Let's Play, "Let's Build a Big Block"

Or would you prefer a nice game of chess?

Our LeMons team has decided to build a new 460 for our LeMons car, a 1975 LTD Landau. As-raced weight is somewhere in the neighborhood of 4000 pounds. We currently run a mostly-stock 460, bored .060 to 472, with advanced cam timing, a windage tray, 0.030" head gaskets, a 625 CFM Edelbrock carb (jetted richer using an A/F meter) on an aluminum dual plane intake, and factory...well, everything else. Automatic trans (C6) and a 3.25 final drive ratio. It runs pretty well, but has a few races under it's belt now, so we're thinking about building up something a bit...hotter.

Enter the new lump: a 30,000 mile engine pulled out of a 1985 Ford motorhome. It's as factory as they come, down to the chalk markings on the cylinder walls in the valley. Tuned up and brand new, it managed about 245 HP and 385 lb-ft.

We'd like, um, more, please. Of course, we have to do it cheaply.

We addressed some of the glaring deficiencies of the snog-era 460 with our current LeMons engine- the poor quench, the retarded cam timing, oil control - and now we want to take it a step further with things like pistons and a cam. Since this engine is so fresh, machine work will be kept to a minimum. (There isn't even a ring ridge at the top of the cylinder bore.)

Stock compression ratio (CR) was about 8.06:1 on this engine. The heads are D3VE, which have about 94 cc combustion chambers according to the internets. The pistons leave about 0.025" to the top of the deck, and the stock head gasket was about 0.050". The pistons have about a 22 cc dish to them, too. The stock cam is...well, it's best not to talk about that.

I know that D0VE heads are the ticket to high compression, with their ~77 cc chambers, but unfortunately I don't have a set of those laying around. And regardless of the head, the exhaust ports kinda universally suck, so some porting is in the plans there.

So the plan is to use the stock D3VE heads, port them, install some taller pistons with less dish, a thinner head gasket, and get CR up to about 9.5:1. This will also get quench down to about 0.040", a more reasonable number (currently it's about 0.075")

Then, the Big Question:

What Cam To Use?

...to be continued...

I'd just have a custom cam made and call it a day- price wise isn't much different than a shelf cam. Ed at http://www.flowtechinduction.com/ did a cam for me for a 302 and it was spot on.

That carb seems small, especially with a dual plane intake. Might want to play around with some open hole spacers at least to see if it wants more (or put a vacuum gauge on it to really know).

Yeah, the biggest problem with the 385-series engines was that all the stock cylinder heads except for the 429 Cobra Jet heads (Which may as well have been buried with King Tut for the price they command) were garbage.

As for what cam, I'd use Comp Cams' High Energy 260 hydraulic flat-tappet (260 degree duration, 0.484" valve lift and 110 LSA). Flat-tappets are cheap, and it's 1500-5200RPM range seems right where I would want to run a 460 Ford, with it's low compression and huge main and rod bearings. Plus, it idles smooth, so less chance of people suspecting a cheater motor, and it makes strong low end torque to help get that barge moving out of corners.

I know you said machine work will be kept to a minimum, but can you shave the heads and deck the block a bit? That will certainly bump compression for you and you may be able to re-use your stock pistons. Would then allow you to grab a cam that has longer duration and therefore lower dynamic compression than the stocker probably has.

If you have the heads off to port, I see no reason not to have them skimmed a bit (or possibly a lot, I'm not sure what the limitations of those heads are).

ross2004 wrote: I'd just have a custom cam made and call it a day- price wise isn't much different than a shelf cam. Ed at http://www.flowtechinduction.com/ did a cam for me for a 302 and it was spot on. That carb seems small, especially with a dual plane intake. Might want to play around with some open hole spacers at least to see if it wants more (or put a vacuum gauge on it to really know).

Intriguing idea about the custom cam. Still, there's about a zillion cams out there for 460s that all do mostly what we want to do (i.e, make power under 5000 RPM) so finding the right one is kindof a challenge.

I hear you on the carb. We have two 625 Edelbrocks that were basically cast-offs from other projects, hence cheap. I'd love to swing a 750 on there but that might stretch the budget a bit too thin. I guess we could get a dual manifold and run both 625s at once.

Maybe find a cheap Holley 4160?

You can take a little of the heads to help compression.

