175 gt to 235gt

Hello im new to building outboard motors but im very experenced in building race motors for the drag strip so this will be my first boat ist possable to convert a 1989 175gt to a 235 while im going through it any help would greatly appreated tthanks Tony

Re: 175 gt to 235gt

The 160 cid 175 and the 160 cid 235 are pretty much the same anyway. The 235 was rated at the flywheel and a little optomistic. The 175 - 160 ci version - is propshaft rated and a bit conservative.

The 2.6 XP / GT had different heads which do make some difference. The 2.6 XP / GT had scolloped pistons and block and the ports were squared. The exhaust stuffers were opened a bit.

Re: 175 gt to 235gt

thanks for the quick reply I was wondering if a head swap or intake mod would help with the rebuild to get a little more power out of it

Re: 175 gt to 235gt

The intakes are the same but there is some untapped power there.

Re: 175 gt to 235gt

I have heard about opening up the plenum under the carbs to feed the cylnders with both sides of the carbs would this be a good place to start

Re: 175 gt to 235gt

Dhadley has offered some good information. You will need an early set of 235 big bore high compression heads: 325638/639. They were standard on the first big bore 235's and were also found on the later 2.6 XP/GT models. Look for 6 of the rubber intake stuffers: 322722. They are NLA, but worth scrounging around for. These were on all 200 and 235's but were dropped when the engine was derated to 175. Worth 5-8 hp. The 2.6 models came with composite reeds from the factory: you might want to consider changing to them. Your engine already has the 1 3/8" carbs. Most of those 175's had plastic carb bowls. You may want to check them for flatness. These always tend to warp and they often leak fuel and can cause lean running conditons if they are out of flat in some places. Your current power pack is rev-limited at 5800-another HP limiting factor.