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Swapping out 283 for 350 - issues / questions

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birrellsa
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Swapping out 283 for 350 - issues / questions

Post by birrellsa » Tue Apr 15, 2008 7:50 pm

I have a 1963, 24’ Sea Skiff and have purchased a new 350 marine crate engine from Michigan Motorz and have several questions related to swapping out my original 283 flywheel forward. I have noticed in the discussions that there are several issues when swapping out a 283 for a 350 but have not seen any specific details on resolving them. The issues are:
1. The 283 distributor is driven by a distributor drive gear that bolts onto the end of the cam at the timing gear end (rear of the engine in a flywheel forward engine). Can this distributor drive assembly be attached to the new 350 so I can use my original distributor and mounting position?
a. Alternatively, can I purchase a new intake manifold and use a new electronic distributor that mounts at the front of the engine? If so where do I then mount the tachometer drive?
2. There were several mentions of the need to drill a hole in the crankshaft to allow oil into the Paragon / manual reverse gear.
a. Is this necessary and if so exactly where does the hole need to be drilled, I am assuming dead center but how large and at what depth?
3. The 350 comes with a harmonic balancer.
a. I have been told by several marine engine suppliers that this is not required as the engine is internally balanced.

Thanks in advance for any advice on these puzzling issues.

Regards,

Steve

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Post by jfrprops » Tue Apr 15, 2008 9:33 pm

No expert here, but I know most of your issues have been addressed on this site and must be in the new archives section.
I don't guess you are that much of a purist, since you have gotten the crate 350, but why do that and even think of not upgrading to elect. ign? Same thought as to using the old manual tach and cable, why not convert to electronic? Guage face can be retained if expertly done.
That is a big boat, and not a fifties model, I am surprised those did not all have the seperate oil paragons? What is the cooler setup?
Balancer, I think that can be done either way.
Would use a marine grade damper plate.
Are you sure this is going to be a simple drop in? to the motor mounts, sure,but ?? Flywheel forward did not change the length from trans to shaft in such a way as to require adjustment there, shaft wise??
Wait for one of our experts to check in on this, and they will, also check the archives.
John in Va.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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evansjw44
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283 Swap

Post by evansjw44 » Wed Apr 16, 2008 8:13 am

You need to check the archives here. There are a number of things you have to do to get a crate 350 to work as a flywheel forward motor. Like, drilling an oil hole in the crank for the maunal gear box. It runs in engine oil. If you can use the crate motor oil pan you will dodge having to check the oil pan clearance. The 283 oil pan will likely be too shallow to allow the longer stroke 350 crank to turn without whipping the oil to froth or hitting the bottom of the pan.

There was a long series of posts within the last year that will get some of these detail out for you.

birrellsa
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283 to 350 detail questions

Post by birrellsa » Wed Apr 16, 2008 8:41 am

Thanks for your thoughts. I have read the threads but can not see anywhere that explains where the hole needs to be drilled in the crank, what size and how deep or long. The other question is about the existing 283 distributor drive gear and if it can be mounted to the timing end of the cam on the new 350. The bolt pattern looks the same and as far as I can see should bolt onto the timing gear top sprocket the same as it was in the 283. Failing that I could go to a 350 marine intake manifold which will allow the use of an electronic distributor. I would then have an issue with the tachometer drive.

Regards,

Steve

jfrprops
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Post by jfrprops » Wed Apr 16, 2008 8:46 am

Us old guys read a lot of these post, I know I have seen a very exact outline of how to do the drill the crank deal for the oil to the trans. I just may not have SEEN IT HERE???
Think so though.
Forget the tach cable, do elect. if you do elec. ign.
just my opinion.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

birrellsa
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drilling crank for oil passage

Post by birrellsa » Wed Apr 16, 2008 9:03 am

I will do another search of the archives to see if I can find the details on drilling the crank.