NickD wrote: Yeah, the biggest problem with the 385-series engines was that all the stock cylinder heads except for the 429 Cobra Jet heads (Which may as well have been buried with King Tut for the price they command) were garbage. As for what cam, I'd use Comp Cams' High Energy 260 hydraulic flat-tappet (260 degree duration, 0.484" valve lift and 110 LSA). Flat-tappets are cheap, and it's 1500-5200RPM range seems right where I would want to run a 460 Ford, with it's low compression and huge main and rod bearings. Plus, it idles smooth, so less chance of people suspecting a cheater motor, and it makes strong low end torque to help get that barge moving out of corners.

The intake ports on the heads aren't terrible; some folks seem to run them as-is up to around 600 HP. The problem is the exhausts. I've read there's a guy who sells 460 porting knowledge on the internet, it might be worth running him down.

I've looked at CompCams lineup and yes, that one stood out to me. I actually created my own spreadsheet to calculate Dynamic CR based on engine mechanicals and cam specs. It calculates cranking pressure and a Volume/ Pressure index to predict low RPM torque. I put all of the 460 Comp Cam in there. I plan on adding some others next, though some other cam companies don't provide as much info as CompCams does.

I've read you can sort-of band-aid the poor stock exhaust ports with a bit more exhaust duration. This will work...up to a point.

The goal here is not stupid power but strong, even power in the RPM range we run (2500 to 4500 mostly) and reliability. Using CompCam's online modeler, we should be able to hit >300HP and >450 lb-ft throughout most of that range.

Robbie wrote: I know you said machine work will be kept to a minimum, but can you shave the heads and deck the block a bit? That will certainly bump compression for you and you may be able to re-use your stock pistons. Would then allow you to grab a cam that has longer duration and therefore lower dynamic compression than the stocker probably has. If you have the heads off to port, I see no reason not to have them skimmed a bit (or possibly a lot, I'm not sure what the limitations of those heads are).

I'm averse to machine work for a couple of reasons. The main being cost. A set of pistons will run around $300, and not require that the entire rest of the bottom end be taken apart. And while I am going to thoroughly dismantle the heads for porting anyway, if I had the heads shaved I'd then have to a) cc them, and b) machine the intake to match.

EDIT: also, machining the heads won't fix the terrible quench. Even with the thinnest head gasket I can find, quench with stock pistons will still be like 0.046". And those dishes...ugh. Factory EFI pistons will let me get quench into the upper thirties, and the dishes are smaller, too.

Speaking of cc-ing heads, that sounds neat. I tried it once on some 360 Mopar heads, and don't really remember it being easy. Anyone here have a trick setup for doing it?

volvoclearinghouse wrote: Maybe find a cheap Holley 4160?

You can get a 750cfm 4160 and a rebuild kit for under $100 easy.

Just go easy on the cam and dial in the cam timing for power instead of emissions. "One up from stock" would probably do it. The biggest restriction in this motor is the heads.

Is boost an option? I'm picturing two junkyard M90s with your pair of Edelbrocks up top

In reply to volvoclearinghouse:

A thirsty 460 for 24 hours I'm guessing 87 octane? I'd feel better at 8.8?9:1 and camshaft chosen lastly for the octane and compression. Lots of pump gas builds out there and differences at 87 to 93.

At 9.5 (or more?) you may have to retard the timing to make it live, and be disappointed at the power results. Maybe 89 octane?

Trying to figure out how rebuilding a big block can happen in a $500 total car race...

Jerry From LA wrote: Just go easy on the cam and dial in the cam timing for power instead of emissions. "One up from stock" would probably do it. The biggest restriction in this motor is the heads.

I'd say the second biggest restriction is the heads. If absolutely nothing else were done to the engine, a cam change would practically double the useable torque, by adding some rpm range. I doubt that lump would hit 5500 rpm in neutral with a brick on the throttle.

Put on a set of aluminum hot rod heads, and use the stock cam, and you would want to shoot yourself every time you tried to spin it above 3500.

Javelin wrote: Trying to figure out how rebuilding a big block can happen in a $500 total car race...

And there it is.

Tell you what. When our mid-seventies land yacht, complete with a 700 pound boat anchor of a motivational unit, on 400 treadwear tires, with the suspension compliance of an oxcart, handles anywhere close to a first-generation Miata that's lost a wheel and missing a spark plug wire, then complain to me about "$500 Car my Azz!!1!1!!!"

