I'll try to keep this short. Running a 265 in my '55. It was a donor motor after recent main bearing failure of the original. Re ringed it, cleaned out as much sludge as possible, new hyd cam (with groove) and lifters. Using correct '55 distributer. Adjusted rockers 3/4 turn. 15-20 psi oil pressure at idle, 30+ cruising. Quiet as a mouse around town. If I cruise at highway speed for more than five minutes 1 or 2 lifter start to clatter.... rolling up to a stop light it actually almost kills a cylinder. Then if I cruise around town or idle for a bit it goes away after a couple minutes only to return on the highway. Assuming sludged passages and crap floating around I sea foamed it twice with little improvement. Running VR1 50w helped the most. Last night I took the car out, ran the shit out of it until it clattered, pulled it into the shop and yanked the covers while it was running. I took the handle of a scredriver and pressed on the lifter side of the rockers until it clattered. I found three that stuck on a few attempts and replaced them. Problem STILL exists. Any ideas?
Is it oiling up top when it is runnin? Is the dist pointed in the correct direction? I believe on those early engines the dist has a correct position it needs to be pointed at,but run with valve cover off and see if oil is comming out all the rockers
Oil is coming out of the pushrods. Not as much as a constant pressure sbc valvetrain, but enough to fling a bit on the exhaust manifolds and piss me off. I have the window of the dist cap pointing at the front of the engine, advance can pointing at number 4ish.
You say the window in the distributor is in the front. The 55-56 chevt 265 Distributor doesn't have a window . If i remember correctly the 265 distributor has a flat on the casting above the gear that directs the oil upstairs. U might want to get the proper distributor. There is another way to fix this. remove the intake manifold and drill and tap 1/8" pipe the center oil gallery and the outer 2 gallerys and attach a copper line to each outer galllery from the center one. I did this on a 265 with a later dual point Distributor . You can't see this from the outside. it does work.
If memory serves me right, there should be a slot ground in the rear journal of the camshaft on the 265 small block. That slot is also related to lifter oiling.
His second sentence states he put the grooved cam in. Have you checked the pick-up? Make sure it's not sucking air or out of position?
The early sbc rear cam bearing, 55 -58?, is also different as far as oil holes and outer diameter. Were you cam bearings replaced with a rebuild? Could be the problem.
Mmmm boy, those little-remembered 265/283 tricks! Lotsa boys on here with excellent memories, that one with the cast iron 265 distributor notch was great! (didn't remember the position being critical, but I always index the distributor to its 'stock' position with correct wire positions...) Still, some pretty smart cookies here, I have to say!
My buddy had a similar problem - in his case there was some gunk in the pan that under extended driving (highway) would shift and block up the oil pump pickup - but when driving around town there wasn't enough suction to make it blocked and all was well - didn't figure out what the heck was going on until the pan was dropped - then it all made sense. BTW his "gunk" was way beyond seafoam.
The distributor isn't a '55 piece but it DOES have the identical flat spot on the base. For shits and giggles I temporarily installed the original distributor with identical results. The pan is clean, oil pump and pickup new and recently checked for debris. I even opened every oil filter to only find a few small flakes of sediment.
That's an awesome idea! If only I didnt have to dismantle the engine to ensure I cleaned al the debris from the drilling and tapping I would probably do it.
That doesn't seem like much oil pressure, although I've had them run about 30 down the road on old engines. I'd be suspecting bearings. You said the most good was putting heavier oil in. Maybe when it warms up good and the viscosity goes down the cam or rod and mains are too worn and the pressure drops below what the lifters need. Just a thought. I don't understand why the clatter goes away after idleing though. Weird. Lippy
If you put grease on the drill bit use a vacuum next the drill bit and also put grease on the tap it can be done . I also used a small pencil sized magnet to get any remaining particles out of the hole. back the tap out often and clean it. I also used a T in the center rail to direct the oil to each side oil gallery . it can be dine without taking the while engine apart . Just the intake.
Donor motor,, hmmm, and you found 3 bad lifters,, maybe flat lobes? check with dial indicator maybe, interested in what you find out
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