Thread: 2,25 low on power

It is very unlikely that the head is shot, at worst may need a valve grind. I would do the following, probably in the same order.

1. Check that the throttle opens fully.

2. Check brakes are not dragging, including handbrake (hot after run)

3. Check points gap and ignition timing.

4. Fit new (correctly gapped) spark plugs and leads(unless leads are pretty new)

5. Check tappet clearance

6. Check compression - the manual gives the correct figure, and importantly, it should be even. Problems are usually poorly sealing valves, rarely rings, and even more rarely head or head gasket problems unless the head has been off and not retensioned after a few hundred kilometres.

There are a few unusual problems that could occur and reduce power; these include:-

Distributor vacuum advance not working, distributor centrifugal advance not working, worn top bush resulting in gap and timing being all over the place as the shaft wobbles.

Air leak into intake manifold, although this usually causes backfiring and poor starting.

Blocked exhaust, although your "loud exhaust" makes this unlikely.

Fuel delivery problems, usually due to the screen on the tank pickup being blocked or a leaking gasket on the sediment bowl on the tank, although this usually shows as hesitation rather than just low power.

Valve timing out due to the camshaft being a tooth out or a very worn timing chain and sprockets - very rare in my experience with this engine.


Worth noting that I recently gave my 2a a tuneup consisting of setting the ignition timing (was about 3 degrees out) and setting the plug gap correctly. I was astounded by the difference it made.

The difference in mass between a lwb and a swb does make a marked difference in performance, and even more importantly, so does tyre size. Also, consider whether you are certain that both vehicles have the same diff ratio - while all 2.25s came from the factory with a 4.7 ratio, fitting 3.54 diffs is a favourite modification to reduce rpm when cruising - but it does affect acceleration.

John

if you have the low comp and he had the hi comp (7:1 vs 8:1 or therishabouts) thats a good difference in the development of the power straight off the bat.

chuck slightly bigger tyres, a wobbly throttle buterfly pivot, timinbg out a couple of degrees and a mix a bit out and that can account for the difference.

as already mentioned, check everything again and get it all back on spec.

I dumped the original Vacuum Retard Distributor and fitted an earlier (than 78) Vacuum Advance Distributor and got rid of the Vacuum Retard device on the Carby, advanced the dissy up to just below pinging, made a big difference, Regards frank.

Just how little power does it have? Has it been that way since you did up the engine?

Much to my embarrassment I know from experience that a Series III will run with the timing chain out by one tooth. I had to run it like that for a week until I got time to fix it.

It was driveable, but really down on power. IIRC it would get up to about 70 -80k flat out. Is yours that bad?