Well, it looks like I'll be boatless until around April.
I recently purchased a 1978 Marlin 18' jet boat, with trailer for $1700. Great fixxer upper...I've had it on the water a few times. Had one problem with it the first time out that wasn't discovered until we pulled the boat out of the water. Somehow the lower steering pin fell out of the steering nozzle. Replaced it along with the upper and lower pin bushings. Took her out on the water about 5-6 more times. No more problems.
However, this boat has an Oldsmobile 455, but for a small jet boat it was a little sluggish on the 'get up and go'...but other than that was a great cruiser. Had a speedometer that never worked...that will be replaced with a GPS speedometer.
Stripped her all apart...interior and all. Pulled the engine out and mounted it on a stand for disassembly. Pulled the jet out...which had the old style plastic transom housing...which was dried out and cracking/breaking all over the place. However, in the jet was a ski tow rope wrapped around the impeller shaft and caught in the impeller...this had been like that since before I owned the boat. This would explain where half my power went.
The hull is currently at a shop known as Fiberglass Unlimited here in Clovis CA, which everyone seems to swear by. They will be doing work to the bottom as well as replacing the flooring and stringers, then a full re-gel coat of the boat.
A little history on this boat...the people I bought it from apparently didn't know that the boat and the trailer are 2 seperate vehicles, so the trailer was not in the name of the people who sold me the boat...found this out via a trip to the DMV. They gave me the guy's address who owned the trailer and I went and found him.
Apparently he bought the boat from eBay from the Monterey area. He ran it quite a bit, then decided to trade it for $1500 plus $1000 worth of electrical work on his house. The contractor he sold/traded the boat to screwed him and the guy got rid of the boat before the owner could say anything about it. Then I ended up with it.
He told me that the guy he bought it from I guess blew the original motor, so they pulled a 455 out of a car and just dropped it in the boat without marine-izing it. When I got the boat it still had a paper element air filter, which we all know is a big 'no-no'.
I disassembled the motor and sent it to Engine Masters here in Fresno CA. They will be installing brass freeze plugs, line honing the crank/cam, new cam bearings, and all the other machine work they do to blocks. The heads are smog era J heads with the smaller valves. They'll be putting the bigger valves in since the heads are the same casting as the big valve 455 heads. They will also be addressing the oil drainback issue by enlarging the drainback holes in the heads. I can't remember what type pistons/cam they spec'd out for the motor but I'm gonna find all that out today.
Now this will be my first 455 reassembly I'll be doing so if anyone can give me any tips/pointers on reassembling one of these bad boyz it would be greatly appreciated.
The jet is completely disassembled and a buddy of mine is redoing the powder coat on it. I've got a new impeller and shaft as well as the master overhaul kit for the pump. The pump is a Berkeley 12JC-A pump...which I'm assuming the -A is the type impeller. I ordered and received a replacement transom housing, which I see that they make them out of aluminum now...no more plastic to dry out and break. It even came with a new bilge drain plug..WOW! LOL
This is also my first pump overhaul I've ever done. The main thing I'm concerned with is what to torque everything down to, as far as the impeller nut, packing gland bolts, etc etc.
The motor and pump will be done long before the boat is. Once the hull is done, I will be reinstalling the motor and pump, then before the interior is done I'm gonna install the new gauges and wire up everything, then take her to the lake and just back the trailer into the water without taking the boat off the trailer and fire it up to allow the new components in the jet to get wet and whatnot. Then after that she'll be going to the upholstery shop to get the interior rebuilt.
Some new things I'll be installing...transom tips for one. The ones that were on the boat had the flappers missing...not good. The 455 in question is either a '73 or '74. The casting numbers, 396021FA classify it as a '72-'76 common 455, while the head castings...411783 are '73-76. This motor didn't originally have HEI ignition...someone did drop an HEI distributor in it though. Which narrows it down to '73-'74 since they started using HEI around '75. I am replacing this with MSD's Marine Ignition system, with the MSD 85296 Marine mechanical advance distributor w/magnetic pickup, 6M-2 ignition pulse amplifier, MSD Soft Touch Rev Limiter 8768, and the MSD Blaster coil. I will also be getting a marine starter, alternator and carburetor so that everything is marine on this boat. Hell I may even hire a Marine to drive it! LOL j/k
This boat originally came with a bow mounted fuel tank...will be changing over to side tanks to open up the bow for storage. Also, it had a pole mount for a ski tow...changed that over to a motor mount one awhile back since the cup that the pole sat in broke loose the first time I tried to use it.
Will be keeping you guys posted as the project progresses. I'm also open to any tips/pointers/suggestions you experienced boaters have as well so feel free to post them.
Jon
OK got the cam specs this morning.
Elgin Pro Stock Camshaft
Cam Lift: 297 Int 297 Exh
Valve Lift: 475 Int 475 Exh
SAE Duration: 328 Int 328 Exh
.050 Duration: 244 Int 244 Exh
.050 Timing: 12 BTC; 52 ABC; 52 BBC; 12 ATC
What carburetor would be the best for this type of cam?
Sounds like it'll be really nice once you get her done. Let's see some before pics...
BRA
Here are some of what I have.
Nice project boat. Wish we could find those deals out here on the east coast.
Good luck!!
Well so far I've got the jet pump reassembled completely...those things don't take near as long to reassemble them as they do to disassemble them.
I've got the camshaft and the crankshaft installed in the block. Checked my bearing clearances...measured about .003" on the plastigauge on those.
Tuesday I gotta pull the engine and tranny out of my girlfriend's Blazer so I'll have 2 motor builds going on at once.
Once I get that motor stripped it will go to the engine shop...then I can finish my motor up while that's over there.
Hope to get the cam degreed and the timing chain on, as well as the pistons in Wednesday or Thursday.
I can't wait to hear what this motor's gonna sound like once it's done.
The carburetor that was on it I found out was a Holley 4011 650cfm, which is way too small for a big block like an Olds 455. Will be putting a 750cfm Holley 4150 upon reassembly.
Jon
My Marlin is titled as a 1972. Allot different looking than yours. I haven't been able to find much info on Marlin. I picked mine up for $500 with a trailer. It was in pretty bad shape but the hull was solid. I had to spilt the top off and relaminate the bow stringer, replaced all the wood from the keel up including the transom. Getting the top back on was tricky but as the pictures show, it turned out pretty good. I've been working on the boat for about two years in my spare time. The 455 Olds had every bearing spun, so I got a rebuildable 455 and did the full boat (LOL) to it.
Us Marlin guys need to talk.
Tom
VERY nice gel coat!
That would be a great idea. Like, start up a "Marlin Jet Boat Owners Association" or something.
I just might get a Marlin boat forum going.
Jon
Hey Jon , I am in Clovis as well . I'm currently rebuilding a 18 ft 75 tahiti from the ground up . Always nice to meet some local jetters. Give me a call and we can talk boats.
later Billy 903-5456
WAY COOL! I will definitely do that.
I don't know if you do your own hull/gel coat work, but if you need any of that, I would recommend Fiberglass Unlimited on San Jose just east of Clovis Ave. EVERYONE around here in the boating community has told me those are THE guys to go to for that. They're expensive, but well worth every dime. That's where my hull is sitting right now.
I'll give you a call sometime this evening bro.
Jon
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