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Project performance WBX build

73K views 89 replies 10 participants last post by  iain ambrose 
#1 · (Edited)
I'm going to mirror this thread as I'm finding myself spending more time on VZI these days....

Though I would share my new engine build currently in progress.
Sadly the current engine has been having some issues of late with a noisy valve train.
I changed the hydro lifters with no improvement and having measured lift across the valves it appears one lobe is going flat :(
Fortunately I have been planning another build as a spare.

I already had a 2.1 MV short block purchased for £75.
It was sold as seized and this turned out to be pistons stuck in the bores.
After a strip down and clean up I checked over all the parts.



The cam was worn on the lobes so that was binned.
All the pistons cleaned up nice but will also be binned as they are the low compression MV type.
The crank looked fine but just needed a polish.

All the parts where dropped off with Jim @ the engine shop for a good check over and crank polish.
He also has a second hand set of DJ High compression pistons kicking around.
2 of the original liners where toast where they had seized so only the other two where honed.
Jim now sells uk made replacement camshafts ranging from stock to several performance versions.
The existing cam i'm running was sourced in the USA and is a CB Performance unit.
It's spec was:

Duration 270 degrees
Lift @ cam .298

I decided on Jim's fast road cam with the following spec:

Duration 290 degrees
Lift @ cam .289


Looks like a nice cam and I will confirm this later.
Anyone who builds these engines will tell you how the cost's escalate compared to a type 1 engine.
Head gasket kit £120 :eek:

A set of piston rings £55 (twice the price of a T1)

Main bearings and big ends come in at £65.

That said Jim only sells the top quality parts.

A quick comparison between the MV and DJ pistons.


You can see where all the extra compression is made in the dishes.
 
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#27 · (Edited)
Couple of engine checks this afternoon.

1. Cam backlash.

This is a little academic as you have very little options available due to the fact aftermarket cam wheels are all the same spec:rolleyes:
The only options in the face of out of tolerance specs are try another and hope, try another crank drive and hope or chuck them both and go straight cut:lol:
Actually I lie as if you had access to a bunch of scrap stock cams you could drill the rivets on one that has a suitable offset and get it machined to work on the aftermarket cam.
With this in mind many body parts where crossed....



Although this camshaft won't actually be used the wheel will be, hopefully.
To get an accurate reading of lash you first rotate the crank in the normal direction a couple of times to mesh things properly and with the crank held in place rock the cam wheel.
If you hear CLUNK CLUNK all is not well as there should be minimal movement.
On mine I get no rock at all, which is either very bad or actually great.
The allowable lash range is .000" to .002" which will allow for expansion when at running temps, but how do you know it's really .000" and not just binding?
To confirm this you rotate the crank backwards a couple of times and check again, but if the cam wheel lifts right out of the case it's binding and you're in trouble.
I actually get some lash which measures an estimated .003" as my gauge only reads in increments of .01".

Upshot is that this wheel looks fine, so happy days :)

2. Conrod side clearances.

The VW manual states upper wear limit is .028" with no lower limit mentioned.



All 4 check out with a range of .012 to 0.15".
As a side note it's interesting to see the original vw drilled holes for balancing along side further material removed when re-balanced.

Not much more to do until the remaining parts arrive and are checked, so things may be quiet for a while.
Thanks for reading.
 
#28 · (Edited)
Phoned JC today after received an email during the week that detailed the final bill and also that the cam selection was out of stock due mid May.
I nearly fell off my chair when I saw mid May as this would mean the bug would completely miss summer and in all likelihood require running in over winter:ticking:
Anyway after a quick discussion I decided to go with the next cam up in the range, the web 86b.
What this cam will offer is more high end rev scope should I want more HP in the future as it will be a simple case of bigger carbs :)
Going 1.25 ratio with this cam actually increases the lift from .468" on the 86a with 1.4's to .479".
Sounds like the right choice in the first place actually.

