Something else that is often overlooked. Lots of times when the Nails are rebuilt a lot of times sb chevy lifters are used. This is fine & dandy if everything is new or close to new. These do not have as much travel as a NailHead lifter does. Depending on how much material was taken off the heads or block will bottom out the lifters. Usually the shim steel gaskets aren't used (they are getting harder & harder to come by. And also by your compression readings you more than likely have composite gaskets installed) so this should be of no concern since the steel gaskets have a compressed thickness of .015"-.018" & the composite gaskets have a compresed thickness of about .036". Something you could try to see if bottoming out could be the cause is to make 8 shims about .030"-.040" thick & install them under the rocker stands. This would bring the pushrods out of the lifter further & if in fact the lifter is bottoming out & causing the rough idle the engine should now smooth out & the vacuum would be more steady. Since the lifters are going to have to fill up the valves will be a little noisey at start-up, but should settle down & be quiet after a few minutes of running. Also, I doubt it, but if it has a stock cam in it, from the factory the cam is pretty hairy. The '63 & early '64/425 engines had the hottest cam Buick ever made for a NailHead. When they were new they idled rough & had unsteady vacuum at idle. Buick even had a TSB in early '64 (technical service bulletin, Jan. I think to remember) that was sent to dealers. If a customer came in complaining of a rough idle & everything checked out OK they were to replace the cam with a cam for a 401. This is also not likely because when I rebuilt my '64/425 in the early 70's I went through about 30 "new" Buick cams before I found the correct '64/425 cam. I would have not known this until I called Buick & was told how to identify the correct cam. More thoughts to ponder. If in fact the lifters are bottoming out an easy fix would be to install adjustable pushrods. Or something to add even more HP & torque, a set of my Adjustable Roller Tip Rocker Arms for our beloved "Nails". Also, most of us are on a 1st. name basis here, it makes things kinda more personnal. Tom Telesco
valve problem My apologies Tom for no info about myself. My wife has accused me of having a bit of tunnel vision when I start on something. My name is Wayne Doyle and I live just outside Halifax, Nova Scotia. I bought my Riviera last June in Michigan and drove it back to Nova Scotia. By bottoming out you mean the lifter collapsed with no or little oil in it? Wayne
ruff idle At this point, with all the info that has been passed back and forth, I am like Tom T. in that I think that engine has the hotter 63/64 cam in it and that is causing the flux in vacume at idle. It remains to be seen, if there is anything that turns up with the valve gear. There needs to be a good look at all the lobes on the cam. Nail head Buicks very, very, very seldom burn a valve. In fact, I cant recall seeing one. All the pushrods do need to be the same. also the tops of the valve spring retainers need to be checked to see if they are all the same height. If all that checks out, I would say that it is the cam grind. The other thing that keeps sticking in my mind is the part about the stinky exhaust. There is only one thing that would cause this on that model car. Running rich, or, Shurly, no one has put cataletic converters on it that are plugged up????????????????????
valve problem No Doc there is no cat. converter, just 1 muffler each side. I'll check the height on the valve spring retainers. To check for a stuck valve, do I need a valve spring compressor (don't have one) or is there another way to do it? Wayne
Let me chime in here...all 3 of my old cars are stinkier than any new car by a lot! Wayne, maybe your Riv is emitting a normal smell for an oldie and you aren't used to it. Since you have good compression and the car isn't making any noises, I suggest you drive the car for awhile to see if it sorts itself out. Old cars don't like to sit for long periods of time (trust me, I'm wrestling with one that did) and a few miles down the road might help things. By the way, I'm a lot like you with the old car tunnel vision, my wife could sure empathize with yours! Good luck! Aaron
Oh yeah, the pinging at high RPMs could be carbon buildup due to a rich mixture or excessive idling or the car not warming up much...OR it could be the mechanical advance in the distributor is worn and overadvancing.
Does your engine have the Carter AFB carb? If so, when you took the carb apart messing with the floats, did you remove the metering rods from the top carb housing and put them in separate when you put it all back together? I have seen people try to put the carb back together with the rods still in the top, and they don't get them inserted into the main jets. The car will run like this, it will just run rich at idle and light load cruising like you are describing.
stuck valve Wayne, Here is Doc s diagnosis; I dont think you have a mechanical problem. :Smarty: I agree with Tom T. I think it is the cam grind that was in the engine when it was new. The compression figures are good, the vacume figures are good, the oil pressure is good, and the temperature is good. There cant be very much wrong with that engine except maby tune up. :Brow: If the 'miss' is regular, and you pull one spark plug wire at a time and if you pull a wire that doesnt change the way it runs then the problem is on that cyl. Take a good look at the spark plug, the wire, the dist cap [inside the tower] ect. If the miss is irregular, look for a fuel drip down into the intake that doesnt go thru the carb venturis for atomization. raw fuel drops will not burn and cause a irregular 'miss'. Otherwise, I would say that it is the cam grind, which is normal. You cant have a stuck valve because the compression would be at or near zero on a cyl with a stuck valve, ditto for a burned valve, blown headgasket, broken ring , holed piston, add to that when a valve sticks, if it sticks shut, it bends the pushrod and then that is easy to spot and makes noise. If it sticks open that leaves the valve train loose and that makes noise. easy to spot. Plus there is a very regular dead miss on the affected cyl. in either case. If an engine has a cam lobe to round off like my Ford did a while back there is a gradual onset of ticking that gets louder and louder as the lift gets less and less on that valve, plus a regular dead miss. At this point I am saying, like Tom, that the flux is just a normal Buick cam action for the year of production. Also there is the possibility that some one has, at some point installed a super cat cam in it. There is even the possibility that Buick did it when the car was built. o No:
valve problem I'm going to give Tom's suggestion of shimming the rocker arms a shot. I found some metal laying around that is @ 0.035 thick so i'm in the process of making the shims. If that doesn't change anything I'll strip the carb again and give it a good cleaning.
When you check the rocker assembly look for a collapsed cup (where the rod sits) in one of the rockers they are prone to damage and will leave metal on collapse.
The rocker cup collapsing is normally due to using 5/16ths. diameter tipped head pushrods, not just a 5/16ths. diameter pushrod. Stock has a 3/8ths. diameter head & is mushroomed shaped, kinda. All the support on the aluminum rocker comes from the outer circumfence of the pushrod cup. There is no support in the middle of the cup, it's hollow to allow oil to lubricate the pushrod tip. When 5/16ths. diameter head tipped pushrods are used the tip also blocks the oiling hole & won't allow the vital lubricate to flow around the tip. If you look closely at the top of a stock pushrod you will see that at the very top it is kinda indented. This is to allow oil to lubricate. Lots of things learned while going through this Roller Tip Rocker Arm Project.
valve problem Well, shimming the rockers didn't make any difference except I did have some tapping noise on #2 and #7. I removed the shims and it went away. I picked up a set of spark plug wires, which I hadn't replaced when I did the tune-up, installed them, but that didn't help either. I'm going to take the carb off, take it apart, and give it a good cleaning again. Think I'll take a close look at the dist. too. Thanks everybody for the pointers and ideas.
