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Kirkham Motorsports

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  #21 (permalink)  
Old 07-03-2017, 04:42 PM
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Quote:
Originally Posted by cycleguy55 View Post
Duration @ 0.050" is 224 degrees on that cam, so a pretty mild build. Should be a nice car to cruise around in.

Good luck with your build.
Considering the extra cubes 428vs 482, I'm thinking that cam is too mild.

Many 482s run cams are in the 250s range (I know of some in the 260 range). If I was building a mild 482 I'd consider cams in the 240 range with a relatively wide lsa (110-112). That way the engine can at least breath easy, across its entire rev range.

Others are better placed to advise, but 224 with 482 cubes I've not seen or heard of. Imho You're really hamstringing that engine with such a small cam. Even from a conservative point of view.
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  #22 (permalink)  
Old 07-03-2017, 04:43 PM
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Ps. Good call on SCAT internals and edelbrock heads are always a safe bet on an fe build.

Good luck with it. Can wait to see/hear it once done.
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Last edited by Dimis; 07-03-2017 at 04:44 PM.. Reason: ****ty iPhone double posts.
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  #23 (permalink)  
Old 07-03-2017, 05:39 PM
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Thanks guys....I will do more research on the cam. It was what was in the 428 with good results.

Maybe just not enough for the 482?

While it will be a blvd cruiser most of the time, it will have some track days on it's calendar. The road coarse stuff. I have been using my GT 500 for that and I want to play with the cobra more.
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Old 07-03-2017, 05:58 PM
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I am of the school that most people use too much cam and generally that is because they should have chosen better heads. I prefer a torque curve that is a flat as possible, but I want it to stay flat past 5000 rpm as far as possible.

That all said, I agree the cam would likely be dropping the torque way too soon with that many cid. I would go another 10 deg duration. Depending how adverse you are to a choppy idle, maybe a little more.

If you have fairly steep ramps with roller lifters, you will not need as much cam. If we are talking flat tappet lifters, you should be talking to someone who knows more than I.
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Old 07-03-2017, 06:06 PM
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With my cam (specs posted above) I have a semi-rough idle at 800-900 rpm but not bad. With a light car, 3:54 rear and stick there are no driveability issues at all. It will pull hard from 2K to 5800 and doesn't start falling off until 6k. Tq peak is around 4K. Doesn't mean a milder cam is bad (after all how often are you going to go past 5K), nor a more aggressive one either. I agree in these cars you don't want (or need) to over do the cam.
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Old 07-03-2017, 06:23 PM
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A choppy idle doesn't bother me, but a solid torque pull is important. i do not see going over the 5000 RPM much.
A strong steady pull will be much easier to control. as apposed to needing to have it matted to get to the power.
As it is now the torque comes in at 3300. and when on the track, it makes the throttle more like an ON/OFF switch.

You guys have me really looking at this
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Old 07-03-2017, 07:03 PM
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60 extra cubes eats up a lot of camshaft duration. You're way under on duration and lift both, even for a conservative application.

I built a 482 for a 65 F250 where the guy pulls a 10000 lb travel trailer and it has more camshaft than that.

FEs are harder to cam for than traditional engines and you can't rely on cam tech lines, catalogs, or guys that build Chevys to nail one down.
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Old 07-03-2017, 07:46 PM
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Quote:
Originally Posted by 2bars View Post
Cam is a Elgin Pro stock # E 963 P. Cam lift .292, Duration 300 and valve lift .505. It Same numbers int and exh
Quote:
Originally Posted by cycleguy55 View Post
Duration @ 0.050" is 224 degrees on that cam
Just for comparison. I have a 5.0 stroked to 347. Cam is 236/242 Dur @ 0.050" lift is .555 / .576 with a 110 deg lobe separation installed at 106 intake center line. Advertised 287 / 293 @ 0.006" roller cam.

Engine idle is choppy, but smooths out by 1800 rpm. It does not like to be lugged in 5th gear below 1800, but it can be driven down to 1600 rpm with a bit of care. It does not lack torque at any rpm in the first 4 gears. I believe the .62 5th gear would drive up a 10 deg grade if you keep it above 2000 rpm (never proven).

347/482 * 1800 = 1295, so in theory my cam / head combination would be smoothed out by 1300 rpm with your cid. Now these two engines are too far different for this to be a valid comparison, but it makes a point.

