crankcase prep 101.... any hints and tips?

[Jonny Grigg]

If anyone feels that they don't want to give away any 'speed secrets' I do understand, but I was hoping I would get some useful hints and tips with regards prepping the crankcase for my race motor.

The bottom end is based around a CB Performance aluminium case (filled behind #3, raised deck and raised roof), 10mm Raceware head studs, 4 quart deep sump, Berg blueprinted pump and Jaycee pressure bypass filter. The case has also been modified for a flange crank, and has an OE oil pick up tube.

Basic things on the agenda are:

• general removal of casting flash and smoothing out inside to aid oil flow back to sump and relieve stress raisers
• enlarge oilway return on the main bearing at the pulley end
• open up the 'port' area between the cylinders to 'manage' the movement of airflow within the case
• Get the case 'decked' to make sure side-for-side the cylinder deck ht is the same
  

The main things I would like help with is the oiling system and how big to enlarge the internal 'ports' between the cylinders. I am not sure what to do with the oil control springs (I presume these should be 'locked out' using the pressure relief filter mount) and I was thinking of getting the little mod that Jaycee is selling to route the oil flow straight onto the main gallery.

Any hints, tips, photos and general guidance would be gratefully received. I have spent alot of time trawling Mike Sheldon's website, which has some great detail on it (especially John Troxell's motor build), but anything further would be great.

Thanks,

Jonny 

[richie]

If anyone feels that they don't want to give away any 'speed secrets' I do understand, but I was hoping I would get some useful hints and tips with regards prepping the crankcase for my race motor.

The bottom end is based around a CB Performance aluminium case (filled behind #3, raised deck and raised roof), 10mm Raceware head studs, 4 quart deep sump, Berg blueprinted pump and Jaycee pressure bypass filter. The case has also been modified for a flange crank, and has an OE oil pick up tube.

Basic things on the agenda are:

• general removal of casting flash and smoothing out inside to aid oil flow back to sump and relieve stress raisers
• enlarge oilway return on the main bearing at the pulley end
• open up the 'port' area between the cylinders to 'manage' the movement of airflow within the case
• Get the case 'decked' to make sure side-for-side the cylinder deck ht is the same
  

The main things I would like help with is the oiling system and how big to enlarge the internal 'ports' between the cylinders. I am not sure what to do with the oil control springs (I presume these should be 'locked out' using the pressure relief filter mount) and I was thinking of getting the little mod that Jaycee is selling to route the oil flow straight onto the main gallery.

Any hints, tips, photos and general guidance would be gratefully received. I have spent alot of time trawling Mike Sheldon's website, which has some great detail on it (especially John Troxell's motor build), but anything further would be great.

Thanks,

Jonny 

To block off the factory oil plungers all I did was use both the grooved and solid at the flywheel end stacked against each other then fit the factory plug and tighten,it holds them tight in there,at the other end if you look inside the case you can see the bleed hole,just tap this for pipe plug and seal it up,then fit the plug at the bottom and you are good,  i did take some pictures,if I can find them i will post them up,and for the internal ports between cylinders

cheers richie

[Jonny Grigg]

Thanks Richie- any photos would be a great help 

[Jon]

use both the grooved and solid at the flywheel end stacked against each other then fit the factory plug and tighten,it holds them tight in there

Hi Richie, how do you regulate oil pressure? Or am I reading you wrong?

[John Maher]

...any photos would be a great help...

I've found a few things that help a lot with internal oil control and case windage.
Long stroke, high rpm engines are the most problematic and stand to gain the most from any internal mods that make it easier for oil to return to the sump ASAP.

**** EDIT****
My pics disappeared from this thread when I changed web host. I've archived my contribution here (complete with pics):
http://johnmaherracing.com/tech-talk/internal-case-modifications/

Equalising pressure between front and rear case halves improves windage and reduces the amount of oil getting beat to death by the crank.



1. Helps equalise air pressure between front and rear case halves - it's almost like clearancing the case for a fifth rod. Used in conjunction with enlarging and radiusing the port area between 1&2 and 3&4 cylinders (as seen in next pic)

2. Slight enlargement of oil return passage to sump at no1 main bearing. I also open up the drilled hole by an extra 0.5mm

3. The figures written on the bearing saddles represent difference in height from case parting line to lowest part of saddle i.e. the crank bores are not centred or true to case centre. Result: pistons don't run straight up and down the cylinders unless corrected. Amount of variance differs from case to case. Case should be bored and decked based off crank centreline, NOT case centreline.

