1974 20' sceptre transom replacement and i/o to outboard bracket conversion

[flyingfrizzle]

The windshield had some oxidation on it and after cleaning it up a bit it looks a hundred times better. I have about half of it polished back up and as soon as I get the rest cleaned up I will be putting it back on. Also I have the bow railing and will reinstall it as well as the rub railing too.
You can see some dullness and water spots on the frame, most of it came right out with a little compound and a cloth wheel. There were some light scratches that came out but it took a little more to get them off. The rubber trim had yellowed but I found a way to bring it back to its original condition. I don't have any pictures of the finished frames yet but here are some pics of the start of the process. You can see just after the first pass it is starting to look better all ready. After some time on them they look much better than pictured below.

[flyingfrizzle]

Took the boat out after lowering down the motor this weekend. I went down two holes to get it at 3.5" above the keel and it done much better. I can trim the motor all the way up now with out any prop slip or breaking loose. My first run was with a 4 blade rev 4 17p and it would go over 6000 rpm easily and need more prop. I change it to a Mirage Plus 19p and it still needed a little more prop to get the rpms down a bit. The four blade gave me a little more lift than the 3 blade but not that big of a difference in the flat calm water in the back creek that I was in. In ruff water offshore the rev 4 would do much better holding but this boat is more intended for inshore anyway even tho it will do better than most out there in the blue water. With the 19p I hit 62 mph on GPS quickly and stopped at 6000. I had a 21p that I slipped on the boat for on last quick run and it seemed to be about right far as RPM range. I got it up almost to wot when I backed out of it. I did a quick glance at the speed and saw 65 for a second but did not watch it much this run due to being in a narrow creek with many turns and short straight stretches. My son that was with me clamed to see 67 mph but I didn't see that due to worrying about where we were pointed. We were also using the GPS speed off of an app on my cell phone so not sure how accurate it is anyhow as 67 seems not possible. The boat defiantly would run 63-65ish tho if you could get it to handle at and behave at those speeds. The boat handle awesome all the way up to 62 great but once you get over that it gets a little loose. It makes you tighten you hole up a bit. Over that speed if you make any slight steering adjustments it will try to get some slight chine walk but not bad as expected for a seacraft 20. That is a common issue with these hulls over 60 but they were not designed to that any how. Also the hull is light at the moment with no gas tank or rigging. just an empty shell with a 6 gallon pony tanks so once loaded down with rigging fuel it will probably not do these numbers. Over all I am really pleased with the performance and handling of the boat. Plenty of power and if I ever used the huge deck space to carry a large load the 3 liter outboard has plenty of torque to handle any weight thrown at it. It is amazing just how much room this model has in it with the bracket and full transom. She is a very fun boat to ride in and have fun with. Just need to get the rub rail back on and the windshield then she will be ready for spring!

[GameOnSalmon]

Frizzle - Been watching this build. Outstanding Job on the Whole boat...and Since I like speed the #'s your posting are Awesome!

It's really making me want to take a I/O Seafari 20' bracket it and drop on a Etec 200 which is only 58 lbs over your 225.

Plenty of power to run with a big load...and Plenty of Ass kicking Power for Blowing The Bass Boats on the lake when its glassy here.

That would be a sight for eyes a little Seafari ripping down the lake at 65mph plus...

SHE Looks fabulous...and I wish i could talk the wife into letting me run a 20' Sceptre, I love the lines and look with the deck space. However she wants a Cabin.

Next you need to run that baby into some Blue Water 3' to 4' and see what happens with that Power Plant on the back.. I would be very interested to see how she shakes out... Well Done!

Robert

[flyingfrizzle]

Originally Posted by GameOnSalmon

Frizzle - Been watching this build. Outstanding Job on the Whole boat...and Since I like speed the #'s your posting are Awesome!

It's really making me want to take a I/O Seafari 20' bracket it and drop on a Etec 200 which is only 58 lbs over your 225.

Plenty of power to run with a big load...and Plenty of Ass kicking Power for Blowing The Bass Boats on the lake when its glassy here.

That would be a sight for eyes a little Seafari ripping down the lake at 65mph plus...

SHE Looks fabulous...and I wish i could talk the wife into letting me run a 20' Sceptre, I love the lines and look with the deck space. However she wants a Cabin.

Next you need to run that baby into some Blue Water 3' to 4' and see what happens with that Power Plant on the back.. I would be very interested to see how she shakes out... Well Done!

