looking to build a 500

[abcdefg1675]

I have a 1977 Coupe deville, and a little diesel car. With gas prices the way they are now, I doubt my cadillac will ever be my daily driver again, unless gas falls back down to around 1.60 a gallon (yeah.. right..like that is ever going to happen).

Ive decided, I might as well build up a 500 and have some fun in it as a weekend cruiser. Im mainly looking for keeping the powerband about where it is at now. Here is what I have thought about so far:

1. Swap in a positrack rear end from a limo/hearse
2. take out the THT400, rebuild it, make sure it is strong enough to handle the job.
3. Get a 500 block from the boneyard or possibly from 500cid.com
a. use a stroker crank (if one exists) to get more cubic inches
b. add in a blower, possibl a roots, maybe 5-7Psi, woudlnt want more than that
c. Megasquirt fuel injection/ignition.

I know that increasing the displacement on this really will cripple it for revving high, because gasoline can only burn so fast. But, redlining at 4500rpm (or less) is fine by me. I drive a diesel right now, Im addicted to torque. I would like the hood to be able to shut, and have it look stock.

I am a noob to engine work, about as far as ive gotten into an engine would be rebuilding lawnmower engines. I do know a few people that have built engines, but they were mainly into the SBC350s. They would be willing to help me with this, but they dont know a whole lot about big block cad hotrodding. Id rather ask about what to do with the engine from this forum first.

And, Im not into 1/4 mile drag racing or anything like that. Although, I would love to have a cad that has a lot of low/mid power.

Right now, Im not sure of what my budget will be. Id rather just sit and think out all the possibilities for this project, then decide.

In the future, I might also need a good car/truck to tow around a trailer to haul more junk cars home, possibly a boat. Id rather be riding in a cadillac, than a ratty old pickup. This engine has to be set up so it doesnt blow apart and melt down while towing or crusing on the highway.

And let me repeat myself. Im not looking for huge horsepower numbers to be pulling single digits in the 1/4 mile. If I wanted to do that, I would have just bought the late 1960s mustang I saw for $1600.00 and built that up.

Anyone want to correct me and point me in the right direction? Im only considering a blower, because I know its probably one of the easiest ways (although not the cheapest) to get more power without shifting the powerband.

[Nashalac]

Blower will not fit under hood. If that is a priority you need to look elsewhere for added torque. Do sme sewarches on this board and you should find some good information.

[STDog]

I have a 1977 Coupe deville
...
1. Swap in a positrack rear end from a limo/hearse
2. take out the THT400, rebuild it, make sure it is strong enough to handle the job.
3. Get a 500 block from the boneyard or possibly from 500cid.com
a. use a stroker crank (if one exists) to get more cubic inches
b. add in a blower, possibl a roots, maybe 5-7Psi, woudlnt want more than that
c. Megasquirt fuel injection/ignition.
...
Although, I would love to have a cad that has a lot of low/mid power.

A lot? Compared to what? You already have a lot compared to most "built" engines (you SBC buddies).

Forget about stroking it. No need. Keep you block, maybe go 60 over. Not needed but you want cubes that the easy way. Same on the blower. maybe a super/turbo charger? I know the turbo has been done.

Trany should be fine. Maybe rebuild to '69 or '70 specs?

FI is a good move, and megasquirt get good comments. Finding a FI manifold/fuel rails could take a while. Better to get a after marker intake, and drill for injectors, then fab the fuel rails.

Rebuild your engine, with good parts. Get a better rocker system, and valespring. Bigger vales if you like. Get a cam that's got the power band whee you want it. Full length headers. Spent money getting the heads/intake ported by somone who know the Cadillac.

I know that increasing the displacement on this really will cripple it for revving high, because gasoline can only burn so fast. But, redlining at 4500rpm (or less) is fine by me.

Naw, just get a good valve train. You can go 5000 rpm on a stock bottom end. Higer revs of bigger cubes have been done.

[dave_brode]

abcdefg1675,


> 1. Swap in a positrack rear end from a limo/hearse

Afaik, not all commercial chassis cars had posi. It was an option, as it was on the "normal" caddys. The 8.5" corporate rear from the later Caprice fits the later CDV, but I'm not sure 'bout yours. The 8.5" is tough. More ratio options, and easier to find posi units. Cop cars often had posis.

> a. use a stroker crank (if one exists) to get more cubic inches

The crank can be offset ground. Figure upwards of $1000 extra if you want to do a stroker. Another option would be a big bore stock stroke
deal. However, anything over apx 4.385" bore is going to require copper head gaskets, or price custom made composite gaskets.

> b. add in a blower, possibl a roots, maybe 5-7Psi, woudlnt want more than that

Blower kits for the caddy are out there. Are your pockets deep?

> I know that increasing the displacement on this really will cripple it for revving high, because gasoline can only burn so fast.

