Anyone have an exhaust gas analyzer?

[max71]

Still trying to solve the high RPM drop off.

Anyone have a gas analyzer that we could hook up so I could see what the fuel mixture is doing at 4800K and up?

I think I've imposed on Malcolm enough to let him sit this one out.

[TEAM ROSBIF]

I am having a similar problem at higher rpm, I plan to take it to Joe Siams where we can get it on the chassis dyno and analyze the exhaust etc. Thinking its a fuel delivery / carb hickup

Mark

[max71]

Wow, Mark. Please let me and all of us know.

[Steve Simmons]

Mark, I assume you're aware that there is a well-known problem with the MGA-TC intake that needs to be addressed. It's the reason they stopped making the engine. The problem is high-RPM vibration leaning out #3 IIRC, and melting pistons. I don't have the specifics on what needs to be done, but it might be a good idea to give Jim Alcorn a call and see what he has to say about it.

[max71]

He knows about it. We discussed it at the Gymkhana.

[Steve Simmons]

What Gymkhana?!?

[max71]

The swap meet

[TEAM ROSBIF]

Thanks Steve, yes know allll about that one !!
They found out that at high revs around 5500, that the engine would develop its own vibration which was fine except the SU Carbs could not handle it and vibrated the fuel into froth, hence leaning out and as you correctly pointed out, melting a piston. That is why a lot of the guys fitted webers, they are not that superior to the SU's really if you look at all the tests they did afterwards but the one element that made a big difference were the soft mount O rings which eliminated vibration through the manifold. All the concours chaps with Twin Cams today, have the original 1 3/4 " SU's fitted but now they have the aftermarket O ring fitment on the manifold.
Its amazing to think that a wee O ring probably lead to the downfall of the MGA Twin Cam, today though all those things have been sorted and I cant go on about how fantastic it is to drive.
The problem I am having is just the jetting on the webers, which I need to address if I need to keep up with Jimmy in that roofless coupe.

cheers

Mark

[Steve Simmons]

Those little o-rings didn't just kill the best engine MG had at the time, it also killed the advancement of the breed in the MGB. Had the MGA Twin Cam succeeded, the B would surely have received a bored out version of it, placing it in better competition with the cars which killed it off in the 70's.

[TEAM ROSBIF]

I think your right.......its frustrating but I think we were headed up a good path only to be cut off and then 30 years later a very similar more developed 1600cc twin cam engine is in just about every Japanese sports car.
Oh well, just have to enjoy my old British piece of iron.


Mark

[Jimmy]

Little O-rings have killed more than good engines. Good people, too, except that was in a shuttle.

But why could you not keep up with my roofless Koopay as it is, Mark??

[max71]

Ok, back on topic.

Anyone have a gas analyzer?