Buildup ideas for a '76 500?

[fast large one]

I've got a '76 500 that I want to put into a '67 Chevelle. I'd like to drive it on the street and take it to the track as well.

I've got a couple of books/manuals on the Cad, but I'm having trouble figuring out what sort of plan I need to put together for this thing. I'm on a budget (what a surprise), but I can spend a little extra here and there for some worthwhile pieces.

I'm wondering if the 3.73 gears I've got currently in the car will spin the engine too high too often, and if I need to gear down what's acceptable? If I can build the engine to handle the revs, what sort of pieces (and what kind of cash) is that going to take?

The engine is currently bone stock, so there will naturally be plenty of room for modifications. About the only thing I know I should get at this point (aside from the rear sump pan/pickup, which I have) is an Edelbrock intake. I'm not sure what sort of cam to use, and I'm up in the air on cylinder head ideas as well as pistons. I know this is a low compression beast, and I'm wondering how much I can push that before I run into detonation problems.

I could go on more, but I'll wait to hear what you have to say and maybe that will answer some other questions.

Great to find this board. I've been looking forward to this project for two or three years now, and I'd really like to make it happen this summer.

[Caddycarlo]

I started out on the monte with 3.70 gears and a 28 inch tall tire and had lots of fun.... with the gear I would run AL's mt15 package and do a little home bowl work and put it in the car....

[fast large one]

Thanks for the input. I looked at Al's catalog, and I take it that the mt15 kit is the Series 15 cam grind. It sounds like with this grind I may need to upgrade to a better rocker system - that right?

I recall seeing your Monte article online about a year ago. Thanks for taking all the trouble to take pics and put that info up for everyone.

I think I'm running 26" tires right now. I'll have to double-check. As it is, the car goes through the lights as I'm shifting into 4th, and that's with a 5800RPM shift point.

I was hoping for around 500HP. Is this doable without breaking the bank? Maybe I'll have to leeeeeeean on the bank a little... Hey, if you're gonna do it, you might as well make it worth the effort.

[Vern]

Define breaking the bank. It will require a good street strip port job and at least bigger intake valves or NOS. Also if you want to do it without NOS it will be a LOT eazier with headers. If you can fit these two into your budget the rest will fall into place as you don't need much. Most people don't spend enough on the heads and put in more cam than they need to for their heads and other vehicle use goals. I would use a 30" tire with a 3.73. If you run 3.73s with 26.1 tall tires it will be a wee bit faster (you will need drag strip time slips to prove it to yourself) but it will suck fuel like a hog rev harder than it wants to and just plain not like it especially with the stock cam.

[fast large one]

Vern said: "Define breaking the bank."

Good point. I guess I was planning on spending something around a grand on it. From various bits of information I'd gathered this didn't sound impossible, but I'm open to the thought that I could so very wrong about that estimate. :roll:

You bring up the heads, and I guess that's a good topic. I know the heads will be the final limiting factor against the rest of the combo, so money spent there is money well spent. Should I consider using the stock '76 120cc heads, or will it be worth it in the long run to go to the 76cc heads? If I swap to the smaller cc head, then I guess that puts me into money for new pistons as well, since I won't want to run the race gas that the resulting 12:1 compression ratio would require.

I know that headers will be more effort and more expense, but I figured that would be one area where I'd ultimately make it easier on myself by doing the work/spending the money. I think it only makes sense that - if I'm doing all that work to make the engine pump more air - I should make it easier for the engine to get rid of it once it's been spent. I intend to run the exhaust open at the strip anyway.

I'm at a little bit of a crossroads on the rear gear. I had the rear end completely rebuilt, and now it's sitting on the floor. I suppose I could either take it back and have them put shorter gears in it, or I could buy another set of tires. Either way I'm looking at spending more money. I'm not sure what to do with that problem.

Thanks for all the help so far. I'm making notes on all of it.

[Vern]

Anyone who has ported and flowed Cad heads will tell you its easier to get better flow from the 76cc heads and that ultimately they can be made to flow better. Also you will get more compression which is more power and generally helps with bigger cams as well. However for your goals and from where you are the 120s will work. As proof look at Terry's flying yellow phonebooth and do the math on that.

