Engine Rebuild vs Crate Questions

[onesubdrvr]

Well,

I've been shopping for my motor for the X, and just about the time I narrowed it down, I got my new issue of Hot Boat Mag.

Inside is an article describing an automotive engine vs marine engine

In this article, the explain the differences between the two.

They state that your ring end-gap, and cylinder to wall clearances should be slightly larger than normal.

Now, if memory serves me correctly, top ring (auto with cast pistons) would be .012-.020, middle .018-.025 and oil control .015-.055. So if you should run clearances larger than normal, where should you be for a marine engine? Obviousilly the higher you go, the quicker a cylinder will leak down, and perhaps lower compression (?). Also curious as to things to ask to "spot check" knowledge of engine builders when specifying that you want a marine engine built (they should know of the clearance issue / etc.).

Also, besides the end-gap and wall clearances, what other clearances to be concerned of?

The article also states that automotive crate engines are a 2nd choice (behind a crate engine from mercruiser / etc.) because of the clearance issues, but will be fine if broken in properly (opening up the clearances a little). So, does anyone have a PROPER breake in procedure so that no-one ruins a crate engine?

I was looking at the HT383 crate, and don't want to spend the $$ if I run the risk of screwin it up because of clearance issues!!

Also article recommends changing valves in the heads to stainless / inconel - makes sense.

I hope my questions make sense and are justified,......or am I just paranoid because I'm looking for a crate engine vice having one specifically rebuilt as I did with the Ragazza?

Thanks Y'all
Wayne

[smokediver]

there is a scorpion 377 for sale on OSO for 5500 or best offer ... turnkey ...

[Cuda]

Osd, I might have a longblock to make you a good deal on. I just took the heads in this morning for a valve job.

[Cuda]

there is a scorpion 377 for sale on OSO for 5500 or best offer ... turnkey ...
If the budget will allow it, I'd definetly go that route.

[onesubdrvr]

Joe,

I'd definately be interested in the Long Block - If I'm gonna spend that kind of change, I'd rather have the engine built like I want. Also, I'm interested in your guages,......I'll give 'ya a call tomorrow.

The engine, is it 2 bolt or 4 bolt? year?

Thanks!
Wayne

[onesubdrvr]

there is a scorpion 377 for sale on OSO for 5500 or best offer ... turnkey ...
Thanks!

But for that kind of $, I'd rather build my own, and get a little more umph from it,......do like the Scorpion though, is it a blue or black? (duh! I guess I can go check it out!!)

Thanks
Wayne

[Cuda]

I don't know if it's a two or four bolt, and I can't get the oil pan off where I have it sitting. I've got a feeling it's a two bolt. I know it was a four bolt I left at his shop. He told me I could come get it, but I never did. Last I knew, it was still sitting there.

[MR MAGOO]

The 383 crate motor makes a fantastic boat motor. I helped a buddy install a pair of them in his 26' Sutphen 3 seasons ago. He's been really hard on them and they run flawlessly. boat picked up a solid 10 mph. At this time he's got over 100 hrs totally trouble free. He bought them from Pace Chevrolet, they were $4850 ea.

...As for the 377 Scorpion on OSO, It's now in my shop ready to be dropped into our 22 Pachanga :biggrin: :lightning :yes:

Kurt

[Rootsy]

with hypereutectic pistons you can run almost the same piston to wall clearance as an automobile engine.... top ring gap is supposed to be greater due to larger sustained loads on the motor which increases crown and top ring temperature. if too tight under a very hard load you can butt the ring and break the piston...

marine engines also utilize a Stainless steel core head gasket and brass freeze plugs, though most auto engines come with brass plugs already... Severe duty SS or inconel valves are nice and the only way to fly if you are putting an engine together yourself but stock merc engines from GM come with sodium filled exhaust valves.

if a factory assembled motor is fine for you then go with a crate motor... if you prefer an engine that is hand assembled, clearances measured, remeasured and the engine assembled and reassembled, etc... plus broken in or dyno'd for you before delivery then a custom engine builder is probably the way to go although more costly in the end generally.. but you can get exactly what you want...

[onesubdrvr]

Jamie,

So if I match the top ring to the middle, I should be OK?

I'm thinking crate, just for "ease" - typically a proven design, no more thinking on my part, I've got enough of that going on right now,.... :confused:

Thanks again,
Wayne

[MOP]

HT383 crate with a year garentee! Or build one maybe $1,500 cheaper. A nice 2 bolt block will do for your app. Maybe even an old 400 block punched to 406, now there is economy cubes! A bud has woods beater with a 400 worked a little for low end let me tell you it has real big nads. You have a few ways to go just have to pick one and go for it, we want to see you wet soon.


Phil