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350 oldsmobile

General engine tech -- Drag Racing to Circle Track

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hadmtrst8
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350 oldsmobile

Post by hadmtrst8 »

anyone done adjustable valvetrain conversion?what studs did u use?rockers? etc? stainless valves for small valve heads?im not apposed to opening up the valve size with my 3d goodson serdi cutters,any advise helpfull thanks howard
Walter R. Malik
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Re: 350 oldsmobile

Post by Walter R. Malik »

hadmtrst8 wrote: Wed Sep 30, 2020 12:50 pm anyone done adjustable valvetrain conversion?what studs did u use?rockers? etc? stainless valves for small valve heads?im not apposed to opening up the valve size with my 3d goodson serdi cutters,any advise helpfull thanks howard
If this is not a race type engine, Comp Cams and others offer guide-plates and studs with the correct thread to install directly into Olds heads to be able to use 3/8" stud type rockers.
http://www.rmcompetition.com
Specialty engine building at its finest.
Schurkey
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Re: 350 oldsmobile

Post by Schurkey »

I converted "big block" 45 degree "C" castings to individual rockers and BBC studs.

My machinist opened the small-diameter holes to 7/16-14 from...5/16?

Machined-down the rocker pads on the head the thickness of the guideplates. I bought Olds guideplates from Comp Cams, which was a mistake. I should have bought Pontiac guideplates--same plate, proper sized rocker stud holes. I had to open the rocker stud holes from 5/16 to 7/16 on the Olds plates.

The "C" heads needed a heap of grinding in the pushrod area to use with 1.6 ratio Comp Cams "Pro Magnum" "Ford small-bllock" rockers. There are better options for rockers but I didn't know about them at the time. Seems to me I also needed longer-than-stock pushrods.
hadmtrst8
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Re: 350 oldsmobile

Post by hadmtrst8 »

head gaskets all the same?,waterpumps too?motor seemed to run hot on run stand
Schurkey
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Re: 350 oldsmobile

Post by Schurkey »

hadmtrst8 wrote: Fri Nov 20, 2020 8:47 pm head gaskets all the same?,waterpumps too?
Far as I know, there's no differences in Olds BB / SB water passages in the head gaskets
There's three or four different "lengths" of water pump, but the impeller should be the same size. The cast impeller seems to be preferred over the stamped-sheetmetal version. Ideally, you'd check the clearance between the impeller and the sheet-steel "front cover", less is better as long as it doesn't rub. Adjustment is a bitch, you'd have to move the impeller on the shaft to change it (or find thinner/thicker water pump gaskets.)
hadmtrst8 wrote: Fri Nov 20, 2020 8:47 pmmotor seemed to run hot on run stand
Fairly common. Radiator on run-stand probably doesn't have a shroud, and the engine often runs at ~2000 rpm with no load. Mixture tends towards lean, adding to heat load.
TAG
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Re: 350 oldsmobile

Post by TAG »

Isky adjustable guideplates 200-AGP, mill the rocker stands down, enlargen the stock 5/16 rocker-stud threads to 7/16, then BBC-studs, Ford Pro-Magnum rockers, 5/16 pushrods. Couldnt fit thicker without enlarging pushrod holes on heads and didnt feel like pulling heads again for that.

Or cheap option, comp-cams stamped guide-plates, conversion studs ( 5/16" base - 3/8" upper portion), magnum roller-tipped rockers and away you go.
Then theres Harland Sharp aluminium rockers, Scorpion rockers etc etc. They are out there.

Water-pump are the same, difference in snout length. Be aware that all the bracketry for PS/ALT/AC goes alongside the length of waterpump- if your car had AC, it has the longest water-pump, and if you buy shorter one, your PS/ALT/AC dont like up anymore.

Head gaskets the same minus the bore-size on them, up to individual to look for it. At 77´? on heads and block they transitioned from 7/16" to 1/2" headbolts, locating dowel pins staying on same place. So if you want to, say, use a 72' head at 77' block, you need to drill head for 1/2" bolts, and if you want to use 77' heads at 72' block, you either use large, machined spacers under bolts, since locating pins are still there so the head cant move around when installing, or then you enlarge the block head-bolt holes to 1/2".
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