Hello all, new thread here for a new endeavor. First a little background:
I love my '48 1600 (3600 south of the border) and it's original 216 has always done me well. I'm also a realist and I know that nothing lasts forever. From the years on this site, I've learned that: 1- It's likely not worth the time and effort to rebuild a 216, should something go wrong 2- A full-pressure 235 and beyond are worth the extra dependability, HP and a relatively simple swap.
With this in mind, I've been watching for something to come up, local to me, but with no real pressure or timelines associated with it. I have yet to jump on anything, until just recently:
Needless to say, after finding the first Canadian Pontiac 261, I was hooked and quickly located and picked up a second one.
There are a number of good articles and discussions that define the American 261's that were mainly intended for big trucks, but the Canadian Pontiac story goes a little further.
In a nutshell, Pontiac Canada wanted something different for their cars, so they took the truck 261, added hydraulic lifters, a fiber cam gear cam out of a Corvette and did not add the full-flow oil filter.
This brings us to the present, where I have this engine sitting in my garage and no clue what to do with it
I can struggle through swapping engines and turning wrenches, but measuring clearances and identifying wear are not skills I currently possess. I would like to 'freshen-up' this engine and get it as reliable as possible. I also need to make some alterations to it to make sure it is compatible with my truck. I would like to do some of the work myself, and send it out for the work that I'm not comfortable in doing.
So to start off this thread (which will likely go on for some time), I was hoping to get some suggestions:
1 - What should I do to fully assess the condition of the engine as it sits? 2 - What actions do I need to add to the game plan to freshen this up?
Some specifics:
Engine ID: W9204502 - GM documentation says it is from a 1960 Canadian Pontiac, apparently it came out of a 1959 Pontiac. Block: 3769717 - 261 for sure Head: 3836848 - May not be original, but has higher compression! Steam holes may be an issue...
I would say that some disassembly would be in order. You would want to measure cylinder wear to see if a rebore is necessary. It would be good to examine the bottom end too to see what is needed there. If you want to pay for a complete rebuild, a place like Parry Automotive could do that for you. I have used them to bore both of my 216s. By the way both my 216s are thriving in the respective vehicles.
Thanks Dragsix, I had read through that link, but I didn't know if I should start off that way, or run any tests (like compression) before I open it up. I'm not sure that I can clearly identify 'bad' scoring, but I will share pics here as I go and hopefully get some words from the wise I am especially curious to see if this head has the 'steam holes' for the 261 block, as the previous engine I bought did not and two of the cylinders were blown.
John - that's encouraging to know. Any idea if they were original or added later? Others, more knowledgeable than I have said that they did not come with these heads originally.
Pull the spark plugs, how do they look? Run a compression check, and leak down. Pull the dip stick, what do you see? If all is OK, change the oil, give it some gas and crank it!
Those cylinders look like they were full of water and broken by freezing. It's pretty unlikely the absence of coolant holes in the head had anything to do with it. Those "steam holes" are needed on the siamesed cylinders of engines like the 261 and the small block 400 V8 to promote coolant flow up the sides of the cylinders and prevent the formation of localized boiling where the coolant can't flow between cylinders. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I've got a 235 engine that sat outside in the weather for several winters. The cylinders with intake valves open looked the same way- - - -badly rusted and cylinder walls utterly destroyed. I haven't magnafluxed the head yet, but there's a good possibility I'll find freeze damage there as well. I think the crankshaft and connecting rods, and the rocker arms and shafts can be salvaged. The rest of it is pretty much scrap iron. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Goach2 Both engines were complete when I got them and looked original and not like they were torn down , but I can't say for sure . Also both engines still had the larger 261 carb, which leads me to believe they weren't messed with .
You can put your photos directly in your thread.instructions are in the left margin of every page. Opening links is a PIA. Hey, it’s easy. Even a tech challenged person like me can do it.
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
Hone the cylinders lightly, then measure the taper using a piston ring, assuming you don't have a dial bore gauge or an inside micrometer. Sending an engine to a machine shop is like asking a personal trainer if you need to exercise- - - - -you're going to get the full treatment. That's how they make their living. Rebore the cylinders- - - -new pistons- - - -regrind the crankshaft- - - -new cam and lifters- - - -rework the cylinder head- - - -pretty soon, your checkbook is going to need CPR! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Ironhead - I know I didn't feel like bolting on the flywheel, bell housing and starter. I really wanted to investigate the steam holes and I'm glad I did now
Hotrod - I agree, I'm only interested in 'freshening' this up, but I don't want to miss out on any opportunities to ensure dependability either. I have never honed any cylinders, I will have to look into what's involved.
