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pipnit
03-02-2004, 09:46 PM
Hey Guys,

I purchased my '74 18' 2+3 last July. I found it on this forum, an orange 74 in Michigan with a 350 and a TRS. "all original" I live in Indiana on the southern tip of Lake Michigan and ran this boat hard for fifty hours during three and a half months. The engine had been rebuilt to "LT1" Specs.
First thing to do was to pull the engine. After removing the heads we discovered there was massive scoring on the cylinder walls. The engine builder measured the compression and it was at 11.250:1 ! Way too high for a boat running on pump gas. We bored it out 30 over and put in dished pistons to bring it down to 9.5:1.
One of the TRS exhaust manifolds revealed a repair on the underside that was failing. I'm wondering if I should put in an OEM one or if I should or can get aluminum risers in there. One thing about the OEM ones is that all the bosses to mount hardware are there---is this the case with aftermarket ones too?
There are some cracks in the stringers in the engine compartment just north of the motor mounts. I've been told this is a weak point on these boats, especially with a lot of air time logged. I am having this glass reinforced. Does is make sense to reinfoce the stringers under the motor with steel??
The "tabs" between the deck and the stringers are gone!?! we are going to put wood in between the deck and the stringers so it's not like a trampoline.
Purchased a new TRS gimbal ring. On the old one, the splines were GONE. Now they have a more four sided design which should last forever.
I'm having the gel coat fixed on dings and scratches.
Lastly, I am fixing the seats and putting in a new interior. Does anyone know of a source to get the oem seat brackets with the same bolt circle?? These ones had been welded before and whoever did it, used the more is better theory of welding. These ones are pretty much trashed. If I can't find new ones, I will make some out of plate aluminum and have them beveled. My idea to reinforce and make the seats very solid is this. I work at a company where we roll structural steel. www.ringmidwest.com I am rolling some 1/4" x 1.5" stainless bar the hard way. I'll weld the butt joint, knock some holes in it then tap the holes. From there, I plan to just screw the bolts in from the top, into the ring and this should make things very stable. I'll let you know how it works. This way too, I will be able to get to the bolts---there is only like a half and inch between the deck and the stringer to get too. I can get to the close side so once two are screwed in, they should all be lined up.
Any suggestions or thoughts are well appreciated during this projects.

Thanks,

Geoff

Tony
03-03-2004, 09:40 AM
I remember this boat for sale...and am glad it went to someone who is taking the time, and has the ability, to fix it up. Welcome to the board and good luck with your restorations!

gcarter
03-03-2004, 11:02 AM
Nice boat, that was a good snag!

Seat bases available from Bilt rite.

The aluminum manifolds will not have holes for brackets on them. What is attached to them?

IMO, use aluminum for the braces. I assume you have a front "offshore mount" connecting the two stringers underneath the engine already, so some reinforcing will not hurt.
Scott, is the "offshore mount" the transverse frame in front of the engine?

George

pipnit
03-03-2004, 10:50 PM
I was orignally going to use some aluminum but then thought that it might corrode easier than stainless. Is there a product that exists already or should I get some angle or a different structural?
One the port manifold, there are some brackets on the "logs" that hold the altenator and power steering.
The starter and alternator or out on rebuild. I'm picking up the engine from the builder. He did the machine work and put the engine back together. I'm debating on getting a new carb or not. I have an older aluminum housing 750cfm mech pumper carb. It is not a marine carb. Any suggestions on a good 750 carb?
Thanks for the welcomes and I'll keep you guys posted on her progress.

pipnit
03-03-2004, 11:01 PM
ManPoodle, thanks for the lead to biltrite. They had the pedestals available at a very reasonable price. I'm going to order a new interior from them as well. The "tabs" under the deck that are gone lead to some stress cracks in the corners. Besides a little comfort, a carpet should hide these.

Rootsy
03-04-2004, 07:22 AM
Congrats, that was a nice boat! I'm happy to see someone is taking care of her :)

If you are going to use a holley style of carburetor IMHO go with a vacuum secondary carburetor vs mechanical. i prefer demon over holley but that's just because they come with all of the bells and whistles already and the craftsmanship is a bit better.

Edelbrock offers carter AFB style marine carburetors also.

so you have a lot of choices. each have good and bad points.. depends on what you wish to accomplish... holley's and demons have more readily adjustable features than the AFB for extensive tuning... but all of them should run reasonably well out of the box...

lastly, i don't know how radical you are making the motor or what kind of rpm you are planning on spinning but you may be better off with a 650 cfm carb than a 750... a 750 is a wee bit large unless you are gonna really spin the motor and need substantial airflow... a 350 @ 85%VE @ 5000 rpm doesn't even ingest 600 cfm of air...

pipnit
03-04-2004, 08:01 AM
The motor was and has been built to spin upto 6500 RPM. I was just going to go through the motor but after taking off the heads and seeing the scoring, I knew that it had to go to a builder. Shaker Industries in Granger Indiana got the job. Old man Shaker is probably about 65 and is a s.b. guru so I know that it has been done right. My buddy who steered me in his direction has had close to ten small blocks done by him. The engine as is according to the computer should be in the 385 h.p. ball park. It was a little higher with the high compression but for pump gas, I'm sure I was getting detonation (although the crank bearings were ok). At the very least, I know I was getting a lot of blowby in the cyl. because of how loosey goosey the pistons were in there. I'm not going to dyno the thing simply because it is built, it's done and I know it's done right. My allowance for money to pour into this thing is pretty much all accounted for. I'm going to get the motor Sat. and will make sure that it spins at 6500 heck I'll call right now.

