I have a 91 z28 with t-tops. Im in the process of replacing my 305 with a 350. Ive herd that gm stopped making the t-top model camaro with the 350 because the frames were not strong enough and were twisting. Is there any truth to that? Im trying to decide if i want to purchase some subframe connectors to strengthen my frame or not.

Regardless of whether it's true or not, subframe connectors are the first modification that these cars should have, whether it's an L98 or an Iron Duke.

Without SFC's the unibody is going to twist some regardless of what's under the hood.

JamesC

Since manufacturers are always trying to match comfort, reliability, performance etc, there's always going to be a tossup from one to another. It's possible that even with extra reinforcing, GM decided a 350 was too much for the third gen platform as a T-top model but I doubt it. My 87 350TPI car came with T-tops.

You'll see lots of different packages in many different models and wonder why others are never offered. I drive a 91 454SS truck. It was only offered from 1990 to 1993 and those were the only years since the 70's that you were able to get a 454 in a 1/2 ton truck. Other options like wanting a 350 in a regular cab truck were not offered. You got a 305 in a regular cab and the 350 was offered in an extended cab. Gone are the days when you could custom order a vehicle with exactly the options you want.

You'll also notice that GM never offered a 350 with a T5 tranny. The real reason many may not be know but most feel that GM knew the torque of the GM was too much for a T5 to handle.

GM also realized the 7.5" diff was too small and upgraded it slightly to 7.625. Not a big improvement but still a little better. The real factory performance option diff was the 7.75" BW 9 bolt which didn't last as an option for very long.

GM is aware of how much a component can take. It costs too much money to over engineer an item if it's not needed. Would a newer car produced on the same assembly line with a 350 and a T-top survive? Probably but if customers kept complaining and squeaks, rattles, leaks etc, profit drops from recalls and repairs.

Many of the convertibles were not produced on the assembly line but were outsourced so the proper modifications could be done to make the car survive. You couldn't do that with every special model.

As mentioned above, all third gens should have SFC installed no matter what engine it has. SFC car keep a chassis from flexing but more in a bow in the middle fashion. Although they'll help, they can't really stop a chassis from twisting because of how they're designed. The only way to keep a chassis from twisting from far too much torque is with a roll bar/cage.

Out of curiosity, what symptoms would a thirdgen have if it was already "twisted"?

The most visible symptom is a small crack behind the drip rail on either side of the car.

JamesC