26 PLUS Most common mistakes We get lots of phone calls and emails everyday, here are the most common mistakes done by builders and machinists.
#1- valve guide clearance too tight (NEVER use bronze guide liners), the new stainless valves require .002-.0025 on intakes and .003-. 0035 on exhaust valves or you will have serious problems. Intake seals can be used BUT never use exhaust valve seals unless using TA roller rockers.
#2- trying to install hardened seats and ruining the heads (75% chance), Buick's don't need them for today's gas.
#3- is leaving out the oil galley plug in front of the distributor on the end of the oil galley that stops inside the block, loosing oil pressure. Plugs are a special size, we make correct ones.
#4- is bolting the flywheel/flexplate on wrong causing the engine to be out of balance, ALL Buick's are externally balanced, line up the index hole.
#5- is buying a cam designed for a Chevy engine,all the camshaft companies just want to sell what they have in stock, you could easily loose 100hp!.
#6- not degreeing a H.P. cam in, ALL custom camshaft grinds must be degreed.
#7- using F-E-L-P-R-O head gaskets that always cause oil leaks where oil goes from the block into the head, oil leaks out between the layers of gasket.
#8- using intake spacers (15 HP loss) and or Offy intakes (75 HP Loss), costing torque and HP.
#9- modifying the heads for non-Buick type springs, that will put the spring in the push rod hole, destroying push rods..
#10- installing any distributor in without re-curving it correctly, especially the MSD units!
#11- not tightening the balancer bolt on the crank to 220 lbs, damaging the crank and cracking the balancer.
#12- listening to Chevy builders and using too small of a carburetor, (huge power loss! GO BIG!).
#13- mixing up 1953-1955 and 56 and lifters and push rods.
#14- using gaskets on the exhaust manifold to head, causing manifold cracks, Buick did not use them.
#15- mixing up water pumps with the wrong timing covers, three different gasket surface shapes.
#16- More problems we are hearing about !! Many defective 53-56 264-322 timing sets out there (retards cam!) and the 57-66 stock timing sets are loose in less than 10K miles, use our roller timing set.
#17-Broken inner valve springs, caused by using the wrong outer valve spring shim with too small of a hole in the center so the inner spring can't fit down in it's own seat. Causes coil bind and breakage.
#18-Broken rockers.. most common causes are exhaust valve guides too tight, locking up the valves, if a intake rocker breaks most common cause is bad gas, old fuel turns to glue and locks up the intake valves in the guides. Reproduction rocker arm failures.. some of the 1953-59 iron repros have push rod holes machined incorrectly breaking the push rod tips off! We always recommend our bronzed bushed rebuilt assemblies. We are getting reports of cheap overseas and Mexican lifters chewing up camshafts. We sell only made in USA.
#19-Failing water pumps! The new 53-55 264-322 water pumps (we sell rebuilt ones only) have plastic impeller vanes that spin on the shaft! stick with high quality rebuilds.
#20-Remember to check your carburetor jetting, most performance cams require richer mixtures, don't ruin the engine running it too lean!
#21 CAM WILL NOT FIT WITH NEW CAM BEARING....
It is very rare that camshaft will slide right in, maybe in one out of 50 engines that will happen. When these engines were new, cam bearings were undersized and line bored in the block..The machinist should always check cam fit before the block leaves the shop. The cam must be the first thing you install in a block. Scraping the bearings with be necessary to fit the cam, someone with experience will be best and only a small amount in the correct places to make the camshaft fit. One of the reasons we grind casting flash from the lifter area when rebuilding these engines is so we don't cut our hands fitting the cam in the block. Front cam bearings can also be put in wrong.
#22-Not installing the distributor all the way down into the block so the oil pump shaft will not engage.
#23-Installing the intake gaskets wrong! the 1957-66 engines have ports that are offset with the bolt holes, there are flags or tags on the ends of these gaskets, they must face toward the other gasket, NOT outboard toward the valve covers. If you see the intake gaskets when you look between the intake and the valve cover they are on wrong causing a vacuum leak! This should be one of the first on the list.
#24-Well they just keep on coming, you would think this is just common sense but here it goes, when bolting the convertor to the flywheel/flexplate make sure you have the stock height bolt head or they will hit the block casting that holds the cam plug, if it is run that way long enough it will tear up the block and crack the flexplate. Install the correct bolts, use red loctite and tighten to proper torque.
#25-Holes in the block and heads but not in the head gaskets??
I get this question over and over so I guess I have to put it in here.. There is not suppose to be extra holes it the gaskets! if your old ones have them the gaskets are rusted out or modified.. The water pump pushes coolant through the block to the back of the engine, comes up in through the rear of the head and then forward to the thermostat. Holes in between will miss direct the coolant, bypassing the rear and overheating it..
#26-Things that kill power with the Nailhead.... Thumpr Camshafts, Offy intakes and using small carburetors, never use a 500cfm on any Nailhead, even with 2-4! always use 600's or 650's for 2-4's and 750-850 with single carb.. 3-2's have never worked well on the Nailhead.. DO NOT lower compression, These engines did NOT come with advertised compression, always lower. Read the full info page at nailheadbuick.com .