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W2 stroker build - too much main bearing clearance? #2964036
09/14/21 02:24 PM
09/14/21 02:24 PM
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Windsor, ON, Canada
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Diplomat360 Offline OP
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Looking for some advice.

These are the numbers for my current build, using forged Eagle crank, .020" under on rods and factory size on the mains. While the rods look pretty good, the mains are a little big, at least based on everything I have always read and heard: 0.001" per 1" of journal diameter, so I should be at 0.003" max, but is that extra 0.0005" going to be an issue here?

ACTUAL BEARING CLEARANCE
Main #1 2.8097 2.8126 0.0029
Main #2 2.8092 2.8127 0.0035
Main #3 2.8095 2.8129 0.0034
Main #4 2.8095 2.8129 0.0034
Main #5 2.8096 2.8130 0.0034

Rod #1 2.1041 2.1062 0.0021
Rod #2 2.1040 2.1064 0.0024
Rod #3 2.1040 2.1064 0.0024
Rod #4 2.1041 2.1064 0.0023
Rod #5 2.1041 2.1064 0.0023
Rod #6 2.1040 2.1060 0.0020
Rod #7 2.1040 2.1063 0.0023
Rod #8 2.1041 2.1064 0.0023

For comparison, here are the numbers for the cast 0.010" under (crank & stock rods) in my old 360 build:

ACTUAL BEARING CLEARANCE
Main #1 2.7997 2.7960 0.0037
Main #2 2.7997 2.7960 0.0037
Main #3 2.7995 2.7960 0.0035
Main #4 2.7994 2.7960 0.0034
Main #5 2.7994 2.7960 0.0034

Rod #1 2.1143 2.1125 0.0018
Rod #2 2.1148 2.1125 0.0023
Rod #3 2.1143 2.1125 0.0018
Rod #4 2.1149 2.1125 0.0024
Rod #5 2.1143 2.1125 0.0018
Rod #6 2.1148 2.1123 0.0025
Rod #7 2.1143 2.1125 0.0018
Rod #8 2.1148 2.1125 0.0023

This motor ran with a 15W40 oil, great oil pressure, summary only weekend "toy" use.

Should I be worried here and should I start looking at the 0.001" thicker main bearings? I have the 3/4 grove FM 120M pieces about to go into this block otherwise.

Thanks!

Re: W2 stroker build - too much main bearing clearance? [Re: Diplomat360] #2964055
09/14/21 03:12 PM
09/14/21 03:12 PM
Joined: Mar 2003
Posts: 9,092
Rogue River, OR
Jeremiah Offline
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What are you using to measure it? Those numbers look okay to me especially for a drag engine. Over the years I haveheard a ton of people say not to run them that loose.
Reasons stated included lack of a hydrodynamic wedge being created by the oil, etc.

On the other hand I know quite a few people that have embarrassingly loose engines and they seem to do just fine as street/strip engines. Perhaps a road race/endurance type of engine would be more susceptible to issues as the oil gets really warm? Maybe some of the guys with automotive engineering backgrounds can chime in on that side of things.



Re: W2 stroker build - too much main bearing clearance? [Re: Jeremiah] #2964061
09/14/21 03:23 PM
09/14/21 03:23 PM
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Marion, South Carolina [><]
an8sec70cuda Offline
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I'd rather it be loose than tight. I'd run it. twocents


CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
Re: W2 stroker build - too much main bearing clearance? [Re: an8sec70cuda] #2964094
09/14/21 05:06 PM
09/14/21 05:06 PM
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So. Burlington, Vt.
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fast68plymouth Offline
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I’ve found that the “calculated clearance” and the “measured clearance”(bearings set into housing bore, torqued to proper spec, measured with a bore gauge that is set and zeroed to shaft diameter) often don’t agree with each other.

I use the “measured clearance” method.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: W2 stroker build - too much main bearing clearance? [Re: Diplomat360] #2964117
09/14/21 06:28 PM
09/14/21 06:28 PM
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Windsor, ON, Canada
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Diplomat360 Offline OP
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Guys,

All numbers are MEASURED, meaning, here is what I used:

1) the main and rod bearings were installed, torqued to the required assembly readings:
- mains => 110 ft-lbs with studs
- rods => 85 ft-lbs to achieve approx. 0.0051-0.0055 both stretch with Eagle spec'ed ARP 2000 bolts

2) the dial bore gauge with 0.0001" precision was used to capture the measurements of the installed bearing diameter

3) the micrometer with 0.0001" precision was used to catpure the measurements of actual journal sizes

So these are all real numbers.

I attempted to record (for the purposes of blueprinting the engine) as much detail as possible.

