Do the Cam Cam?

[KirstMin]

Please excuse the pun.... Thanks to advice from a few members on the board (Cam especially), I am due to pick up my shiny convertible that has been in the garage having a few uprated components fitted. It’s dangerously addictive though and I’m already thinking about what I can do next!

What’s been done: 1275 marina engine, HIF 44 Carb, metro water heated inlet manifold, large bore SS manifold and exhaust, K&N air filter.

I was wondering if there is any power benefit to be gained by introducing a new camshaft and double chain timing gear without modifying the head? Or should I consider a head modification first (although the cost of this will prob be too much for now).

I was thinking about the Kent Cams 256 or perhaps the 266 for ease of round the town use and with a mildly tuned engine.

What about the timing chain – any advice which one? I notice that Birmingham do a range from about £30 to £60 but is there any point in the more expensive one that is adjustable?

What about the oil pump? Does this have to be changed?

Thanks all

[Cam]

I personally would do the head first but to fully exploit it's potential you'll need the cam to suit!

The choice of cam depends upon application. A 276 is about the limit for city driving. If you want a cam for round town use and a bit of blasting then go for the 266.

The timing chain, go for the non-adjustable duplex (twin chain) one. Are you sure yor 1275 engine doesn't already have one fitted?
The adjustable one is only really needed if you are trying to extract the last few BHP out of a race engine in practical terms...

Oil pump should be fine as standard if it's in good condition. I have a slightly higher capacity one but really speaking it takes BHP to turn it so you should get the smallest one capable of doing the job. The standard one should be fine.

[KirstMin]

Hi again, not sure if the engine has a twin chain - I'm picking the car up on Monday - its my day off coz i'm doing the London Triathlon on Sunday - and willl take a look then.

I've heard that a 276 is pushing it for city driving which is why I thought the 266 would be better - I live in London.

If I were to put say a 266 in, and assuming I had a twin chain, would I notice any difference in the power without doing the head?

[Cam]

Yes, the power delivery will change. If you change the cam first, you will loose some power (torque) at low revs and gain some at higher revs. If you did the head first, you will notice a power increase across the rev range which will increase even more at higher revs when you uprate the cam. That's the general rule of thumb although the specifics will be different depending upon application.

[KirstMin]

I get you... thanks for the information.

I'll keep you posted about the results of the first upgrades on Monday and see what I can do about a new camshaft after that.

[Peetee]

I agree with Cam in that the head is the first thing to change. It is the inlet ports around the valve stem and head that cause the greatest restriction.

[salty_monk]

A Vernier puller (or adjustable chain in this case) can make a lot of difference when dialling in the CAM - only any real use though if you get it on a rolling road with someone who knows what they are doing....

[Cam]

Agreed, but for a mildy tuned 1275 it isn't going to be worth the extra cash for the gains produced. In fact I don't have one on my 1380. Just the normal non-adjustable duplex timing chain.

[KirstMin]

but... my first problem is cash... I dont have the space (road parked) and so unfortunately, most of the work has to be done by a specialist. Changing the head falls into this bracket... what would people expect to pay? And are there recomendations for people who do this (well!) in the London/SE area?

[Cam]

Well... there are lots of heads available but it's very much a case of you get what you pay for. You can pick up a better head than standard for £10 - £20 on eBay (when and if they come up) or you can pay £500 and have one specially machined from MED racing engines that is superb! or anything inbetween.

If you are buying 2nd hand then you need to know what to look for to avoid being ripped off. If I were you, I'd shelve the plans for the head until you have got the spare cash then buy a decent one, but it's up to you really.

[KirstMin]

I think saving up is probably a good idea... besides, I JUST got a call from the garage and the vibration I have at 50mph is down to a buggered diff (having had the gearbox and prop changed twice because the garage thought that they had introduced the vibration by putting a new gearbox and prop in). Hmmm... and to think that I had a reconditioned one put in only 18 months ago by a mm specialist in stafford

The garage did ask me if I had noticed a vibration at 50 but I said no - because I must just be used to it and didn't realise - and they are p*ssed off with me now coz they have had the gearbox and prop out twice before realising it was a problem that already existed.

[bmcecosse]

Get a head from an early MG Metro - bigger inlet valves ! I paid £20 for an excellent one recently. Check ebay. Modify it if you will - but if you take any metal out of the chambers you will drop the compression ratio - and so it will need skimming. The camshaft from an MG Metro (NOT turbo) is also ideal - this was developed by Rover to give excellent torque and city driving , and still give good power up to 6000. Again ebay - usually £5/10. Of course cam change (on a 1275) means engine out because the followers will fall down inside. The biggest improvement you can make is to get the bigger 1.75" SU and the alloy inlet manifold - again from the MG Metro, and again on ebay for £20/30. Also invest in a copy of Mr Vizard's A series tuning book - yes, ebay again !
Oh - and you will need an oil pump to match the drive on the end of the cam - MG one is 'peg' drive. Duplex chain is the answer - and don't worry about adjustable - dot to dot works just fine. If you fit duplex you need to countersink the two screw holes where the front plate is fixed to the front main bearing - and fit c/sunk screws with loctite.

[Cam]

I did not know there were any MM specialists in Stafford?!?!? Where about? I used to work at the university at the end of Beaconside!

[KirstMin]

Sorry Cam, I didn't mean Stafford itself - I meant MM specialist in Staffordshire...

[Cam]

Oh right! Staffordshire Minors then I presume? Which is just outside Market Drayton...

[KirstMin]

Before I say "yes, they're the ones" I need to double check the company name on my receipt - I wouldn't want to say I was disappointed by a company only to find out I have named the wrong one