Datsun Roadster Forum-311s.org

Hello all,

Anyone have experience with cross drilling a 3 main crank? In the race motor we are having issues with bearings failing. We are only running up to 6.5k or so and have lots of oil pressure. Assuming that it is an oiling issue does anyone have any experience that might be of use?

keith0alan wrote: Thu Mar 15, 2018 4:29 pm Hello all,

Anyone have experience with cross drilling a 3 main crank? In the race motor we are having issues with bearings failing. We are only running up to 6.5k or so and have lots of oil pressure. Assuming that it is an oiling issue does anyone have any experience that might be of use?

I have no experience but was just reading exactly about what Col Hauser did about it just a few days ago HERE ,
Maybe that will be useful to you

Here what it says on the page
The 1600 engine had a very sturdy bottom end in terms of strength especially the 5 main engine. However that made it a good street engine but not so good as a race engine. For example we found that the bearings in the 3 main would last up to about 7200 RPM, while the 5 main was no good over about 6700 RPM. So what to do? Something had to be done to the rod bearing oiling system. A friend named Ron Frazer and I got our heads together and decided to do something after he had rod bearing failures on two engines he was running on the dynamometer. We couldn’t agree on the way to solve the problem. So we decided that each would do it his way. Both worked. Ron only ran 5 main engines so his way worked OK I ran both 5 main and 3 main engines and found that the 3 main was a little lighter and just as, if not more reliable than the 5 main. To keep from throwing rod bearings, (burning them out), I redrilled the crankshaft, both the rods and the mains.

Click Here for Crank Modifications
CLICK HERE FOR A DETAILED EXPLANATION OF JOE'S CRANK MODIFICATIONS

The mains I just cross drilled, but for the rods I had to drill two holes, one on each side of the crank pin to intercept the original drilling. I then plugged the original hole outside where the new holes intercepted the old hole. This method completely cured the rod problems and rod and main bearings would last a whole season. The stock connecting rods were pretty sturdy but after having one break I made it a habit to change them about every other season.

Thank you very much. Anyone else have any thoughts on this?

You should do it.

The following is a cut and paste from the nearly now defunct Datsun Roadster Racing forum. http://www.risensonracing.com/forums/in ... ddeea7bf39

I wrote this in 2009, so it's a tad dated, but it is still good info and may help you. Follow the thread and you'll get the whole idea.

End the bottom end blues

Postby Bill Wessel » Sat May 23, 2009 1:27 am
Something Al said in the race results folder got me thinking that folks really shouldn't be having these issues with the 3 and 5 main bottom ends anymore. Given proper care and feeding (ie, oiling) you should be able to put this behind you. I shall try to provide links to the descriptions for the mods to keep you on the track and off the stands.

For the 3-main and 5 main R16, Col. Joe provided an excellent description and Rob Beddington posted it here: http://www.datsun.org/fairlady/JoeEngine.htm
Joe also mentions some aspects of the 5 main engine but ran the 3 main engine primarily, so he concentrated on that. I continue with the 3 main doing my cranks in this way and having good luck keeping them alive season after season. I've seen this method also described in A. Graham Bell's book Four-Stroke Performance Tuning, which I highly recommend. Bob Waar also diagrams how to do it in his book How to Hotrod and Race your Datsun. Your local library loan can locate you a copy within two weeks. I also drill out the center 3-main bearing shell oil hole to match the hole feeding in from the block. The only issue I've had with the 3-main is the rarity of main bearings, but 5-main and rod bearings can be readily bought. I always get quality NDC bearings direct from Yamato-Shokai in Florida.

