Cam shaft

Post by **rogerb** » Tue Mar 27, 2007 4:22 pm

Hi folks, has anyone heard of a 'half road 'Cam?

If so what is it and does it have any characteristics?

I have a 1275 fitted and it might have a 'half road cam' fitted. It seems to run reasonably well with one exception.

It starts no problem, it ticks over OK. It has plenty of torque when accelerating, but on what I call the overrun (when you are going at a slow speed and no throttle, say in town traffic) it tends to lurch a little.

I do not think it is 'missing' or cutting out, because you just need to press the throttle a little and it picks up well.

It is disconcerting though and is worrying my wife who drives the car every day.

Could it be just a characteristics or is there some way I can tune it out?

I think the mixture and timing are fairly well set up as it starts and drives under power well.

It has a HIFF 44 carb on a Holby heated inlet manifold with a 'pancake' air filter. I have changed the needle to suit the air filter previously.

There is one other thing that may just be connected. Occasionally the engine will just stop. Not when you are driving, but say coming up to traffic lights, take you foot off the pedal and the the revs just keep slowing down and stop. It starts again no problem.

Anysuggestions?
Roger

Post by **bmcecosse** » Tue Mar 27, 2007 8:01 pm

Why would you think it had a fancy cam in there ? Cams are sometimes called 'fast road' or 'half race' that sort of thing. In any case - they don't show themselves in the manner you describe, they would tend to have slightly lumpy idle and as you accelerate they will quite suddenly (sometimes) come 'on the cam' and the car will roar away much more rapidly than at lower revs. This would not be ideal for Mrs R. Rover designed the Mg Metro cam to give reasonable idle, reasonable economy, pass emissions test, and yet be quite 'sporty' up to about 6000 rpm when it tends to die. This of course was the idea - to try to contain warranty claims yet still have a lively engine. It's a very good cam for everyday use - but perhaps not ideal for Granny who should stick to the standard cam.

Post by **JimK** » Wed Mar 28, 2007 8:45 am

BMC, what (if any) differences are there between the MG Metro cam and the turbo cam?

Post by **chrisd87** » Wed Mar 28, 2007 12:24 pm

The turbo cam is the same as the standard 1275 Metro cam, which itself is the same as the 1098 Minor cam but the whole lot is advanced by 4º. The MG Metro cam has longer duration on both the inlet and exhaust (252/268 vs. 230/252). If you have the Vizard book then it's all in there.

Post by **JimK** » Wed Mar 28, 2007 12:26 pm

Thanks. Yes, I really must get round to buying a copy of Vizard.

Post by **bmcecosse** » Wed Mar 28, 2007 10:38 pm

It's essential!

Post by **Innovator** » Sat Mar 31, 2007 6:03 am

A rolling road tune up by a good operator will help with all your problems. It is the most effecient way to get the correct mixture. Even such a tuning guru as Vizard will not guess which needle is required if a change is made to an engine.

The term pancake air filter gives me images of a restrictive air filter. Fit a K&N and get it on the rollers. It will be the best money you will ever spend.

Post by **wibble_puppy** » Sat Mar 31, 2007 12:11 pm

bmcecosse wrote:This would not be ideal for Mrs R.

I guess that depends on Mrs R.'s spec, doesn't it

perhaps not ideal for Granny who should stick to the standard cam.

Perhaps being a granny is not the only reason for sticking to a standard cam?

Inoovator what is a K&N? (excuse my ignorance, still learning, blah blah)

Post by **alex_holden** » Sat Mar 31, 2007 1:31 pm

wibble_puppy wrote:what is a K&N?

It's a company that makes high performance washable air filters. http://www.knfilters.com/

Post by **wibble_puppy** » Sat Mar 31, 2007 1:38 pm

thank you alex

How do you find which filter to buy? The "Find your model" function doesn't seem to return any results for morris minors.

Post by **chrisd87** » Sat Mar 31, 2007 5:28 pm

Mini Sport do them for SU carbs - there's either a cone or pancake type.

I've got a 54mm pancake type one waiting to go on my tuned engine, and it looks great!

Post by **bmcecosse** » Sat Mar 31, 2007 6:23 pm

Think of it as a 998 Mini when selecting a K&N filter.

Post by **wibble_puppy** » Sat Mar 31, 2007 9:45 pm

ah - cheers - thanks guys

Post by **picky** » Sun Apr 01, 2007 3:53 pm

the K&N air filters are very good in terms of flow - hardly restrict the air going into the engine BUT you will get alot more noise coming from the engine. I fitted a big K&N to a tuned 1098 engine and ended up putting some soundproofing foam inside it as the noise got very annoying. I would recommend getting the standard air filter setup from a metro - and buying a performance K&N filter for a metro.

Sorry for moving away from the topic of camshafts!! rolling road definitely the way to go roger.

Post by **bmcecosse** » Sun Apr 01, 2007 6:58 pm

The original problem was 'lurching' etc - not stuff that will be seen on a rolling road very easily. i would just sort it out on the highway first - worry about RR later if you feel the performance is not as expected.