Thanks Steve

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Drilling crankshaft end options

Post by birrellsa » Thu Apr 17, 2008 9:21 pm

After some additional investigation and conversations with various engine shops the following recommendations have been made for drilling the end of the crankshaft:
1. Drill a 1/8” whole in the end of the crank until it reaches the first oil journal. Then drill and chamfer the first oil journal to ensure it meets the newly drilled center passage. Do this while the crank is still in the engine and carefully remove all shavings.
2. Do exactly as above but remove the crank first to ensure no shavings remain in the oil journals.
3. One shop recommended not drilling a hole in the crank but running a separate oil line to the Paragon transmission. The recommended method is to use a 1/8” line connected to an oil take off just above the oil filter and running to a fitting place on the inspection cover on the top the transmission. They feel it will provide the same oil flow with minimal disruption to the new engine.

I would appreciate any thoughts, comment or feedback on the above recommendations.

Thanks Steve

jfrprops
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Post by jfrprops » Thu Apr 17, 2008 10:21 pm

I ask again Steve, what sort of cooler do this paragon have/require....how will you get that in the loop?
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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Post by Wood Commander » Thu Apr 17, 2008 11:18 pm

Whew! I'd be scared to drill into a crank like that while still in the engine. First off check your crank. Some harmonic balancer bolts need to have sealant applied because oil can already come out the front of the crank. I don't know what rhyme or reason there is to this to predetermine what engines might be like this. You'd just have to check it out. And you probably already did that.

I don't know how your transmission is set up to receive the engine oil. If it needs to be supplied in the location at the end of the crank, you will have to determine if you could supply it via an alternate location or not. You may be able to do that and it might mean that you could have to block the original passage location, or not? We don't know. The best thing is to check around your local ACBS(Antique and Classic Boat Society) chapter to see if anyone has gone here before you and get their advice. Often the local chapters have some very knowledgeable people. I know our Pacific Northwest chapter does. A lot of the guys have put newer Chris Craft/Chevy flywheel forward "283" (bigger engines using the original ff 283 stuff) and "Q" conversions in older Chris Craft hulls. If you want me to I can ask some of our guys or put you in touch with them. But we'd need to know very specific information on your engine and transmission.

OK, if I had to drill a crank in the engine, I might try it (very carefully!)if I pressurized the oil pump by running a tool chucked up into a drill motor in place of the distributor and into the intermediate shaft to pressurize the first crank oil passage so that pressurized oil would push the chips and shavings out (I hope!). And you would need a way to collect the contaminated oil and not let it fall back down into the pan. Doable, but probably not too easy, especially in the boat.
Note- If you need to pressurize the top end as well as the bottom end, an old distributor with the top cut off leaving the shaft stick up and the distributor cam gear ground or machined down so it won't touch the cam gear, driven by a drill motor works best. The distributor body partially blocks a passageway allowing pressure to build to the top end of the engine. If you just use a skinny screwdriver- type tool, this passage above the main bearing galley doesn't get blocked off and oil will just fall back down the distributor block hole with very little pumping up toward the top end.

To answer some of your earlier questions, if the rotation is right, you have brass freeze plugs, you have transmission oil supplied if needed and you can mount up all of your front and rear housings and accessories, and have the needed oil pan and sealing, you are well on your way to running a newer engine in your boat.

When running a flywheel forward Chevy engine, you are driving everything off of the harmonic balancer keys (usually two in one pair of inline keyway slots) and the center bolted, taper fit of whatever drive hub is replacing the balancer. The engine was not designed to run without a harmonic balancer to dampen the harmonics and vibration of crankshaft torsional twisting and other forces. But the general opinion is that the prop shaft and propellor running in the water let these forces travel on down and out the drive train into the water, somewhat doing the same job as the harmonic balancer. Evidently it works OK because many different marine engine builders have done it succesfully for many years.
Bret

1953 35' Commander "Adonis III"

1970 23' lancer project

birrellsa
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Response to jfrprops oil cooler question

Post by birrellsa » Fri Apr 18, 2008 12:18 pm

I have a Paragon manual reverse with 1:1.5 reduction gear. There is no cooler of anu kind.

