'84 Chris Craft 268 Commander, 305 to 318 Swap

So, it's looking like my oil press drop (see "305 low oil pressure" thread) is at least partially a result from a blown seal...unconfirmed yet. I've got oil in the bilge after every run and it appears to be losing 1-2 qts per hour. Although unconfirmed, it's looking like I'll need to pull the engine and not knowing how many hrs are on either eng, I'm considering swapping engines out and starting from a clean slate. I've located twin 318's that have been rebuilt from top to bottom and have been in storage since 2008. Assuming all concerns about engines being in storage for five yrs have been met, is this swap a viable one? Some concerns I have are:

- mounts; does 318 have same eng mount pattern?
- Tranny's; will existing mate up with 318; if not, what ratio (1:1 or 1.5:1or other?) works with my props?
- props; will current props be adequate or will 318 be over/under powered?

Anyone have experience with this swap out?

A 305 is a Chevy, right? The Chrysler 318s will NOT bolt up.

Jeff

That is correct if you were planning to bolt the 318 into the GM flywheel cover.
However, your new 318 engine is Borg Warner capable. Most any engine that is Borg Warner capable can be made to work with a B/W pattern transmission since Borg Warner is Borg Warner pattern all day long. It's an industry standard pattern.

Here is a GM V-8 Borg Warner F/C.
Forward face fits GM V-8 rear engine block flange arrangement......., aft face is B/W bolt pattern.


Here is a BB Chrysler Borg Warner F/C.... should look similar to the 318.
Forward face fits Chrysler V-8 rear engine flange arrangement........., aft face is B/W bolt pattern.




Borg Warner flywheel stand-off dimensions should be the same between engine makes.
The six hole B/W bolt pattern is definitely the same.

The engine mounts where they attach to the actual engine will be different, but I beleive that where they attach to the stringers will be very similar, if not the same.
You'll be adjusting for alignment anyway.


I don't know for certain, but if the 318 and 305 horse power and torque are similar, I don't believe that you'll need to change ratios.


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Thanks Ric...can you think of anything else?...wire harness?

So far, it's not sounding like that big of a problem doing this swap.
Have you heard of anyone else doing this swap and if so, is there a thread or another member you can put me in touch with for further details?

Thanks again.

dhudge said:

Thanks Ric...can you think of anything else?...wire harness?

So far, it's not sounding like that big of a problem doing this swap.
Have you heard of anyone else doing this swap and if so, is there a thread or another member you can put me in touch with for further details?

Thanks again.

Click to expand...

Ayuh,.... 1 Issue I see is, Chrysler has been outa the marine business since the 70s, 'n parts cost more than for a Chevy, which is still in the marine business...

You'll be steppin' Backwards by 40 years...

Agreed. I'd go with a Chevy 350; more power thana 305, but with no more weight.

Jeff

I don't recall seeing any ME.com threads discussing a swap like this.
But I agree with Bill....... many more parts are available for SBC engines.

I also see no reason for worry regarding the SBC's being an unorthodox installation, nor any deficit to resale value.
As long as the installation is nice an clean, and if using all Marine components (as per what would have been OEM had these been SBC's from day one), you'll be OK.

As for the engine harness, you can build one, or possibly rework the 318 harness.

Exhaust will change, but exhaust systems for the SBC are very common, and are easy to find in an array of configurations.
Outlet diameters can be matched or adapted, etc.
Lots of reducers, elbows, Marine exhaust hose, etc, are also available.

A few "Upsides" to this swap:

If you have the space in front of the engines, this would be a great opportunity to go with crankshaft sea water pumps, and rid yourself of belt driven sea water pumps. Here's a thread regarding the crankshaft pump as an alternative for the Chrysler engines.
Same applies to the SBC Marine engines, but no custom adaptation is required.

You won't have to worry about finding the elusive and non-existant 318/360 Chrysler engine Ignition Timing specs for TA (total advance), as the TA specs for the SBC Marine engine are available!

And perhaps most importantly..... You won't have to worry about where #1 cylinder is located!


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dhudge said:

I've located twin 318's that have been rebuilt from top to bottom and have been in storage since 2008. Assuming all concerns about engines being in storage for five yrs have been met, is this swap a viable one?

Click to expand...

I think that I have egg on my face. I've been posting as though you were replacing the Chrysler 318's with GM SBC's.
As it stands, it's the reverse of this..... correct?


Looks like it's my turn in the barrel this week.


I guess that most still applies with exception to common parts and exhaust options and availability.

All that being said.... I'd forgo the 318's, and would either build or purchase a pair of GM SBC's.
And yes.... the 5.7L will not only offer better performance, but often the 5.7L is less expensive (apposed to the 5.0L) to build in the Marine version.
If one engine must be Reverse RH rotation, then this would add some to the cost.





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RicardoMarine said:

I think that I have egg on my face. I've been posting as though you were replacing the Chrysler 318's with GM SBC's.
As it stands, it's the reverse of this..... correct?

Looks like it's my turn in the barrel this week.


I guess that most still applies with exception to common parts and exhaust options and availability.

All that being said.... I'd forgo the 318's, and would either build or purchase a pair of GM SBC's.
And yes.... the 5.7L will not only offer better performance, but often the 5.7L is less expensive (apposed to the 5.0L) to build in the Marine version.
If one engine must be Reverse RH rotation, then this would add some to the cost.