No offense meant, but that's silly. Look at an IHRA prostocker. 600 cubes+ and 8-9K rpm. The reason many large cube engines will not rev is they don't have near enough cylinder head flow to make high rpm power. Medium pocket depth [I mean $] porting on iron caddy heads will get you power to 5800-6K on a 500, but the common and affordable edel intake will not go there. More money can make for a 7K+ rpm deal.

> Id rather be riding in a cadillac, than a ratty old pickup.

A caddy engine makes ratty old pu trucks run really well. LOL.

This engine has to be set up so it doesnt blow apart and melt down while towing or crusing on the highway.

> Anyone want to correct me and point me in the right direction? Im only considering a blower, because I know its probably one of the easiest ways (although not the cheapest) to get more power without shifting the powerband.[/quote]

True. You *could* do a properly built basic blower-less '74-'76 500 with 8.5-1 compression. You don't need a bunch of exotic stuff if you don't want to rev past 5K. It would be quite able to withstand a low psi blower later, when budget allowed. At most, a cam swap and ignition timing changes would be required.

Fwiw, an N/A'd 8.5-1 500 with ported heads, bigger valves, a 4800 rpm cam, an 2115 edel intake and headers would probably feel like a blower engine compared to your stock 425.
Dave

[abcdefg1675]

Hmm. I didnt know they were so capable. ive always been told the opposite by everyone that I know.

I have a rebuilt 425 in my cad that I got for free (lucky me). I was thinking, just sell it to my friend. he has a 9 ton dump truck with a 351 inch V8 in it, I cant imagine it going up any hills. Im sure it would be fine pushing around a 9 ton dumptruck, if a 351 moved it around. If he doesnt want it/cant use it, Ill get my own truck to stick it in.

Ive read the 425s wernt the best to build up. Not sure if thats true, but more cubic inches is always better, right?

Ill start out with a 500 block, see where that takes me. Im only considering fuel injection, just because I dont like messing around with carburetors. I think the megasquirt can be set up to do sequential multiport injection, I hope going this route will be interesting and easier to tune.

I thought some people were trying to B.S. me, 1hp per cubic inch isnt too crazy for a motor, and 2hp per cid was done in the 1920s (or was it the 1930s).

my current TH400 has 152,000 miles on it, and sometimes cant make up its mind what gear it wants to go into. Might be plugged up, not sure. It shouldnt be hard to get someone to help me with that part.

Thanks for all of the responses, and straighting me out on this. Im leaving for the airforce soon, I can hardly wait to drag home some cad engines. If the airforce works out for me, I should have at least $1000 spending cash every month.

[dave_brode]

abcdefg1675,

"]Hmm. I didnt know they were so capable. ive always been told the opposite by everyone that I know.

The block and crank are very sturdy. The 2.5" rod journal makes for high bearing speed. For a normal 500 build, the bearing speed isn't an issue. Most real serious higher rpm efforts use a 2.375" mopar journal to slow that down.

For your purpose, imo, a run of the mill 500 will do very well. A fresh low CR 500, w/a edel intake and a mild cam would surprise you, I bet. You can get by with stock rockers, with a slow ramp cam. An aggressive grind will require upgraded rockers. The next step up would be some porting and larger valves in a 76cc head 10-1 CR combo. The edel will pull only to 5500 or so, although w/o expensive pro ported heads, it ain't going there anyway.


> I have a rebuilt 425 in my cad that I got for free (lucky me). I was thinking, just sell it to my friend. he has a 9 ton dump truck with a 351 inch V8 in it, I cant imagine it going up any hills. Im sure it would be fine pushing around a 9 ton dumptruck, if a 351 moved it around. If he doesnt want it/cant use it, Ill get my own truck to stick it in.

Ive read the 425s wernt the best to build up. Not sure if thats true, but more cubic inches is always better, right?

They are a fine engine, but the cost to build one is the same as for a 472/500, so it's not too logical imo.

> Ill start out with a 500 block, see where that takes me. Im only considering fuel injection, just because I dont like messing around with carburetors. I think the megasquirt can be set up to do sequential multiport injection, I hope going this route will be interesting and easier to tune.

Many have had good luck with the MS route.

> I thought some people were trying to B.S. me, 1hp per cubic inch isnt too crazy for a motor, and 2hp per cid was done in the 1920s (or was it the 1930s).

It's tough to get over 1hp per, but torque will be much higher than horse. Afaik, typically, a 9.5-1 CR 500 with some porting, larger valves, a hot street cam, an 850 and headers can make 600 lbs-ft on pump gas.

> my current TH400 has 152,000 miles on it, and sometimes cant make up its mind what gear it wants to go into. Might be plugged up, not sure. It shouldnt be hard to get someone to help me with that part.

I'd change trans filter asap.

> Thanks for all of the responses, and straighting me out on this. Im leaving for the airforce soon, I can hardly wait to drag home some cad engines. If the airforce works out for me, I should have at least $1000 spending cash every month.[/quote]

I'll e-mail you some links.
Dave