: making a 74 500 perform like a 1970 500



davefedoroff
07-14-12, 05:18 PM
they started choking these engines more and more after 1970......any advise?

BRUCE ROE
07-14-12, 10:56 PM
After the timing chain is replaced, step one is a low restriction (dual) exhaust
WITHOUT that terrible cat converter. Be sure the ignition is in good shape;
mine would get an HEI. Bruce Roe

drmenard
07-15-12, 12:54 PM
Try going to the MTS website. They sell all the parts for these motors. You can learn all you need to know there.

The Ape Man
07-18-12, 08:57 AM
After the timing chain is replaced, step one is a low restriction (dual) exhaust
WITHOUT that terrible cat converter. Be sure the ignition is in good shape;
mine would get an HEI. Bruce Roe

Hi Bruce.

The 74 500 already has HEI.

If I hear the word timing chain again I'm going to puke.

I've ripped apart a lot of these engines and have not come across a chain bad enough to cause any power issues yet. Also have not seen the plastic coated ones on Cadillac engines. If they used them I missed it. I'm tempted to tear into my all original 368 just to look.

The oil slinger may be a reason.

davefedoroff
07-18-12, 02:00 PM
what about the compression ratio? the 1970 was around 10:1, 74 8:1. did this do a ton to starve power? is the only way to change that replace heads and or pistons?

also, was looking at headers online, and they're really expensive. how restrictive are the stock exhaust manifolds? wouldn't i see great gains if i just put a dual exhaust in with thick pipes, free flowing mufflers and removed cat converter?

cadillac_al
07-20-12, 09:39 AM
Yes. I wouldn't waste money on headers. A good tune up and dual exhaust will make plenty of power. In high school I used to race plenty of "hot rods" with my Mom's Olds 98 with 455 and single exhaust. A lot of people got surprised by a stock quiet vehicle with a good tune up. If you need more power than that, then the engine should come out for a full rebuild from the MTS catalog.

caddydaddy
07-23-12, 08:55 PM
Also have not seen the plastic coated ones on Cadillac engines. If they used them I missed it.

I've cleaned the remnants of the plastic coated gears out of the bottom of a few oil pans! I'm not sure what years they were used, but I'm pretty sure the oil pan of my '72 472 was full of plastic pieces!

Ranger
07-23-12, 10:42 PM
what about the compression ratio? the 1970 was around 10:1, 74 8:1. did this do a ton to starve power? is the only way to change that replace heads and or pistons?


I think that was the big killer. Yeah, probably mill the heads and/or change pistons.

caddydaddy
07-23-12, 11:27 PM
I had the heads on my 472 milled to raise the compression to 9:1. Along with porting and a better cam, it made a huge difference.

The Ape Man
07-24-12, 08:52 PM
I've cleaned the remnants of the plastic coated gears out of the bottom of a few oil pans! I'm not sure what years they were used, but I'm pretty sure the oil pan of my '72 472 was full of plastic pieces!

I've cleaned 16 broken piston skirts out of Cadillac 500 oil pans but missed out on the plastic. I know that plastic was death for later V6s if not removed.

tsgrpr97
07-25-12, 02:55 AM
Hi Bruce.

The 74 500 already has HEI.


I think HEI was an option in 74. At least on the deville.

davefedoroff
07-25-12, 03:54 PM
how much did it cost you to have the heads milled?

The Ape Man
07-26-12, 07:08 PM
I think HEI was an option in 74. At least on the deville.

Yes it was an option in 74 so it's possible to have a 74 500 engine with points.

So I'm off on that point. Some of the people from the old CML would probably have the production figures.

DouglasJRizzo
07-26-12, 11:37 PM
Making good power from a 74 500 motor is fairly easy. First, there's no cat on a 74, those were introduced in 75. If you must keep your cats for the street there are low restriction varieties that don't choke the flow like the original GM cats did.

MTS (there may be others) has all manner of goodies to wake up the Cad. Points ignition systems should be scrapped on all but some show cars that need to remain all original. They just don't throw enough fire to ignite todays swill gasoline.

davefedoroff
07-27-12, 08:03 PM
mine has the hei option. it looks like there are two mufflers, makes sense cuz the car's so quiet. the exhaust doesnt look restrictive at all until after the first muffler. then it makes all sorts of bends before going through the second muffler and out the tailpipe. what if i just cut the exhaust after the first muffler? how restrictive were the stock mufflers?

im thinking if i do K&N air filter, ram air intake, good tune up and free up exhaust a little i should get much better power out of it, no?

tsgrpr97
07-30-12, 10:03 AM
what if i just cut the exhaust after the first muffler?

That second muffler is really just a resonator. Its hollow all the way through. Just a straight pipe with holes punched in it. I don't think its restrictive at all. Mine fell off somewhere :( and I just replaced it with a piece of straight pipe. I don't even think it sounds different. Except maybe under a load.

Just start with the tuneup. My 472 pulls like a freight train and its almost bone stock.