#5 main oil plug....not used in Hyd Roller SB's?
#346384
06/14/09 10:06 AM
06/14/09 10:06 AM
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Posts: 9,892 Weddington, N.C.
Streetwize
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This 318 block is an 88 Hydraulic roller, I'll be running a 236/240 @.050 Comp XE grind spinning it about 6200-6500. I noticed when I tore it down there was not the typical Plug in the #5 passeage that restricts the oil from going directly to the lifters... so no I'm wondering should I leave it out, plug it or if anybody knows any tricks for these Hydraulic roller motors. I've done a lot of smallblocks but mainly older 340's and 360's that all had the plug. I always open up the main cap oil passage and pump discharge hole to 1/2" and was going to open up the main saddles a tad, but knowing a lot of you are racing these later blocks I figured I'd ask for any tips-n-tricks you guys might use. Leaving the plug out drops the oil pressure and diverts some oil that would normally pump directly through the mains which was why the plug was normally used, but it's got me wondering if anybody drills the plug to allow some oil through. I'm going to run one of the Kevko rear sump pans (pretty nice stuff, they do mainly circle track)and if you don't have t orun a center sump it's arguably a lot more 'bank for the buck' than the 30 yr old Milo or Moroso design and pick-ups and a ported HV pump. http://www.kevkoracing.com/mopar.htmBTW, one little 318/341 nuggett to pass on....I set the crank in it to mock up the slugs on the aluminum rods to check clearance....both bottom sdies of the bores need to be 'tootsie rolled' to clear the fatty rods....the downside to a small bore that wouldn't even be an issue with a 4+ inch bore block....the price of being different I guess
Last edited by Streetwize; 06/14/09 10:13 AM.
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Re: #5 main oil plug....not used in Hyd Roller SB's?
[Re: dizuster]
#346388
06/14/09 07:26 PM
06/14/09 07:26 PM
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Streetwize
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Umm....no, ALL the oil won't bypass the filter but some percentage does....it would all bypass if the filter was somehow totally blocked though.....it splits the hydraulic circuit, most goes through the filter but some bypasses. I thought that it was as you said until I sprayed water down it while cleaning the block. My question is what was the original purpose? Is it another hold-over from the Poly (like the lifter bore angle?)
I'll put the plug in but I'm just curious if they used this bypass (for whatever reason) in the later Hyd roller blocks.
Last edited by Streetwize; 06/14/09 07:28 PM.
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Re: #5 main oil plug....not used in Hyd Roller SB's?
[Re: S/ST 3040]
#346390
06/14/09 07:44 PM
06/14/09 07:44 PM
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I was just wondering if that circuit had a purpose inthe old poly "a" motor block...the LA (Late A) is essentially the same block design as the old "polysperic" 318 of the early 60's, they basically adapted wedge heads to the old block.....believe it or not I'm just wondering what the original purpose of the bypass circuit was. Spent 2 hours clearancing for the Aluminum rods, it would have been less work to clearance a 4.25" arm
Last edited by Streetwize; 06/14/09 07:46 PM.
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Re: #5 main oil plug....not used in Hyd Roller SB's?
[Re: S/ST 3040]
#346392
06/14/09 09:34 PM
06/14/09 09:34 PM
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Streetwize
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What you say is true....Except the bypass route is very small internally and all the oil coming directly out of the pump discharge couldn't possibly pass through at such a high flow rate so the circuit has to "split" with the majority of it passing through the much larger filter passage. However the idle oil pressure (if you measured from the conventional sending unit location) will be much lower as there's not a lot of volume through the pump at idle speed. That's usually a tell-tale whether somebody forgot to put it in....low O/P at idle. I didn't mean to go off topic (especially in my own thread ) I was really just wondering if there were any changes to the later hyd roller motor oil circuits I wasn't aware of, like maybe they needed more or less oil up top compared to a flat tappet. Like i said all the ones I've built before were pre Roller eras....and most of them had MUCH BIGGER BORES!!
Last edited by Streetwize; 06/14/09 09:54 PM.
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Re: #5 main oil plug....not used in Hyd Roller SB's?
[Re: dizuster]
#346394
06/15/09 11:11 PM
06/15/09 11:11 PM
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dizuster
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Also, oil WILL NOT be filtered without the plug. The pressure in the vertical oil feed is constant. Any pressure causing oil to flow to the filter, would be cancled by the same pressure pushing back against filtered oil. Zero pressure differential = Zero flow.
Also, there is no severe restriction in the vertical oil shaft until after the RH main oil gallery feed. (except the small step where the plug is pressed in.)
If anything without the plug the oil pressure will be better at the sending unit because it doesn't have to make the four 90 degree turns to get to/from the oil filter, not to mention the restriction of the oil filter itself.
Now leave the rear plug out of the driver side oil gallery, and low oil pressure at idle is a tell tale sign it was forgotten.
(by the way, you might need to click "Attachment" to read these pictures better.)
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Re: #5 main oil plug....not used in Hyd Roller SB's?
[Re: Streetwize]
#346395
06/16/09 11:00 AM
06/16/09 11:00 AM
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Posts: 8,547 State College, PA
RyanJ
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Quote:
This 318 block is an 88 Hydraulic roller, I noticed when I tore it down there was not the typical Plug in the #5 passeage that restricts the oil from going directly to the lifters...
Somebody just forgot to put the plug in in a previous life of the engine. It's a 9/16" cup plug ~ .572-.573" OD is the appropriate Pioneer brand cup plug (they offer 9/16 plugs in multiple OD's, 9/16" does not always mean .5625" apparently to plug companies)
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Re: #5 main oil plug....not used in Hyd Roller SB's?
[Re: b1dartsport]
#346397
06/16/09 12:28 PM
06/16/09 12:28 PM
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Streetwize
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Thanks for the replies.... so if what is stated is true....this block (which appeared to never have been opened before), had oem head gaskets, etc.. Are you saying this motor would have never had oil circulating through the filter??? The bores still had cross hatch in them....could this had been a factory oversight? Thanks for the info....guess I never really thought about it cause I always stuck the plug in....when i saw it missing and it being a roller block it got me to so I trhought I'd post it up!!
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