Brief intro. Purchased 74 boat with 455 Olds, been in storage over 15 years. I reached out to boating forums, but most reply's are guys having fun saying "use the engine for an anchor and put in a BBC". I want to keep the boat as original as possible so after viewing your forum, I bet I get better help. Because I have no history on the boat and with it stored so long, rather than run it, I decided to remove the heads and take a peek.

I would love to know year and any other info on the engine. I attached pics of block and head numbers. Also checked the bore with my mediocre caliper and it appears to be 4.15 maybe 4.16. The cylinders don't appear to have much wear, some light rust, hopefully from sitting so long.

Lastly, input please for recommended Head Gasket to order as I get ready to put it back together and run it.

Block


Head


All triunions same except one on the right???

 

455 F block with Ka heads. Ka is an industrial or marine application. Standard issue boat engine.
Look for the serial number stamped below the left head (what would be the driver's side in a car) for the date.

 

The different rocker bridge is an aftermarket replacement which is basically these: 181-1057 — (Rocker Arm Kits)
What you have currently should work fine.
For replacement look for the same or Melling Rocker Arms MRK-550-2 or move to an aftermarket roller setup.

Stock bore on a Oldsmobile 455 is 4.126" so you may already be .030" overbore.
You probably will just want to go with a Fel-Pro head gasket. See Summit - OLDSMOBILE 7.5L/455 Oldsmobile V8 Head Gaskets for a list of available gaskets.
If you want to use an MLS gasket you will need to have the head and block surfaced.

 

Thank you, nice to get serious reply. I may post other questions as I continue to put this back to run

 

Looks pretty clean. They were really popular with the Jet Boat guys for a while. The only thing I would do if it has been sitting for 15 years is take the valve springs off and make sure none of the valves are tight or stuck. Squirt some oil on the stems and work them up and down. The regular Fel Pro car head gaskets will work fine.

I would also make sure to flush out the entire fuel system.

 

Thank you, I did take out both tanks and clean them out. Will replace all fuel lines and filters.

 

Thank you.

 

If you have a need to replace the cam (rusty lobes?), I have a NIB Erson JB100 "Jet Boat cam", that I haven't yet used.
I've loved the Jet/Olds combo since taking a ride in one at 13 yrs old, awesome combination!!!! (75 mph in the FL Keys)

Lets see those boat pics!

 

Did you pull the heads yourself , and which head gaskets were on it..were they Felpro blue?

 

I have read that the Oldsmobile 455 engines were used quite a bit in boating and in industrial use like irrigation pumps back in the early seventies. There must have been a reason, don't let the haters on the boat site bumm you, they are all over the interweb.

 

Neighbor had one with duals on a high-rise tunnel. Used to start it up and I'd come running from 3 doors down just to feel the concussion of those open headers. Probably 7-8 years old. He had a 68 Nova with a 427 in it...race car. Same deal.
Dad and I just ran into him after 50 years at a local show. Still the same guy still playing with big engines. Has a nice custom 62 Chev pick up. Told him hes one of the reasons I have the disease. He just smiled.
He (John) said the reason he always ran the BBO was the usable down-low torque that would bring the boat out of the water better than a Chevy Ford Hemi etc.

I did have some cool neighbors. 3 houses in the opposite direction was a Mopar nut. He had all the usual suspects as he flipped them... hemis winged cars vert Challengers wild blown chargers...its no wonder I'm totally sick.

 

Neighbor 2 doors down had a '70 Chevelle SS 454, HUGE cam 4 speed and 4.88 gears , I was 14. I feel ya!! Yes, I drove out of high school in a '70 Chevelle, just not a SS, or 454 (but I'd already bought one), that was 1976.