Piston Slap: MGB ignition worries and EFI future-proofing?

David writes:

I have a question about my 1967 MGB with electronic ignition, cross-flow aluminum cylinder head, 1 3/4-inch SU carbs (HS6), road fast camshaft (or is it Fast Road? — SM), .060-over pistons, 8.8:1 compression, new Mazda Miata five-speed trans, and lightened aluminum flywheel. Legendary Motor Car said the car was misfiring because the electronic ignition was made in China and faulty. They went back to traditional points, condenser, rotor.

I road-tested the car in November and it flew, but I am worried that this will not give road-fast performance. And, with an extra 10 hours of labor to remove the carb assembly to get at the ignition, it’s not something I want to deal with every few seasons.

Anything German or American made you are aware of?

Sajeev answers:

Perhaps others are luckier than me, but I’ve bought parts from well-regarded German and American manufacturers that were garbage. And sometimes the parts weren’t surreptitiously made in China, either. Pertronix distributors are a commonplace upgrade for classic British iron, but they have a hit-or-miss track record (depending on who you ask) across many classic car forums, and are probably made in China. Even if Legendary Motor Car didn’t replace a failed Pertronix already, I’d be hesitant to add one.

The MG forums suggest letting Advanced Distributors rebuild your distributor with electronic guts, but I would contact them to ensure they stand by whatever electric internals they source for their rebuilds. If they aren’t winning you over with confidence, perhaps you have the best equipment in your MGB already. You can always learn the truth of your car’s fuel/ignition performance by spending a few bucks to get dyno tested.

If you choose to upgrade for reliability and durability (10 hours of labor? Oh my!), switch the SU carbs for throttle bodies, and get a self-learning fuel injection system. New EFI systems learn the finer points of your MGB’s ignition and fuel calibrations, which might really come in handy considering your hotter camshaft.

But these self-learning EFI conversions are not a weekend job for cars like an MGB, as they don’t have the technical support of your average Detroit muscle car. I am surprised at how little information I see on EFI conversions for the B-series engine, but, in theory, you need to follow the steps outlined here and apply them to your engine’s specific needs. This sounds like a cop out, but since you are already a customer of LMC, they likely have the resources to get you a realistic conversion price on an EFI swap.

One last comment: You made great choices in period engine modifications with a more modern gearbox; perhaps taking the MGB to the next level of performance actually requires upgrading to modern, self-learning electronic fuel injection. Odds are you will not regret the conversion!

Have a question you’d like answered on Piston Slap? Send your queries to pistonslap@hagerty.com, give us as much detail as possible so we can help! If you need an expedited resolution, make a post on the Hagerty Community!