Ok, Jim - how about some hints for eliminating the R16 center main and #2/3
rod oiling problems. I have never had problems until last year, then I had
more than my share, although most , if not all of it was my fault.
I've always run a crank that was cross-drilled on the center main and all
rod journals, and haven't had problems when bearings changed every 3 race
weekends or so. The problems started when a rubber plug was left in the
oiling system when reassembled and lodged in the center main feed passage.
Actually, the engine ran an amazingly long time - I ran for all the
practices and for about 5 laps of the national at Pocono before the engine
seized. I was in a rush with the replacement crank and didn't get it
cross-drilled - that one lasted for practice and half the race at Bryar,
(dn. because the pivot pin for the shift lever fell out after the cotter key
that holds it in sheared) then practice and half the race at Mid-Ohio (lost
the center rod bearings and some other unrelated stuff).
Now I have to get the two lunched cranks built up (both are not cracked and
straight). I'm looking for suggestions on that. My current thinking is get
them welded up at a shop that specializes in that - I've found number of
them on the internet and even a shop that has rebuilt cranks in stock for
older Datsuns (not R16s or U20s alas). I also have considered some other
forms of rebuilding the surfaces like plasma spray (there's a local place
that does that) but I don't know if plasma spray is good for cranks or if it
will work for the .030 - .040 that these have to have put on them.
After rebuild I want to get the one with stock passages cross-drilled. I am
hoping that the rebuilding shop can do that - they will have the other one
for a model.
Now the questions - what else can be done? I got the impression from your
note that there were a number of tricks. Should the center main passage be
enlarged? How much? Should the crank passages be enlarged (if so how
much)?
BTW, both cranks have a tapered channel machined for about 3/4 inch on the
leading side of the center main feed hole that tapers to nothing. On my
Abarth cranks some years ago, I had a channel machined all the way around to
improve oil flow to the center main and to the 3/2 rods (same type of 3 main
design). Has anyone tried that with the 3 main R16s? What about drilling up
thru the web between rod 1 and 2 to tap into the #1 feed (that sounds pretty
tough to do to me, but I'd try to get it done if has been tried and works).
What pressures are recommended? Any thoughts about clearances for rods and
mains?
I aim to run ~70/75 lbs at revs over 3 to 4 thousand. I shift at ~7500,
occasionally (maybe 5/10% of the time) as high as 7700/7800 depending on
circumstances. I've heard that Cool Joe said there's no performance reason
to go over 7500/7800. The last several seasons I've used 15/50 Mobil 1 which
seems to add a significant amount of top end power. I'd prefer not to use
Redline - Mobil 1 is expensive enough and has seemed to work ok until last
year.
As long as as I'm asking - any thoughts on reducing cam wear - I've not been
getting much life from the cast cams/stock followers. The followers get
chewed up, then start to eat the cam.
That's all I can think of for the moment (probably more that enough). Any
positive help, thoughts, ideas, etc appreciated.
Thanks,
Pete Dehmler
> From: Jim Tyler <toplessdatsun@ga.prestige.net>
> Reply-To: Jim Tyler <toplessdatsun@ga.prestige.net>
> Date: Tue, 02 May 2000 16:48:26 -0400
> To: datsun-roadsters@autox.team.net
> Subject: Re: Why #3?
>
> Don't lump the number 2 or 3 rod bearing failures from the r-16 (GP) into the
> U20.
> The U20 doesn't have any inherent cylinder faults like the 1600.
> Those of us who have built a lot of modified R16 engines, know about the 2/3
> problem. It is inherent in the oiling system of both the 3 main, and
> 5 main R16 designs. With quite a bit of money and specific machine work it
> can
> be eliminated. Nissan eliminated it for us in the U20 design.
>
> Jim
>
>
> What Mark wrote below only applies to R16's:
>
>
>
> Mark van der Hoek wrote:
>>
>> Paul wrote:
>>>
>>> It would appear that it might have something to do with the oil feed
>> also?
>>> I have been working with SCCA GP racer Jim Sloan this spring. He was
>>> commenting that #3 crank journal is always the one that burns when he loses
>>> a motor on the track. He quickly explained the stock oil flow through the
>>> crank, then talked about the modifications he currently makes ( enlarged
>> oil
>>> passage in crank and journal bearing ) and went on to talk about the
>>> possibilities of cross drilling the crank for still better oil feed.
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