ]
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Damn Dan! I'm glad I wasn't trying to drink something when I opened that! LM@O! (...good thing I was not drinking an MGD -ed)

Author:	slantzilla [ Thu Oct 25, 2007 7:24 pm ]
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I thought the reason the factory went to less blades was to keep the water circulating slower to pick up more heat?

Author:	Doctor Dodge [ Thu Oct 25, 2007 8:52 pm ]
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Truth is, this new pump came in a Cardone box but upon close inspection, has the GMB logo casted into the die-cast housing. The pump looks just like other GMB unit I have purchased in the past, in GMB packaging. Anyway, these pumps seem to be the ones you get at the discount auto parts stores these days, this perticular one was on "special" at my local Kregans. I don't have any good way to figure-out which impeller type is the best. There are a few different types of impellers and I have changed water pumps to ones with different impellers and never saw any difference in the engine's running temp. The only time I saw a difference is when I cut every other blade off a 6 blade pump impeller and ran that pump on a race engine. That pump did not curculate much water at low RPMs. DD

Author:	Nathan in MN [ Fri Oct 26, 2007 7:44 pm ]
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What's the story on the one with the disc full of holes? Never seen one like that.

Author:	Doctor Dodge [ Fri Oct 26, 2007 8:15 pm ]
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The cast iron pump impellers were used on many of the OEM 'factory' pumps in the 1960's. DD

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Author:	Doctor Dodge [ Fri Oct 26, 2007 8:16 pm ]
Post subject:	For Aluminum Block SL6 Only....
The aluminum block SL6 has an open section in the water pump cavity that tends to fill-up with sediment. The gasket does not seal this cored-out section from the water, as a result, all the standing muck rots out the wall that deflects water flow into the block. I welded-up the damaged area on Twiggy and thought about ways to prevent future problems. Not wanting to add extra metal or a 'lump" of filler, (block rock) I decided to drill a small hole thru the adjacent wall, in hopes of creating enough coolant 'cross flow' so the muck does not settle in this spot. Here are a few photos of the "empty pocket" and the modification. DD

Author:	ceej [ Fri Oct 26, 2007 10:17 pm ]
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Hi Doug, You suggested asking questions before you get to your next project. Back several pages you showed how you drilled an oil passage from the oil ring in the piston to improve piston pin oiling. Is there a size for that oiling passage that you suggest? In an iron block, what size would you suggest opening the oil passages up to? How about the passages down to the cam and the mains? I noted the cam bearing modification. What about the method of scoring the rear cam journal to increase top end oiling? is there a depth of cut that should be observed? Thanks! CJ

Author:	SlantSixDan [ Sat Oct 27, 2007 6:33 am ]
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Quote: What about the method of scoring the rear cam journal to increase top end oiling? is there a depth of cut that should be observed? Covered in this thread; additional info here and here,

Author:	SlantSixDan [ Sat Oct 27, 2007 6:39 am ]
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Doug, this what you're showing us with reconstruction and modification of the water pump scroll area gets me thinking (if you thought you smelt something burning, that's why): From a fair number of cooling system and pump experts over the years now, I've heard/read that in a centrifugal pump setup like the SL6 water pump, the tighter you can get the clearance between the OD of the impeller and the ID of its scroll, the more efficient becomes the pumping action. This makes sense to me; we've got a 3½" impeller splashin' around in a much larger cavity, so there are bound to be stray currents of water just recirculating from one side of the impeller to the other â€” much like a radiator fan without a fan shroud is less efficient than a radiator fan with a shroud, because the shroud stops air recirculating around the fan blades. Have you ever thought about building up the walls of the scroll to bring them closer to the impeller? What would you use if you were going to do so â€” welded metal, or block filler?