Steve

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Drilling carnkshaft

Post by birrellsa » Fri Apr 18, 2008 12:37 pm

Wood Commander

The oil comes thru the center whole in the crank which is approximately 1/8” in diameter; it is then channeled through a 1/32” diameter whole in the bolt that threads into the end of the crank to hold the transmission gear in place. The oil is fed to the center of the transmission gears and drains by centrifugal force back to the casing and overflows back into the oil pan thru two holes. After studying the setup, I believe that the oil must be directed to the center or the gears would be starved of oil. This would eliminate the possibility of a separate oil feed line versus drilling the crank.

The existing 283 flywheel forward setup does not have any harmonic balancer as the transmission is runoff the timing gear end. I am assuming Chris Craft felt this was sufficient, maybe the shaft and prop act as the balancer as you suggested.

I would greatly appreciate if you could ask around to see if anyone has done this job before and what methods they employed.

It sounds to me that I might be wise to have the crank hole drilled with the crank removed. Big pain but penny wise pound foolish as they say.

Thanks, Steve

mcisaac inc
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Post by mcisaac inc » Fri Apr 18, 2008 3:51 pm

a well respected mechanic in northern michigan told me that it is not that important to drill the by pass in the crank for oiling the trans. he claims enough oil flows through the oil pan and lays in the transmission area, thus giving the mechanical gear plenty of lubercation. i have repowered a number of boats over the years, here some of the latest bolt on upgrades that may be helpfull to you......glm 4" high rise aluminum exhaust manifolds.......distributer mallary ylm624av marine electronic ignition.......coil echlin ic-14 12 volt no resister needed........water pump glen-l marine 1" magnaflow cam drive model 91-000. ac delco marine alternator #3147m single pulley.........here are a few pics..............mark mcisaac
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birrellsa
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drilling end of crankshaft

Post by birrellsa » Sun Apr 20, 2008 4:56 pm

Thanks for information. What is the engine in the photographs? It looks fantastic with careful attention to detail.

I also feel that the transmisson would have enough oil in the bottom.

Have you ever done a 283 to 350 swap and what did you do about the crankshaft hole?

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reply to Wood Comander

Post by birrellsa » Sun Apr 20, 2008 5:12 pm

You mentioned that when running a flywheel forward Chevy everything is driven of off the harmonic balancer keys. In my 282 there is a bolt in the end of the crankshaft which has been removed and I am now trying to pull the gear of the end of the crank. I can see it has a key but can not get the gear off the end of the crank. I have tried a 3 arm puller but it won't budge. I am going to step up to a larger puller to see if that will free the gear.

Any thoughts on how to get this gear free?

Thanks again!

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Post by Wood Commander » Sun Apr 20, 2008 5:46 pm

Are you talking about the harmonic balancer or the actual cam drive chain gear (on the crankshaft)? The harmonic balancer comes off with a special puller that is like a steering wheel puller- at least three slotted arms with long, fine thread bolts that screw into the balancer itself where the lower belt pulley bolts on. An end cone or flat disc at the end of the puller's main threaded bolt centers into the balancer and/or it's bolt hole and pull the balancer off as you thread the puller's bolt down onto the nose of the crank.

If you have a very stubborn cam shaft gear on the crank, you can heat it up to get it to expand for easier removal. WARNING! The front main bearing is right behind the gear! You don't want to melt the babbit in that bearing shell,or get the snout of the crank too hot.
To avoid this, take a shop rag and soak it in water and wrap it around the crank snout behind the gear. Keep pouring water on that rag as you heat the gear. It usually works pretty well.
Bret

1953 35' Commander "Adonis III"

1970 23' lancer project

mcisaac inc
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Post by mcisaac inc » Sun Apr 20, 2008 8:12 pm

:D the chris craft gear was pressed on.take your crank to a machine shop and have them put it in a press and push the crank off the gear.the engine pictured has a hf-7 hydraulic trans so the crank drilling does not apply. your new long block harmonic balencer will come off easily with a puller.............mark

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Pulling gear

Post by birrellsa » Mon Apr 21, 2008 8:17 am

I am talking about the gear that is press fit onto the end of the crankshaft that drives the transmission. I have tried a puller but it didn't budge. I will try a bigger puller.