On a different tangent one thing that has been bugging me is the WBX oil dipstick setup.
It's stock position interferes with the boot lid so I previously modified it to sit further round, but it's hard to pull out and I actually snapped the one I have whilst trying to make it straighter.
After a brainwave I wondered if a T1 would fit?

Nice Jim at the engine shop donated a spare one and also a spacer tube.
Although the spacer pipe needs cutting down it's a nice fit and the dipstick does sit low enough to take a reading.
The issue is going to be whether the cooling pipe gets in the way or not, so once the heads are back I will mock up the pipes again and check.
 
#29 · (Edited)
Parcel arrived Tuesday :)



Empi 1.25 Rockers, hopefully something quality from Empi.

Looks like the shaft shims will need some tweaking.
Sadly this rocker set does not have any lash caps but I have some used ones that will allow me to set the rocker geometry.

Lightweight lifters.


These are 90 grams which compares very well against my 125 gram converted hydro lifters.
Note the little holes that will lube the camshaft lobes.
Much like the T25 hydro units they also have better oiling due to the single large groove rather than the T1 style of 2 grooves.
As I understand it this will provide oil pressure through to the rockers all the time unlike T1 which only works when the lifter is in line with the smaller groove.
A common mod on T1 lifters is to cut a slot between the grooves.


Camshaft looks good but will get a complete check.

Should liven up this engine:D

The heads are all sealed up having been cleaned, but the valve setup looks good.
I plan to check the head cc's now all the head work is done and made a suitable bore cover by grinding down an old CD to fit. I have a pipette kicking around from my old Bio diesel making kit that I can use with some gearbox oil.


Lot's of checking and measuring ahead....
 
#30 · (Edited)
Camshaft has been switched over, no drama's there :)
Due to the cam lift being so much more than stock it was worth checking the lift bore clearance although as i'm not running T1 style tappets you don't really have an issue to start with.

I don't have a picture but the cam lobe does get close to the crank in one place so this cam would be an issue if the crank had a longer throw than the stock 76mm.
A quick lobe check was performed:

#
#=1=2=3=4=
#

1. 378'
2. 374'
3. 375'
4. 377'

Cam card states 575' on a 1.5 rocker for both inlet and exhaust which is 383' on the lobe, so a bit under spec but consistent enough.
With my 1.25 I should be getting around 472' although JC say's you usually get more than 1.25, so will be interesting to check when doing the geometry.

Next is to check for valve to piston clearance.
I went well below the advised 500' with this camshaft/rocker combo so there should be no worries , but I would be a fool not to check.
JC states 80' - 100' clearance is required.
With the crank/cam installed correctly meshed the case was closed secured with a couple of nuts.
Next a piston/liner was installed without rings.
The other rod end was protected with some paper and tape to prevent it from knocking about inside the other empty liner.
Two lifters where dropped in followed by pushrods.
A thin layer of playdoh was added to the piston crown where the valve pockets are.
The head was lightly bolted down and includes a couple of used compression rings to get the correct deck height.

The rockers where adjusted to have zero clearance and the engine was turned over a few times.
Took the head off and the playdoh was completely untouched, so a thicker layer was added and a test impression was also made in the middle.
Head back on, more revolutions and head off again.

Great, there is plenty of clearance as the valves don't even get close :)

Last thing done was a bit more work on the heads to better balance the chambers.
First I re-tested all 4 chambers to confirm that 18.5cc is the upper target.
After some more work with the dremel I have 1 & 2 @ 18.5cc and 3 & 4 @ 18cc which will have to do as I have run out of sanding media.

Next job is checking the camshaft timing which is going to be interesting without a degree pulley wheel:lol:
Going to need to get creative for this one.

I guess this thread is primarily an aide-mémoire to ensure I don't miss anything and for recording results.
I've had to trawl through so many web based guides to get to this point not to mention help from various individuals.
Trying to choose the correct parts has been a nightmare with so many conflicting views on what's tried and tested against what looks good on paper, not to mention the lack of suitable performance parts!
I knew this engine was going to be trouble to modify and so far i've not been disappointed
 
#31 · (Edited)
Now that I have the head cc details though I would check what compression has been lost due to the head work.