Author:	Doctor Dodge [ Sat Oct 27, 2007 9:56 am ]
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Quote: ...drilled an oil passage from the oil ring in the piston to improve piston pin oiling. Is there a size for that oiling passage that you suggest? .020 to .032 is the size range, you do not need a big hole. Drills this small are hard to work with in aluminum so do some practice holes on a scrap piston. Quote: In an iron block, what size would you suggest opening the oil passages up to? How about the passages down to the cam and the mains? I noted the cam bearing modification. I have a long shank 5/16th drill for this job. (.312) Push away from the cam bearing opening as you approach and drill past it. This large drill size is going to break-out a 'slot' as it passes the cam bearing bore. I find that it is best to do this drilling while the old cam bearings are still in their bores because the bearing's steel shell helps deflect the drill towards the softer cast iron. This oil passage mod is the most important of them all, the other work in mostly rounding-off all the passages sharp corner edges and "porting work" with-in the oil pump itself. Quote: What about the method of scoring the rear cam journal to increase top end oiling? is there a depth of cut that should be observed? The other threads do a good job covering that, you just need a steady hand and not much groove. DD

Author:	ceej [ Sat Oct 27, 2007 7:02 pm ]
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That's the stuff I was looking for! Thanks Doug and Dan! Now, should I do both mods, or just one? Drill the cam to match, or go with the groove? CJ

Author:	66aCUDA [ Sat Oct 27, 2007 7:13 pm ]
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Doug Is this the Blue Printed oil pumps I here about? (refering to porting them) Also is there a good way to get the plug( 3/8 sq head) out of a CI block? Oppsite of the freeze plugs. Im having a hard time figuring out where to drill from. Thanks Frank

Author:	Doctor Dodge [ Sun Oct 28, 2007 9:38 pm ]
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Quote: ...Now, should I do both mods, or just one? Drill the cam to match, or go with the groove? CJ Drilling the cam so the oil passageway lines-up once every revolution, will provide the correct amount of oil to the rocker arm shaft. No need to groove the cam journal if your running a mechanical cam. DD

Author:	Doctor Dodge [ Sun Oct 28, 2007 9:45 pm ]
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Quote: Is this the Blue Printed oil pumps I here about? (refering to porting them) Yes, you can "port" the oil pump's passageways and set all the clearances to get maximum pump flow. I also install one of my case hardened drive gears as part of the "blueprinting" process. Quote: Also, is there a good way to get the plug( 3/8 sq head) out of a CI block? Oppsite of the freeze plugs. If the plug is stuck, apply heat DD

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Author:	440_Magnum [ Mon Oct 29, 2007 8:25 am ]
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Quote: Doug, this what you're showing us with reconstruction and modification of the water pump scroll area gets me thinking (if you thought you smelt something burning, that's why): From a fair number of cooling system and pump experts over the years now, I've heard/read that in a centrifugal pump setup like the SL6 water pump, the tighter you can get the clearance between the OD of the impeller and the ID of its scroll, the more efficient becomes the pumping action. This makes sense to me; we've got a 3Â½" impeller splashin' around in a much larger cavity, so there are bound to be stray currents of water just recirculating from one side of the impeller to the other â€” much like a radiator fan without a fan shroud is less efficient than a radiator fan with a shroud, because the shroud stops air recirculating around the fan blades. Have you ever thought about building up the walls of the scroll to bring them closer to the impeller? What would you use if you were going to do so â€” welded metal, or block filler? Actually, I don't think you want to bring the ID of the case in too close to the OD of the impeller. Very efficient centrifugal pumps actually have a smoothly increasing clearance, ending up at a maximum clearance adjacent to the outlet port (think of an impeller in the center of a nautilus shell). The point of clearance that really should be tight is the gap between the SIDES of the impeller blades and the taper around the central shaft and the opening where the water is drawn into the pump. And the back side of the impeller should be a solid disk (more like the old iron pump than the new cheapies). This is the inside of an Edelbrock high-efficiency water pump (for a shivvy, I think, but you get the point): http://www.edelbrock.com/automotive_new ... _img_1.jpg The tapered "seat" surrounding the center hole is what I'm talking about. Its machined to fit extremely close to the edges of the impeller blades. Here's the impeller that goes with that pump, showing that it is also a solid disk on the back side to prevent water reversion around the impeller blades: http://www.edelbrock.com/automotive_new ... _img_2.jpg I wish they had an image of their Big-Block Chrysler pump and housing, because its even better. It feeds water in from the opposite side from the shaft, so the center of the "seat" is wide open. And the vanes on the impeller are much more precisely machined than on that Chevy part, too.