Plot Question about John and General Tilney

I thought I was the only one who wondered about this. I've spent several hours seeking an answer, and finally I see your recent post. My impression was that he spoke to the General in order to cause trouble, but this didn't make any sense.

I don't have a copy of the book nearby, but I read through some plot summaries, and finally I found this in SparkNotes: "In Bath, when John thought Catherine loved him, he had told General Tilney that Catherine was from a very wealthy family. When the General ran into John much later, after Isabella had told John about Catherine's true feelings, John had angrily told the General that the Morlands were almost poor."

This goes along with later idea, which is that John, true to his obnoxious nature, was merely bragging. If he was confident that Catherine loved him, this would make sense.

Does anyone have any other answers?

John had no idea whatsoever that Henry was a potential rival.

When John met the general, he intended proposing to Catherine himself. He had failed to realise that she wasn't in the least bit interested in him. To make himself look important in the eyes of the general, he boasted about Catherine's fortune. As in, look at this really fabulously rich wife I'm going to get! The general, on hearing this, decided Catherine would be an ideal, rich daughter-in-law for him and was trying to separate John and Catherine by inviting her to Northanger.

John Thorpe had first misled him. The general, perceiving his son one night at the theatre to be paying considerable attention to Miss Morland, had accidentally inquired of Thorpe if he knew more of her than her name. Thorpe, most happy to be on speaking terms with a man of General Tilney’s importance, had been joyfully and proudly communicative; and being at that time not only in daily expectation of Morland’s engaging Isabella, but likewise pretty well resolved upon marrying Catherine himself, his vanity induced him to represent the family as yet more wealthy than his vanity and avarice had made him believe them. With whomsoever he was, or was likely to be connected, his own consequence always required that theirs should be great, and as his intimacy with any acquaintance grew, so regularly grew their fortune. The expectations of his friend Morland, therefore, from the first overrated, had ever since his introduction to Isabella been gradually increasing; and by merely adding twice as much for the grandeur of the moment, by doubling what he chose to think the amount of Mr. Morland’s preferment, trebling his private fortune, bestowing a rich aunt, and sinking half the children, he was able to represent the whole family to the general in a most respectable light. For Catherine, however, the peculiar object of the general’s curiosity, and his own speculations, he had yet something more in reserve, and the ten or fifteen thousand pounds which her father could give her would be a pretty addition to Mr. Allen’s estate. Her intimacy there had made him seriously determine on her being handsomely legacied hereafter; and to speak of her therefore as the almost acknowledged future heiress of Fullerton naturally followed. Upon such intelligence the general had proceeded; for never had it occurred to him to doubt its authority. Thorpe’s interest in the family, by his sister’s approaching connection with one of its members, and his own views on another (circumstances of which he boasted with almost equal openness), seemed sufficient vouchers for his truth; and to these were added the absolute facts of the Allens being wealthy and childless, of Miss Morland’s being under their care, and — as soon as his acquaintance allowed him to judge — of their treating her with parental kindness. His resolution was soon formed. Already had he discerned a liking towards Miss Morland in the countenance of his son; and thankful for Mr. Thorpe’s communication, he almost instantly determined to spare no pains in weakening his boasted interest and ruining his dearest hopes.

He looks like what happens when you punch a cow!

John Thorpe does believe that she is heir to the Allens.
During the first carriage ride that Catherine takes with John ( in the book), John says something to the effect of "Old Allen is as rich as a Jew, is he not?" Then he asks if Allen is her (Catherine's) godfather.
Most interpret this to understand that since the Allens are childless and that they were responsible for her in Bath, the Thorpes believed she had been named heir.