4. Minor relief work to further improve internal pressure equalisation between front and rear halves of case. It's a minor increase in area but every little helps

5. Difficult to see in this pic... enlarge oil passageway to improve oil flow to right case half (more on this below)

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Ported case - as mentioned above


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Better view of cam oil groove mod - only lower half has been completed in this pic


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Drilling through to allow oil flow to rearmost cam journal in right case half. Also involves drilling down into the new longer hole from the saddle nearest oil pump (as per Bob Hoover's HVX mods). Main benefit is much improved oiling to the cam follower bores and will reduce lifter bore wear, especially on stock mag cases. Can be a tricky operation. See next pic for why...


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Cases often have the long cam oiling drill hole run off centre. Lengthening the drill hole on such a case can result in breakthrough in the bottom of this recessed area.
BIG problem!


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Check oil hole alignment on all bearings. More of a problem with aluminium cases than stock and definitely an issue with flanged crank bearings.
On flanged cranks with all Type 4 mains I relocate thrust to no3 and use stock Type 4 split centre bearings in no1 location . Eliminates issues with poor tolerances I've found with the sawn in half style thrust bearings and (so far) appears to work fine for long term use - even on regularly used/abused street cars. Note: the pic shows Scat supplied split no1 which was later replaced with no3 thrust mod

Hopefully some of this is of use.

If anyone feels that they don't want to give away any 'speed secrets' I do understand...

Some of my other mods are being kept 'secret' for now and reserved for customer engines  

[richie]

Heres the rear oil mod nearest pulley

Jon,I am using the pressure relief filter head with this to control oil pressure

[drgouk]

On flanged cranks with all Type 4 mains I relocate thrust to no3 and use stock Type 4 split centre bearings in no1 location . Eliminates issues with poor tolerances I've found with the sawn in half style thrust bearings and (so far) appears to work fine for long term use - even on regularly used/abused street cars. Note: the pic shows Scat supplied split no1 which was later replaced with no3 thrust mod


Hi John,
           Are you using the No 1 bearing in the No 3 spot, narrowing the timming gear, making a spacer and running 3x flywheel shims? or are you running a different system? thanks. Good info above.

[Eddie DVK]

Whoo cool info Richie and John, more pictures please  .
Very informatif. Thanks for sharing.

[mychatype3]

Great info, THANKS

[Jon]

Jon,I am using the pressure relief filter head with this to control oil pressure

Ahh, thanks! Interesting solution, is this something you have done before and have had good results with? What size oil pump are you feeding this with?

Cool info John!!

[j-f]

I've read something about Bob Hoover's modifications but don't really understand the benefits and when its necessary.

I've seen this mods on this blog http://2s-koncept.skynetblogs.be/





As shown on this pics, there a difference between an as21 and as41 case.

[Jon]

I've read something about Bob Hoover modification but don't really understand the benefits and when its necessary.

Here you go:
http://bobhooversblog.blogspot.com/search?updated-min=2007-05-01T00%3A00%3A00-07%3A00&updated-max=2007-06-01T00%3A00%3A00-07%3A00&max-results=10

[j-f]

I've read something about Bob Hoover modification but don't really understand the benefits and when its necessary.

Here you go:
http://bobhooversblog.blogspot.com/search?updated-min=2007-05-01T00%3A00%3A00-07%3A00&updated-max=2007-06-01T00%3A00%3A00-07%3A00&max-results=10

Whow, thanks JHU. I have some interesting reading for the afternoon 

[Jonny Grigg]

Thanks for all the info and photos- they are really a great help and in this case a picture does tell a thousand words....

I'm going to make a start on the case next week- it'll be nice to see the motor coming together after having most of the parts stored in my understairs cupboard for the best part of 2 years  . The wife is please to see them moving into the garage now......

I'll get cracking. 

[John Maher]

Hi John,
           Are you using the No 1 bearing in the No 3 spot, narrowing the timming gear, making a spacer and running 3x flywheel shims? or are you running a different system? thanks. Good info above.

Yes, no1 main in no3 location. Case must be machined to make no3 bearing saddle correct width (22mm).
Fortunately flywheel side of crankcase no3 bearing saddle tends to be machined flat and true - but pulley side is as cast and must be modified to accept flanged no1 bearing.
Bearing needs increased chamfer on flywheel side to account for radius ground into crank journal.
Also add four oiling slots/grooves to cam gear side of bearing, duplicating four factory grooves on stock thrust face to improve oiling on shim side.



