Replacing 472 With 500 in my 1968 SDV

01devilledts · #1 (**permalink**) 10-16-09, 12:31 AM

So last Friday I was driving to get some dinner and my SDV decided to stall right as I was making a left across a large street. I managed to start it up and put out of harms way into a parking lot where I was unable to turn the motor over anymore. It has 140k on it (from what I know) and was running fine until this day. I didn't hear anything (actually I didn't even notice it stalled out until I saw the oil light on since the ignition was on and not running).

1hr later and the tow truck was there and dropped it off at my shop. After checking all the normal stuff (spark, fuel etc..) i pulled the #1 spark plug and when it came out, the head was smashed flat. (

) I pulled the left side valve cover and found that the 2nd valve was stuck down and i was able to wiggle the rocker. (

)

When I removed the piece that holds the rockers down the 1st valve was sticking up much higher than all the others. so i figured the next step was to pull the head to see whats going on.

So after unbolting everything from the top and pulling the intake manifold, I got the awesome view of push-rods that are supposed to be straight and now the #2 pushrod looks like the letter "S". Good news huh! Well then, exhaust manifold comes off, and head is unbolted, once I wrestle the heavy "sob" out of there I see that the head of the #2 valve is sitting on the piston head. (GREAT) after feeling around the cylinder walls to feel for gouges, and feeling nothing i go to grab the valve head, well it seems as if it is pressed into the piston head. with a little force and wiggle, it popped out and now i have a huge hole in the #1 piston.

not a good thing.

So I figured, the local Vintage Cadillac parts store, has a "good running" 500 motor that I can purchase and put in there. He said i would need to change the oil pan and oil pump, and it would bolt right over.

My questions are:
Would that be all I need to do? (as far as getting new parts) I know id replace the normal stuff while the motor is out but i dont know if i would need anything to do the swap.
Also are the exhaust manifolds the same or will i have to change them too?

Will i still be able to bolt the factory a/c compressor back in to the same location?

This is going to be my first motor swap and I have knowledgeable mechanics to help, just not Cadillac guys. So any help would be appreciated.

I also want to keep the 472 that comes out, and slowly build it in my garage and then replace it when that one is finished. Maybe build it up with a nice cam and nice heads. That is for the future though

Here is the only picture I have of the damage so far and its from my iPhone so its not the best quality.

BRUCE ROE · #2 (**permalink**) 10-16-09, 12:50 AM

472 & 500 are easy swap; same block, just different stroke. Manifolds, oil pan, etc might need to swap. Get a new timing chain on the 500 while its out. Your biggest problem might end up being broken exhaust manifold bolts in the heads of the motor; check it out. Bruce Roe CLC # 14630

01devilledts · #3 (**permalink**) 10-16-09, 12:59 AM

Thank you, yeah, I have both Exhaust manifolds off and all the bolts out of the 472, I don't know about the 500 yet. the timing chain will be replaced before the 500 goes in for sure. will the jetting on the carb have to be changed? I just had it rebuilt about 3 months ago. I would like to put headers on the motor, and eventually when the 472 goes back in would like to swap them back if that would be possible...

steelybill · #4 (**permalink**) 10-17-09, 09:22 PM

I'm still looking for a 500 power steering pump mount bracket. Do you suppose that place where your engine came from has one?? A phone number would be nice

If that front plate on your 500 is rust pitted bad (mine is) , the Cad Co has a stainless replacement plate. Not real cheap, 125 bucks, but it's a lifetime piece. Hard to get gaskets to seal if the plate is severely pitted.

01devilledts · #5 (**permalink**) 10-18-09, 02:34 AM

There are 2 great places here in AZ that may have that part

http://www.dvap.com/
800-905-8024

&

http://www.azvintageparts.com/
1-800-433-9977

Both of those are within 10mi from my house.
If they have the part but wont ship it for some weird reason let me know and I can ship it to you

Also, I haven't seen the front timing cover on the 500 yet, but I know about cad500 co. there in NM about a 7hr drive from me, and I will be ordering a bunch of parts for the rebuild of the 472. Thanks for the heads up though

drmenard · #6 (**permalink**) 10-18-09, 04:25 PM

What happened was your plastic coated cam timing gear broke and it jumped timing... now when this happened it bent all your your pushrods and valves... more than likey thats all the damage...If it were mine I would pull the heads, get a new set of SS valves .. have a valve job done and put on a new roller chain and gear timing set-up...

01devilledts · #7 (**permalink**) 10-18-09, 10:27 PM

Well the 500 will be ready on Tuesday, the 472 is out and there is a lot of clean up from 40+ years of build-up. I spent the whole day pressure washing the motor compartment and starting to hide all the wiring. Here are some pictures.

After the pressure wash and a little grinding

steelybill · #8 (**permalink**) 10-18-09, 10:29 PM

Thanks for the two parts places info

I'll ask them about the parts I need.
BILL

01devilledts · #9 (**permalink**) 10-19-09, 12:17 AM

Quote:

Originally Posted by drmenard

What happened was your plastic coated cam timing gear broke and it jumped timing... now when this happened it bent all your your pushrods and valves... more than likey thats all the damage...If it were mine I would pull the heads, get a new set of SS valves .. have a valve job done and put on a new roller chain and gear timing set-up...

Why did they use plastic timing gears? Makes no sense to me.

steelybill · #10 (**permalink**) 10-19-09, 06:10 PM

The large cam "gears" (sprockets) are steel, but have plastic teeth molded on them, which have been used since the 60s on GM cars. Changed the first one on a '62 Pontiac. Never did hear a good reason for their use.

drmenard · #11 (**permalink**) 10-21-09, 11:05 PM

They used plastic because they were quiet and lasted longer than there expected life...but when they get 20 years old they can break anytime..after 40 years your on borrowed time..

steelybill · #12 (**permalink**) 10-22-09, 02:03 AM

Yup!!:d

01devilledts · #13 (**permalink**) 10-23-09, 02:07 AM

I got the "new" motor to my shop late last night and started to pull the old parts off of it to start cleaning it up today. It is a 500 from a 74 Eldorado. I have been doing a little searching on the internets and it looks like this motor has way less HP and torque than the orig. 472. Why is that? Or am I just not reading something right? Also will I have to use the single pulley system on that motor or can I use my dual pulley system that I had on the 472? And the HEI, will that interfere with the belts if the dual belt system is on?

Here are a few pictures of it dirty

steelybill · #14 (**permalink**) 10-23-09, 04:21 PM

I believe the belt problem is common when using the later HEI. Why not use the pulleys that it came with? Must be OK, it worked so far

01devilledts · #15 (**permalink**) 10-23-09, 11:49 PM

well I was thinking about using the pulleys that it came with, but my New A/C and power steering pump are both dual belt pulleys. can I just swap the pulleys on both of those items?