Last edited by olddog; 07-03-2017 at 08:02 PM..
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Old 07-03-2017, 08:00 PM
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I am grateful for all this input. I will be re evaluating the cam for sure. I guess I started there because I was satisfied with the 428. This is my first "stroked" engine

But the order of importance was/is
1 reliable
2 pump gas
3 Even Torque
4 HP
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Old 07-03-2017, 08:30 PM
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I looked that cam up on Elgin's website.
Elgin Industries

Intake opens 3 BTDC and exhaust closes 3 ATDC for only 6 deg of valve overlap.

Intake 3 BTDC to 41 ABDC and 180 + 3 + 41 adds to 224 deg.
Exhaust 47 BBDC to 3 ATDC and 180 + 3 + 47 adds to 230 deg, not the 224 stated.

So the exhaust is running 6 deg more duration than the intake.

I thinking motor homes use bigger cams than that.
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Old 07-03-2017, 08:40 PM
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I do not know how easy or hard it is to use roller lifters in the block you are using. If at all possible go with a hydraulic roller cam.

1) Roller cams work with today's oil. Flat tappet lifters need more ZDP than is put in modern oil. It was removed to extend O2 Sensor life. All modern engines have roller cams or overhead cams. Roller cams are more reliable.

2) Roller lifters can easily roll up a much steeper ramp than a flat tappet lifter. You can get the valve open quicker, and you can keep it open longer because you can close it quicker. This increases flow substantially at the same duration.

.600 lift is nothing for a FE head. People are running small blocks with more lift.

Last edited by olddog; 07-03-2017 at 08:43 PM..
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Old 07-03-2017, 09:03 PM
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From Edelbrock FE Stage II - Craft Performance Engines

Edelbrock FE Stage II

2.19/1.75 Valves
28" Water 2"x6" Pipe

Lift ...... Intake CFM ...... Exhaust CFM
.300 .......... 227 ................ 161
.400 .......... 276 ................ 195
.500 .......... 307 ................ 226
.600 .......... 324 ................ 249
.700 .......... 336 ................ 265
.800 .......... 344 ................ 276

Going from 500 to 600 lift is a ~6% flow increase. Of course that is not a 6% Hp increase because the valve is only at maximum lift a short period out of the total duration time.

I did read a book on the 4.6 modular. The author claimed to have reduced the valve lift on a cam profile he was running all out in drag racing, to get a flatter torque curve for a road race car. Same duration just less lift. The dyno sheet he showed did have a flatter torque curve, but he gave up torque pretty much everywhere, which was less Hp. I do believe that at some point going more and more lift, starts giving a higher peak torque in the middle. So you may want to consult with experts -- builders who have a lot of dyno data to compare.

Just one last comment. It has been my observation that builders have to sell Hp because us consumers are unreasonable egomaniacs, who will not listen to reason. So builders are going for maximum hp and rarely look at the torque below 3500-4000 rpm. They cannot afford the time to make sure the timing curve does not came in too fast at low rpm and that is where detonation is at its highest risk. They can skip all that by starting the dyno pull at an rpm above max timing. I'm not tossing rocks here, because I do not blame them. The point being that few people are looking at the torque at lower rpms, unless they have a compelling reason. Drag racers couldn't care less.

Last edited by olddog; 07-03-2017 at 09:28 PM..
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Old 07-04-2017, 05:11 AM
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2bars, if you need help selecting a camshaft, I can help you. All of my cams are custom grinds, no matter if they are hydraulic flat tappet or solid roller. I take into account each and every engine parameter along with each and every car parameter, while listening to the concerns of the customer.

Bottom line is that your camshaft is too small for the application. At 224 @ .050" duration, you will have all torque and no horsepower, and as olddog pointed out, a .500" lift camshaft isn't taking advantage of the cylinder heads. Now, you don't have to go .700" to do that, but a .550-.600" lift camshaft is extremely common.

My customer up above with the 482 in the truck has a 224 @ .050" hydraulic roller on a 112 LSA and .570" lift. He can hook to his 10000 lb travel trailer, put it in 1st gear, let the clutch out without giving it any gas, and walk along side of it as it pulls his trailer around his yard....

You need more camshaft and there aren't many cams for an FE that work off the shelf. The tech guys at the camshaft companies have never seen an FE, much less built one or had one on the dyno.

olddog:

I have a few customers who are honest in their expectations. Not all of them chase numbers. With that being said, I always look at torque at around 3500-4000 because it's easy to do. On a street engine that peaks the hp at around 5500-6000, that's in the general ballpark of where the torque peak is going to be.

