300 Marine Engine?

[Wilitrun]

Hi all,
While gathering parts for my '64 300 build, I have been keeping an eye out for another core as I haven't sonic or pressure checked my block yet, and who knows.
Recently, I've been given the opportunity to put in an offer on a '66 300 marine engine. I'm told it's an OMC TU140, and certainly looks like a 300, and by my online searching, I've found at least one source claiming that OMC did use the 300 in '66 and '67, with the SBC 307 taking its place for a few years afterward.
As you can imagine, I'm in the midst of some furious researching so I can make an educated offer based on its utility to me. OBVIOUSLY there are going to be some differences, such as cam profile and distributor configuration, that would have to be changed. Nothing I'm seeing suggests this engine was ever used in a twin configuration, so I don't think it's a counter-rotating model. But what I am concerned about is the addition or deletion of threaded wells for the marine version that would make it unacceptable to use in automotive. So as part of my researching, I'm wondering if anyone here is familiar. I'm told this example has low hours and runs great.

[tr8todd]

A buddy of mine ordered a distributor and it was built for reverse rotation for a marine application, or at least thats what Mallory said when we tried to get it to run and the advance curve went backwards.  Sent it back and got a proper one.  Never looked into it further, but reverse rotation might be a real thing if that is truly a marine engine.

[mgb260]

David, 225 V6 was used in the same era. Cast iron timing cover. I think it can be converted rather easily.Could have corrosion issues if used in saltwater without freshwater cooling.

[Wilitrun]

Hey Jim,
Thanks for the insight. (my knowledge of marine engine particularities is very limited).
Say you were to go look at this engine, what would be a practicable way of checking for this type of damage without putting off the seller? Seller states the engine can be run on request before buying.
From what I can parse from the pictures, this looks to be a raw water system e.g. the water is drawn in from below deck, water pump forces it through the engine and out the manifold exchangers where it's mixed with the exhaust gas and expelled together. So if this engine was ever run in the ocean and wasn't blown out properly we may have a problem. HOWEVER, as this is the Toronto area it's a long way out to sea and the boats I'm seeing this engine in are modestly sized, tri-hull type boats and one would have to be very motivated to either haul this to the coast or go all the way out the St Lawrence Seaway to saltwater, so I'd say chances are good this hasn't happened. Unless it had been owned by someone like me. Cheers.

[mgb260]

David, It's probably OK. Looks clean on the outside.I live about 3 miles from saltwater and would never buy a marine engine without freshwater cooling.

[Wilitrun]

Hey Jim,
Indeed, I've heard back from the seller and according to the older gentleman that he bought the hulk from, it was a local boat and never saw seawater, so while it's good to verify this, I think the probability is low enough to warrant a viewing and a cash offer.
My own engine here has an oil pressure switch at the front beside the timing cover, which I'm assuming would be a good place to thread in a gauge to check oil pressure? I've also asked we either blow out standing water or mix it with plumbing antifreeze to keep it from freezing during transport and storage.
If anyone else has any suggestions on what to look for regarding marine-only differences, it'd be much appreciated. If it's something that can be exchanged with an automotive engine, I do have the '64 here to rob parts from, but the front timing cover and integral pump is trashed from the run-to-fail no-oil-changes previous owner so I'm hoping the marine cover is usable here. What's really important to me is knowing if there's a missing or out-of-place boss somewhere on the block disqualifying it for automotive. Cheers.

[BlownMGB-V8]

Should be fine. Check the rotation first, if it is reversed advance will be clockwise from zero on the timing tab. If so the piston offset will be backward for normal rotation. The cam and dizzy should be the only other differences. Not really valid reasons not to make an offer, but might be cause to reduce it. GSJohnny on V8Buick went searching to find a marine timing cover because apparently they used cast iron for those and he felt he needed that because of his blower setup. Not sure I agree but it's not my engine. So check the cover with a magnet. Aside from that I know of no other relevant differences. Could be a real good find.

Jim

[Wilitrun]

Hi Jim,
Thanks for that note about offset - I never would have thought of that!
I did get another note from the seller clarifying two things: it is indeed from a single-engine boat, and the pulleys spin clockwise, so we can rule out counter rotation.
Is there anything objectionable about the cast cover besides a weight penalty? My whole alloy cover is hooped due to oil pump wear, and while a couple of pounds off the engine would be nice, I'd happily trade a few pounds off my ass if it means I can service the oil pump without having to hunt for an out of production timing cover. If that's all it is I'm tempted to leave it alone.... Cheers.