Re: W2 stroker build - too much main bearing clearance? [Re: an8sec70cuda] #2964131
09/14/21 07:33 PM
09/14/21 07:33 PM
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Tulsa OK
Bad340fish Offline
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Originally Posted by an8sec70cuda
I'd rather it be loose than tight. I'd run it. twocents


I have heard if its to loose only you will know, its its too tight everyone will know during the track cleanup lol


68 Barracuda Formula S 340
87 "Chrysler" Conquest
Re: W2 stroker build - too much main bearing clearance? [Re: Bad340fish] #2964138
09/14/21 08:04 PM
09/14/21 08:04 PM
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Apollo, PA.
B1MAXX Offline
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my Indy block is almost .005. It never had an issue. Actually it 's probably good to have a little extra main clearance, more to feed the rods.

Re: W2 stroker build - too much main bearing clearance? [Re: Diplomat360] #2964209
09/14/21 10:38 PM
09/14/21 10:38 PM
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Bend,OR USA
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Cab_Burge Online work
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I've never heard or seen a rod bearing or main bearing spin from being to loose, not so on being to tight tsk
Your good on those clearances, I run similar on all my motors up

Last edited by Cab_Burge; 09/14/21 10:38 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: W2 stroker build - too much main bearing clearance? [Re: Cab_Burge] #2964211
09/14/21 10:44 PM
09/14/21 10:44 PM
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Fancy Farm Ky
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wyoming Offline
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Your good IMHO, thats about what Id shoot for clearance

Re: W2 stroker build - too much main bearing clearance? [Re: wyoming] #2964230
09/14/21 11:29 PM
09/14/21 11:29 PM
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MI, usa
dvw Offline
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Wouldn't scare me at all. Run it.
Doug

Re: W2 stroker build - too much main bearing clearance? [Re: dvw] #2964239
09/14/21 11:56 PM
09/14/21 11:56 PM
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Howell, Michigan
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Hemidavey Offline
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Your good to go, Start that thing up lets hear it rumble !!!

Re: W2 stroker build - too much main bearing clearance? [Re: Hemidavey] #2964244
09/15/21 12:24 AM
09/15/21 12:24 AM
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Washington
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madscientist Offline
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I wouldn’t run it that loose on the mains. It’s not 1975 any more. Even the rods are a bit loose for me. I’m glad the oft repeated “if it’s loose only you will know it” wives tale was brought up. With 1975 oils you need Grand Canyon clearance like that. Run a modern oil and close up the clearance. It’s the 21st century.


Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
Re: W2 stroker build - too much main bearing clearance? [Re: Diplomat360] #2964302
09/15/21 09:14 AM
09/15/21 09:14 AM
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W. Kentucky
justinp61 Offline
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My clearances are similar in my 434, .0022-.0025” with a 2.00” journal. The mains are .003-.0032”, the crank has 340 size mains. It’s been together for five years with no issues.

Re: W2 stroker build - too much main bearing clearance? [Re: madscientist] #2964324
09/15/21 10:37 AM
09/15/21 10:37 AM
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Windsor, ON, Canada
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Diplomat360 Offline OP
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Originally Posted by madscientist
...With 1975 oils you need Grand Canyon clearance like that. Run a modern oil and close up the clearance. It’s the 21st century.

This point here that madscientist brings up is part of the reason why I'm hesitant to run with that clearance. My intention with this build was to move to a lighter oil, something like a 10W30 for example instead of the 15W40. There is some obvious hp gain to be had by doing so, although quite frankly I doubt it would have a noticable impact given my intended use, that being a street car.

Since I am running a HV oil pump that provides more feed, with the larger clearance the oil loss that's occuring there is most likely made up for by the higher volume. Probably the reason why my old 360 motor had a spotless looking crank journals when I took everything apart. That feels a bit like a band-aid fix though...LOL! whistling

Any suggestions as to what alternative bearing set I could look at?

I do not want to re-grind the crank to something like 0.010" under on the mains. I will measure the main housing sizes (which I did not do so far), perhaps they are a tad wider and are NOT compressing the bearings sufficiently?

The FM 120M bearing spec calls for a max of 0.0027" clearance, so I'm past that value. Unfortunately they do not have a 0.001" larger size available, which would mean I'd need to look at an alternative in that size.

Re: W2 stroker build - too much main bearing clearance? [Re: Diplomat360] #2964337
09/15/21 11:21 AM
09/15/21 11:21 AM
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W. Kentucky
justinp61 Offline
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Check and see if King offers a -.001” bearing. I know they made a +.001” main.

Re: W2 stroker build - too much main bearing clearance? [Re: Diplomat360] #2964372
09/15/21 12:43 PM
09/15/21 12:43 PM
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Bend,OR USA
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Cab_Burge Online work
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I've used Valvoline 5W20Wt oil in my street and strip motors for dyno testing for years due to no HP gain or loss on oil temps. from 80F to 220 F with loose clearances like I posted already.
As far as synthetic oils I don't like them due to many bad results from switching to them during dyno tests years ago work
Maybe I will try again, maybe not shruggy


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: W2 stroker build - too much main bearing clearance? [Re: Cab_Burge] #2964378
09/15/21 01:04 PM
09/15/21 01:04 PM
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I would be more worried about the tight rod bearings in your old engine. Get that sucker together and “send it”. The day I worry about .0005 to much clearance I quit.


