Pulled the 305 out of the 64 Chevy c-10 (old rusty) due to a rotten freeze plug ( don't know why anyone wouldn't pay a few extra bucks for br*** instead of steel). Anyway, I'm freshening it up while it's out (timing chain and gears, gaskets, oil pump, valve adjustment, degrease and paint) and would like some input on whether to use a high volume or standard oil pump. It's a high miler and I didn't know if a high volume pump might help it in its old age. It doesn't smoke or knock and I can't spring for more cubes so I'm going to run it a while longer.
Is it a V-6 or a small block 305???.... If it's a small block V-8, I'd go with the standard Z/28 oil pump...
its all about the bearing clearance, standard to spec bearing clearance - standard pump tight clearance - high pressure pump loose clearance - high volume pump make sense? the detailed explanations as to why are a few chapters long and delve the relationship between volume and pressure with the oil path thru the engine.
tight clearance - high pressure pump loose clearance - high volume pump <I'm ***uming you meant to put "standard" here, right? At this point in life, ^^^this^^^ all I need to know. And even then, it'll probably get screwed-up in the old memory bank . Thanks 31.
stock....and if the oil pressure was kind of low, might want to think about replacing bearings. Bearings wear out more easily than oil pumps, eh? I think I would take the pump apart and inspect it, and if it's not noticeably worn, I would just put it back in.
Google pics and procedure You can check wear on the gears and clearance between the gears and housing. If your thinking of replacing the pump New bearings and rings are not a big deal at that point either Not a rebuild but a freshen up as it were
just found this, haven't read it yet but seems to be lots of good info... http://garage.grumpysperformance.com/index.php?threads/testing-a-chevy-oil-pump.6479/
Dan - Interesting write-up. Back when I ran my Pro Gas (as it was called back in the day !) Anglia, I ran a stock pressure spring, big block pump in my small block Chevy engine (three different engines). I figured the higher tooth count would smooth the pressure pulses. According to the article above, it would. So maybe I'm not so dumb as I look..! 13 years, a LOTA laps down most of SoCals tracks, same pump. Never hurt a bearing because of oil related problems. Mike
Exactly. I have a friend that races a big block GM in an altered. Has used several blocks but the same Melling pump since the '60s. If it were mine I would leave the pump that is in it. If it was holding oil pressure before it will still hold oil pressure. If there is a problem at a later date it is easily addressed without pulling the engine.
1973/74 I was building a 355 sbc for my first race car, still in trade school, not a lot of money so trying to spend money wisely.......right! Bought a used Melling pump (looked new) at the swap meet for half the cost of a new one. I'LL NEVER DO THAT AGAIN! Blew three new oil filters completely off the engine on initial startup, .I was ready to pull the engine because I had not heard of this and didn't know what to do, my friend who was older and more experienced said just pull the pan and take the oil pump off and check it out, had a stuck (rusted) bip*** spring. Just spend the money on a new stock replacement pump, it is the most important part in your engine and the least expensive of all the engines' components.
High oil pressure does not translate to longer engine life or more HP. Use a stock oil pump. If you have 10 PSI for every 1000 RPM that is plenty.
HV pumps are designed for low RPM,when used in racing or big foot{most of us},only thing the big HV pump dose is heat the oil up forcing oil out byp***.High oil Temp is a bad thing. Standard pump works fine.
The article in how to hotrod small block chevies shows how to blue print the oil pump... It's worth reading!!! .....
You tube videos on dis***embly and "blueprinting" chevy oil pumps. Its worth a little time to check the components even if you dont go all out. I did a few pumps 20 some years ago from instructions in a book, dont recall all the steps now. I do remember finding some tolerance differences. Seems most auto parts have just gotten ****tier in the past 25 years...worth checking. Me and Dueces are thinking alike, he types faster.
if it's been working ok, just look for noticeable wear on the gears or housing or shaft. Clean the byp*** valve.
Okay, I got it. I thought that since it is a high miler "bearing clearance" would be "Loose" and a hi volume would be warranted. I'm slow but I like to think I'm worth waiting for . Thanks again 31.
The Small Block Chevrolet has one of the best oil systems ever designed. I’m absolutely sure the engineers knew so much more than I do, so I only run stock oil pumps. Sent from my iPhone using The H.A.M.B. mobile app
I run an HV in my 355, but I set it up loose. I do use good oil and change it often. My biggest worry with the high volume is high pressure in cold weather. I know everyone says high volume means low pressure but that is not actually true. when the mercury dips into the 20s here 20W40 Castrol is too thick. Cold off idle I was pulling 110 plus (which is about where to start washing the babbit off the inserts). So for me it is summer and winter oil. @DDDenny I cut corners on rockers about 20 years back on a small block. Standard stamped steel rockers and kept either busting studs or rockers. I actually got to the point that I could change a rocker on the side of the road like the normal man of our era changing a tire. LOL One night I came home from work (second shift) and there lay a box full of Crane rollers on the couch. They got installed in the morning.
It doesn't smoke or knock, how's the oil pressure? If it is decent(25-30) I would say polish the oil pump plate on a surface plate to get the swirl marks out from the gears and put everything back as it was. If it ain't broke don't fix it and save the money for the next thing that goes to hell.
Read this , follow the procedure, and your pump will be about as perfect as it gets. I have been prepping oil pumps like this for years and years. It is also kind of fun to do.
I have a 354 Hemi Industrial motor using the Hot Heads HV oil pump, 75# oil pressure then may drop to 0 and not recover. The pump checks out fine but I'm very leary of trying it again. This happened to me before, 75# and then may go to 0, shut it off, check oil ok, start up 75#. I'm thinking it is pumping the pan dry. Using a Milodon oil pan with flat windage tray, thinking about drilling some holes in it. I want 50#. Any ideas? The problem was the motor has a 392 rear main cap which wouldn't allow the oil pump shaft to fully engage the intermediate shaft. The 392 intermediate shaft solved the motor losing oil pressure. Now have 75-80# all the time. Too much pressure.
Birdsgarage : How far off the bottom of the pan is your pickup screen? (should be somewhere around 1/2" to 5/8"?) Also check for plugged screen(how much "Gorilla-Snot" did you use on the gaskets when ***embling?) How does the pickup attach to the pump? could it have come off(or just loose & be ****ing air?)
The Jalopy Journal
