Can a truack 351w block be uses as a bas for a AQ240 rebuild?

[cwhiting]

I am a new owner of a used 77 Fiberform with a AQ240 Penta setup. Found a cracked block today leaking water into the lifter valley. I need a new block for the rebuild. Will a car or truck block work for the marine application. Most concerend about mounting to the bell housing. Thanks for the help.

 

[captmello]

Re: Can a truack 351w block be uses as a bas for a AQ240 rebuild?

Yes the automotive block will work. You will need to swap the camshaft from the original motor along with the rest of the bolt ons.

Just a work of caution. The exhaust manifolds should ba suspect as well and are not going to be easy to find if bad. If they are bad and you run them on your new motor, it will ruin the new motor. So, just be careful trying to bring the obsolete motor back to life. You can buy manifolds the the 351s but not the ones that will fit your old style "Y" pipe. If you decide to go ahead with the work, thru hull exhaust may be your best alternative, eliminating the y pipe altogether.

 

[cwhiting]

Re: Can a truack 351w block be uses as a bas for a AQ240 rebuild?

Yes the automotive block will work. You will need to swap the camshaft from the original motor along with the rest of the bolt ons.

Just a work of caution. The exhaust manifolds should ba suspect as well and are not going to be easy to find if bad. If they are bad and you run them on your new motor, it will ruin the new motor. So, just be careful trying to bring the obsolete motor back to life. You can buy manifolds the the 351s but not the ones that will fit your old style "Y" pipe. If you decide to go ahead with the work, thru hull exhaust may be your best alternative, eliminating the y pipe altogether.

Thanks for the response. Two follow up questions. I assume the exhaust manifolds being suspect means that they can have cracks in them as well? The old cam and lifters shows some pitting on a few lifters so a new cam would be needed. I know that I would need something more than what a car uses. I would think a performance cam would be needed. Nothing wild but just above stock so it still behaves well and will idle but still be responsive. Is there any suggestions on a cam?

 

[RogersJetboat454]

Re: Can a truack 351w block be uses as a bas for a AQ240 rebuild?

Yes, typically when the block cracks the manifolds are suspected to be cracked if the original owner didn't drain them either. Other problem is manifolds will rot/rust out with age (particularly if they are cooled with salt water).

If the donor engine is pulled from a truck, the FACTORY STOCK truck cam should be a fairly close profile to a marine grind. Problem with stabbing any old cam in a marine engine is you risk water reversion. That is, an aggressive cam can hold the exhaust valves open long enough that they can actually draw some exhaust back into the cylinder. Being that a typical boat has a water cooled exhaust, it will draw exhaust AND WATER back into the cylinder which can cause bad things to happen.

A mild MARINE cam from say Comp Cams, or Crane, or Isky, or who ever you like the name of should be OK.