That's a fair drop from 10.5 : 1 but it's to be expected and should easily be offset by the port work flow increases.
If I wanted to regain the compression I could still get the heads flycut.
It's also possible to run without the 1mm compression rings although this would still required 1mm taken off the head in order to not squish the head gaskets and I would be concerned by leakage into the cooling system.

Major headaches with setting the correct geometry :(
I've managed to correctly shim the rocker shafts but I will cover that later.
With the engine mocked up once more I started by confirming the actual lift as being 497'.
This means the rockers are more like 1.3:1 rather than the advertised 1.25:1 but JC warned this may happen.
There are numerous 'guides' on the interweb about correctly setting geometry and many conflicting suggestions.
I won't go into details but I think one picture summed up the actual goal.



This makes perfect sense so it's my goal to get a 90 degree angle between the rocker pivot and valve stem at 50% lift.

After a quick play with shims under the rockers it was immediately obvious I was going the wrong way, so I removed them and recorded a straight fit.

Trying to get a consistent picture without a proper stand is tricky but I think it's giving a pretty good indication.
Clearly the angle is too acute:rolleyes:
I have two sets (well nearly too sets having lost a couple of used ones) of lash caps that are different thicknesses.

Both sourced from JC but the right one is a new scat unit and thinner than the used left one.



As i need to either lower the rocker pivot or raise the valve height I ran the check again but using the old thicker cap.

Definitely an improvement, but not enough and in any case I don't have a complete set :mad:
Based on what I am seeing it looks like the rocker stands will need machining down to get things square with the new lash caps.
 
#32 · (Edited)
I've just run through another check but this time focusing more on accurate camera positions.
There are no base shims and i'm using the new lash caps.

I might have to consult with the guru as my approach appears too inaccurate for repeatable results.

Ok, think I know how to sort the geometry.

First a hopefully more accurate picture at half life using the rocker pivot point as the center of the photo.


I got confirmation from JC that 90 degrees is the correct angle to achieve at half lift on both sides.
From the picture it's clear the pushrod is well short of 90 degrees and the valve side is just a little high.
The swipe pattern currently looks great on the tip.


I measured the thickness of the two types of lash caps I have:

1. Manley tight fit - 088' / 2.25mm - Fitted for this test.
2. Scat loose fit - 066' / 1.68mm

These seem to be the only thicknesses readily available for 8mm stem valves.

The solution appears to be machining the rocker stands and using the Scat caps.
Dropping the rockers should bring the pushrod closer to 90 degrees and lowering the valve height using the thinner caps should hopefully keep things close to 90 degrees that side.
As I have a selection of rocker stand shims it will allow me to fine tune things, which is something I cannot current do.
I'll see if JC will confirm my judgement and undertake the required machining.

On a related note I spent 5 1/2 hours getting the gearbox/drive train back into the bug this weekend so it's pretty much ready for an engine, should that be arriving anytime soon :lol:
 
#33 · (Edited)
Update time:

Whilst I wait for my rocker stands to be machined I've moved onto dialing in the camshaft.
Having established an accurate TDC the goal is to confirm both inlet and exhaust open/close times match the cam card and subsequently the timing position is good.
An acceptable tolerance for a street engine is +- 1 degree off spec.
For fine tuning you can machine the cam wheel with slots so that it can be turned to adjust the timing position and there are also aftermarket wheels with eccentric bolts that achieve the same results.


My first issue is that the wbx engine has a different style of pulley wheel than a T1, so an off the shelf degree pulley wheel is not an option.
I located a printable degree template off the late and great Bob Hoover's blog page.

Not being sure of the required size I printed 3 options.
I also marked them up with the cam inlet/exhaust specs for checking.
Modified another cd so that I can fine tune the position once TDC has been established.


