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Crusader 350 re-power

W

Will Long

New member
Hi all

I purchased a Luhrs 290 last year and decided to re-power after a full re-fit.

Living in Oman sourcing engines isn't easy and so I managed to buy a new pair of short blocks from the Uk and had them shipped out here.

My question is I have recently read an article on counter rotation units, the yellow stickers that Crusader put on the old engines have long since gone and so I have no way of knowing if the engines are counter rotation or the gearboxes which are are BW's Velvet Drive.

Is there somewhere I can check via engine numbers on the web ?

Many thanks in advance

Will
 
The old starter motors will tell you if the motors are the same rotation or not. Power them up with cables and see which way the gears rotate. If they both spin the same way, there's your answer.

Jeff

PS: The shipping cost must have ben outrageous!
 
Hi Jeff

Thanks for replying.

If only life were so simple, the starter motors don't work, due to a natty little feature on a Luhrs of a poorly fitting deck hatch above them !!!

Any other idea ?

Thanks
 
Ok, so I've found the plate on the Bell housing which states C350LH and C350RH, so that's one question answered, I've just emailed the engine suppliers to find out which new one is which, if both standard, I assume I have a problem ?
 
Will, just an FYI for you......
The Rev RH rotation SBC will need the following:

Piston wrist pin offset installed correctly for Reverse RH rotation
Front and rear main seals must be correct for RH rotation

*************************************

With any engine, rotation is always determined while viewing from the flywheel end.

images


Your firing order for the Std LH rotation SBC engine is 18436572
Your firing order for the Rev RH rotation SBC engine is 12756348

NOTE: this image shows rotation arrows as though viewing the front of the engine.
This is NOT standard practice.

attachment.php


As shown correctly, with either rotation engine, the distributor will rotate CW when viewed from above it.



One of several methods for checking the SBC engine rotation:

1..... Assuming that the camshaft is chain driven.... look at the distributor's driven gear.
If REV RH rotation, the gear cut will be opposite of the Std rotation engine.
(see image below)



2..... Remove the distributor cap.
If the distributor is not installed, temporarily install one with the correct "driven" gear on it.

Rotate the crankshaft and see which direction the distributor shaft is turning.
Correct direction will be CW viewed from above.

If rotating in the Std LH direction......, the distributor shaft will be turning in the Std CW direction.
If rotating in the REV RH direction....., the distributor shaft will still be turning in the Std CW direction.


3..... Bring the crankshaft around to #1 cylinder TDC on the compression stroke (must be on the compression stroke).
Note where the distributor rotor is aiming.... (should be aiming towards the #1 cylinder spark plug wire cap tower).

Now rotate the crankshaft 90* in the REV Rotation direction of which will be CCW when viewing the harmonic balancer (just opposite from viewing the flywheel end).

The rotor should now be aiming towards the cap tower for #2 cylinder.
If so, this will be a REV RH rotation engine.
 

Attachments

  • SBC LH vs RH rotation.jpg
    SBC LH vs RH rotation.jpg
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Hi Rick

Thanks for that, it turns out that I have been supplied two standard rotation engines as they didn't think to ask, do I now have a very expensive paper weight or can one be modified ?

Thanks

Will
 
you can modify what you have (if parts are available)...or sell it and order the correct short block.If you modify what you have, I'd suggest getting the pistons "fixed" and then changing the camshaft and use the gear drive approach...as rick noted, you may or may not need the correct main seals....(newer designs have ben around for a while that don't discriminate.)
 
Or you could replace the transmission with a ZF Hurth. That is the way my boat came from the factory. The ZFs can transmit full power in reverse as well as forward. Shift cables are arranged so that one transmission is in reverse when the other is in forward resulting in counter rotating props but with two standard rotation engines. It could be a lot cheaper and easier than rebuilding or replacing the engine even if you have to change both transmissions (someone else may comment on the wisdom of having a ZF on one side and a Velvet Drive on the other). I'm thinking the ZFs are something like $2500, but you would have to check that.
 
CaboJohn, that style transmission is what we call "opposite of engine rotation" capable. There is actually no reverse per 'se, we simply realize reverse prop rotation from a shift change to the other direction.

You'd first want to find out if one is available and in your final drive ratio.
I'd think that you'd also want to stay with Borg Warner.

Cheapest and easiest way out of this may be to send the one engine back, and ask for the Rev RH engine as a replacement.



.
 
Guys thanks for your help so far.

I'm waiting to hear what the supplier comes back with.

Probably a stupid question, but I'm assuming a velvet drive can't cope with the full loading in the opposite direction as a ZF can ?

Unfortunately being in in the Middle East, sourcing parts is an absolute nightmare.

But it what has been written is encouraging in that the engine can be modified with the correct parts. Is there a good place in the US to buy the required items as it's easier than dealing with the UK.

Thanks again for your help one and all.