[BlownMGB-V8]

Should add about 10 lbs give or take a couple. Not really a make or break decision but the pounds do add up. Can you post a photo of the damage to the aluminum one? It might not be as bad as you fear.

Jim

[Wilitrun]

I got it! Still have to go over it to verify its condition completely but it ran very smooth with no smoke, and at the price I don't think I can lose - in any case I'm better off than I was before. This will definitely be changing things a bit, but almost certainly means my dad will be around to see this project finished, so no complaints here. I'll post some more details once I've had a chance to get in some wrench time. Cheers.

[mgb260]

David Congrats! The iron heads have the biggest ports and valves beside the TA heads. Your idea of painting the interior of the block with glyptol would also be good for inside of the iron timing cover. The open areas of the lifter valley need to be cleaned up of casting flash. Must be oil free and a very thin coat so it doesn't peel off later. Looking forward to pictures.

[BlownMGB-V8]

Run a leak-down test (HF sells a kit cheap) and see if it's in the "good" range. An oil pressure test will give the condition of the bearings. You can pressurize the water jacket to 20psi to check the integrity of other seals. If all that looks good and the plugs look normal the only teardown I'd do is for gaskets. Original rope seals will expand once they are getting some oil regularly and seal acceptably. May take 6 months or a year even. You might pull the front cover for a new timing set and to do the oiling mods. My iron head makes 60+psi with 30wt oil after the mods. Look for an aluminum 4bb intake. TB-EFI is a bolt-on and good.

Jim

[Wilitrun]

Jims,
I'm just heading out to get some work done, so will shoot some video and snap some pictures while I shuffle things around in the shop.
A part of me is slightly disappointed in that there's no longer any justifiable reason to tamper with the rotating assembly seeing as this engine is in such sound condition. However, that makes a roller cam conversion much more within reach for the short term and if I'm not stroking with a 350 crank I can explore a more aggressive cam profile that might help with breathing a bit more. I think I'll start another thread when I get to that stage.
Jim B, I've really been enjoying the photos I can see on the little guy thread now that my v8buick membership is validated, in particular the roller lifter pairs. Do those just drop in or was some machining required?
Jim N, I think all of the above and the stroker plans can always be carried out on my other 300 block if it checks out. But I'd really rather fast-track the marine engine so my dad has a chance to enjoy it, and build the other engine at my leisure. It's funny how problems tend to resolve themselves with better options when you're not in a rush, isn't it?
The Glyptal coating I wouldn't consider doing until the cleanup, hot-tanking and baking was done to the block first, as you say we don't want to chance any adhesion problems sending paint into the oil pump. The '64 block can have it and I'll enjoy the marine '66 in the short term.
As an aside, as I get into this build I'll happily post any differences I find in the two engines right here as I really haven't found much documentation in my own searches at all. Cheers.
(Ed.: Sorry, I waited to post this, Jim I'm wondering if it's possible to replace the rope seals with conventional lip seals before I throw it in? Also, if the oiling mods involve drilling out the galleries, how would we ensure the tailings are all purged out if we're not doing a bottomend teardown?

[BlownMGB-V8]

David, the rear main replacement with a lip seal requires that the crank be removed so that the hash marks can be ground/turned/polished out of the seal journal. No need for that. In most cases the rope seal will soak up oil and swell over time and seal up just fine. Save the lip seals for your stroker. Replace the front seal if you like.

The oiling mods only require you to enlarge the suction galley and passages in the timing cover and oil pump. Once you remove the pickup tube the suction galley is easily flushed and brushed. No need to go deeper into the block.

One other item. While you have the valve covers off put an indicator on the valve spring retainers and check that they all have the same travel. (intake/exhaust) Cam lobe wear sometimes is an issue. IF you have to replace the cam consider a new dual groove front cam bearing from TA. Bear in mind it may need to be reamed after install.

The roller lifters cross to a SBC p/n but I haven't checked the oiling yet.

