Rebuilding a 425 any suggestions for better HP?

[guyrobert]

Another quick question will I need to replace the oil pump or rebuild it and can I use one from a 425 for the 472 or does it need to be specific to the engine?
Thanks in advance...

["Cadillac Kid" Greg Surfas 15364]

The oil pump for the 425 has a slightly different angle, allowing the pump to fit in the frame.  Use a 425 pump.  It is the same as the 472/500piump as far as flow and pressure is concerned.
Greg Surfas

[OldFatBald]

I put an offer in on the 472, I will have a pile of parts with two 425's and one 472 if I can get it for the right price...
My hope for a cheap and quick swap with the 425 for $1,500  or so seems to have gone out the window 

Oh, too bad. I would have sold you my MTS built brand new 472 and T400 tranny with a SWP.  But then again not for $1,500

Good luck with the swap

[TJ Hopland]

Yep I'm with Greg.   The 472/500 pump which has the filter boss on it kinda angled the filter away from the crank.  The 425 version angles it towards the crank likely because the frame or steering was in the way.  If you also use the 425's pulleys I think you would have to use the 425 spec narrow oil filter too.   I think the earlier or aftermarket pulleys may let you use the fatter filters.  The gasket and thread were super common for American engines of the era so there are literally 100's of filters that would thread on and seal so its more about clearance than anything else.   

I don't know if the issue has been fixed but at one time there was only one company making oil pumps for these engines and many of them had a slight defect that would cause them to loose pressure.   The Cad vendors would check for this issue and correct it if needed.  General parts suppliers you were on your own.  It was something to do with the bypass valve sticking on a rough part of casting. 

["Cadillac Kid" Greg Surfas 15364]

On MY 79 the 472 motor uses the 425 oil pump and a regular PF 24 AC  filter.
Greg Surfas

[guyrobert]

Oh, too bad. I would have sold you my MTS built brand new 472 and T400 tranny with a SWP.  But then again not for $1,500

Good luck with the swap

Thanks, I was hoping for a quick fix with the 425 I bought for $190 . Sadly it is in worse condition than my current engine . I found a 472 and picked it up today for $190 also. My $1,500 budget is gonzo so I would like to be in the $5k range when it is all done 

[guyrobert]

On MY 79 the 472 motor uses the 425 oil pump and a regular PF 24 AC  filter.
Greg Surfas

Will I need an new oil pump or just rebuild the existing one?

["Cadillac Kid" Greg Surfas 15364]

My suggestion, since you do not know the condition of either of the 425 pumps you have is to buy a new Mellong pump.  Cheap insurance.
Greg Surfas

[TJ Hopland]

I have not looked lately but at one time you could buy a rebuild kit which was the gears some other small parts.   The factory pumps were aluminum so the housing tended to wear more than the gears did so new gears didn't gain you back much performance.  As far as I know all the aftermarket pumps are iron so they wear much longer.

And just in case its not clear to anyone following along on this family of engines (472/500/425/368) the oil pump is external.  Its bolted on the front corner of the block.  The main body of the pump also has the boss on it for the oil filter.   The Cad 390/429 and the Buicks had a similar design but in those cases the body of the pump was the aluminum timing cover.  Bummer there is you wear the housing you need a new timing cover.   The guys that designed the 472 kinda reversed that so in this case the main housing bolts on and the iron block basically becomes the cover plate.  Much better design IMHO.   

In classic American engine designs the oil pump is almost always below the distributor and the oil filter is usually as close as they can get to the pump so think of a small block Chev with the distributor in the back and slightly to the left.  That puts the oil pump next to the crank in the oil pan and the oil filter on the left back corner.

[guyrobert]

I have not looked lately but at one time you could buy a rebuild kit which was the gears some other small parts.   The factory pumps were aluminum so the housing tended to wear more than the gears did so new gears didn't gain you back much performance.  As far as I know all the aftermarket pumps are iron so they wear much longer.

And just in case its not clear to anyone following along on this family of engines (472/500/425/368) the oil pump is external.  Its bolted on the front corner of the block.  The main body of the pump also has the boss on it for the oil filter.   The Cad 390/429 and the Buicks had a similar design but in those cases the body of the pump was the aluminum timing cover.  Bummer there is you wear the housing you need a new timing cover.   The guys that designed the 472 kinda reversed that so in this case the main housing bolts on and the iron block basically becomes the cover plate.  Much better design IMHO.   

In classic American engine designs the oil pump is almost always below the distributor and the oil filter is usually as close as they can get to the pump so think of a small block Chev with the distributor in the back and slightly to the left.  That puts the oil pump next to the crank in the oil pan and the oil filter on the left back corner.

Great Info, thanks for that, I had already bought lots of parts for the 425 rebuild so glad the oil pump will cross over, Now I will need to buy 472 specific parts like the water pump, gaskets etc....

[guyrobert]

Had the heads checked today and one of them is cracked...
Will need a 1970 head bare or complete # 1495950

["Cadillac Kid" Greg Surfas 15364]

Left or right head?  The right side has the heater water outlet at the rear.  E sure and put a 90 degree elbow in place of the straight fitting or you will not have enough space for the connection.
Greg Surfas

[The Tassie Devil(le)]

I would have thought that these heads would be interchangeable.

Bruce.

["Cadillac Kid" Greg Surfas 15364]

They are, but getting the plug and the heater hose fitting out of them (the opposoite sides) can REALLY BE A BEAR.
Greg Surfas

[guyrobert]

Left or right head?  The right side has the heater water outlet at the rear.  E sure and put a 90 degree elbow in place of the straight fitting or you will not have enough space for the connection.
Greg Surfas

Thanks That's very helpful. I have posted in the wanted section for a 1970 head, let's hope something pops up soon!

["Cadillac Kid" Greg Surfas 15364]

Robert,
1970 heads are a premium piece because they have no AIR passages and are more desirable for high performance modifications.  You can use any 1971 to 1973 head.  They are all the same, and they are used on ALL engines of those years so would be much more plentiful.
Greg Surfas

[TJ Hopland]

1497902 is the casting number of the 71-73 heads.

Wonder if its bad luck or age and there are no more good Cad motors in Canada?

[guyrobert]

I was doing some research on buying new head bolts "Arp 135-4007 Cadillac 472-500 head stud kit"
Someone reported that on the 70 block the bolt holes are not drilled deep enough so they don't work
Has anyone got any suggestions on which ones are correct?
BTW the block and crank checked out ok today!

["Cadillac Kid" Greg Surfas 15364]

Robert,
A "Head stud Kit"  is not a set of head bolts.  There is absolutely no need to use studs for a stock motor.  I have re-used head bolts countless times without a failure.  If the bolts are not obviously corroded, rusted or worn they can be re-used.
Greg Surfas

[guyrobert]

Great thanks for that, looks like I have found a head  so things can get moving again.
The block will need to be bored .30 over any suggestions for pistons and can I use the stock rods?
Thanks in advance...