Am I looking to hone the whole cylinder? Or just the ridge at the top? I'm just wondering if I need a hone, or a ridge reamer...
If there's a wear ridge at the top, not just carbon buildup, you'll need a ridge reamer. If it's just carbon, scrape it off and proceed with honing.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
Measure the cylinder taper first. That can be done with the pistons in place, since the majority of the wear happens within the first 2" or less of the top of the block. If there's more than about 5 thousandths of taper wear, a re-ring job will be pretty much a waste of time and money. Rebore the cylinders and install new oversize pistons. That gets into major overhaul territory. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
You can measure in the areas just below the ridge. That’s what HRL is suggesting. Do this before you do any ridge removal to see what condition the cylinder is in. Removing the ridge just makes it easier to get the pistons out the top. Honing is done to even things up and provide a surface for the new rings to seat on. You can’t re-ring without taking the pistons out just as you can’t properly hone w/o taking the pistons out. HRL is telling you that reboreing and new pistons gets expensive. Read HRL’s post again slowly and follow his advice.
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
Yes, I'd rather not have to rebore. HRL's earlier post said hone then measure, so that's what I wanted to clarify. I may even have some inside calipers, have to look through my stuff...
The Full Monte gets expensive. The piece of mind from going that route is priceless. I am fortunate to have a machine shop which does top notch work and really cares about supporting crowds like ours. They make their money elsewhere, but they get their joy from helping us out. Furthermore, the 261 is the envy of a lot of us, and I for one, would not like to hear about one flying apart from missing something due to lack of knowledge.
Last edited by 52Carl; 09/03/20201:15 AM.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
You'll only be able to measure the very top of the cylinder with that. You need a true inside caliper
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Dang! I fat-fingered the keyboard and lost several paragraphs of a reply! There is a detailed procedure on how to measure cylinder taper accurately with nothing but an old piston ring and a feeler gauge in John's tech tip on rebuilding his 261. Stand by- - - - -! Jerry
Note: A ring running in a taper-worn cylinder at 2000 RPM is flexing 60 times per second, trying to maintain contact with the cylinder wall- - - -expanding and contracting in less than 2 inches of piston movement. It doesn't take long for the ring to lose its spring tension and stop sealing compression and/or oil. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
So, if I understand the tech article, I would take off the top ring, put it in the cylinder, just under the top ridge, turn the crank so the piston goes to the top to keep it level, and then use feeler gauges stacked up to measure the gap.
Yes, as long as the piston you've got out of the engine is the same size as the cylinder you're measuring. If one engine has a different bore size than the other, you might have a little difficulty measuring the end gaps. Once you measure the gap at the top, you'll need to push the ring down 2-3 inches to get the bottom gap measurement. What you're doing is measuring the difference in circumference of the cylinder walls at different levels and dividing the difference by Pi. (3.14, actually, but 3 is close enough). "Circumference = Pi X Diameter"- - - - -basic high school plane geometry with a practical application! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
So the top gap measures out to 0.096" and the bottom to 0.085". which leaves a difference of 0.011"
Divided by PI that gives me 0.00367. From the tech articles, it looks like up to 0.005 is acceptable without reboring and new rings. I was going to try and do this with a caliper as well, but this seems to be pretty accurate in itself.
So now, I'm assuming I need to do this to all cylinders and if they all check out, then perhaps move on to the bottom end?
Ok, had time to check the rest of the cylinders, some were .005 or over, so I guess that puts this one at a rebore, with new piston territory, based on earlier comments. Is there any value in looking at the bottom end now? Based on some calls I've made, looks like I'm in the $4000-$5500 price range to shop it out.
I am especially curious to see if this head has the 'steam holes' for the 261 block, as the previous engine I bought did not and two of the cylinders were blown.
I didn't feel like bolting on the flywheel, bell housing and starter. I really wanted to investigate the steam holes and I'm glad I did now 