I ALWAYS take the time to recurve the distributor on engine assembly. I afford the time and it's part of my assembly process. The dyno process starts the pull above the total timing mark (I usually bring total in at 2500-2700, higher than that is a waste for a performance car) because it has to. Dynos are harder on engines than the actual cars and pulling the guts out of an engine at 2500 rpm proves nothing.
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Old 07-04-2017, 08:29 AM
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Brent - I apologize if I over generalized and painted with too wide a brush. Obviously some builders are looking at how to get a flatter torque curve or I would never have read it in a book.

In my quest to understand how to tune my EFI, I took a deep dive down that road. I was surprised to learn how much time the OEMs spend trying to perfect the low rpm torque curves on engines. They are also trying to find MBT at every driving condition, as that is how you get the best fuel economy. Well they are concerned with fuel economy, when they are at light to moderate driving conditions, where emissions matter. Once you get to WOT, they dump extra fuel and back off on the timing to assure the engine will not detonate with crappy fuel. They are quite willing to give up Hp to make sure they do not have to replace engines. I think I am rambling around again. I guess my point is that the OEM are spending a great deal of time at the opposite end of the spectrum from a performance guy.

Anyway, it would be hard to get into trouble with bring the timing in a tad too quick in a Cobra. Your only going to roll into the throttle hard at low rpm in a low gear. The tires cannot hook up huge torque numbers anyway, and even if they did it will only be there a second or two. These engine are not likely to ever pull hard at a low rpm for a long period, like a truck pulling a trailer. Most guys are going to down shift before they hammer it anyway.

2bars - Take Brent up on the offer to help you with your cam and purchase it from him, if that doesn't kill the deal you have with your builder. Honestly I'm surprised your builder didn't try to steer you away from that cam. It shouldn't bother the builder if you do this. He just has to make sure he has piston to valve clearance so he needs to know before he assembles the short block. Then he has to get the valve geometry right. I don't see the cam change as a big deal.

Last edited by olddog; 07-04-2017 at 08:37 AM..
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Old 07-04-2017, 09:23 AM
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And that's the point. All the guys complaining that we don't pull the engines down to 2000-2500 on the dyno really don't have a leg to stand on. There will be zero chance that the engine will ever be dead-headed in any car at that rpm. It's either going to accelerate or blow the tires off. Either way, peak torque at that rpm is meaningless.
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Old 07-04-2017, 10:05 AM
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I know you are absolutely right, but your killing us analytical types who need to fret over meaningless data that has no practical use.

There are two times when that 2000 rpm data is important.

1) Trucks pulling heavy loads.

2) Hard headed, old school guys who will not give up on huge massive monster flowing ports on tiny engines. They have to look at 2000 rpm to make sure they have more than 75 ft-lb, even though they have 400 ft-lb at 7000.

Good thing we have desk top dyno software to amuse and delude ourselves with.
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Old 07-04-2017, 10:14 AM
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Brent, I will take you up on your offer. I hate to have this much in it and miss on the cam. I will give you a call after the holiday.
I myself do not have enough education regarding Cam's.
But it seems that there is an entire group saying.... Woah
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Old 07-04-2017, 10:31 AM
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Quote:
Originally Posted by 2bars View Post
Brent, I will take you up on your offer. I hate to have this much in it and miss on the cam. I will give you a call after the holiday.
I myself do not have enough education regarding Cam's.
But it seems that there is an entire group saying.... Woah
Seriously, you are in good hands with this decision. You will get great advise from someone who actually does things and really knows things. As apposed to some couch potato, talks about it, know it all, who has only built 4 engines in his entire life, such as myself.
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Old 07-04-2017, 10:33 AM
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Call today if you want.

My wife took our daughter and our nieces to see a movie. I assembled a set of heads this morning, ran out of valves seals, so now I'm just chilling and watching episodes of "Untold stories of the ER"....

If you're busier than I am, just let me know what you're looking for: hydraulic flat tappet, solid flat tappet, hydraulic roller, etc., so that I can be thumbing through the lobe catalogs.
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Old 07-04-2017, 02:52 PM
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Thanks guys for all the information. I did talk to Brent today and we have a plane once the heads have been flow tested.
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