supercharged fools home brew rattling noise

Post by **superchargedfool** » Mon May 19, 2008 8:22 pm

My engine has always had and is getting slightly more annoying a high pitch fast little rattle from the depths of the n/s of the engine.

It sounds a bit like pinking but it isn't. Does it sometimes at tickover and sometimes when driving. It is more annoying than worrying.

If I had to guess and get stuck in I would fit new cam followers, but my point is when you discuss things with people in the know you often find out more quickly which way to go, so HELP.

If it is followers are they easy and should I fit anything else at the same time? Remember we are talking ital 1275 A+ here though.

Oil pressure is 60psi cold above idle and 20psi warm after good thrashing at tickover. No smoke, no other funny noises. So advice sought before pulling it apart again.

PS. I may have just stumbled across a set of 1.5 roller rockers brand new at give away money from a friend so these will probably go into the equation at the same time.

Post by **minor_hickup** » Mon May 19, 2008 9:25 pm

How fresh is this engine? Was it rebuilt before it was supercharged. I only ask because for a fresh engine your oil pressure reading sound low. My well thrashed but healthy 1098 produced 70psi above idle cold, 40-50psi tickover when warm and 60psi at anything above idle when warm.

Post by **bmcecosse** » Mon May 19, 2008 10:28 pm

Cam follower would be heard all the time - especially at idle. If it's wearing then the valve gap will be increasing - worth checking. If this has happened then the camshaft will be ruined too. Changing cam followers on 1275 is not easy - sump off, push rods removed and camshaft removed whereupon the followers will drop out. If lucky you may be able to get the new ones in (from below) and get them to stay in place with heavy grease while you slide the cam back in. Normal replacement method would involve popping the engine out and turning it on it's side. I strongly recommend NOT using the high ratio rockers. They give approx 1 extra bhp - and vastly increase the wear rate on cam/followers/rocker shaft/rockers/valve tips/valve stems and valve guides. Put them on ebay and get rid of them!

Post by **Stig** » Wed May 21, 2008 7:59 am

Not sure where you got such a bad opinion about high-lift rockers, Roy, but I fitted them to my engine a few years ago and got a noticeable increase in torque throughout the rev range and have seen no evidence of increased wear at all. I'd agree that there are usually much more cost effective ways to increase power but if they're that cheap then go for it. Remember to increase the valve clearances accordingly though.

Post by **bmcecosse** » Wed May 21, 2008 12:59 pm

Many failures on Mini engines - including dropped valves. Agree this may be with ultra strong springs and high lift cam - but an engine test I read a while back reported precisely 1 bhp extra power.