IMO if you really are set on seeing that 500 number on the dyno you will want to spend the money on the headers. If you are ok with say 450 or so just open up the exhaust manifolds and hook em to some 3" pipe. Keep in mind power/flow levels and just one engine to another vary a bit so its not its not a cut & dry hard number kind of thing its just my general experience and history of what I have seen.

You need all the traction you can get. IMO try the gear and buy some 30" tires.

[Andy V]

For a reasonably priced combo, I'd look to bump your compression.

76cc heads, ported mildly w/ bigger valves 2.19/1.77 or 1.84
MT15 cam kit like you said
KB382 pistons for 10:1 ($345) these are hypereut's not forged though.

You'll get pretty darned close to 500 hp w/ headers, an edelbrock intake, and a well set-up carb on this combo.
Punch the block .060 for a few more cubes (514), pistons cost the same and are off the shelf in .030/.060 I know for sure.

[Andy V]

Another thing I thought of, Ross forged pistons have been on Ebay recently in the $550 range, for a 10:1 motor w/ 76cc heads.

Al (MTS) also had decently priced forged units I believe too. If you go forged then you can always add a 250hp shot of spray in a few years when you want to go faster (or a few weeks?).
You'll be needing a cage in no time

[dave_brode]

Depends on budget vs goals. If you bores and pistons look good, a block cut for a .040"quench distance and a little head cut on the 120s will get you to maybe 9-1. To get more, dished KBs or other pistons and 76cc heads will be a must, or more expensive custom domed pistons for the 120s.

Another option is 425 heads on your '74-76 pistons, which afaik, would get you to 9.6-1 or so, *maybe* a tad higher. Afaik, the 425 heads really need some porting to match 120cc heads' flow, and 76cc heads are best overall. The 120s will do ok, as should the 425 heads, WITH some porting.

Not sure if it's in your budget, but there are 2.11" int and 1.66 and 1.77" exh valves from pontiacs that fit the 120cc and 425 heads like a glove. Most of the pontiac intakes are 30 degree face, but can be re-cut for a 45. There are some aftermarket pontiacs with 45 faces on the intakes too. Beware, you have to use the proper length poncho valves, and there are several different lengths. If you go w/larger valves, make damned sure that your machinist know what he's doing to get the valve tips all at the proper hiegth. Afaik, they need to be 2.040" -2.050" from the stock spring seat.
Dave

[Modly]

I'm about to do a buildup on a '74 500, and I'm curious if anybody has tried a windage tray. I haven't gotten to open up the 500 yet (still sitting in a friend's barn), so I don't know how the design of it looks in person, but I know a tray can help on the Chevy blocks.

I'm curious as to modifying the stock intake. Is it just removing the divider, and port matching it up, or is it more involved than that?

For this engine, I'm looking for a low compression daily driver, with maybe 75-100 ft/lbs of torque than stock. I'm looking at a CompCam 260 grind, new .060 pistons, and some porting. When I'm grinding the heads, I'll take out some extra metal below the seat, for some better flow, and I'll block off all the EGR.

Did I cover all the bases, or am I missing anything for a good Cadillac build? I work at a machine shop, and through the years, nobody there has ever done more than a valve job for a 472/500, so nobody at work can offer me any suggestions.

[dave_brode]

Modly,

Afaik, the Comp shelf grinds are on a 110 LSA. Most experts claim the caddy *normally* does best with a wider LSA.

You could work the sharp hook in the exhaust floors down a bit while you're at it.

Fyi - KB has flat tops that are taller than most elcheapo cast pistons.
That'd help keep the quench tighter.
Dave




"]I'm about to do a buildup on a '74 500, and I'm curious if anybody has tried a windage tray. I haven't gotten to open up the 500 yet (still sitting in a friend's barn), so I don't know how the design of it looks in person, but I know a tray can help on the Chevy blocks.

I'm curious as to modifying the stock intake. Is it just removing the divider, and port matching it up, or is it more involved than that?

For this engine, I'm looking for a low compression daily driver, with maybe 75-100 ft/lbs of torque than stock. I'm looking at a CompCam 260 grind, new .060 pistons, and some porting. When I'm grinding the heads, I'll take out some extra metal below the seat, for some better flow, and I'll block off all the EGR.

Did I cover all the bases, or am I missing anything for a good Cadillac build? I work at a machine shop, and through the years, nobody there has ever done more than a valve job for a 472/500, so nobody at work can offer me any suggestions.[/quote]