We're just trying to have a little fun here, folks.

¯\_(ツ)_/¯ wrote: Is boost an option? I'm picturing two junkyard M90s with your pair of Edelbrocks up top

I've never tried boosting anything. A draw-through could potentially be hilarious, or kill us.

I'm beginning to think nobody at these races actually cares about that number unless you bring an E30 or a leftover circle track engine.

Gasoline wrote: In reply to volvoclearinghouse: A thirsty 460 for 24 hours I'm guessing 87 octane? I'd feel better at 8.8?9:1 and camshaft chosen lastly for the octane and compression. Lots of pump gas builds out there and differences at 87 to 93. At 9.5 (or more?) you may have to retard the timing to make it live, and be disappointed at the power results. Maybe 89 octane?

We were figuring on having to run 93 octane. Our current burn rate is about 8 gph; that might rise to 10 or so with the hot engine. Over a typical race weekend (which is only about 12 to 14 hours of actual driving) we'll burn about 100 gallons of gas- figure 120 now. Even 93 octane is around $2.50 a gallon, that's $300 or so of fuel for the weekend, or $60 per driver. We spend that much on brake pads and beer.

One race we lucked into a 460 out of a 68 Lincoln. That had D0VE heads, 10:1 compression, and a 4 bbl carb. Man it was a hot setup. We blew that engine up, and everything since just hasn't quite been the same.

Crower makes a couple of interesting cams. Both have 268 advertised intake, but one is 274 exh and the other is 286. This would seem to work well with the stock poor-flowing exhaust ports.

What's sort of irritating is that some of these cam manufacturers don't just give you all the data. I know I can calculate the Intake Closing Angle, but it's just easier if you give it to me. I know you've calculated it, Mr. Manufacturer. Geesh.

Crower gives the Lobe Separation Angle but not the Intake Centerline. grumble

Learn to port the heads? There is a porting threads here somewhere.

volvoclearinghouse wrote:

Javelin wrote: Trying to figure out how rebuilding a big block can happen in a $500 total car race...

And there it is. Tell you what. When our mid-seventies land yacht, complete with a 700 pound boat anchor of a motivational unit, on 400 treadwear tires, with the suspension compliance of an oxcart, handles anywhere close to a first-generation Miata that's lost a wheel and missing a spark plug wire, then complain to me about "$500 Car my Azz!!1!1!!!" We're just trying to have a little fun here, folks.

Justify it all you want, you are still breaking both the letter and the spirit of the rules for that kind of racing. Rebuilding the motor out of used garbage parts or bolting on four junk turbos is one thing, but you are talking about an actual performance build with all new aftermarket parts, many of which cost a significant portion of or more than the total the car is supposed to be. If it's too slow, build a different car! Or if you are going to spend money, do it for the wacky like the radial MR2 guys or speedycop's creations. Building a ringer motor just isn't cool man.

volvoclearinghouse wrote:

¯\_(ツ)_/¯ wrote: Is boost an option? I'm picturing two junkyard M90s with your pair of Edelbrocks up top

I've never tried boosting anything. A draw-through could potentially be hilarious, or kill us.

When I raced LeMons at CMP years ago, one of my favorite cars there was a Merkur with (IIRC) a 351w, with a bus turbo blowing straight into a .50-cal ammo box which contained the carb. At the green flag, it went "PSSSSSHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH" and passed like 15 of us before exploding in a cloud of smoke. I think they got it back on track and did the same thing like 5 or 6 times throughout the race.

So, like that, but maybe dial the boost back until it stops blowing up. Plus, some sort of absurd looking dual supercharger setup should net you major LeMons street cred.

I thought they had changed the rules to an agreed price format. For example an 75 LTD is worth $300 no matter what you paid for it but if you do X engine mods they add $200 in value no matter what the engine mods cost you.

In reply to Stampie:

I think that's Chump Car you're thinking of.

Yeah, that's Chump. In LeMons its more like, roll up in a '75 LTD, tell Judge Phil what you did to the engine, he laughs, assigns you Class C Zero Laps and we all have fun.

And people on the internet whine about the whole $500 thing, and none of the organizers care because they'd rather see a hundred 70's era barges with "ringer motors" in them than another dumb E30 or Miata.

Now, can we focus on building an engine please?