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#53831 12/01/09 04:39 AM
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Fellas,

First a little history. I bought a low mile, (less than 10,000 mile) 1954 261 to drop into my 50 Fleetline. Since this has the early bypass oiling system I decided to convert to full flow and thanks to Ken on this message board I had all of the info I needed to do the job.

Reading about the full flow conversion it became very clear that drilling and tapping a bare block was the only option to do the job safely. Thus began the teardown. I noticed a reasonable amount of surface rust on the rockers, inside the block, on the crank etc. Again after reading more it sounds like this is in line with an engine that hasn't run for long periods at a time and sees infrequent use. Which make sense with my 261.

Since I now have it all apart, the crank, bearings and bores all look good. I want to give it a thorough cleaning and get the block hot tanked. I figured I would just put it all back together again with new gaskets and upgrade to a street performance cam, along the specs outlined in Pat Smith's 261 street engine build article.

Unfortunately I broke 2 piston rings when disassembling so a new set of rings are in order. That made me think whether I should get the bores honed and deck milled since I'm already down to a bare block.

Now the questions!

1. Should I check the crank bearing clearances with Plastigage?
2. Can I reuse the aluminum cam timing gear or do I need to replace it?
3. Do I need new cam bearings if I'm going with a reground cam?
4. With the reground cam I should get new lifters and possibly pushrods?
5. How much should I get the deck milled?
6. With new rings, cylinder hone or not?

Sorry for the long winded post but I want to make sure I rebuild this right the first time. Many thanks in advance!

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Anytime an engine is hot tanked, the bearings will need to be removed from the block. The acid will damage the bearings, plus the chemical reaction with the bearings and acid will hurt the potency of the acid bath, usually making the machine shop unhappy because they now have to replace the acid. If the timing gears appear to be original pieces, they are approaching 50 years of age, and should be replaced. They are machined as a set, and need to be replaced as a set, not just one gear or the other. If you are having a machine shop regrind the crankshaft for you, then they can use a dial bore gage to measure and fit you bearing clearances when they turn it. Plastigage will only tell you what the clearance is at that exact spot where it is, while a dial bore gage can be used to measure the clearances at the parting lines and a full 360° degrees of rotation around the housing bores, much, much more accurate to use a dial bore gage. Are you planning to use new pistons or the old ones. You first will need to see how much the block needs to be honed to clean it up if using the same pistons, you could already have too much cylinder wall clearance and need an overbore and new pistons. If your dead set on reusing the old pistons even if you have too much clearance, you will need to check the deck clearance as you disassemble the engine to determine how much to deck the block. And yes, new rings need to always have a fresh hone to help them seal. But if you still have any ring wear left at the top of the cylinders, the new rings can easily be damaged as they move up and down in the cylinders, so I would advise having a fresh bore as well. Old rings will rarely reseal in a cylinder if they are honed, especially if they have close to 50 years worth of wear on them.



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Thanks for the info CNC-Dude, your input is greatly appreciated.

I guess my thinking on this rebuild was to use as many of the original parts as possible, replacing what was worn, or in the case of the camshaft, a performance upgrade. I'm trying not to spend a ton of money on this one!

Due to the low miles on this 261 I'm hoping the crankshaft and pistons are OK to reuse. I will have to replace the rings as I broke 2. I can live with replacing the timing gears, although they looked pretty good to me too. I just wasn't sure about taking the camshaft timing gear off and reusing it on a reground cam.

I'll look at all of the areas you mentioned before I put this back together.

Thanks again, Mark.

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Ok Mark, keep us posted on how you make out with your rebuild.



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Will do.

One more question for now: Has anyone replaced the stock balancer with Buffalo's 292 harmonic balancer? And if so was there a noticeable difference? I also found this balancer online but have no idea on the cost: http://www.bhjdynamics.com/index.php?main_page=product_info&cPath=1_2_35&products_id=39

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Mark,
I differ somewhat with CNC. With the engine only having 10K miles. I'd throw rings, bearings and rerun the timing gears if they are metal( not fiber).
Of course you will need to hone it to make the new rings seat. It would also be a good time to get better seals put on the valves.
New lifters will be needed and should be just fine. Tom

Last edited by tlowe #1716; 12/02/09 01:56 AM.

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I didn't see that he mentioned it had that few miles on it, my bad.



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Tom & CNC-dude,

Thanks again for the input, it's all greatly appreciated!

Yes it is low in miles and that's the main reason I'm trying to keep the machining to a minimum if I can help it. I mean I'd love to go the Tom Langdon route and build the "Cadillac" 290 version of this motor. But the reality is I'd like to button this back up with the new rings, hone and cam upgrade with a mild amount of money spent wisely!

And that is why I also mentioned the harmonic balancer. From what I've read a good balancer will make the engine run more smoothly. Is it worth spending the money or reinstalling the stock unit?

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I am not against the stock balancer. Here is is what i would recomend while it is apart. BALANCE IT! Get it done to the crank, Flywheel, balancer, rods, and pistons. That is money well spent. Tom


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The BEST balancer out there is the one we made with BHJ for the 235/261 (this is the one yoy referenced). A little spendy, but you will really notice a difference if you balance it and use this damper.


Last edited by 6inarow I.I. #14; 12/02/09 12:55 PM.

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Thanks again Tom and 6inarow. Sounds like a combination of the two is the way to go if I can afford it!

I'll keep you guys posted on the progress. Mark


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