Tips / Advice on rebuilding my '76 500

[mgbeda]

Hi Folks,

I found a recommended shop to rebuild Bessie's motor (that was still in business).  It will be going down there in a week or so.

I wanted to ask a couple questions about the rebuild.  Should the oil pump definitely be replaced?  It has about 180,000 miles on it, but seems to work fine.

Pretty much the same question about the harmonic balancer...should it be replaced no matter what or only if it has a problem?

Should I get the engine balanced?

My goal is to (eventually) end up with a brand new '76 Cadillac.  I don't want to take shortcuts, but I also don't want to do unneeded work.

I'd also appreciate any general tips on having the engine rebuilt.  This is my first time, so I could use the voice of experience.  Belated thanks, by the way, to TJ Hopland for his advice on the Cloyes timing chain and the known problem with new Melling oil pumps.

Thanks,

-mB

[76eldo]

NEW Oil pump for sure.

Balance for sure.

Check out the modified guys to find out some tips and tricks to get more performance out of it.

Why not rebuild it with 1970 spec internals.  400 hp is a lot more interesting than 180 hp.

Brian

[waterzap]

I just got a oil pump rebuild kit for my Seville. $30 or so. It came with all the internals of the pump. (gears, spring, gasket) The external parts of the pump will probably outlast you (just a shell). Even my gears did not really have to be replaced, just did it as a precaution. No reason to get a new pump if you can get a rebuild kit. Save some money and metal.
Harmonic balancer is a good idea. The rubber does get bad.

[76eldo]

All due respect, why fool around with rebuilding an oil pump.  The relationship of the gears to the case is (I think) important in how much pressure there is, and there is a relief spring too that has to be adjusted.

If and when I do my engine, I'd get new stuff and not worry if I did everything correctly.

The earlier engines had way more HP so I would also look into using those internals, just my opinion.

Brian

[TJ Hopland]

To make a 76 into a 70 you would have to change the heads.  You would need heads form a 68-73.  They are around and if you are planning on a full rebuild should not really cost that much more to buy a set of 'cores'.  Likely cost more in shipping than what the heads are worth.  You would also then need a different set of pistons.  If you have not already ordered them again no big deal to make the change.  If you didnt need to change the original pistons then you have some additional expenses.

Sure if you build it to 70 specs you can get a bit more power but you will for sure then have to run premium gas.   In theory a 71-76 will run fine on 'regular'. 

The oil pump waterzap is talking about is an Oldsmobile.  The Olds were more typical in that they were cast iron housings and located in the oil pan.  With that type of pump you rarely replace the housing.  The 472-500-425-368's used an external oil pump.  The factory pumps were aluminum bodies.  Unlike the 390, 429 and the Buicks where the main body of the pump was the timing cover our Cadillacs the main body of the pump is a separate part so where it bolts to the block is essentially just the cover.   The aluminum housings usually show some wear but not always.  If you decide to get a replacement pump I would strongly recommend buying it from MTS.  There is only one maker of replacement pumps but they often have minor flaws that can lead to catastrophic failures.  MTS takes these pumps and carefully inspects them to be sure there are no issues.   MTS site is 500cid.com.    They are good guys and can help you out with any and all things related to that engine.  They not only sort the crap from the good parts that are out there they have developed and manufactured parts for these engines.   From what I have seen their prices on the stuff everyone has are competitive so I try to buy the 'regular' parts from them when I can just to keep them going and working on the unique products.  I have not priced it out myself but have been told that they have a pretty good deal with a freight company to ship complete engines so having them do a full rebuild for you is also competitive.     

[mgbeda]

Thanks for the tips.  I think I'll pass on the hp increase; just seems like more things that could go wrong, and the car always had "sufficient" power.  (When I was in high school I used to drag race new Trans Ams and such and win.  Of course early 80's cars were pretty lame, but still it was a shock to their drivers.)  Otherwise I'll follow your advice.

-mB

[Hankk17]

tangent - yet still related to the original thread.  Did the '76 500s have nylon gears for the timing chain?  I'm having some really odd timing issues with my '76 EFI 500.  It doesn't seem to like what the recommended timing is and I've had to advance it a few degrees to keep things running smoothly.  When I used recommended timing I actually had a little fire in the trunk because the exhaust got so hot so quick.  that was a fun time, oohhh yes.

So I'm thinking tired timing chain even though the car only has 34K on it... perhaps the fact it sat in a barn since 1982 did it in and caused the nylon teeth to dry out and now that I've been using it they've all fallen off?

I dunno.. pulling at straws here..

-Hank K.

[The Tassie Devil(le)]

G'day Hank,

Yes, I think that ALL GM V8's had these rotten Nylon-covered Aluminium Cam Gears.   Any engine I have had to pull down, be it Chevrolet, Cadillac, Oldsmobile, Buick or Pontiac.

And age, through non-use, will destroy them, just as much as high mileage.

Bruce.

[Hankk17]

well I have to replace the oil pan because it's rusted badly in a lot of spots so that's just more fuel for the fire...  Where's a good place to get a new chain set?  rockauto like always?

-Hank

[The Tassie Devil(le)]

I got all my parts from Rock Auto, and was very happy with them.

When you replace the Timing Set, make sure that the bolts you take out of the Cam go back in.

They are the same thread as that of the Oil Pickup, but short enough as to not protrude through the cam boss to hit on the gallery protrusion in the block.   They have a serrated spring washer behind the head.

When the Timing Cover Gasket Kit comes, it will include the Oil Pump and Pickup Gaskets, as the Oil Pump has to come off, and it will be necessary to clean out the Pick-up screen of all those little bits of nylon, if they have started to come off.

In my case, they were all off, and all inside the pickup, and nothing went through the screen.   Some serious tapping and encouragement got them all out, but don't damage the screen, or you will have to replace that as well.

Bruce.

[TJ Hopland]

For a chain set be sure to get a Cloyes brand one.  There have been multiple cases with other brands and their crank sprockets shattering.   Cloyes is a major brand that is handled by most people that handle such things.  Cloyes has 3 levels of sets.   There is the OE style with the link belt chain.  These are fine for a stock type engine.  They also have 2 roller chain options.  A roller chain is like a bicycle chain.  One set has a imported chain and the other has an American chain.   The roller chains cost more. 

[Gene Beaird]

<SNIP>  The roller chains cost more.

And don't seem to last as long.  The roller chain is a 'performance upgrade'.  It's supposed to take less HP to move that chain, as it had less resistance in the links, and the links are a little lighter.  While it probably won't matter much to a very limited use car like your 76, I'd try to get performance elsewhere and put a stock replacement chain in the car.

I have never seen a roller chain with some miles on it that _didn't_ have some slop in it.