To establish TDC I fitted up number 1 piston and used a dial gauge through the spark plug hole.

For a precise position I measured 10' BTDC and marked on the pulley wheel and then 10' ATDC with another mark.


The center of the two marks is TDC which happily corresponds with the oem mark.
Accurate measuring is critical for this as the margins are less than 1 degree for a well dialed in cam, so I used one of my solid lifters on the cam and secured the gauge tightly on the case.

My dial gauge was original purchased to set a diesel fuel pump timing and came with a handy extension to the reading tip.
This has proved invaluable for this test and simplified the whole process as you would normally be forced to read the lift off the rocker or even the valve retainer.
The results don't look good:rolleyes:

I retested 3 or 4 times but came to the same results, so it appears I have an issue with the camshaft.
The exhaust is pretty close and could be down to measuring inaccuracies but the inlet is way off the closing spec.
Gonna need to consult with JC on this one.
And it was all going so well.....
 
#34 · (Edited)
Just been researching about this cam and it appears the measurements should be taken at 50' of 'valve lift' rather than 'cam lift'.

Done some maths on my figures so far:

Inlet Open 23 BTDC
Inlet Close 53 ABDC

50' duration = 180 + 53 + 23 = 256 degrees.
Lobe centre = 256 / 2 - IO = 128 - 23 = 105 degrees.

Exhaust Open 56 BBDC
Exhaust Close 21 ATDC

50' duration = 180 + 56 + 21 = 257 degrees.
Lobe centre = 257 / 2 - EC = 128.5 - 21 = 107.5 degrees.

Lobe separation is (105 + 107.5) / 2 = 106.25 degrees.



Lobe center's are advertised as 108 degrees for both inlet and exhaust.
I fail to see how measuring lift from the valve rather than the lifter will change the lobe separations so IMO there is still an issue with the inlet lobe.
 
#35 ·
Good news regarding the cam readings.
Spoke to JC and it appears I have a lobe offset camshaft with a 105/108 degree split.
This is an available option from Web but to be sure I need to dig out the original box/cam sheet to confirm.
Having some lobe separation should work nicely for me as it will extend the torque power band at the expense of maximum torque, but with so much torque to start with it's a trade off i'm very happy with:D
More specific details here --> http://www.compcams.com/technical/FAQ/LSAproperties.asp
Apparently my rocker shaft stands have been machined so I should be able to complete the geometry, order the pushrods and start the actual build.
Bloody hell, it's been over a year!

And that is everything up to date, but there is some exciting news coming early next week....
 
#38 · (Edited)
Good read Iain. What is your expected output with the build in its latest form. And the question that is the back of my head, and probably the answer is that you already have the carbs, but was FI a consideration?
Thanks :)
Output is somewhat unknown but the latest addition to the project will certainly help!




Refurbished Dellorto 48's :mental:
I looked at FI but the cost is too high for a setup suitable for this build.
The stock system would never work and is way too simple by modern standards anyway.
Also the rocker stands are back so I hope to get the geometry finalised this weekend.
 
#39 · (Edited)
Finally it's done:D

The machined stands brings the geometry spot on.
Interestingly the adjustable pushrod length is almost identical to the stock wbx one so I can use them.
All checks are now complete so I can start to actually build the engine:lol:
The case has been re-cleaned (had a quick bath) ready for assembly next week.
 
#40 · (Edited)
Started on the case cleaning.
It's already had a chemical clean plus several 'baths', but there is plenty of stubborn grime in all the nooks and crannies.
After some research I ruled out using oven cleaner as it's not aluminum friendly.
Stuff like kerosene is out as this is being done inside, so nothing with fumes or anything that might damage the bath tub.
First I use a scouring pad with washing up liquid on the accessible areas.
Next up I used WD40 and left it soaking for a few hours.
It does work but you can't just wash it away with plain water and it required washing up liquid with more scrubbing.
Lastly I used some bath cleaner.