This is same style modification Revmaster use on their aircraft engines. In aero application thrust is applied from opposite end of crank... propellor mounted on pulley end. Strictly speaking this mod isn't perfect for use in rear engined car as main thrust force (from clutch actuation) now pushes crank directly against bearing flange rather than endfloat shims.
BUT... Scat supplied split bearing works exactly the same - main difference in switching thrust to no3 location is you have full circle bearing as opposed to one chopped in two.  I've found it works fine... street driven car sees whole lot more fore and aft moevement than a pure drag motor so is a good test

In the pic you see trial cam gear (stock) I use to set everything up before transferring the dimensions across to the straight cut gear.
I use Type 4 endloat shims and set float at .005" - much less than recommended when using sawn in half style thrust bearing.
Crank mounted cam gear is step cut to accept endfloat shims and large cam gear is narrowed to prevent shim interference.

Stock split centre main bearings, same as no2 location, are used in no1 spot by the flywheel. Out of the box stock bearings are dimensionally correct, unlike many of the split flanged bearings I've measured. Right case half has to be drilled for extra dowel pin plus bearing oil hole modified to line up with case oil hole. Bearing may also need narrowing so crank journal is centred correctly.

FWIW, my theory on why split flanged Type 4 bearings fail...
Currently available Type 4 flanged bearings are not steel backed. Cut them in half and they cannot maintain correct dimension.
Flanged cranks using Type 1 size no1 mains and sawn in half STEEL backed split no1 bearings don't suffer the same problems.
This appears to be an issue with Type 4 dimension split flanged bearings only.
Scat changed their approach by offsetting Type 4 bearing centreline parting so the join didn't coincide with case centreline. I assume this was done in an attempt to stop bearing failure issues??  Doesn't appear to have worked because plenty of people have had problems with that style also.
I suspect synthetic oil also contributes to success by providing superior protection between crank and bearing thrust face.

[Jon]

How cool information is this!!! Wow! To bad we need the radius on the inside of the bearing for strength, otherwise that would be a even cooler solution.
Thanks for sharing!

[181]

If I understand well this mod is only performed on No. 2 cam bearing saddle IF you do not drill the passageways at the same time. If you drill the oil passages according to R.S.Hoover HVX Mods, you can also modify the groove on No. 3 cam bearing saddle right? It is performed to help oil flow to the right side valve lifters.

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Better view of cam oil groove mod - only lower half has been completed in this pic

[wheelerdealer]

how did you guys solve the problem with the oil gallery between cylinder 3 and 4?
Thanks
Tom

[Eddie DVK]

Any tips for Typ 4 cases?
I already did the ported case for better airflow in the case.

[Airspeed]

Any tips for Typ 4 cases?

IIRC, Mr. Hoover said in his ramblings that the type 4 case already has most all of the above mods as stock... Looks like you then understand where he got the ideas from huh? 

[Eddie DVK]

Any tips for Typ 4 cases?

IIRC, Mr. Hoover said in his ramblings that the type 4 case already has most all of the above mods as stock... Looks like you then understand where he got the ideas from huh? 

Ok thanks. Did not reed the whole articel.

[Berger]

I wonder if any of you do any modifications to the pick-up tube when a extra sump is used? Except for making it longer of course.

The "hat" on the tube is what bothers me, it must be a reduction, making the oil return slower to the extra sump? 

[viNce]

Here's mine to help oil return

[181]

what is the original purpose of that "umbrella"?

[viNce]

Hold the oil screen in its place? or avoid windage

[JS]

I guess the intention behind the umbrella is to make sure that the oil filters trough the mesh screen and to work as a windage so the pickup does not suck air in sharp turns etc.
I have also wondered about it´s function when you don´t run the mesh screen and have a large sump with the oil level in the case much lower than in a stock engine.
I´m thinking about cutting it away completely when my 2276 is being reassembled to help oil return. Any thoughts?

[Lee.C]

Here's mine to help oil return

Cool idea dude - these are ALL quality tips 

[Sander/DVK]

I agree, very interesting topic!

[181]

And now..another hot topic for you all..do you guys run stock oil strainer in your hi-po engines? Some opinions are it can be restrictive for oil flow to the oil pickup, but also it can protect oil pump in case of engine failure..

[Jesse/DVK]

My new as41 case doesn't have a small cut out for the nr1 cam bearing on both sides of the case. Should I make a cut out in the case of sand down the dual thrust bearing?