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Hot street 343 build

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SC397 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/13/2018 at 12:49pm
Originally posted by Red Devil Red Devil wrote:

Originally posted by PHAT69AMX PHAT69AMX wrote:

Gonna drill extra holes in the lifter valley for improved drainback? Work the front Main Cap and Timing Cover?

Often wondered if drilling holes in the valley and dumping oil onto a spinning cam, crank and rods would make it worse for oil to get back to the sump ... and maybe even toss more oil mist from below up top? Really need a low-pressure to draw oil back to the sump or rely on surface tension and gravity to drain.


That's a good question. In my opinion, I would rather direct the oil to a cam lobe than have it pool up.
017 by Rick Jones, on Flickr
Learned this one from Mr. Landis. I drill the 2 holes in the very back to 5/16" and smooth out a channel to make it a little easier for the oil to flow.
IMG_4319 by Rick Jones, on Flickr
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Jun/13/2018 at 6:20pm
Looking at it, it seems that the drilled holes would direct oil away from the am rather than onto it. All I did with mine was clean up the casting flash on the existing drain back holes, not that there is likelt be any restriction there. Is there any benefit of drilling out the oil return holes in the heads to a larger size?

Would there be any benefit in running a longer rod and a dished piston to achieve some quench in a 343? It seems you have that covered by decking the block and retaining the flat tops anyway.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jun/13/2018 at 7:10pm
The heads drain to the Lifter Valley, there has got to be a lot of oil that collects in the valley at rpm
and in the heads before it drains to the valley.  Long time ago Bulltear Matt posted what size
the head drain back holes could be enlarged to, fail to remember to what size...
I lack real world hands-on, but it just seems with high rpm drainback becomes an "issue"...
How many times have you made a mess pouring old oil too fast into a funnel into a jug ?
In the Projects Section, the dude with the awesome vintage SCCA BP car,
has the Drain Back Lines that go from Valve Covers to the Pan like in the PAS book.
In the old AMC TransAm video, when Penske & Mark D. first started with AMC Oil was a problem
which once they figured out they did much better, wonder if it involved Drainback?
It makes sense, AMC's Oil Pump outlet feeds the Lifter Galleys first, a bunch of oil
has to end up on the heads and in the valley faster than it can drain back to the pan... at high rpm anyways...
All 16 Lifters in their bores are potential "oil leaks" like loose main / rod bearings...
Lifter Bores are seldom bushed, new replacement lifter diameters maybe "compromised" to Mopar size...
Not like I "know", but I can just see how, thinking about it...
Chevs oiling from the bottom feeding the crank first if it's loose / leaks, less of an issue...
And the 3.28 Stroke 290-343 Crank is gonna just beg to be rev'd...
And agree, would look at reducing the stock .060 Deck Clearance for better Quench...
Then open up the Head Combustion Chambers to unshroud the valves to keep CR reasonable... 


Edited by PHAT69AMX - Jun/13/2018 at 7:18pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Jun/13/2018 at 7:47pm
Getting that oil past everything that rotates is the best solution.

You can EASILY store a few quarts in the valve covers and the back of the lifter gallery
under hard acceleration and at high rpm.

IMO if you have a roller cam you do not want or need any oil on the cam and crank from above.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jun/14/2018 at 7:01am
Everything is like a pendulum, swings one extreme and back. I like removing all flashings, internal and external, just seems prudent to remove the little pieces that may come loose or start the beginings of a crack.
But here is an old post that goes to the extreme end:
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: Jun/14/2018 at 9:14am
Originally posted by Trader Trader wrote:

Everything is like a pendulum, swings one extreme and back. I like removing all flashings, internal and external, just seems prudent to remove the little pieces that may come loose or start the beginings of a crack.
But here is an old post that goes to the extreme end:

Wow that's one way to "fix" things!

Just goes to show,
you never really know what the last guy did until you pull it all apart ConfusedConfusedConfused
71 Javelin AMX P-code Go pac 360/4spd/3.91's
was Green/green now T/A red w/blk leather

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Jun/14/2018 at 12:24pm
That seems like a bad idea to me.

IMO Keeping oil OFF the rotating assembly is best.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote gremlinsteve Quote  Post ReplyReply Direct Link To This Post Posted: Jun/14/2018 at 12:56pm
I agree
Keep oil off the rotating assembly
They make hi performance coatings that help do that
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