What would cause an A-series 1100 to fall flat at 4000RPM?

[9triton]

+1 for getting a strobe and checking advance at full revs- what is total advance at engine pulley ?

...unless you have done this allready....

is vacuum disconnected when you do that - looks like dizzy has twin pipe vac cannister - does the mini even have two vacuum lines to connect?

[BMWTurbo]

I've modifed the vacuum advance canistor back to a std mini distributor one.

I was under the impression that the vacuum advance should only be in play/active when the throttle is backed off and under decel? Base timing w/o the vac advance connected is set at 10 deg. Connected the vac advance line back to the canistor and the base timing doesn't change at idle? Canistor works as I can move it by sucking on the line.

The thing that convinces me it's not related to that is that I've walked the base timing around from 10-20+ degrees in increments and it bugger all difference.

[Dave75]

+1 for getting a strobe and checking advance at full revs- what is total advance at engine pulley ?

...unless you have done this allready....

is vacuum disconnected when you do that - looks like dizzy has twin pipe vac cannister - does the mini even have two vacuum lines to connect?

#1 Flywheel on a Mini..

#2 should always disconnect to tune??

#3 no

[BMWTurbo]

Timing advances no issue with the engine RPM increase, confirmed with the timing light.

I did notice that even free revving the engine doesn't want to push past 5000 RPM, not that I was trying to hold it there, but it just seemed very resistant to revving, which again starts suggesting to me the exhaust...

M10x1 nut to be welded into the exhaust fairly soon I think for back pressure testing.

[HoonBoy]

have you checked the CAM timing?

[BMWTurbo]

I haven't Hoonboy :- I'm not sure it's a simple check without having to pull the engine and box to drop off the timing cover?

I also have NFI what cam is in it. could be something from a 998 or 1100...

[HoonBoy]

You can check it using a dial guage on the valves, but you need something to measure the engine location which ain't easy on a mini. Like just about any other job, you will need to take out the radiator first.

[Jim]

no, as mentioned the timing (and TDC) marks are beehind a little plate on the bellhousing. Not on the front pulley. will need a torch and a mirror tho

[BMWTurbo]

I can see TDC by the timing mark on the flywheel.. That's easy enough. *EDIT* beaten by Jim

How do you check the cam timing without knowing where the base circle starts on the cam or where the top of the lobe is relative to TDC?

My interest in resolving the problem, doesn't quite extend to the effort of removing the radiator and balancer etc A tooth out on the timing chain is going to be a good 10-15 deg advanced or retarded, which would cause it to run like a dog wouldn't it?

The engine feels relatively fine up until the higher range, if anything, it's nice and torquey (for a mini).

[HoonBoy]

Is there enough there to check cam timing? Been too many years to remember

[BMWTurbo]

0-10 are marked on the FW.

How do I ID the cam relative to the FW? Where 'should' it be?

[Dave75]

0-10 are marked on the FW.

How do I ID the cam relative to the FW? Where 'should' it be?

Behind the timing gear cover... 2 dots should line up on the drive gears. You can change the cam timing by fitting off set keyways.Engine out or radiator out & stand on your head.

[stockymcstock]

fark welding a bung onto the exhaust to check the back pressure, just disconnect it at the dump pipe and go for a quick squirt

[cheapracer]

How do you check the cam timing without knowing where the base circle starts on the cam or where the top of the lobe is relative to TDC?

.

You can at least check if valve rock is close to TDC with a screwdriver in a plug hole and the rocker cover off.

[Jim]

You know honda 4 cyls rotate the wrong way yeah? the mechanical advance bob weights may not be operating.