Engine and speed question
 

Ok I have original 454 mag's 365 hp.

They have over 900 hours on them. I may have an engine that could be getting sick, noticed low oil pressure after a run. This may be due to oil or sending unit at this point, but may be the engine. It runs fine at this point so we are going to run some higher weight oil in it and check the pressure with a manual gauge. If this does not solve the problem, I am hoping I caught it before I have major problems.

Now on to my questions. Assuming I do not have a problem with the engine. I currently get high 60's out of this boat with a set of 3 blades. I got a set of 4 blades that really makes the boat ride nice, but can only spin them 4400 RPM. So if I were to do some work on these motors to be able to spin those new props at say 5000 RPM or a bit more, what would I need to do?

I am on a budget so I don't want to go crazy, and I am really not looking for a huge speed gain. Just want to spin these props right, and if I hit 70 that would be great.

It is really nice to see someone get those hours our of motors and keep them stock. I know of a 454 with 1500 original hours and several pairs of 500 EFI's over 500 hours.

My guess at this point is that a complete rebuild would be in order to try and gain extra HP. I assume they are fuel injected motors and all you can do is change the heads, cams and reprogram the ecm's for added horsepower. You can expect to spend around $4k to $5K per motor pretty easy.

Nah these things are old 1988 no EFI.

I originally planed to get 1000 hours on them before I did anything with them. This oil things has me nervous, even though it could turn out to be nothing.

I have had oil pressure sensors and guages read low when they get old. First thing I would do is to plug in a pressure guage to the engine and compare it to what your panel guage is telling you.
I would bet it's the sender. I had one once reading ~20lb@idle and 35#@ 4K. Plugged in a different sender and guage and the pressure was actually 35#@ idle and 50# at speed.

Oil pressure problem is fixed. Combination on what looks like old oil, that was supposed to be changed, and sender that is readding funky.

Max Life 20-50 and Mechanical gauge shows 40 psi at idle and 70 around 3500 RPM.

tyler crocket he's in hot boat, buddy had good luck on budget, 70's full roller,head work,intakes,barry grant carbs,msd ing,good prop shop!