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Click to expand...

.....Rick, you always have the best pics. !!!!!!!!

Believe me.... it was tuff taking that picture without being able to see!
Removing the egg was another story because I forgot to use Pam Spray!





Well.............., I'm off to post on other topics and to see if I can keep things straight.

Yours truely, Ricardo.

to pull a sbc and install a chrysler engine would be a huge mistake. SBC parts are cheap and plentiful. You already have the mounts and accessories for the most common marine V8 on earth... don't mess that up.

bondo said:

Ayuh,.... 1 Issue I see is, Chrysler has been outa the marine business since the 70s, 'n parts cost more than for a Chevy, which is still in the marine business...


You'll be steppin' Backwards by 40 years...

Click to expand...

They closed in the 80's! A 305 is no more advanced than a 318 and the block was cast in the USA not Mexico!

Thanks for the inputs fellas. I appreciate your thoughts on the (old, hard to find parts for) 318 vs (305 or 350) SBC. The opportunity I have with the rebuilt 318's is one I'm finding hard to pass up. I may be able to walk away with two professionally rebuilt 318's for about $2k (total). Simply a case of right time and right place...the seller had plans for these engines that just didn't pan out and now he needs to offload in a hurry. Minus the carbs, they include everything up to and including the risers. Their history is such that they've never seen salt water, so I know they were viable rebuilds.

does this change anyone's mind?...or do you still recommend not straying from the SBC?

Personally, I like the small block Mopars: easy to work on, and rebuilt blocks are cheaper than Chevies. Parts aren't as easy to find, of course, but if you already have most of what you need...

Jeff

I too like the Mopars....... I've been a Chrysler/Dodge car/truck fan for years and have owned several 360's over the years.
However, I have much more experience with the SBC's in both Auto and Marine.
Both make good Marine engines.

Perhaps ask yourself a few questions;
Are the 318's fitted with Borg Warner Flywheel Covers and B/W drive couplers...... or will you need to source these?
Have you inspected the 318 exhaust systems and are they serviceable?
Are the existing SBC exhaust manifolds serviceable?
What about sea water pumps? You OK with the typical Chrysler Sherwood style belt driven sea water pumps????
What would the cost difference be if you were to stay with SBC's?
What about new starter motors???? It would a shame to NOT install new HTGR starter motors, IMO.
How about alternators and brackets?
What about Ignition systems? Chrysler is synonymous with using VR triggering, and that's good stuff, but how old are the advancing systems?
What about the SBC Ignition systems? What triggering system, and how old are the advancing systems?
Flywheel ring gears..... have you inspected these???
Engine mounts..... do you have a source for the 318 mounts? If you need to purchase these, what cost does this represent?
What SBC parts would be saleable and could create a return for you?

When the 318's were over-hauled, who did the work? Are they reputable with a good history??
Do you require a RH Reverse rotation engine and a LH Standard rotation engine?
If so.... was the RH Reverse 318 built correctly... I.E., piston wrist pin off-set, main seals for RH rotation, etc.???


I'd not let fresh water use influence me as to the condition of a previously raw water cooled engine block. I've seen rive/lake engines whereby the corrosion took it's tole on these, yet it's not proven to cause failure............ YET.
Is this borrowed time? If so, where's the clock at on this?
Whereas if you built two SBC's, you can start out with automotive cores that have seen Ethylene Glycol ONLY for their entire life.


Tough decision, I'll admit.


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RicardoMarine said:

That is correct if you were planning to bolt the 318 into the GM flywheel cover.
However, your new 318 engine is Borg Warner capable. Most any engine that is Borg Warner capable can be made to work with a B/W pattern transmission since Borg Warner is Borg Warner pattern all day long. It's an industry standard pattern.

Here is a GM V-8 Borg Warner F/C.
Forward face fits GM V-8 rear engine block flange arrangement......., aft face is B/W bolt pattern.

Here is a BB Chrysler Borg Warner F/C.... should look similar to the 318.
Forward face fits Chrysler V-8 rear engine flange arrangement........., aft face is B/W bolt pattern.

Borg Warner flywheel stand-off dimensions should be the same between engine makes.
The six hole B/W bolt pattern is definitely the same.

The engine mounts where they attach to the actual engine will be different, but I beleive that where they attach to the stringers will be very similar, if not the same.
You'll be adjusting for alignment anyway.

I don't know for certain, but if the 318 and 305 horse power and torque are similar, I don't believe that you'll need to change ratios.

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Click to expand...

Ric,
I got the seller to take a couple of pics of drive coupler. Can you confirm B/W or not?
Thanks.

For sh**'s & giggles, here are some pics of the 318's I'm considering.

Those are original Chrysler exhaust manifolds (ie: old). I would suggest you inspect them where the exhaust comes out of the head to see how corroded they are.

Even with FWCooling, they rust out in this area.

Jeff

dhudge said:

Ric, I got the seller to take a couple of pics of drive coupler. Can you confirm B/W or not?
Thanks.

View attachment 5860

View attachment 5866

Click to expand...

I was asking about the Borg Warner drive couplers..... not prop shaft coupling flanges!

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