For the 5-main U20, there was at one time printed a Datsun Performance Guide put out by Nissan Comp. In it it had such things as R and U series special parts, oil cooler kit, optional trans ratios, front disk drilling, A-frame bolt replacement, valve grinding, and a U20 oil flow improvement that described how to improve the oil flow. I've searched for a pdf copy on-line and came up empty. I'm sure some of you know to what I'm referring and maybe know of a link somewhere. I only have a photocopy I acquired somehow over the years. The gist of this mod is to even out the flow to the #2 and #4 main bearing and involves punching out the oil pump drive spindle bushing, then drilling out the passage from the main oil gallery to the #2 and #4 main to 0.332", Q drill bit (but not past the point where the passage angles up to feed the main). Thoroughly clean everything and replace the pump spindle bushing.

I can't speak to this mod because I've not prepped a 5-main R16 or U20 (and #2 and #4 main don't feed anything), so it seems to me that the afore mentioned mains cross drilling and rod journal drilling applies since regardless 3 or 5-main, U20 or R16, the center main feeds #2 and #3 rods and invariably it's one of those rod bearings that spins. So cross drill the mains that feed rod journals and drill the rod jounals into the main feeds as described. Does this machining cost $$$? yes...but then what's the cost of a spun rod or blown block? If you wish to twist to > 8K, you got to pay to play....

Good luck and good laps!

Postby Sidney Raper » Sat May 23, 2009 2:35 pm
If anyone needs them, I have a couple of 5 main cranks and blocks. CHeap!!
Sid Raper
1964 1500 (project car - to be a driver)
1967 2000 (driving project - to autocross one day...)
plus loads of Roadster stuff....


Postby Albert Gast » Sun May 24, 2009 6:25 pm
hi bill ; thanks for the post an oiling problems . went back through joe's writing on crank prep and found my copy of the datsun performance guide . i have been doing the mods to #2 and4 gallery passages . on the U20 ,the rods and mains are all cross drilled except #3 main that does not feed a rod . so there are four mains feeding 4 rods . before i sent the crank off to the machine shop i enlarged the holes and passages somewhat using a good h.s.s.reamer instead of a drill . this gave a nice bright finish to the passages . happy with that .
the last motor we added a spray bar for extra oil to the cam without enough restriction . this also starved the rod bearings . this will be fixed .
now to the big question . how large should each passage be to ensure proper and even pressure and flow to all the bearings?????
sam has a copy of how to hotrod your datsun , will read up on that .
i will be thankfull for any thoughts and direction you may have .
regards ; al gast


Postby Bill Wessel » Tue May 26, 2009 11:18 pm
That's what I get for trying to speak to the U20 crank without even having one for reference on the shelf. It's only the 5-main R16 where #2 and #4 main feed nothing.

Hence the mod in the Performance Guide for #2 and #4 main is specific for the U20 only.

As to how big to go, the Performance Guide says 0.332", ~8.5mm for the passages leading to the mains feeds.

I drill out the bearing shells to match the feed holes in the block and then cross drill the mains as well on the 3-main R16. The hole in the block (#3 main) is about 17/64 - 9/32", ~7mm, whereas the hole in the bearing shell is only about 13/64, ~5mm. So I drill the center main hole in the shell against the block to 9/32", ~7mm. The last cranks I had machined were cross drilled through at only 3/16", ~4.75mm, though the holes start in at ~1/4", ~6.5mm*. The drilling on the rods journals (per Hauser, Waar and Bell) are 5/32", ~4mm. with a 3/16" pilot*. This was done off a sample of Joe's crank (thanks Joe!).

*as Joe points out, the crank is hardened, so you must first drill through the hardening with a carbide bit.

Hope that helps. It's worked for me.

Postby Mike Poorboy » Tue May 26, 2009 11:41 pm
Hey Guys,
One of the local guys has a Vern Colvin built U20. It has been close to 10 years, since I have been over to his place to see his car and the motor. It did come with a cam spray bar on it. I need to ask him if he got a build sheet with the car. I know he had reciepts that came with the car with the rebuild cost from Vern. He is palnning on bring it up this way on Fathers day weekend.


Postby Randy Carter » Wed May 27, 2009 8:23 am
Bill and Al,

Thanks for all of the information. This is really a hot topic in my garage right now.

Al, please email me a copy of the Datsun Performance guide.