Thanks

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Post by Wood Commander » Mon Apr 21, 2008 4:23 pm

Unless something really bad is going on, you should be able to get the gear off without resorting to the press method. But if it truly won't budge (I've never run across that), taking the bare crank to a machine shop is definately better than damaging anything.

When trying a puller, make sure not to just let the turned- down end of the puller screw bolt go down into the crank center bolt hole. A good puller will have interchangeable tips for different uses. The flat disc would be used for when it would go down inside the hole in the harmonic balacer and be surrounded by the balancer's bore to keep it from sliding off to the side.
The cone tip would be used to center in the crank center bolt hole to keep it centered and would only ride on the very top edge of the hole, not the inner bolt threads, allowing you to apply the force needed to overcome the press fit.
In all of the engine work I have done over the years (I'm not a professional by any means), I have only seen that one crank gear that needed to be heated. Good luck and let us know how it comes out.
Bret

1953 35' Commander "Adonis III"

1970 23' lancer project

Russ Arrand
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Post by Russ Arrand » Mon Apr 21, 2008 7:20 pm

I have a 283/350 conversion in my boat. My engine guy(CD Engines) told me it is important to get the crank drilled--it supplies oil to the needle bearing at the end of the crank. Why would Chris Craft do it if it is not necessary?
Russ Arrand

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river rat 1939
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Post by river rat 1939 » Mon Apr 21, 2008 7:22 pm

Image


birrellsa
here is a picture of the puller i use to remove that gear hope it helps.
it's a bit__ [/list]
1965 30' cc constellation
1939 15'6" cc deluxe runabout project


steve pavao

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Post by Wood Commander » Sat May 03, 2008 3:33 pm

Steve, I finally got to talk to the two main guys in our ACBS chapter that have experience with the crank oil passageway.

Both of these guys are very knowledgeable and skilled, know each other and have worked on each other's boats. And we are assuming that you are working on the old manual style Paragon transmission.

Karl has a cruiser where the engine sits fairly flat in the hull. He says he took his 283 crank to the machine shop and had them duplicate the holes in the 350 crank snout. He then took the slightly larger diameter 350 crank bolt and drilled it almost to the end (lengthwise from the bottom of the bolt towards the head, but of course not all of the way through). Then he drilled down through one of the flats on the head and into the previously drilled lengthwise hole. He couldn't remember for certain what size the hole was that connected the hole from the flat to the long hole, but guessed it to be in the neighborhood of .060. Again, if you have these parts from a 283 you can duplicate the process. Karl definately recommends having the engine disassembled when doing this.

The other fellow, Craig, told me that in the smaller runabouts or in any application where the prop shaft angle exceeds 8 degrees, the hole is not necessary due to the fact that the oil will accumulate low in the rear of the transmission and get thrown up and around by the gears in a sufficient manner to lubricate everything satisfactorilly. I might add that in a brand new installation that you might want to be absolutely sure that oil does indeed make it into the transmission by prefilling it, possibly independantly of filling the engine oil and perhaps partially before assembly. Craig seemed to think you could drill the crank if necessary and pressurize air or oil to make sure the chips get cleaned out of the hole.

I hope this helps.
Bret

1953 35' Commander "Adonis III"

1970 23' lancer project

birrellsa
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Drilling crankshaft

Post by birrellsa » Sun May 11, 2008 7:22 pm

Hi Bret,

Thanks very much for the great feedback. I removed the 350 crank and had the engine shop duplicate the hole and nut from the 283 crank.

I went with an electronic distributor and will run an electronic tachometer.

The other important point for anyone else doing the same 283 to 350 swap is that you must retain the old 283 oil pan as it has a deeper section where the oil from the transmission overflows back into the bottom of the oil pan.

Regards,

Steve

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Jeff
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Re: Swapping out 283 for 350 - issues / questions

Post by Jeff » Mon May 09, 2022 8:40 pm

Very helpful comments regarding the 283/350 conversion. Thank you Boat Buzz for retaining conversations like these!
Jeff Light
1964 19' Sea Skiff Sportsman
Perseverance
Woodville, VA

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