CU engine build

[callyspoy]

Hi Folks,

I am soon to start a 2.0 Aircooled rebuild as mine is struggling a bit with low oil pressure and leaks from many orifices.

I decided to buy a replacement engine as i don't want to take mine off the road for too long.

I do plan to do a full rebuild, cost will be not insignificant i should imagine.

My aim is to get it to a point where i can continue to use it most days as i do currently, without being too petrified to take it long distances. For reference, when it is hot, my pressure gauge is reading around 15psi at 55mph. So it is tired and deserves a spruce up.

Does anybody have any decent pointers or what to go for? I was looking to go for a mild cam upgrade, i have heard the Scat C25 is quite good? I am aware that it would require solid lifters/pushrods.

It currently runs a pair of ICT's, so i'd most likely stick with those as i can't see me having the spare cash for some big boys.

Other than that, was looking at the flat top 96mm pistons/barrels, they seem a fair price and should improve the comp for the cam to work better?

If you have any things to look for or suggestions, please let me know. Just awaiting my engine stand before i strip the bottom end down.

Cheers
Callum

[diesel11]

I did see on here that Newman cams did a custom made camshaft, I gave them a call the other day, can't speak highly enough of Ken ( Newman) he definitely knows what he's talking about, I said what I wanted and he suggested a camshaft, for half the price of some of these "off the shelf" camshafts.

Sent from my Pixel 6 using Tapatalk

[callyspoy]

Cor, it's been some time and i have done not very much on this build.
We decided that that the front room required work more, so my time was spent doing that instead.
But...i am slowly getting myself in position to start with the build.

I did buy all (probably not all) the bits i needed for the build.
I am going for a mild build, so have-
• Scat C25 cam
• 96mm flat top pistons
• Using my standard AMC heads (2 years old)
• Cam requires solid lifters, so am converting to those, includes correct pushrods

I will be running it initially on my ICT's, but i did buy a second hand set of 40 IDF's. But as the ICT's are running the van, figured best to get the new engine run in on know carburetion before starting on the big boys.

All new bearings/shells are being installed, the only work other than the full engine strip down i have done so far is to machine the cam wheel. You can buy them, but they are £100, so figured i'd buy a counterbore drill bit and do it myself to the one that came out of the engine. Picture attached. This is required to install bolts where the original cam had rivets. The holes required drilling out to 8mm and the recess is required to maintain clearance to the oil pump studs.

I was going to replace the valves with stainless, but i couldn't find the correct ones. If anybody has a contact for where to buy online, that'd be appreciated.

[Dueller]

Nice plan

Ive a 1800 AN motor i will be getting into, stock was 86bhp and hoping for 110

So far ive collected a SCAT C25 cam and a Turbo Thomes Stainless Exhaust, will also do the cam wheel as you are doing

My heads are big valve and OK to reuse after a rebuild but im sticking with the stock pistons and upping the compression with a 0.75mm cut, will see how it goes and adjust from there. Theres a guy on Ebay selling 96mm pistons for my engine but once you start to machine the barrels and fit new rings it became costly and its pushing the costs too high hence the TT exhaust 

Keep posting on how its going

[callyspoy]

Hello all.
Well i've had an absolute palava with this engine build. Close to throwing in the towel!
A run down...
I built up my engine. I checked big ends and mains and they appeared to be within tolerance, so i bought new standard size bearings for both.
New cam and cam bearings.
New CB Performance Maxi oil pump
Big bore pistons and barrels
Had valves lapped in at machine shop on used AMC heads.
Pressure relief valve i went with what i had which was almost new.

For context...i decided to go down this route as my old engine had lowish oil pressure (circa 20psi at 60mph, on a cheap gauge) when running, but had multiple leaks. I figured best to jump on it before it died.
So bought an old engine and built that up so i could keep the van off the road for as short a time as possible.
Anyway, built up, did the break in procedure as specified by cam manufacturer (Scat), which is hold the revs high for 20 mins, between 2000rpm and 3000rpm.
I am using 15w50 golden film oil.

The engine runs nicely and has a fairly decent amount of power compared to before! Really can feel it pulls nicely.

Anyway, every time when starting the engine, it took a little while for the oil pressure to register on the gauge, previously it was always pretty quick.
When hot, the gauge idiot light would illuminate, which is illuminated at a higher reading than factory, when at idle and the gauge would read very low psi. The factory light would come on from time to time.

As a rebuilt engine, i believed this to be pretty unacceptable. When driving, the pressure would build instantly and would run around at 40 psi when hot. When very hot and driving around town, this did drop a fair bit too.

Having scoured sites and panicking lots, i decided to change oil pump back to the factory pump that was in my original engine, as i have read multiple forums stating that new pumps are garbage and the interference fit is not as interference as needed.
This had zero discernible effect on the oil pressure.
For information, the original engine did always built pressure instantly, using that pump.
So decided to look at the PRV, in desperation, i bought an oversized valve and bored out to suit. Again, zero difference.
Reading forums, it has been said that oil pickup can be loose, so as a last resort, i decided to take the engine apart and put sealant on the pick up.
And again, zero difference.

So...
I figured it could be wear in the block so decided to rebuild my original engine.
I had the crank mains and big ends machined to accept .5mm oversize bearings.
I refitted the CB pump.
Used the pistons and barrels and cylinder heads from rebuilt engine.
Cam bearings and followers taken from other engine.
New PRV from CSP.

I installed the engine on Tuesday and it appears to be very similar to how it was in the other built engine.

It is running a vacuum dizzy with standard control module.
Weber ICT's (i have IDF's ready to go on, but wanted to run it in first with the old ICT's so i wasn't breaking it in and tuning carbs at the same time).

So...if i didn't have an oil pressure gauge, i would very rarely see low oil pressure light as the factory light has only come on when very hot.
That said, it is noticeably worse looking than it was before.

Do i persevere? It has, as i'm sure you'll be able to guess, cost me a lot of money to do this.
I am losing faith in myself and the van and that is not good!

Can anybody think of anything simple that i have done obviously wrong?
I did try 20w50 oil also, that made no difference.
I think if i have to go down the route of stripping it again, it will be the end of this experience!
The only other thing i can think, is that the engine *may* be running a bit hotter whilst it is still bedding in, so the oil will naturally be less viscous.
It is just the idle pressure and the fact it doesn't build pressure instantly when started cold that is really messing with my brain!

But it drives really nicely pulls like a train, for an old Aircooled bus!

[callyspoy]

To add to this...
I have just driven in to work. Only a 7 mile journey, 4 miles of which are on the A27 from Portsmouth. When i pulled up to a stop, oil pressure was around 10psi at idle, no light on

[colinthefox]

The oil pump cover gaskets supplied in the gasket kit used to be too thick, giving the oil pump too much axial clearance. I don't know whether they have put this right yet. It is supposed to be 0.1mm thick if I remember correctly.
I cured this by leaving the cover gasket off altogether, and using just a smidge of Hylomar on the flange outside the pressure relief groove only.

[colinthefox]

Yes, in case you're wondering mine is diesel, but I was building a petrol one for a friend

[callyspoy]

Hey,
Thanks for response.
Sadly, the gasket is indeed the correct wafer thin type.

I have been driving it about today, i live in the city (Portsmouth), so not really any good long runs to get it properly hot, hot, but thus far today, no warning light.

I'm not convinced, but i am aiming to persevere and see what i can do hopefully make it better. Seems tricky to magic oil pressure though!