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Engine Rebuild Tips


By Tom Volpone (originally written in answer to Garnet Ross and edited with their permission)

 

The following article is a list of things to consider when planning a rebuild of your 428.

Does your Rebuilder know FE’s?
In your conversations with the machine shops, find out if they know FEs, and the oiling issues with it.  If the shop primarily does Chevy motors, then they may not be a premier choice for an FE.  I'm assuming you are having them assemble the engine and put it back in the car.  If you can, see if you can do a big cleanup of the engine bay while the motor is out of it.  It can make a big aesthetic improvement easily without the block in there.  Ask the shop to replace the cam bearings.  If they do any oil gallery modification, make sure the .090 restrictors are still in place on the heads. 

High Volume Oil Pump?
 It is debatable if you need a high volume oil pump.  If you choose to, then there are some modifications the shop can do to improve things, such as opening up and aligning the galley hole between the block and oil filter mount.  With a high volume pump and stock 5 quart pan, you should consider using 6 quarts of oil every time.  You don’t want to starve the bearings because the pump is pushing all that oil out of the pan.  The restrictors in the heads are a must with the HV pump. 

What cam will you install? 
If no other modifications, I'd recommend a 260 or so advertised duration.  Comp Cams makes an Extreme Energy series cam that works well, it has steeper lobe ramps which improves breathing but still doesn’t require a higher stall converter.  Ask them if they are going to degree the cam.  I found my cam to be 8° retarded, if I wouldn’t have degreed it, it would have run terribly.  Most cams run best around 4° advanced, and many have this ground into them already.  This is not usual, but sometimes you get a cam that doesn’t align up quite right especially if you are using updated or performance timing gears.  The 260 cam should be a decent choice which would avoid lumpiness.  That lumpy idle is dependant on the overlap of the cam, not the lobe lift or duration.  Just so happens that when the duration increases, the lobes eventually will have to overlap unless they can make the lobs tighter which is what I was indicating by the Extreme Energy cam.  When I built the 283 in my Chevy, I chose a 240 cam which basically is just a little bit above a stock cam.  It idles so smooth.  But, the 283 is a small block, and the Impala is a big car so I chose the smaller duration cam.  The smaller durations aid in low end torque, while the larger ones are for upper end HP.  That is why you always read about the racing engines and their big lopey cams.  When you hear one of those at a cruise, it may sound real cool but it basically will make that car run crappy at lower RPMs unless the engine has a large stroke that the inherent torque can be lowered/sacrificed without much notice other than a little less wheelspin.  Those magazines make it sound like every engine needs those big cams, but it is a misconception unless you are wanting to race.  The components you choose should match in an RPM range, which your car will almost never see anything above 5000 RPM.  You can discuss with your machinist what he recommends for a cam based on how you use the car. 

Other Considerations
See if the rebuilder will tap the oil galley plugs instead of using the stock push-in type.  There is an oil channel alignment issue on all FEs, the front 3 main bearing caps do not align oiling holes with the main bearings.  The holes in the saddles need to be adjusted to make them align.  I'd recommend a double roller timing chain, as it is less prone to stretching and remains accurate.  Of course, a steel cam gear instead of the nylon type is a necessity in my opinion.  You'd probably want to install new rod bolts, which means the journals need to be trued.  Find out what kind of piston rings they will use, standard chrome rings are ok, but they are hard material and wear at the cylinders faster than moly compression rings.  You really don’t need forged pistons. Cast or hypereutectic pistons will work fine for street engines.  Forged actually are less thermally stable and require larger ring gaps to accommodate the expansion rate, but if you want to, I'd go with forged because they are stronger.  If they are rebuilding the heads, have them install hardened exhaust valve seats, and also use bronze valve guides.  If you have any reason to suspect cracks anywhere, like losing coolant, you could have them check for cracks in the head & block.  If they find alot of “junk” in the water jackets you might consider having the radiator cleaned out as well as the heater core.If I were to have a shop do the assembly, I'd want to see the clearance measurements.  I've always assembled my engines, which allowed me to check everything; mains, rods, rings, etc and also allowed me to clean things right, paint it detailingly, and apply plenty of assembly lube.  At minimum, if you ask questions like this the shop will know that you aren’t a blind patron that doesn’t know anything about engines.  They may tend to pay better attention if they are working with a car-guy. 

While the Engine is out…

Is the shop going to paint the engine for you?  While it is apart, you can get the peripherals such as starter, water pump (probably want a new one), alternator and clean them up/paint them nice. Hopefully, when they hot-tank/clean the block they will also throw in the intake and oil pan.  

Pistons
My 428 is 0.030 over bore.  We had no trouble finding pistons. They are of stock height with valve reliefs and are 10.5:1 CR like the stock ones.  My machine shop procured them. They are forged.   After the shop determines what you need, they will order them. Then they should size each piston to its cylinder and bore it exactly to fit, since there are small variances between each.  You can ask him if he plans to balance the assembly, which is a good thing if new pistons and rod bolts are going to be used. 

Rear Main Seal
 One other thought is to talk to your machinest about the rear main seal as well, because it uses that strange split seal with side rails and many FEs leak because they aren’t installed optimally.  The rope seals are things of the past, use a neoprene installed offset along with good RV on the side rails. They have to be fully inserted and make sure they are trimmed flush to the bearing cap (one of those FE specific things).

Breaking in the Engine
You will want to break your motor in using high zinc content motor oil.  For sure, add a pint of GM EOS (Engine Oil Supplement), which you can get at your local GM dealer.  You also will want to use either Rotella-T motor oil, or Valvoline racing motor oil.  These both have the higher zinc content.  You will break the cam in running the engine at 2000 rpm for 20 minutes.  Then, change the oil, fill it back up with the same stuff (high zinc with GM EOS) and will then change it again at 500 miles.  There have been different ideas on how to break a motor in; drive it soft for those 500 miles or let it rip.  My opinion is to drive it aggressive, varying rpm as much as you can for the first 100 miles for sure.  A cruise control on the freeway is not what you want.  This will help seat the rings in the best manner.  If you plan on running synthetic oil, don’t do so for 2 or 3 thousand miles.  I'm a bit surprised at them wanting you to run 10W-30, but it all depends on what clearances they set the bearings up at.  Your rebuilder's recommendation is what you should follow.

Tom

 
 
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