carbed 454 mag 365hp to 540 swap
 

I have a carbed 454 mag 265hp rebuilt 2 seasons ago runs perfect but I would like to cruise at a faster speed so I was wanting to change the short block out for more cubic inches. I was under the impression that I could buy a 540 short block and be able to reuse my top end, just go to a bigger carb. It has the rectangle port heads and everything is new, crane cam, springs and rocker arms. Then someone told me my heads will kill that motor as far as power. I don't have alot of dealing with high performance combinations, I would like to be able to reuse what I can off my current motor to keep costs down. Would a 502 short block be better? Thanks for your help

i was doing the same thing .,but my heads were crack it can be done i put a 540 dart motor in my baja best thing i did . boat runs great . i dail it in with the rigth prop . race about 30 boats last summer and beat all of them that i race ps. i wish i put the 572motor in

IF you have the 454 mag then you have the rec port heads. The larger cubic inch your considering will love those heads. Sure you can gain more HP with after markets however you can always change them out down the road. Not sure what your planning on spending on a short block however there are some pretty good deals here on the board for complete engines.

I doubt will see the gains you are looking for. You would need a bigger, preferably roller cam/lifters and then different springs also($1500) to make decent power. Then you would need better exhaust also($2000). The heads will work, but they are by no means ideal.

I think you would be a lot better off adding a supercharger and running 4-5lbs of boost. It would be easier and probably less $$$.

i looked into procharging it but there systems seem to be for 92 and up, I have issues with my powersteering location is where they want there blower mounted and it seemed like root blowers weren't that effiecent. I thought I might have to cut the engine hatch up also.

Merc racing "Bulldogs ran that head....500hp and ran forever
They had more cam, Roller Rockers and better Exhaust
600-650 hp is easy to get Reliably

i agree with birdog..do your motor like the bulldog. blowers and procharger are more promblens in setup and things go wrong i like n/a motor less moving parts to break

I guess I or we should have asked what Crane cam and exhaust do you have currently and or plan on using?

Do you have performance exhausts? If not you need to have a set if you are going to see the potential of the 540. Rather than add the heads from your motor to a 540 short block, you might be better off to sell your current engine to offset the cost of a complete 540 engine. There have been some good deals here on the forum. Super charging your current engine is a pretty cost effective way to go as well, and if you set it up right, it should be very reliable.

Okay, I'm back, been plowing alot of snow here lately, haha. I currently have the crane powermax 272 cam. lift is .484"/.515" duration 260/272. Exhaust is factory but I did pick up some gil stainless risers dirt cheap I was going to put on the top of the stock manifolds just to see if it gave it a different tone. Don't know if they'll help it flow much better or not.