Jim

[mgb260]

David, On the roller cam i would use the short GM 3.1/3.4 V6 or 2.2 lifters with the Ford dogbones and 4.9 Cadillac spider. You would
need to use 1"spacers and tap the valley for hold down bolts. Adjustable pushrod to figure pushrod length. You will also need a thrust plate or cam button.  Hundreds of dollars less than the link bar lifters. Pic of 4.9 spider, lifters and dogbone:

[BlownMGB-V8]

Jim, I may try that on John's engine, do you have any part numbers?

Jim

[mgb260]

Jim, No part numbers, just previous discussions. On the 4.9 Cadillac thread we found with the 215 heads the spider and lifters line up. The Buick V6 guys and some SBC V8's have used the shorter lifters. The Ford dogbones are smaller and will allow a better fit with the block. Fred found all the various dogbones have the same size slots.

[Airwreckc]

Jim, is there any big advantage to the roller lifters, besides minimizng cam wear, particularly on a stroker configuration?  I've heard that there's not a significant or even measurable increase in power, but I'm sure that opinion is controversial.

[mgb260]

Usually roller cams have a wider power band and the advantage of less friction/wear. The high cost of the cam is what I don't like. Lunati and Comp Cams have fast opening profiles that have a similar wide powerband, but if you don't have enough Zinc in the oil will wear down the lobes and lifters. Chris's build, Ian's car has Crower camsaver flat lifters that have a little lengthwise groove or Comp Cams sells a tool to groove the lifter bores. Allows a little more oil between the cam lobe and lifter. Some solids have a small hole in the face of the lifter. Chris's engine runs better than ever going on 8 years now. You also need pushrod oiling. Smith Bros have nice tubular pushrods.

[Airwreckc]

Jim, are the Crower camsaver cams hydraulic? I like the idea of accomplishing the same sort of thing without the expense and modifications for the roller cams.  I'd be interested in your thoughts on a cam profile, too, for my stroker with the configuration we previously discussed.  Also, are there any mods needed for the tubular pushrods, or do they just replace the solid ones?

[mgb260]

Eric, The cams are regular hydraulic cams. It is the lifters that are different. Their 50233 grind is what Chris used. Lunati and Comp Cams have faster opening and closing but unfortunately they don't carry them for the 215/300/340 Buick. They do Buick V6 and Buick 350 and 455 V8's. They may be able to do a custom grind but it would be more expensive.

https://www.crower.com/camshafts/buick/buick-215-340-compu-pro-hydraulic-cam-280-hdp.html

https://www.crower.com/hydraulic-lifter-buick-v8-with-upgraded-snap-ring-cam-saver-oiling-10694.html

[Airwreckc]

Jim, thanks for the clarification and information.

[Wilitrun]

Hi all,
Here's a short video I shot of the current situation once I got everything shuffled around and organized.
I haven't found any specific information on the marine cam for this engine, but what I've read so far suggests marine cams in general are close to a truck/RV grind in that the torque curve is broader and flatter, and because the exhaust exits below the waterline, the lobe separation angle is wider by a few degrees, to prevent negative pulses from drawing seawater up into the exhaust during idle (a theory that makes sense to me) and the effect it would have for me is that the idle would be very smooth, and breathing at high RPM would be quite poor (this I don't necessarily find objectionable as I really don't want to overspeed the engine, but I may have a problem with my wide-ratio T5 and certainly with a 3.9 axle ratio). With the money I'm saving I don't mind revisiting that part of the equation, though.
The mild concern for me at this point is I'm seeing a slow ramp-up of oil pressure to about 30PSI at a brisk idle, so I'm going to have to look a bit deeper. Compression/leakdown test still isn't done, hopefully there will be time for that this weekend. In any case, this puts the project light-years ahead of where I was at with the other engine, and for very little money, comparatively.

https://youtu.be/XQfpk2bJbuA

[BlownMGB-V8]

For now unless you have a flattened lobe you are much better off leaving the cam alone. The stock cam is not BAD, and the engine will make more than adequate power with it. See if you can find compression specs for that marine engine, maybe run a compression test. You'll note that the factory spec for HP is at 4600 rpm so I would not expect anything much over 5K from it unless you make changes. Definitely fit the 4bb intake if you have one. Your oil pressure is quite good. No real need to even touch that if you don't want to, but you are going to need a different oil filter base. When you swap that, get the TA shim pack and set the end gap on the gears tight. The booster plate is a good addition.

Great find. You'll be happy with that one. Be sure and use oil made for vintage engines.

Jim

[MGBV8]

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