Hi all, I posted a while back on the wet behind the ears forum about my 55 special. It was my grandfather's and I got it running, driving, and stopping back in November. At that point, it had a pretty good transmission leak; I added brake fluid to swell the seals, but it made minimal effect. A neighbor and I just pulled the engine and trans so the trans can be rebuilt (I have a guy getting ready to do it) and I put the engine on the stand. So the engine seemed to be running well enough to avoid a full rebuild at this point (compression was 120-140 on all cylinders BEFORE the first start), but I figured I might as well refresh the engine as much as possible while it's out. I believe this is the first time it's been out of the car. I definitely need new expansion plugs on the block because one has rusted through a bit and was leaking coolant on the floor. I figured I'd also drop the oil pan, clean it out, and put in a new pan gasket. I already replaced a lot of the ignition components to get it started (points, rotor, cap, plug wires, spark plugs, coil, ballast resistor, battery), but what else? I rebuilt carb and fuel pump too. Do I need to go as far as replacing timing chain cover gasket? I did have some hard starting when the engine was warm or after I took a short drive, and some have suggested new intake manifold gaskets to fix that (Best brand I think?) So I'm planning to: 1. Clean whole engine; degreaser and pressure wash? 2. Clean oil pan and replace gasket 3. New expansion plugs; hose out as much rust before putting new plugs? 4. Pull exhaust manifold, bead blast, and repaint (I have new exhaust on the way) 5. Change oil and filter (again; I did it before starting it). 6. New intake manifold gaskets What else should I be looking to do?
If your timing chain is shot then the retarded cam was making the engine run hotter then it should. Gas without being cut with 10% Alky boils at 150 degrees ( a easy to hit under hood temp in summer ) and with Alky the boiling point is even lower. This will make for hard starting after a heat soak since all the fuel can evaporate from the carb and the motor has no fuel to restart on until the pump has had enough cranking time to get some fuel back in the bowl. with the block out of the car I would ball hone the bores ( with 320 grit) and rearing the motor. You can also at this time buy or rent from a tool rental store a ring groove cleaner. Rings that can’t rotate freely around the pistons are a sealing and ware making disaster! While things are down I would also get the valve guides cut for positive type seals and replace the valve springs. Don’t worry about getting rust scale out of the motor. When it’s all back together and ready to start just put water in it. once running and all looks ok then get a can of DuPont two part flush. The use of this will remove everything that could possibly be removed. In fact when doing the acid flush( the first step ) I would bypass the heater core with a length of hose if your heat is currently working ok.
** valve seals are not recommended for the exhaust valves. Buick only put seals on the intakes towards the end of the Nailhead production run. You could get away with not using them, it's not a big deal. It was primarily done for the 'smoking on startup' complaints.
You say that you are wet behind the ears, do you know how to check the timing chain without pulling the timing case? the easy way is to align the timing mark with the pointer, then put a wrench on the crank pully. Move the wrench one way then the other until you feel additional resistance to the crankshaft moving. If there are five degrees (at the timing marks and pointer) or more of crank movement before the timing chain slop is taken up and the cam starts moving, you need a timing chain and all-metal camshaft gear, and should do it now. If there are 3-5 degrees of "free" crank movement , decide whether you would like to replace the chain now when it is a piece of cake to access everything, or in a year or so when it's in the car and a bit more of a PITA. if there are less then 3 degrees of play, everything is OK for now, but ask yourself if you really want to drive your '55 with a 58 year old Nylon cam gear in it? For me, the decision is easy. If you pull the timing case and find an all-metal cam gear, then the chain and gears have already been replaced - if the slop is less then three degrees, just replace the timing case gasket And the water pump 0-rings (note that I said rings; there is only one from the factory) I install two; it makes reinstalling the water manifold a bit more difficult, but after all these years the casting surfaces may not be perfect, I have had new, fresh O-rings seep a little. If you have trouble finding the O-rings, I have some.
Just get this: https://www.ebay.com/itm/4030783378...G7LSxPLWXci3yWT8HQove7CwtmvL|tkp:BFBMpLSZu-1h Any old stock chain offered in a long box will be very tight unlike the others that fold in your hand. TC491 will work also. Use the old gears as long as you cannot catch a finger nail on the witness marks.
I forgot to mention that when you have the oil pan off, look carefully at the pistons. I have seen Nailheads - usually with high mileage, that had one or more cracked piston skirts still running beautifully with no abnormal noises.
Sorry for the long lapse in updates. 4 kids take a lot of time. So the more I read and the more I thought about just redoing gaskets, I made the decision to take it to a machine shop and have it rebuilt. The guy I took it to had experience with nailheads and had a decently quick turnaround. It was bored .020 over, polished the original crankshaft, new bearings, new cam, new cam bearings, new lifters, pushrods, valves, springs, rocker arms, etc. The whole deal. Not cheap, but it lasted 70 years from the factory; I feel like it's a worthwhile investment. I just got the engine back last week and I'm just about ready for break-in. I was planning to break-in on the engine stand so I know I'll need to run a jerry can, makeshift radiator stand, etc. I have some capable people coming to help, but I'm nervous. I checked the vacuum advance on the distributor, and it appears to hold vacuum and move the plate inside. I know the standard break-in is a total of 30 minutes at 2000 rpms and that it can be broken up, but how do people usually check RPMs during break-in? One of the higher end timing lights? I also know I'll want a gauge on temperature and oil pressure. Anybody have recommendations? I'm just nervous about ruining a fresh rebuild. Here are some pictures after the first coat of paint.