Robert

Thanks Robert,

The boat is a little rear heavy but with the forward weight of the sceptre and seafari you can almost get away with the bracket and lager outboard. My bracket is a little over built and heavy so I imaging a Hermco would be 50-60 lbs lighter than mine so a E-tech 200 would be about the same weight with the lighter bracket and should float similar. I don't think you could do this to a center console with a heavy motor like you can with these style hulls. If I had infinite funds I would rather had the Mercury 175 pro xs for power. The 2.5's are lighter than the 3.0 by a bit and 175 hp propped right would carry this hull over 60 mph. Or even better a light weight 2.0 liter F1 motor from mercury racing. Motor really needs to be lighter, but if you have the need for speed its doable if you keep all the weight forward as possible. A 115 hp is best for balance but just not a as fast as I like. Anything over 62 gets a little scary and will make you nervous driving. It gets very touchy and will chine walk if not careful at high speeds. Very fun to drive tho.

[GameOnSalmon]

Frizz,

Ya, after watching you go crazy with the Sceptre, i mean i know you got some serious hours into that ride and it looks amazing.

I am hoping the Seafari has enough weight forward that a 200 etec on a bracket fits perfect. When i get a little closer... (have to find the right seafari) I am looking now, I will run a few things past Denny and get some feedback.

Curious if a larger in floor tank would help a little on balance. I have seen some pictures of Seafari and Sceptre boats all 20"s with big motors but all under 430 lbs.. that look to be balanced perfect sitting in the water.

However there are a few sitting out there with big 4 strokes that the ass looks like its going to drown. I know Strick has a 140 zuki on his sceptre and i thought that engine was arouond 410 or 420 if i remember right. I can't believe that 20 lbs give or take will make any difference.

I did...because i know you're a merc nut, check out the 175 pro xs and Eds Marine has a mongo sale about 11k out the door. But i think i got my mind set on a Bracketed 20 Seafari with a 200 Etec.

Keep us posted here... and for what its worth.... I love the idea of the Chopped down windshield on your Sceptre. That looked Bad Ass to the Bone!

Robert

[flyingfrizzle]

Originally Posted by GameOnSalmon

Frizz,

Ya, after watching you go crazy with the Sceptre, i mean i know you got some serious hours into that ride and it looks amazing.

I am hoping the Seafari has enough weight forward that a 200 etec on a bracket fits perfect. When i get a little closer... (have to find the right seafari) I am looking now, I will run a few things past Denny and get some feedback.

Curious if a larger in floor tank would help a little on balance. I have seen some pictures of Seafari and Sceptre boats all 20"s with big motors but all under 430 lbs.. that look to be balanced perfect sitting in the water.

However there are a few sitting out there with big 4 strokes that the ass looks like its going to drown. I know Strick has a 140 zuki on his sceptre and i thought that engine was arouond 410 or 420 if i remember right. I can't believe that 20 lbs give or take will make any difference.

I did...because i know you're a merc nut, check out the 175 pro xs and Eds Marine has a mongo sale about 11k out the door. But i think i got my mind set on a Bracketed 20 Seafari with a 200 Etec.

Keep us posted here... and for what its worth.... I love the idea of the Chopped down windshield on your Sceptre. That looked Bad Ass to the Bone!

Robert

If wish mine sat a little higher in the back but it is not too bad, In the PICs you can see where it sits fairly good in some of the pictures but the one with the black windshield it is sitting a lot lower in the rear because my bracket has two drain holes. There is one in the rear and one under the bottom of the flotation chamber at the low point and the one at the low point got left out and the bracket filled with water in that picture. You can see how much lower the swim platform is in that pic. Also looking between the 2 pictures you can see that the floatation chamber makes a big difference of about 2-3" when both plugs are in. I wish I made the chamber different and built it lighter due to I could of easily shaved off another 50 lbs or so. Also in the pics I am running off of a 6 gallon tank all the way in the rear. Once I put 40-50 gallons of gas all the way forward in the tank compartment it should help a lot.

Good luck finding the right boat, there are a few mint ones left out there but they are getting hard to find. Most have issues here and there but I did see a seafari a while back that was stored in a building for the last 20 years or so that looked like it was new all original unmolested. Think it was up north some where? I cant remember where but it was around $6k or so and not sure what power but think it was an 70's evenrude 140 maybe. It was on CL, might still be around. I will let you know if I see anything super clean that is in top shape if stumble across one.

[flyingfrizzle]

After some time this winter passing and with spring in the air I decided to finish up the little 20'sceptre. I got out there this weekend and spent 3.5-4 hrs tapeing off the deck to get the original plank strip design back painted on. I used 2 part polyurethane interlux perfection with alw grip medium griptex non-skid mixed in to do the planks. Finding the right width tape to match the original spacing was not easy or available at the big box stores so I had to search around to find some but finally did. It was a very titious process getting the lines taped in straight and true but slow and steady four hours latter I was ready to roll the grip paint on. I took several coats to get the grip additive consistent and even but it looks good now that it is down and the tape removed. I didn't get any pics of the tape off but here are a few of the final floor. Up next is pulling the too heavy 3.0 225hp and installing a 2.5 that will be more what this boat needs weight wise. With the weight forward of this model it floated the bigger motor but should preform much better. I have a 2001 200hp that has a like new 100 hr 2007 drop on power head on it to try next.