pipnit
03-04-2004, 08:20 AM
Ok, just got off the horn a minute ago. He said the the way this motor is setup now it should turn at about 6000. He said it will spin higher and faster but I won't be making any power. He said that the 750CFM would suit the engine real well. The previous owner said that the engine was designed to spin at 6500 but I don't hold much stock in what that guy said. For example the compression according to him was 10:1 but after measuring it, it was over 11:1! I was also told that the boat was 100% original minus the rebuild on the engine. Upon further inspection, found out that the gel had been resprayed on the bottom in a hap hazard way. In hindsite, I probably paid a little too much for the boat and now know to get a marine survey. Really the thing is pretty sound though. Now soft/wet spots and I'm still happy and willing to pour some dough into it which is what counts.
Why do you prefer vacum secondaries over mechanical? I would think that the mechanical would give you better performance and easier to tune. Holly i've been told is on thier last leg. I have a friend who does R&D at Edelbrock and he can get me a good deal---which one?? Thanks for the help!

Geoff :moped:

Cuda
03-04-2004, 09:16 AM
I'm certainly no expert, but I think spinnig 6000+ will be awfuly hard on your transmission and drive. Others on here have more TRS experience.

pipnit
03-04-2004, 11:23 AM
Hey Madpoodle,

The cam was changed to make up for the lowered compression.
In@114
Duration 224 @ .0050
Lift 450-460

Rootsy
03-04-2004, 11:51 AM
as poodle said... i prefer vacuum secondaries for the ability to tailor when they come in. if i am on a long cruise i delay them with a mere spring change... whala better fuel economy by essentially choking the engine off some which will hurt my WOT rpm capability... i generalyl cruise at 3500 rpm... now gregk has a holley with mechanical secondaries that has some trick stuff done to it and it runs well on his 502... really well...

rpm doesn't really kill the drive.. well it will if excessive... but if you take a look at the OB guys.. they are turning some serious rpm's through the gearcase... the trick is to keep it COOL and have GOOD lubrication.

as a matter of fact.. more rpm often aids in longevity... if you are making big torque numbers in the 4000 - 5000 rpm range and peak hp in the mid 5 - 6000 range... spinning it to say 5500 will decrease torque (it's a pure mathematical function)... torque is what breaks drives... Torque gets you there.. HP keeps you there... but to each their own :)

i'd go edelbrock over holley these days.. unless you want to spend big buckaroos on one of the HP carbs... especially if you have access to edelbrocks inexpensively. a 750 will work fine... but a bit smaller will make it more responsive in the lower rpm range..

you want to spin the motor to an rpm which falls within a few hundred rpm of the HP peak... wherever that is in the rpm band... so prop it accordingly to achieve that.. if it happens to be 5000 i'd shoot for 4700 - 5000... my motor peaks about 5600... so i turn it 5300 - 5600... generally right around 5500 by myself and generally 5300 with another person or two..

good luck with your motor!

Root - where is summer when i need it?

pipnit
03-04-2004, 12:01 PM
Thanks for all the info, advice, insight, and knowledge. It's a lot of fun here! Anyone out there running a similar setup? I have to check what kinda prop I have now. I know it is a four blade mirage and I wanna say it is a 21. It was previously setup for a small lake where he couldn't really open it up for any amount of time. What is a good one for this boat for top speed on Lake Michigan. Thanks again!

pipnit
03-04-2004, 11:47 PM
I have my feelers out for the TRS question. On a OB board a lot of the guys can't believe that my 18 footer has a TRS on it. Here was one of the replys

TRS on a Donzi 18"?!?!? Yikes! I had one on the back of my 22 Classic and it looked like it was ready to sink. Have you had that thing in the water yet? When you're ready to get rid of the TRS let me know, I can always use spares.

I ran my 22 for years with a pumped up 454 mag and a TRS. Couldn't brake it when I tried.


Here is a picture of what the cyl. wall looked like before the rebuild

Rootsy
03-05-2004, 07:35 AM
scott,

i'll give it to you on the trs rpm thing... i neglected to remember there are things other than gears, shafts and bearings in there... my bad...

they aren't heavy enough to give me a hernia and i've carried one or two from point A to point B when i was younger... heavier than a bravo though if my back recollects... :lookaroun

Root - Grenade equipped

smoothie
03-10-2004, 08:07 PM
I was curious as to the max rpm,because I run my TRS at 5200,5400 rpm and I blow a little fluid out the breather,so a email was sent to a well known TRS,trany rebuilder and this was his reply...

QUOTE:
All Mercruiser engines have a top operating range of 4400 - 4800 RPM. Turning the drive faster isn't a problem, but I would keep it under 6000 RPM.


So I guess I should be OOO TAAA :yes: