225 power loss, fix or swap

To clarify, if I swap, it is for a 225 that is sitting in the corner, "ran when pulled" (according to PO).

For background, the engine has been running ok for last 2 years, since carb rebuild. Needs choke till 190 degrees reached, then ran fine. I put on pertronix with flamethrower coil and new wires / cap, etc. and gained some this spring.

Lately, I have been losing power after the engine is warm. (stumble at WOT pulling hills on highway). between that and the cold starts, I started adjusting on the carb.... Now it is worse. It idles fine, but stumbles on accel. I have the carb emission screws out about 3.5 turns to get it to run. I thought I was fuel starved, so I changed filters, with some improvement, until it was warm again. My timing is a steady 7.5 at idle, and with vac adv. connected it is advancing, but it seems to advance all at once vs. slowly. I am also noticing a tap from the front end, first thinking the noise was water pump, but now thinking maybe timing chain after a lot of searching here. Also could be a vac leak (I can't find any major one, but could try replacing carb/intake gasket)

My choices are: keep working on the carb and pull fuel pump and or cover to check out the timing chain, or.... swap for the other engine and cross my fingers. My intent was to go through it "someday" and put it in fresh along with the T-14 trans to replace my T-86.

suggestions?

 

Try rebuilding the carb.

 

Well, I started it up cold last night, and took it for a spin, runs great when cool, I am thinking something a vac leak is getting worse when hot, or fuel pump is getting weak when hot, or the timing chain gets much worse when hot, as I think that is the noise I am hearing from the front of the engine.

thanks for input, cheapest and easiest is pulling carb and at least replacing the carb/intake man. gasket.