Bearing Clearance

[87buickracer]

What's the most clearance anyone has ran on their main bearings with high volume oil pump?Also rod bearings,thanks in advance for any input.

 

[bison]

With the stock type oil pump and oiling in a stock or stage 1 block there is no point in going over .002in. Almost all the well known and respected builders around the country run .0015-.002in on the rods and mains.

 

[87buickracer]

Thanks,anyone else running anything different?anything between .002-.003 on the mains?

 

[blown okie]

.0025 would be a max but i wouldnt recommend it, i also dont care for the high vol. pump im switching back to a std. vol. .0020 is a good safe clearance for the rods & mains on the turbo 6

 

[87buickracer]

My friend and I was talking about high horsepower engines that rev higher than 6,000 rpm,should they have a little more clearance to keep things lubricated?If I'm running 6,500 to 7,000 rpm,I wouldn't want my bearings at
.0015 but more around .002-.0025.

 

[Blown&Injected]

.0023/.0023 with standard pump with fine pressure

.0025 would be a max but i wouldnt recommend it, i also dont care for the high vol. pump im switching back to a std. vol. .0020 is a good safe clearance for the rods & mains on the turbo 6

What do you not like about the oil pump - I am about to put one on my engine.

 

[87buickracer]

I'm thinking of putting high volume pump on my engine as well.Looking for maximum oil pressure.

 

[bison]

I'm thinking of putting high volume pump on my engine as well.Looking for maximum oil pressure.

Just make sure the oil is hot before pounding it. I wiped out the front of my block (cam thrust form excessive load). Probably was a little too tight. If you have a billet roller with a torrington thrust bearing i wouldnt worry at all. I would worry about bursting the oil filter if the engine oil is not hot enough though and you have a high volume pump. I still wouldnt go with over .002in if you are running the standard oiling setup in the stock block.

 

[Blazer406]

I would worry about bursting the oil filter if the engine oil is not hot enough though and you have a high volume pump. I

In my previous experience... (insert inexperienced dumb@ss)....I shimmed an oil pump pressure relief spring too much on a SBC one time.... and with 20W50 oil... at the first startup.. the engine did fine... pegged out my 80 psi gauge.... idling... after 20-30 sec or so... I started raising the engine speed some..... and promptly blew the rubber gasket on the oil filter. I learned not to build any significant RPM's until fully warmed up... if I did that... no problem.

In hindsight... I should have never shimmed the oil pump spring... poor bandaid for an engine with excessive clearances..... and doesn't work in the end...

Back to the above quoted comment......In my experience though... the filter will hold the pressure... the rubber oring type gasket... won't.

 

[Lee Thompson]

Imo

.0015 or as close as possible to that #. Has always worked well for me. No need for a HV cover. 6400 RPM

 

[PhilM]

2.5 mains, 2.2ish rods. HV pump a must if you go loose... btw, dont let ppl tell you if you run those clearances you dont need a HV pump and it's bad for the cam... well screw the cam life, if the engine wipes, you dont need a cam; and btw I found out the hard way. I'm not stepping into the debate on what clearances should be... All I know is that the 109 is a weak block and it will move! Another thing to maybe ask is clearance measured with what instrument? Plastigages never were too accurate for me (even averaged)... maybe to about 1/2 thou or so but anything smaller, you need a professional bore mic.

I've got 4k miles on this rebuild sofar and with 10-40 amsoil i have appx 16# idle hot OP and about 60 up high. I used to run 2050 but I don't think I need it so i'm with 1040 now. I drive the car >30 miles everyday back and forth to work.

By the way... 'oil pressure' really dont mean squat to me other than a 'yea, i'm kinda in the ballpark' or a 'shoot, i got none!' ... just by shoving thicker oil in there doesn't mean it's better for the engine just because OP is higher... Higher pressures are due to more resistive paths, whether it be tighter clearances or thicker oil. Of course, if there's no pressure, it HASN'T any resistance which is just as bad!

Phil

 

[Quicksilver]

If running the hi-volume pump, IMHO use a deep pan or overfill the stock pan by a quart. My bearings showed signs of low pressure after some 6,000 RPM shifts:0 I believe that the oil was everywhere but the pan & brgs

 

[87buickracer]

Now thats what I call some good feed back.This engine was professionally check by a machine shop that cranks out pro mod engines and grand national motors.The builder also has a gn and runs a high volume pump on his motor with no oil mods and btw his clearance is .0022-0023 with no problems.his car has a street motor with fmic and 44 turbo runs 11flat @ 22psi.My front cover oil journal is modified and I'm getting the cam journals drilled to feed more oil to the mains first and having the crank cross drilled.With these modifications I want to have the hv oil pump for extra insurance.I'm running a billet roller cam and it has the torrington bearing that goes behind the cam against the block.Hopefully everything will work out.If not,I have more 109 blocks to build another or maybe a v8 turbo:smile:.

 

[Blown&Injected]

warm it up

About the warm oil thing:

Of course it is important to warm up the engine before hitting it but if anybody doubts what cold oil is like get this...

Even with one oil galley plug out, my cold oil pressure was about what it was with the plug in place - about 65 PSI. After about five minutes it would fall to about 15 PSI, and after 15 minutes - hot it was about 8 - 9 PSI and would not climb much past 20PSI.

Amazing how much pressure cold oil will build.

 

[PhilM]

U do the Weber's cam route?

I love their setup!

 

[ijames]

About the warm oil thing:

Of course it is important to warm up the engine before hitting it but if anybody doubts what cold oil is like get this...

Even with one oil galley plug out, my cold oil pressure was about what it was with the plug in place - about 65 PSI. After about five minutes it would fall to about 15 PSI, and after 15 minutes - hot it was about 8 - 9 PSI and would not climb much past 20PSI.

Amazing how much pressure cold oil will build.

That was the gallery plug after the front cam bearing, right? Also says how restrictive that passage must be.

 

[Blown&Injected]

Hey Carl what's up man? Tuesday sneaked in on the first of the month this month - Got to catch up with you on e-mail.

Yes, it was the galley plug on the left side of the block so the oil, I think, had only the groove in the block's front cam bearing journal to flow from the pump side to the left side of the block. I think it only feeds the lifters and the top on that side.