Max overlap for MOT pass

[Gunnytron]

I got my car MOTd a while back and it failed emissions. Which was fine I thought, I will get some CATs fitted and job done.

Unfortunately it has been brought to my attention that my cam may have too much overlap (4 degrees).

My tune is a bit ropey at the moment and needs sorting out, but before I take it to get tuned I need to make a judgment on wether or not to replace the cam with one that has less overlap or take the risk and hope it will pass after CATs and a tune. Otherwise I will end up paying for a tune (and transportation to the tuners) twice.

So, what is the max overlap anyone has got an MOT pass on. I am talking true, legal pass here not "friendly MOT centre" pass

Here's my engine spec:

227/234 .614"/.576" 113+2

Thanks

Edited by Gunnytron on Monday 14th August 19:26

[Gunnytron]

robbyd said:

Do you have CATs fitted at the moment? Sounds like not... they'll clean it up a lot!

No, not currently.

[Gunnytron]

It's a 94 RX7 (I should have mentioned that) so technically doesn't need CATs.

[Gunnytron]

stevieturbo said:

It's a how long is a piece of string question.

Well it is when you look at my predicament, however, it would be nice to know if anyone has gotten a 4* overlap cam through a legit MOT so I can start making some decisions.

[Gunnytron]

stevieturbo said:

Well if you just have to bass a basic MOT...ie sub 3.5% CO and 1200ppm HCC, then that should be a piece of piss.

But technically a 1994 car should require catalytic converters. Almost every car post August 1992 should, with only a handful of exceptions.

How does yours fall into the exceptions ? Or is it a rotary thing ?

As it's a pre-95 import there isn't a legal requirement for it to have CATs fitted. Obviously it still needs to pass emissions though.

[Gunnytron]

MyM8V8 said:

You have an emissions problem for a start.

I'd begin by wanting to know the state of the tune. If that's guaranteed optimum, I'd be looking at a set of cats. If that doesn't sort it you have a cam problem,

That is a logical way of looking at it. This may lead to having to get it tuned twice, but the auto-tune of the ECU I have (Holley) may be good enough to compensate for a different cam.

I guess I can also take it for another emissions test after it's tuned, then from those results, the tuner/exhaust place may be able to have a guess as wether or not the CATs will allow it to pass.

[Gunnytron]

JAMESHSV1 said:

Where are you based any friendly mot testers around your area

I'm in Basingstoke. I have no idea how people find these "friendly" testers.

[Gunnytron]

stevieturbo said:

And as I said, if does not have to pass a cat based test, and only the basic, then that should be a piece of piss, unless your car is fked.

hmm, you do raise an interesting point. I know it was tested as a 94, I assume they tap the number into the database and it tells them what to test it as?

Might make some enquiries about that as the reason I got a 94 was so that I didn't have to run CATs

[Gunnytron]

mjf93 said:

On an unhelpful and unrelated note, was it you I saw on the M27 near Eastleigh last Wednesday evening?
I was in a Monaro VXR.

Edited by mjf93 on Wednesday 21st June 16:16

Lol, no it wasn't. Mine will be sitting in the garage till I sort this emissions thing.