Thanks,

Randy

Postby Mike Poorboy » Wed May 27, 2009 12:07 pm
With the discussion of oiling, and the increase of passage sizes. Is the factory pump able to meet these additional requirements ? I know the
dry sump system can be adjusted to do it, but what are the options with the factory pump other then pressure changes ?

Mike


Postby Bill Wessel » Wed May 27, 2009 7:47 pm
The factory 2L pump is all I've used to the present. I set mine as Joe mentions in his post to ~60psi. You must make sure that the shaft spins freely when building the engine. In other words, when you first bolt in the pump, make sure that the shaft spins freely in the bushing and doesn't bind as you draw down the bolt and nut on the stud (1600). On a recent build, I could not get the pump to spin free no matter what I tried in terms of positioning, gasket, or fasteners. In the end I changed the pump body. Problem solved, but had I not, the increased parasitic drag would have been fatal, in terms of lost HP and possible broken cam.

Bill

ps. Joe made one more mod in the 1600 to the factory pump which was to place a spacer block of ~0.5" between the inlet steel net and the housing and a corresponding small extension (chamfered on the sides) on the inlet tube inside the net to insure that the draw was off the bottom of the comp pan and avoid sucking air in hard prolonged cornering (carousels). I always try to keep the oil to the top mark on the stick. I have seen the pressure drop rounding the carousel at RA when the oil level was below the top mark. Not a comforting sight!


Postby Albert Gast » Wed May 27, 2009 9:27 pm
this is great stuff!!! been really hard at a lot of things and taking the time to check it out . we use a pickup from a VW with the comp pan and the fully baffeled pan set up with the trap doors . will make sure the pump spins freely before final assembly . found that passages between the pump and block are miss matched , and the passage before the filter block were not drilled to match . going to ream all the oil passages ,and match the intersections . plus ream over size .
sending the block out to be align bored . hope the machinist can repair the crank i sent him as i have only one more good crank left in stock
this post is helping out a great deal . getting me thinking and doing things that should have been taken care of all along . every thing that we can think of will be checked . the old saying " you can be own worst enemy
' may apply here .
thanks a lot bill ;
al gast

Postby Zriley510 » Mon Jun 01, 2009 3:36 pm
Here is a link to the 1500/1600 PDF. (10+MB) It is a direct link to the file.
Download will begin immediately.
http://datsun.org/roadster/resources/sharp1600.pdf
(some PDF readers will try to open the file for reading if you click the link-
to save the file to your computer, right-click the link and choose "save target as"

Here is a link to the page that contains a download link to the 2000 Prep PDF.
It appears to be the 1500/1600 manual updated with 2000 info. (13+MB)
The same downloading instructions from above
apply to the link on this page.
http://datsun.org/roadster/resources/compmanual.html

Also, I have several copies of the How to Hotrod your L engine books in stock.

Regards,

Riley
8004432117
parts
at
lynchburgnissan
dot
com

Postby Randy Carter » Wed Jun 03, 2009 7:12 am
Riley,

Thanks for the link.

Randy

Thanks. The cross drilled crank is in the car and off to it's first race this weekend.

My buddy that lives here in Hood River knew Col. Joe from racing Roadsters in SCCA. Russ was just starting out as a pilot for NW Airlines and was based in Minneapolis. He flew to Friendship (BWI) and would lay over in MD and go over to Joe’s house and work on various parts that he would bring with him from MN. He was telling me about how Joe would cross drill the 3 main cranks by hand with just a drill motor, no press. Same guy also has a photo album full of old racing with Paul Newman. Fun to look at over cold beverages.

hey thanks for re-posting the thread...hope it has worked for you. No news good news and good laps! (I should get on here more often...)

see you at the track,

Bill

So far so good on the first crank. Will know for sure in a few months when the engine comes back apart for a refresh. Currently working on doing a second for the spare motor. This is no doubt the hardest single job in building a motor. Heads take longer but crank drilling is way more stressful.