These are not good pic's, took them at dark and they are low quality images but it turned out much better than it looks!

[flyingfrizzle]

I have seen tons of boat builds up here but no motor builds so I figured I would do a outboard rebuild for the little sceptre up here if any body has interest in seeing it done. Nothing wild like the race boat will have but a basic rebuild and hop up on a common 2 stroke outboard. With the racing season over I made some time to get my new motor for the sceptre put together. I started out with a 2001 Mercury 200 efi 2.5 outboard (2.5 is the best and most popular block mercury ever made) that had a new 2017 power head installed on it. The power head suppose to have around an 100 hours on it and be like new but I decided to pull it apart and add new rings just so it would be a fresh new motor once it went on the boat. Once apart it looked like new, I was questioning myself for even opening it up. We now that it was apart, I decided to do the rings anyway just because at this point why not start the hour counter over again. The bores all looked good but I took it to Tommy Dunn of Get it dunn racing just to have him to check the tolerances. Tommy is one of the best racing mercury mechanics on the east coast. He builds big power outboards for the drag racers that are all over the us and other parts of the world. Any way, he checked it and told me I took apart a perfectly good motor for no reason but at least now I know what I got. He did do a slight hone to give it some better oiling hone marks to keep the pistons lubed better. The block got some rod slots to help direct the fuel mixture to the ports better for a little more power and a few other little tricks to hop it up slightly. While he had it I let him check the crank and add new high performance metal caged rod bearings instead of the factor plastic mercury ones. Polished up the crank journals and assembled the rotating assembly after he spent 3 hours cleaning the block. They are meticulous about cleaning the blocks and keeping them clean. The 2.5 blocks they build turn over 10,500 rpms and make 350 plus horse power. Mine will stay under 6200 and make 225-230ish so no near as much but still good to keep it clean a possible. Once back to the house I got the block and set up on the work bench and started putting it back together. I started with the exhaust divider, gasket and bolting it on while checking toque specks. I use the factory Mercury manual to aide in assemble due to it is 100x better than the aftermarket type service manuals. They run $100 but you can find them on ebay for $20 buck or so normally. Next I installed the heads, Got the surfaces prepped well then added the gasket and installed. Factory heads get installed with yield to torque bolts so you are suppose to torque to like 30 lbs then 1/4 turn to stretch the bolts. If you reuse the bolts you need to install them at just standard 40 lbs and no extra turns due to the bolts are already stretched and will not need the extra turn. If you do the extra turn, it will likely strip out the aluminum threads due to it ends up tighter cause the bolt has no give after pre-stretched. Next I try to get the reeds and adapter plate on so that it will close off the block and keep any dust out. The reeds I use normally are carbon or an epoxy/glass type. If you suck one in the motor if it breaks it will not hurt much. The factory ones are metal and will tear up a bunch of stuff it one fails. The reed cages I am using are plastic coated aluminum. The plastic coating will help them seat better for less blow back and that means more power! All that gets torqued to the correct speck then its on to the popet valve. The popet gets new gaskets, a new diaphragm, spring and block bushing/seat. These things leak all the time and get a little tear in the diaphragm and start dripping out the weep hole. If not fixed it will fill up the lower cowl with water and possibly suck some in the motor. I had my son help me with the torque on it. Some Pics of the rebuild:

Service Manual:


Block/Rotating assembly:


Port side:


Cylinder Hone:


O-ring Head:


Exhaust port & new Rings:


Exhaust divider in:


Keep it clean!


Reeds:


Popet Valve:

[gofastsandman]

Nice relief work on the ports. You have a good machinist. Saw 4 old v8 rudes at an
auction preview. Tiller arms had nothing left. Makes you think if someone ran them that way.

[flyingfrizzle]

Originally Posted by gofastsandman

Nice relief work on the ports. You have a good machinist. Saw 4 old v8 rudes at an
auction preview. Tiller arms had nothing left. Makes you think if someone ran them that way.

Those v8's are getting harder to find in good shape, I see a few nice ones pop up on s&f ever now and then.

Everything on this block has been mild to maintain low end torque. On My other two blocks for the race hull they are a little more cut up. Not as extreme as some but a nice cut to flow and still not loose all the bottom end.

Similar to my exaust chest cut on my other blocks:



A extreme cut for 10,000 plus rpm: