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Okay guys my theory with my engine the lt1 oil pump gear drive lost all the teeth and the metal got into the rear main bearing and spun putting a groove in my block, cap, and fusing my bearing to the crank. Now before you go after me I made a bad trade on this car it was not running and I thought opti because it would turn over at times and not fire, so I found the oil pump is a melling m55hv oil pump and from everyone's experience and research the gear drives do not like high volume oil pumps, I'm building a new engine for the car I ordered a forged 383 stroker short block and I'm buying all new parts to put it together. Here are my questions. I bought a melling m55 standard to go back in so there will be no added stress to the gear drive.
1. The nylon bushing that came with my m55 is it needed and where does it go?
I can see a nylon bushing on my m55hv but the shaft seems to be the same diameter all the way up my new m55 has a female adapter end that is larger than the shaft.
2. Do I need a oil pump gasket because I don't believe my kit came with a gasket. If so what does it look like or could someone please point me to a part number. I'm thinking this is a stupid question because I'm leaning towards it needing a o ring seal or a gasket but would love the confirmation.
Thank you to any and all advice ahead of time it is much appreciated.
I have attached two pics the m55hv(old) in the fine China plastic plate and my new m55.
The oil pump drive gear on the cam was eaten up? If so, that's not necessarily due to the HV pump. Loads of us are running them with zero issues. Just make sure you have the proper drive-gear on the cam and you'll be fine. I'd wager a guess that your M55HV is just fine. Pull it apart and check... That said, your new pump came with the proper drive shaft with a steel retaining collar in place of the nylon one. You also do not need a gasket between the pump and the main-cap. Make sure you set the proper pickup depth in your install.
Will it be OK to run that m55 or do I need to clean out the hv and reuse it, I bought a good used drive gear oem and I will be using the comp extreme 07-468-8. I just don't want to go through the engine chewing up another drive gear. So for your guys expertise what route should I take.
The oil pump drive gear on the cam was eaten up? If so, that's not necessarily due to the HV pump. Loads of us are running them with zero issues. Just make sure you have the proper drive-gear on the cam and you'll be fine. I'd wager a guess that your M55HV is just fine. Pull it apart and check... That said, your new pump came with the proper drive shaft with a steel retaining collar in place of the nylon one. You also do not need a gasket between the pump and the main-cap. Make sure you set the proper pickup depth in your install.
Also another bit of information that comes to mind the drive gear was eaten up by a stock cam it was the performance version for the birds but oem stock by the numbers I researched I think 96? Model...
Engine is a completely rebuilt 383 notched block stroker assembly, bored 0.030 over standard bearing clearances nothing special. Just wondering about the higher rpm and starving the engine from oil, don't know how far I will turn the engine but I have seen people taking them at least to 6200 rpm and have heard of higher rpm ranges. I just want to make sure she gets plenty of oil and that my drive gear dosent get devoured again I don't want to put another motor in it till I can go lsx. I love my older car because we have the north Carolina state inspections which can be a real pain in the **** for 96+vehicles so I will much rather put the ls1 in my car and update the front end.
So am I reading correctly on a metal hold down tab for the gear instead of the plastic because I have also heard the plastic let's the gear lift from the cam which causes the gears to mismesh if you will which causes them to fight to the death.
You can fashion your own metal hold-down tab if you want, but a fat washer that's ground for clearance against the block will work fine too. What most people do is over-torque the plastic housing which causes them to crack and fail. There are lots of folks spinning a properly balanced LT1 well beyond 6200. Regarding the gear on the cam, tell whoever is grinding the cam for you that you want the hardened oil pump gear. I know Comp and Bullet will accommodate this request. I think all of Comp's gears are hardened, but I could be wrong....
Engine is a completely rebuilt 383 notched block stroker assembly, bored 0.030 over standard bearing clearances nothing special. Just wondering about the higher rpm and starving the engine from oil.
You won't. If standard bearing clearances are used then a standard volume pump is all you need. However for higher RPM a high pressure spring can be used. There are pumps that already have this feature, but I can't remember which one. Something worth looking into.
If we are talking about the gear that is held on with one small bolt under intake manifold that went bad, new replacements are available for about $75-$80 at dealership parts counter. Maybe cheaper elsewhere. That gear mesh is to the cam gear which ideally is a "melonized" gear. Billet cam gears can wear a stock factory oil pump drive gear
"Often" 383 builds are made with "slightly" wider bearing clearances typically with a cam combination that will see higher than stock RPM operating conditions (6k+ RPM) with the aftermarket tune it has. In these motors a HV oil pump is advised. Pic below is a 90+k mi stock oil pump gear in my 383. No wear issues due to a HV pump.
Motors with stock bearing clearances should not run a HV pump, just install a "high pressure" spring in a standard volume pump
On the oil pump drive gear the top is plastic and aged it gets more brittle than when new and can easily crack if to much TQ is put on the small bolt. Even stock TQ can crack a old gear assembly so just hand tight and use some blue loc tite. You can also use a larger flat washer under the small bolt head to distribute the load more over the plastic top. There are metal "caps" I have seen for these oil pump drive gears that will also help.
Get a one piece oil pump drive shaft if the oil pump does not come with one. The plastic collar on the stock drive shaft gets brittle with age and on re-install can crack (and you can't see that when you install it easily) and when it breaks..no more oil pressure. ARP and Miloden make them for around $10
Melling Select 10554 pump (std vol, 3/4" inlet. Should come with Melling IS-55E shaft with metal coupler and 70# pink spring). If it does not come with the shaft, get one. Not expensive. Don't use the plastic/nylon coupler on the shaft. The pic of your M55 pump looks like it has the shaft with metal coupler, so may not be needed. The select series pumps have a stronger casting than the regular M series that have been somewhat prone to cracking.
I already have my cam and it is not a custom grind it's factory comp cam. I will be tuning the car once I get it running.
So what if I just upgrade the spring in my m55 to the #70 beef up the hold down for my drive gear with a washer.???
And yes folks I already have the same shaft with metal coupler for my m55.
Thanks again for all the responses I want to do this engine right the first time so it will last me till I get the lsx engine built. I imagine it will be a pretty fun daily driver with the sound I've always dreamed of Especially with the six speed.
Older post but I have nothing but issues with mellings in the past. I spent the cash and ended up getting an oem unit. Granted its 300 miles old with no issues but will probably get replaced with this fresh rebuild. One of my engines years ago go screwed over in 137 miles by a melling pump. Was fine when it went in. When I pulled it out it was smooth.....ruff......very ruff.......smooth....rinse repeat. After seeing their pumps fail most sub 10k miles they will never go into another one of my cars.
That being said my 383 will just be getting a std volume GM Pump if it gets put back together.
Older post but I have nothing but issues with mellings in the past. I spent the cash and ended up getting an oem unit. Granted its 300 miles old with no issues but will probably get replaced with this fresh rebuild. One of my engines years ago go screwed over in 137 miles by a melling pump. Was fine when it went in. When I pulled it out it was smooth.....ruff......very ruff.......smooth....rinse repeat. After seeing their pumps fail most sub 10k miles they will never go into another one of my cars.
That being said my 383 will just be getting a std volume GM Pump if it gets put back together.
I would assume you guys know that higher oil pressure is harder on the cam & pump drive gears? Mine goes 8300 + RPM all the time with a std volume pump, putting out 45 psi. Have run lower than std volume pumps (spacer & shortened gears, about 5 hp at the crank) @ 40 psi with absolutely no issues.
I can not imagine why a high volume pump is even manufactured. Wasted time testing that crap over 20 years ago. You do not need it. I used an old rear main cap, tapped the oil hole for pipe threads, screwed in a hose with an oil pressure gauge on the other end, for checking oil pressure before installing it. Drop in water, (I use solvent) or ATF to simulate hot oil. Spin it with a 1/2" drill motor, there is your oil pressure (if the engine is correct internally). Clip springs, swap springs, etc. Easier than trying to adjust it after the engine is in the car. LOL
There have been a bunch of threads lately about oil pressure. In a (probably vain) attempt to clarify some issues in that regard, I offer the following.
Oil pressure is NOT IMPORTANT! Well, that's an exaggeration to get your attention. But what IS important is oil flow. The plain bearings in an engine work as follows. There is no metal to metal contact except at startup and shutdown. What separate the shaft and bearings is a film (actually a wedge) of oil. Oil is constantly flowing out from the edges of the bearings, so a constant flow of oil is needed to replenish this.
The oil is supplied by a pump, which is of the positive displacement type. The volume the pump flows is directly proportional to the rpm of the pump gears. The oil pump does not produce any pressure!!!!! It produces flow. The oil coming out is at the same pressure as when it went in to the pump - zero relative to the oil in the sump.
So why can we measure oil pressure above zero? Well, the pump is flowing a fixed volume of oil into the oil passages of the block and out through the bearings. This causes resistance to flow and the result is pressure. Oil pressure is thus a surrogate way of measuring oil flow - the more oil flow (from higher pump output), the more pressure will be produced. If we increase the resistance, by using a more viscous oil, the pressure will also go up because of the increased resistance to flow. When the oil is cold, it is more viscous, and there will be more oil pressure.
How much oil pressure is enough? Keep in mind that what counts is flow. A time proven rule of thumb for a SBC is 10psi/1,000rpm. This assumes the normal range of engine bearing clearances and it is well proven that 10psi/1,000rpm will supply enough oil flow. Since we have no convenient way to measure flow, we use pressure as a surrogate. If the bearing clearances are larger, we need more flow to keep an adequate film of oil between the bearings and the shaft. Do we need more oil pressure? No, but it will take more volume to produce the same pressure because the resistance is lower. So, we need a high volume pump to maintain oil pressure. This costs hp - more power is needed to drive a HV pump. The reasons to choose large clearances are beyond what I want to go into now.
What if the bearing clearances are tight? Well, we will see more pressure with the same output but we don't need it. In that case, we can use a lower viscosity oil with less friction and less resistance to pumping. This will lower the oil pressure and gain hp because of the lower pumping losses and less friction. This is what the OEM's are doing to improve mileage and performance. Some new vehicles come with a recommendation for 5W-20 oil. There are real hp gains from using a low viscosity oil. Some hard core racers will use 0W-10 weight. The problem is that there is a general relationship between viscosity and shear strength. Low viscosity oil may not provide enough resistance to shear to protect bearings (avoid metal to metal contact) under very high loads (high boost blower cars, heavy nitrous use, etc.). Many racers are using 5W-20 for the same reasons but with a little more protection.
I am one of those dinosaurs who wants a little more bearing clearance and a heavier oil for a hi-po motor. The idea is that with high loads, more clearance and greater shear strength is needed to avoid metal to metal contact when there is parts deflection. I use dino oil. Actually, a semi-synthetic 20W-50. And I need a HV pump because of the bearing clearances. But I realize I am giving up hp and am slowly coming around to considering using a thinner oil and tighter clearances.
There is a lot more to be said. But maybe now you believe me that you don't need a HV pump unless you KNOW you need an HV pump? The issue of a high pressure spring has been discussed a lot. I think it's not a bad idea if you run over 6,000rpm. The stock pressure relief spring limits oil pressure to 55-60psi, so if using it you will not see the desired 10psi/1,000rpm at high rpm. It does not cost power like a HV pump does.
So just to be on the safe side should I change the spring, my pump looks like it has a green spring in it. Could I use the spring from the hv pump to get more pressure just in case this engine is spun over 6k to protect the bearings?
If we are talking about the gear that is held on with one small bolt under intake manifold that went bad, new replacements are available for about $75-$80 at dealership parts counter. Maybe cheaper elsewhere. That gear mesh is to the cam gear which ideally is a "melonized" gear. Billet cam gears can wear a stock factory oil pump drive gear
"Often" 383 builds are made with "slightly" wider bearing clearances typically with a cam combination that will see higher than stock RPM operating conditions (6k+ RPM) with the aftermarket tune it has. In these motors a HV oil pump is advised. Pic below is a 90+k mi stock oil pump gear in my 383. No wear issues due to a HV pump.
Motors with stock bearing clearances should not run a HV pump, just install a "high pressure" spring in a standard volume pump
On the oil pump drive gear the top is plastic and aged it gets more brittle than when new and can easily crack if to much TQ is put on the small bolt. Even stock TQ can crack a old gear assembly so just hand tight and use some blue loc tite. You can also use a larger flat washer under the small bolt head to distribute the load more over the plastic top. There are metal "caps" I have seen for these oil pump drive gears that will also help.
Get a one piece oil pump drive shaft if the oil pump does not come with one. The plastic collar on the stock drive shaft gets brittle with age and on re-install can crack (and you can't see that when you install it easily) and when it breaks..no more oil pressure. ARP and Miloden make them for around $10
What are you guys calling "std bearing clearances" and "wider bearing clearances"?
So just to be on the safe side should I change the spring, my pump looks like it has a green spring in it. Could I use the spring from the hv pump to get more pressure just in case this engine is spun over 6k to protect the bearings?
What RPM is your engine going to see and how long will it be in that range?
Originally Posted by Ed Wright
What are you guys calling "std bearing clearances" and "wider bearing clearances"?
What I mean by "standard" are the factory stock clearances used for this particular engine.
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A little help with oil pumps 
