ACR PowerPlus Timing

[RPR]

Anyone out there with an ACR PowerPlus upgrade on their 2.25? I can't recall what the ideal timing is supposed to be and can't find where I had it written down? I thought it was a bit retarded vs standard but perhaps I am wrong... Help please.

[Mark]

Anyone out there with an ACR PowerPlus upgrade on their 2.25? I can't recall what the ideal timing is supposed to be and can't find where I had it written down? I thought it was a bit retarded vs standard but perhaps I am wrong... Help please.

I have just looked through all the paperwork that came with the ACR Kit, and it dosn't actually mention timing. The kit was fitted when I bought the lightweight, and it is running on Gas, so the timing should be a slightly advanced for that so it would be difficult to comapre...

Sorry, not really any help. Roland used to post on the old forum, it might be worth a post on there to see if he still looks in?

Cheers

Mark

[RPR]

Thanks Mark. I'll give them a bell Monday. I was just going to fit the Pertronix ignition today and reset timing but it was cold and snowy anyway, so I did not.

[Diff]

I have just looked through all the paperwork that came with the ACR Kit, and it dosn't actually mention timing. The kit was fitted when I bought the lightweight, and it is running on Gas, so the timing should be a slightly advanced for that so it would be difficult to comapre...

Sorry, not really any help. Roland used to post on the old forum, it might be worth a post on there to see if he still looks in?

Cheers

Mark

Hi Richard,

When I spoke to Roland a year or so ago, he recommended a static timing of 6 degrees BTDC for stage II 9:1 engines. He said this setting should give 38 degrees BTDC at 4250rpm.

Although the standard dizzy 'should' have approx 40 degrees of centrifugal advance(according to the book specs), in practice it has less, so running at 6 degrees static shouldn't end up at max advance of 46 degrees BTDC which would be way too much.

The bottom line is - don't let the engine pink! You may have lower octane fuel in the USA than our unleaded. If this is the case, you may have to time it only a few degrees BTDC or even at 0 degrees TDC.

Hope this helps,

Regards, Diff

[RPR]

Hi Richard,

When I spoke to Roland a year or so ago, he recommended a static timing of 6 degrees BTDC for stage II 9:1 engines. He said this setting should give 38 degrees BTDC at 4250rpm.

Although the standard dizzy 'should' have approx 40 degrees of centrifugal advance(according to the book specs), in practice it has less, so running at 6 degrees static shouldn't end up at max advance of 46 degrees BTDC which would be way too much.

The bottom line is - don't let the engine pink! You may have lower octane fuel in the USA than our unleaded. If this is the case, you may have to time it only a few degrees BTDC or even at 0 degrees TDC.

Hope this helps,

Regards, Diff

Cheers Diff. I think you will have nailed it. I have it at 4* BTDC as I recall and on anything less than premium here, it has a tendency to pink. I had hoped to get a bit more low end power by advancing it some but I guess this is too optimistic...

[RPR]

Roland, as usual, was extremely helpful and quick to reply. For those who may remember the "Everything you ever wanted to know about tuning the 2.25 petrol engine" thread on the old site, this was largely covered there. The short version is that the Power Plus camshaft from ACR is very similarly profiled to the original 2.25 cam but with a bit more lift to allow a greater cylinder charge. It's a reasonably mild profile and while a bit more advance could be done on it - beyond the IVO at 6* BTDC - Roland doesn't think it would do so much as to merit oiking around with it. I have always been very happy with the ACR set-up so no complaints at my end. 6* BTDC is shall be.