B & G cross drilled camshaft

[Simon Sadubin]

Dear All,

I'm finally getting somewhere with TC2575. A ground up rebuild of the body is done, so I'm moving onto rebuilding the mechanicals. I'm putting together a specification for my engine rebuild and I was wondering if anyone has had experience with the B&G cross drilled camshafts? They seem like a simple and excellent solution to reducing cam and cam follower wear especially when coupled with more modern valve springs to reduce the loading on the valve train.

I've searched on the B&G website and done plenty of online searches but can't turn up a specification on the B&G cam. I am looking at their cross drilled fast road - AAA3096XD - does anyone have any more information on this cam?

I do want the car to look totally original but wish to enhance performance so that it is a really nice car to drive.

Planned setup is:

1) Over bored to 68.5mm = 0.80” 1320cc
2) Head ported to factory stage 2 specs with 36mm inlets and 34mm exhausts
3) Compression ratio - currently a stock 76.75mm thick head - what is a good compression ratio to run with the fast road cam?
4 Camshaft - possibly B&G fast road with bucket followers and pushrods to suit
5) New modern valve springs and spacers to reduce cam loading
6 Distributor - regraphed - to suit camshaft and modern unleaded fuels
7) lightened flywheel - to MG spec - 1951 drawing to remove 4 1/2 lbs
will a standard 7 1/4" clutch be adequate ? I want to kept light and positive.
9) all components balanced
10) final drive 4.6 ratio crown wheel and pinion via original TC 4 x speed box. I should also add I will be running the car on 19” wheels with Blockley tyres.
11) I will be running standard 1 1/4” twin SU’s on the original inlet manifold which has been tidied up internally. The air cleaner has been modified to utilise a high flow K&N air cleaner element.
12) Exhaust is factory manifold, again cleaned up internally to remove casting dags and sharp corners and the exhaust system is a 1 1/2” bore Bell system.

Thanks for your excellent forum always interesting to read.

regards,

Simon Sadubin
TC2575
Sydney, Australia

[Steve Simmons]

I have no experience with that cam but your plans look solid. The clutch should be fine. I took 6 pounds off my flywheel and wish I had taken a little more, but there was a slight improvement. Your compression ratio will be increased just with the overbore, and while I'm no expert I would aim for at least 9:1, maybe as high as 9.5:1. I'm currently running about 9.1 on standard high octane with no issues. It will also run on mid octane if necessary.

[i.thomson]

Hasn't the x-drilled cam got much more to do with extending it's life, especially in this time of oils without ZDDP, than out and out power? I am running much the same spec as you, factory stage 2, with larger valves and gas flowed head and mainfold, but with 1 1/4 carbs which are all you need if you are not using frequent high revs. My c/r is 9.3 which means, if I remember rightly, taking 1/8 in off. I am still on the 7 1/4 in clutch but without the lightened flywheel.

Ian

[Simon Sadubin]

Thanks Steve, that sounds good. This was the drawing copied from Bob Grenau from an original MG factory drawing. I've used to take weight out of the flywheel - do you think its safe to take out a bit more?

regards,

Simon TC2575

[Simon Sadubin]

Sorry that was the flywheel image, here is the drawing :

bobG flywheel .jpg (45.54 KiB) Viewed 3057 times

[Simon Sadubin]

Hi Ian,

Yes I think the whole idea of the cross drilled camshaft is to get positive lubrication directly to the cam lobe / cam follower interface to reduce wear. B & G offer a range of camshafts - Standard T Type, improved profile, Fast road, Full Race - so it would be interesting to know what the specs of each cam are. Good to know the standard clutch seems to cope fine with your setup.

Regards,

Simon TC2575

[Steve Simmons]

I got my last flywheel from a friend already done, but I was told it was essentially done as that drawing shows. Original weight was 22 pounds, lightened weight 16 pounds.

[Keith Beningfield]

Hi Simon
I believe Newman Camshafts in the UK, who incidentally make cams for most other UK parts suppliers, will cross drill any of their XPAG cams. I run a Bibby Profile Supercharger cam cross drilled and after several years of hillclimbing is still in perfect condition. I use it in combination with their nitrided steel followers. Good luck

[Duncan M]

Interesting that Newman charges the same price for any of the 5 different XPAG cams they offer...
Good info, Keith

[Simon Sadubin]

Hi Keith,
Thanks for the info on Newman Camshafts - I'll ask them about their cross drilling for camshafts
regards,
Simon TC2575

[Ray White]

I bought a Newman fast road cam and fitted into my supercharged engine. I knew nothing about cross drilling; this is the first I have heard about it.

I can't imagine taking it out again.