Will
 
The standard in-line velvet drive is not capable of operating in "full power reverse" mode....

a ZF/hurth is not a painless option...I think the correct assembly or modifying what you have is the least painful approach.

before you worry about sourcing parts, I'd suggest you find out exactly what you have, generate a list of parts and then seek to find a supplier...
 
Having both props turn the same direction will work, but the boat will prop walk like crazy at low speeds, like when you're trying to slip it.

Jeff
 
Will, if you keep the Std LH roation engine and change it to a REV RH roation, here's what you'll be up against:

The crankshaft won't know nor care if it's direction is reversed.

The pistons will need to be rotated on the connecting rods 180* as to correct the wrist pin offset. This is pretty straight forward.
The rings are still fresh, and this should not be an issue.


The camshaft will care, as it must now become a REV RH engine camshaft.
While the REV RH camshaft will now rotate same as the REV RH crankashaft (if chain drive is used), we cannnot simply change it's rotation and expect the valve timing to be correct. So.... you'll need the correct REV RH rotation camshaft.
Your cam followers (aka lifters) can be re-used.

The oil pump can remain.

Since the oil pump and distributor rotation direction remains Standard, the camshaft's helical cut "drive" gear is reversed (again, if chain drive is used).
This creates the need for a reverse cut distributor "driven" gear.

Also... the vertical thrust load at the "driven" gear now changes.
The standard rotation distributor driven gear undergoes an Up-Lift force, which is checked by the thrust washer just above the driven gear.
The Rev rotation distributor "driven" gear now undergoes a Down-load force, which is checked near the upper area of the shaft.
(with either engine rotation, the oil pump and distributor shaft will rotate CW when viewed from above)
If by chance you were using Mallory, they refer to these as AV (std LH) and BV (Rev RH).


While I did mention that the front/rear main seals will need to be changed for REV rotation, apparently from what Mark said, this may not be true.
(this has to do with the very fine "wicking" serrations found just outside of the seal lip. typically these are directional)

You can just barely see them here.

images


I'd certainly find out.



.
 
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Hi Rick

Thank you for your great help. I'm just waiting on the supplier to see what they are prepared to do.

Going on what you have outlined, the only things I need are the cams and a set of gaskets, as I have an existing RH engine to take all the rest from, indeed, i guess I could take the cams if need be at an absolute last resort.

Many thanks once again

Will
 
Will Long said:
Hi Rick

Going on what you have outlined, the only things I need are the cams and a set of gaskets, as I have an existing RH engine to take all the rest from, indeed, i guess I could take the cams if need be at an absolute last resort.
Click to expand...
Will, here's a recap:

Pistons would need to be turned around due to the wrist pin offset required for a REV RH Engine.
NOTE: the GM style Full Dished pistons with double valve reliefs are capable of this.
If you have a different style piston, please post images of them.

Camshaft and cam followers could only be re-used if roller (you would not want to re-use a flat tappet camshaft).

Double check me re; the main crankshaft seals (I'm thinking that these need to be changed for std rotation... see post #14 again).

Your ignition distributor (with the thrust washer above the driven gear) will be thrust load protected for Std LH rotation.... so no concern there.

Your oil pump rotates CW regardless of Engine Rotation.... so no concerns there.

A REV RH engine circulating pump would most likely be Bi-Directional.... so no concerns there either.



.
 
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While I agree with Rick on reversing the pistons, and I did so on the rebuild/repower I did on my 270's a couple years back. The cores I used , Marine Power 350's recovered from a hurricane damaged boat, did not have them reversed so I believe you can get away with leaving them as is. As far as the crankshaft seals, I was able to source a reverse rotation rear but could not find a front so I used a standard one. 2 yrs - no leaks
 
This is an interesting thread (thanks OP) because I am going to be repowering from CH220's (LH+RH) soon.

What is a typical cost for this labor-wise for a full repower? Either in dollars or hours...
 
juryduty said:
This is an interesting thread (thanks OP) because I am going to be repowering from CH220's (LH+RH) soon.

What is a typical cost for this labor-wise for a full repower? Either in dollars or hours...
Click to expand...

It would be best to start a new thread for your specific questions.

In short, I can't answer your cost question. Much will depend on who you have build these engines for you.

I will suggest that you NOT go back together with the silly GM full dished pistons.
There is a much better alternative for any of us with the SBC engines for Marine cruiser use.

Start at post #7 here.
http://www.marineengine.com/boat-forum/showthread.php?394668-V6-to-V8-engine-swap


.
 
juryduty said:
This is an interesting thread (thanks OP) because I am going to be repowering from CH220's (LH+RH) soon.

What is a typical cost for this labor-wise for a full repower? Either in dollars or hours...
Click to expand...

Too many unknowns for anybody to give you a ballpark number without a visit to the boat; either for the engines & gears or the R&R costs - will be driven by the configuration of the hull as well as the condition of the rest of the gear...an open day cruiser in serviceable condition will let a good crew swap both engines in a day....a salon over the engine room could take a week or more....
 
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