Actually to my surprise it is very effective and some work with a toothbrush has shifted the worst of the baked on crud.



This is a good start but I really want to get all that gunk out of there so I will get some more of this cleaner as it's working nicely:D
When this is all done I plan to use compressed air to flush out any particles that may have strayed into the oil galleries.

Just out of interest here is a wbx case along side a T1 case for comparison.



Red shows the head studs do not enter the case to prevent oil leaks and probably more strength.
Yellow shows two oil returns from the flywheel end to help prevent main rear seal leakage due to pressure.
Blue shows the gallery that returns circulated oil direct to the oil pump rather than to the sump.
Green shows the strengthening web removed to allow crank case pressure to flow between the piston banks.
You can clearly see that VW based the WBX on the T1 engine but made important changes required for a more performance application.
Also note the higher case roof to facilitate a 74mm crank and also the extra strengthening.

Unsurprisingly many performance T1 engine builders modify their cases in similar ways.
 
#42 ·
Have you tried brake cleaner or engine degreaser to clean the block. Or is that too harsh on the bath?
Yep, too risky for the bath as I rent this place.
The case is now as clean as I can practically get it and I'm waiting on some Curil sealant for the case half's as the 'full' gasket kit does not have any:mad:
I also sorted out the hardware for the build with mostly new nuts but somehow I've managed to misplace a couple of the long bolts that fit on the case bottom.
If I can't find them I will rob them off the original engine.
Looks like next weekend for the short block at this rate:rolleyes:
 
#43 · (Edited)
Big weekend, the engine is together.

The cam lube arrived.



Closing up the case is pretty simple but I wanted to also ensure no oil leaks in the future if possible.
Additional to using the curil on the case halves I also used it on the bottom of all the washers.
I also used new nyloc nuts where possible as this should prevent any oil seeping down the threads.

The other tip is to use a magnetic pickup tool to start any nuts that could potentially fall into the case.


In my previous builds I fit the flywheel oil seal and front seal when the case is split and this seems to work and is a lot simpler than trying to press it in later.

Short block complete.
 
#44 · (Edited)
Thread from the dead :lol:

Things went a bit sideways last year after putting the engine together.
After a swipe check on the lifter it turns out my cam/lifter choice was not compatible so everything was stripped apart.

Had I run this engine the cam would have eaten itself!
This video shows the cam riding on the lifter edge.

After discussions with JC at stateside it was decided to fit bronze bushes to the case and run T1 style lifters.

This should resolve all the issues and also allow some more flexibility on lifter choice.
In the end I went all in and bought a set of lightweight Thorsten's, 59 grams and made of tool steel.

These and the case where shipped off for machining and so the problems really started.
After some seriously delays I got an email telling me that a bush had been pressed in and a check showed the lifter was loose in the bore.
We are talking out of spec loose based on new components.
After checking an aluminum type bush and seeing the same problem it appears to be a combination of issues:
Although all in 'spec' the lifter was at it's smallest diameter and the bush was at it's largest diameter.
This with suspected worn bores in the case resulting in a loss of 'crush' on the bush when pressed in.

More months rolled on and finally the plan now is to fit 912 style bushes as they have a much smaller i/d suitable for 912 lifters.
Once pressed in they can be drilled and honed to match my lifters.

That aside, I have been 'tinkering' with other parts of the build.
One thing I originally did not do was to remove the hard edges off the camshaft.

This is important for two reasons, the edges can promote wear on the lifters and it's common for it to flake off and contaminate the oil.
Bear in mind the camshaft lobes are hardened so the flakes could score the pump on there way to the filter.
Using some electrical tape as protection a hand file was used to round the edges.

 
#45 · (Edited)
Having much time on my hands I turned my attention to port work again, specifically the inlet manifolds.
Although the previous clean up process was fine I figure why not eak every last drop of HP I can.
Using a method I found online I took a metal bar, drilled a slot in one end and then used sanding paper rolled up.

