Let me start off with saying I have built several engines. And I do not consider myself an amateur builder. I have never had any trouble with the engines I have built. But the current problem I am having just completely baffles me. I am doing a basic rebuild on a 292 Y-block. I installed the cam lifters, cam bearings, and then the cam. Then I installed the crank bearings and the crank...at this point everything was turning smoothly. I then installed the rods and rod bearing. Everything was still turning smoothly. Then I installed the timing gears and chains, bolted down the heads and added the rocker ***embly and pushrods. Everything at this point was still Turning smoothly. Now here is where my problem comes in. I stopped working on the engine for the night....the next day I go out to work on the engine and it is LOCKED up tight. I had to back the crank bolts off to get it to turn...I then spun it a few times and then re torqued the main bolts. The engine was turning freely at this point. I took a break to work on other things...spinning the engine about every 30 mins...I left for a couple of hours and when I got back the engine was locked up again. and again I had to back off the main bolts. The mains are torqued to 90lbs, the rods are torqued to 40lbs. I stepped all the torque increments up in intervals of 20lbs. All of the bearing where checked and are the correct size. If anyone has any idea of what could be causing this pleas let me know...I am completely clueless on this....Im at the point now where I am thinking about tearing the engine back down and giving either the main bearing or the main journals a light sanding. Thanks in advance for any help you guys can offer.
Your main bearing saddles could be out of line slightly. You may need to take it to an engine shop for a line bore.
What are you using for ***embly lube? If it turns free while you are working it then seems to "lockup" when it sets it souds to me like you are using something that gets stiff when it sets, like some sort of grease? Is it really locked up or can you throw a long bar on it and break it with out dis***ebbly?
Could the rear seal be what's binding? I realize you know what you're doing, but there's always a chance...
Im using regular white ***embly lube. and I soaked my rings in oil before I installed them. I put a long bar on it and with all my weight on it the crank nut starts to turn a little so I back off...Im afraid of snapping the crank nut off of it.
Plastiguage is little strips of plastic you buy @ the parts store to check bearing clearances, rod & main. Clearances should be checked. Odd that it binds after sitting a while....
Yeah...thats what I was thinking. It just doesn't make since to me that it spins freely and then locks up after sitting.
yes....I think so anyway...there is a chance they might be out of order. I will check them when I get home.
You are using a new timing chain? it's link belt no doubt. Have you tried pulling the timing chain? Maybe before loosening up the mains try pulling the timing chain. I'm just thinking out loud here. I used to use white grease for ***embly lube when I was a kid, then in the '70s I built a couple of engines for a fella that sold a certain oil additive. He brought me a case of the additive while I was still trial fitting and checking clearances. I told him I was going to stop right there if he was planning on running that **** in his engines. He laughed and said that he wouldn't put that stuff in his engine for love or money, but it was probably the best ***embly lube on the market. I still use it for ***embly lube, well all except for my cam shafts, I use break in lube on my cams. OK that was a side trip it was just info that I needed to get out of my brain. Sorry about that. Back to your problem. Your thrust bearing is on the correct journal? I mean it is almost impossible to get wrong. Just thinking out loud here again. I haven't had a Y block apart in a lot of years.
I know the caps are turned correctly. and the thrust bearing is on the center bearing where it belongs.
You no doubt have them in the correct order. I have seen guys that were building professionaly for years get them switched on occaision.
If you have ***embled an engine with out checking the mains and rods with plastigauge I'm not to sure you "know" what you are doing, it is always a good practice to check them, I bent a 396 Chevy crank because I had installed a main that was marked incorrectly and had too much clearance when I was younger, I learned the hard way to use those cheap pieces of wax!!!
Also check the rear main seal. A rope type seal can soak up the ***y lube and stick. A rubber lip type seal might get slightly "melted" by the ***y lube an when it drys a mite "glue" itself to the crank. When you got a weird problem, you got to check every thing.
A good set of micrometers (inside and outside) trumps plastigauge any day. It's OK to use plastigauge to double check your precision tool measurements, but I wouldn't use it as the only method to check clearances.
I used my buddies micrometer to check. I will go look at the rear main seal again too. I am NOT using the rope type seal...I have the newer neoprene seal.
Sounds like your mains are the problem, since you say when you back off the cap bolts you can turn the engine. What puzzles me is the coming and going of the effort required to spin the engine. Porkn****** could be right about the ***embly lube being an issue. I have not overhauled a Y block, but on FE engines the cam bearing clearance, or lack of clearance, can prevent the engine from turning normally, moreso than anyother engine I have ever dealt with. I've had to replace new cam bearings in the past on an FE rebuild because the clearance just was not there. Prior to installing the cam gear and timing chain, could you easily turn the camshaft? I think you're at the point you need to re-mic the main journals and caps as your first effort, as previously suggested, but at least give the camshaft a spin with the timing chain OFF and check the effort required to turn the camshaft. Good Luck. BOutlaw
Kage, torque the mains back on ,Torgque in sequence and each "move" check for freewheeling ... might just be that one giving you problems . It sounds like a misread on the mic .... should you decide to check with plastigage make sure all lube is off the surfaces first
I've been building engines for more than a 'few years'. Seen lots. Remove the crank and have the block align-honed. The core has 'adjusted' to misalignment over the years, and is aggravated by the new, closer fitting main bearings. It is a bind, not inertia. Plastigage may tell on which journal the bind is, but you can tell that by process of elimination, checking them one-by-one, until you find the culprit. It will be in one spot on the insert fit with the journal, not necessarily where you lay the plastigage. (if you are ***uming one of the bores is ovalled flat, it is not so; the normal 'stretch' is ovalled in from the sides. The deep lower block skirts on the 'Y' block were designed with that in mind) Align hone the block/main caps. Then ***emble with Red Line ***embly lube. Every engine I got in for 'checking before firing' (customer 'builds') that were ***embled with white grease got torn down before even cranking. (all the oil filters I cut open on engines ***embled with white grease were clogged. With white grease! And some had little pieces of plastigage...) Leave the white grease for the door jambs strikers. One more thing about Red Line: Holman & Moody used to keep fresh 427 Side Oilers in stock for long periods of time. They found the ***embly lube they were using (black molybdenum disulphate) turned to powder, (graphite-like) and siezed bearings on startup after 2 years shelf time. Red Line was introduced then, and they used it for the duration.
It seems like some aren't really listening to the interesting portion of this dilemma. He says that it turns fine after everything is torqued down and after it sits for a period of time it then locks up. I think that has to throw out all the theories of align boring, too tight cam bearings, mixed up main caps etc. Any of those problems should manifest themselves as soon as they were introduced to the equations ie: when the cam was installed, the mains were torqued or what ever. Now I am not discounting that any or all of those things could still be off - especially when he uses White Grease for ***embly lube and talks of "SANDING" the mains - but they are not what is causing this mysterious lockup when sitting. If I were totally confident that all the clearances and bearing sizes were correct (am I'm not since I'm not the one doing it) I would start by cleaning all that white grease out of there and then re***embling with proper *** lube and a little oil and see what happens. If it doesn't lock up, problem solved, if it still does, then I definitely would take the crank out, torque the caps, measure the diameter, and then Mic the crank and figure your clearance.
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