My current engine is a 431A which was in production from 1989-1991 well before the vortec was introduced. Not concerned about the year my boat was built as it is not a production boat. It was custom made and the engine bought for it.
My situation is that my current non vortec engine has had it. I have been recommended to buy a remanufactured engine but upgrade to the vortec engine rather than rebuild my existing engine. I don't want to have less HP than what I currently have. A bit more is always nice to have. My current engine is rated at 205 HP. Don't know whether this rating is at the prop or crank. From what I have read and concluded from here is that the replacement engine I intend to get being a vortec is only rated at 190HP with a 2 barrel carb. Does this mean I will have less final HP at the prop because its only rated at 190HP compared to my current 205HP or will I have more because one is rated at the prop and the other at the crank. Or will it be about the same. If I go to the 4 barrel carb it looks like I will gain 10 to 20 HP. Again is this gain a direct comparison to my current set up or is the 215 to 220 HP claimed rated differently to my current set up. Hope this clarifies the situation and someone can help me with my questions.
I need to replace my intake manifold but can I use my existing 4 barrel carb (its a rochestor #17088142) or will I need a different 4 barrel carb to suit the intake manifold as well as the fuel and air requirements of the vortec engine.(Either, or, the vortec fuel requirements are the same, different carb could mean different linkages, depends on the intake ya buy) Will the new engine bolt straight up to my existing stern leg or will there be other parts I need.(All the bolt holes are the Same, except the intake manifold) My current engine has a mechanical fuel pump will this need to be changed to electrical.(Yes, 'n use a relay or Oil pressure switch for safety) Things like fly wheel and starter motor.(Flywheel diameter, 'n starter bolt patterns follow each other, if ya got a 12" flywheel, ya need the straight across bolt pattern drillin's in the block, if ya got the 14" flywheel, ya need the staggered pattern starter bolt hole pattern drillin's in the block, some but not all blocks come with Both drillin's done) Any other info greatly appreciated.
Sometimes its hard to explain exactly what it is you are after.