This allows you to smooth out the casting marks and keep the port round. Add more sanding paper for the wider areas and reduce as you reach the narrow points.
One issue with WBX engines is the head ports are rectangular so it took some time to smooth out the transition.
All told it took more than 20 hours to get to the point where I was happy.


The other issue with these manifolds is that the head mounting holes are too large meaning the whole thing moves around on the head studs.
This is a serious problem if you are fine tuning the port work ensuring a precision transition from the manifold, through the gasket and into the head.
IIRC aircooled heads have a dowel pin used for centering but VW dropped this with the wbx engine and used sleeved manifold bolts to ensure a correct fit.

I considered retro fitting a dowel pin but gave up when I realised the work involved.
To solve this problem I bought some suitable sized bronze bushes usually used as bearings.
I drilled out the existing holes on the manifolds in mm increments and pressed them in.
I used a washer the same thickness as the gasket to leave them a little proud to also seat the gasket in the correct position.



When torqued up to the head they will press back into the manifold as the gasket gets crushed.

After a little poor mans reaming they where a tight fit on the head.


Here is the matched gasket positioned with bushes to confirm a good transition.

Now I could confirm the required work still needed on the manifolds.


The finished product, but note how little meat there is to seal, which is a cause for concern.

I may have to get them welded if they suffer from air leaks but for now I can finally put them aside.

I am also revisiting the wbx oil system whilst the case is apart and also at the machine shop.
Now that I am going to be using T1 style lifters I will be losing the hydro lifters wide oiling groove and subsequently oil flow will be greatly reduced.
This is a problem that all performance T1 engine suffer from and why Bob Hoover's oiling mods are so important.
That said, my issue is ensuring good oil flow through the drive train at high revs and not providing oil for cooling purposes.
Regardless, the plan is to drill a new oil feed to the lifters and also machine slots into the lifter bushes allowing uninterrupted oil flow.
This I feel is sensible as a precaution with the modifications being made.
I've probably posted this link already but worth a read if you want to learn more.
http://bobhooversblog.blogspot.co.uk/2007/05/hvx-mods.html

Most other work has been prepping the beetle for use again having sat for so long.
This weekend I will be fitting an uprated front anti roll bar and also a camber compensator at the rear in an attempt to reduce the tail happy rear end:lol:

When the case eventually re-appears I will update again, but it won't been soon....
 
#46 · (Edited)
Update time:D

I decided not to modify the oiling system other than open out the oil feed holes to the lifters. This should compensate for the narrow oil grooves.
Just waiting on the work being done and build #2 can commence.

Whilst I wait I have been studying up on conrod bolts, specifically stretch bolts.
As this engine will have the capacity to rev over 6k it will for sure, so getting the correct stretch on the bolts will be crucial.
The bolts have a stretch window of operation to keep the required clamping force.
Too little initial stretch causes clamping loss as the revs increase causing oil pressure loss and failure.
Too much initial stretch and the bolts will extend past the elastic limit at high revs once again leading to failure.
Although Scat states a specific torque with special lube and through a number of cycles this will never be as accurate as a stretch gauge.
Buying an ARP gauge @ £160 for this one job was not sensible so I ordered a Jegs gauge direct from the states.
Like most cheaper gauges it lacks a stronger spring for better clamping but did the job.

Tools for the job: Torque wrench, breaker bar, stretch gauge and a slide gauge.


First need to check the bolt length to get the correct torque.
http://www.manleyperformance.com/dl/tech/rod-hbeam.pdf
1.6" Under the head, so for 3/8th should be between 60-70 lb ft range.


Not wishing to over torque started at 50 and worked up.
The stretch gauge was zeroed out for each bolt.

The special Scat lube was used on the threads and under the head as directed.

Trying to hold the gauge steady and take a picture was fun but each bolt was tweaked to exactly .006" sitting nicely in the .0058" - .0062" spec.
There were several bolts with only .0055" at Scat's recommended 50 lb ft, so well worth doing this job IMO.
 
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