1971 Donzi Classic 18 power....

[Greg G]

My opinion based on that and 70 mph top speed is you can delay the external hydraulic steering until the following year. This will help maintain your budget and ensure you like everything an 18 Classic represents before you dig into the bank again.

[Classic18]

My opinion based on that and 70 mph top speed is you can delay the external hydraulic steering until the following year. This will help maintain your budget and ensure you like everything an 18 Classic represents before you dig into the bank again.

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Thank you! I'll feel better knowing I am exercising good (safe) judgment!

[flabum1017]

My opinion based on that and 70 mph top speed is you can delay the external hydraulic steering until the following year. This will help maintain your budget and ensure you like everything an 18 Classic represents before you dig into the bank again.

just make sure the gimball to steering arm has no play, used ones tend to loosen up and most people don't service those parts like they should.

[Greg G]

Yep, 100% agree.

[Classic18]

Need to get the appx outdrive location....setting up according to Merc specs, my prop center comes about 8" from the bottom of the hull. Is there a chance one of you have a production (non modified) outdrive in a Classic 18 that you could measure the prop center line to hull bottom for me? I have a Bravo One. ..thank you

[Classic18]

Am getting ready to place my engine and am thinking exhaust. Are the standard Mercruiser really bad for back pressure or are they "ok"? If not, any suggestions for a good averaged price exhaust manifold and riser?

[FMP]

Noticed a thread a day or two back, small block performance ex manifolds.

[Classic18]

Need to get the appx outdrive location....setting up according to Merc specs, my prop center comes about 8" from the bottom of the hull. Is there a chance one of you have a production (non modified) outdrive in a Classic 18 that you could measure the prop center line to hull bottom for me? I have a Bravo One. ..thank you

I cut cut the hole and have established my drive positon. Thx for the insights and feedback. I concluded with 400 hp on a classic 18 I did not need the extra few mph

[Classic18]

Now onto the engine. This Engine was removed from the from the donor boat that I had bought from an owner that indicated he had some engine repairs done and then later found out the stringers were rotted. After pulling the engine down, it seems that at least one of the eight cylinders were not firing and the piston actually looks brand-new. Additionally, it looks like they are 30 over. Interested in any thoughts regarding keeping this arrangement, or boring out a little more...quite the conundrum

[Capt.Insane-o]

Those blocks suck. A good machinist will look at you funny if you want to go more than .040 over.

[Classic18]

Those blocks suck. A good machinist will look at you funny if you want to go more than .040 over.

Capn', what do you mean? These blocks are routinely bored. I've not heard of going more that 30, but I'm not an expert so I asked.

[JPEROG]

Am getting ready to place my engine and am thinking exhaust. Are the standard Mercruiser really bad for back pressure or are they "ok"? If not, any suggestions for a good averaged price exhaust manifold and riser?

Check into lightning headers, they are the only reasonably priced ones that I know of and you will experience real world gains.

Joe

[Capt.Insane-o]

Capn', what do you mean? These blocks are routinely bored. I've not heard of going more that 30, but I'm not an expert so I asked.

They are a production gm block made for ~250 hp. They have thin decks and cylinder liners, both of which get thinner every season in a fresh water cooled engine. The lifter bores aren't even close to being centered etc and several other things. This is why I was leading you to someone who builds marine engines proper. Things that can be got away with in Jimmies bitchin' Camaro don't work well in boats.

Example this is a block that has had the lifter bores straightened out squared up and sleeved.

[Greg G]

Classic18, please don't take this the wrong way but you would really be far better off in the short and long run IMO seeing what prices you get on Merc CPO stuff. I can't tell you how many times I have seen folks start to get into an engine build and when they are all done it is twice the amount they planned on. If you keep the notebook and really write down all the costs you'd be amazed at how things can add up. Just saying look at the almost new marine options completely. There is a lot of stuff out there in car/marine motors that would be plug and play. Now back to the regular programming and good luck.

[Classic18]

Thank you for the comments...I understand and appreciate the points you make. I'd love to buy a fully-built racing marine engine, but the funds just aren't there. When I talk to my buddy about what needs to be done, I'll make these points. He isn't quite a boy racer, he does build most of the race engines used by many of the guys I run... he is not an expert marine builder, but is concerned about the loads seen in marine applications that aren't there even in race car motors. I'll write up what he suggests....

Dave