1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time




Re: W2 stroker build - too much main bearing clearance? [Re: justinp61] #2964428
09/15/21 03:18 PM
09/15/21 03:18 PM
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Windsor, ON, Canada
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Diplomat360 Offline OP
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Originally Posted by justinp61
Check and see if King offers a -.001” bearing. I know they made a +.001” main.

Funny (but sad) story about King bearings here.

So a few months back, alright, more than a year now since I started planning this and acquiring the parts, I had originally decided to give the King stuff a try. I ordered both the mains and the connecting rod bearings from Summit...and waited....waited, waited some more. After a couple of months I got tired of it...sure, I didn't need them at the moment, but I was itching to get the block over to the machine shop.

Needless to say, I cancelled that order and shipped the FM stuff straight to the shop the very next day. What irked me about this was that I actually called King directly about this delay, gave them my Summit order (which they found), and was told these would ship out "...within another week...". That was around the tail end of the first "wait" event...lol, it never got any better afterwards. So from a customer service perspective I wasn't impressed.

So now looking at this again I see that I can get a 0.0005" oversized bearing (choice of up or down as well, so that's nice), unfortunately their ETA shows December timeframe right now. Based on my prior experience with King I trust that statement...NOT!!!

Besides, really if all I'm making up is 0.0005", well like pittsburghracer said, I probably should find something else to do instead! ha...

Gents, appreciate everyone's great feedback. I'm going to run with what I have, will measure the housing dimensions as well, just to know what those are.

Thanks!

Re: W2 stroker build - too much main bearing clearance? [Re: Diplomat360] #2964450
09/15/21 04:54 PM
09/15/21 04:54 PM
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Posts: 11,678
W. Kentucky
justinp61 Offline
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It looks like I may need to have parts in hand before I tear my engine down this winter.

Re: W2 stroker build - too much main bearing clearance? [Re: Diplomat360] #2964458
09/15/21 05:24 PM
09/15/21 05:24 PM
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Moparteacher Offline
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Originally Posted by Diplomat360
Originally Posted by justinp61
Check and see if King offers a -.001” bearing. I know they made a +.001” main.

Funny (but sad) story about King bearings here.

So a few months back, alright, more than a year now since I started planning this and acquiring the parts, I had originally decided to give the King stuff a try. I ordered both the mains and the connecting rod bearings from Summit...and waited....waited, waited some more. After a couple of months I got tired of it...sure, I didn't need them at the moment, but I was itching to get the block over to the machine shop.

Needless to say, I cancelled that order and shipped the FM stuff straight to the shop the very next day. What irked me about this was that I actually called King directly about this delay, gave them my Summit order (which they found), and was told these would ship out "...within another week...". That was around the tail end of the first "wait" event...lol, it never got any better afterwards. So from a customer service perspective I wasn't impressed.

So now looking at this again I see that I can get a 0.0005" oversized bearing (choice of up or down as well, so that's nice), unfortunately their ETA shows December timeframe right now. Based on my prior experience with King I trust that statement...NOT!!!

Besides, really if all I'm making up is 0.0005", well like pittsburghracer said, I probably should find something else to do instead! ha...

Gents, appreciate everyone's great feedback. I'm going to run with what I have, will measure the housing dimensions as well, just to know what those are.

Thanks!


Is that .0005" per shell or .0005" for upper and lower combo? If it's .0005" per shell then you can always replace just one shell with an oversized, without issue.
One of two ways to compensate for the loose clearances IMO, run a heavier oil or run an HV pump, but probably not both. If you've got HV pump in place already then you may want to sneak-up (actually down) on the viscosity. Start with maybe a 20w50 and observe idle pressure at full temp and then move down in viscosity until you pressure starts dropping below desired at idle. All testing done at operating temp.
But, there is definitely a correlation between journal area, clearance and sufficient hydroscopic wedge to protect the journal. Oil pressure alone doesn't determine the level of protection.
As for a HV pump, reconsider if you choose to close-up those clearances, and avoid high pressure all together (not that you ever stated such).
Here's a fwiw.
I recently primed a fresh 383 on the engine stand with 6 quarts in a Hemi pan with Milodon full windage tray and IJ crank scraper. Valve covers and valley tray off. HV ported oil pump with the MIlodon high pressure spring. Similar clearances. Quickly gained 80psi and all looked good so I continued to run the drill for a few more minutes while observing. It took about three minutes and I started to get splurging (air bubbles) coming around the flat tappet .0005" undersize lifters and out the spray holes on the ductile rockers yet the pressure gauge held steady at 80psi. The longer I ran the drill, the worst the cavitation in the pan yet maintaining 80 psi on the gauge the whole time. I was shocked! I then switched to a standard pressure spring in the pump. 60 psi, similar more-than-sufficient flow rate out the rockers and around the lifters, but after nearly 20 minutes no air bubbles, cavitation or drop in max pressure of 60psi. 10w30 Joe Gibbs Driven break-in oil FWIW.

I doubt I'll ever run a HP oil pump spring again and the next build will seriously reconsider the HV.

Good luck on whatever you choose.

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