camshaft question- big block vs smallblock

I have been bouncing back with the idea of dropping the 4v cleveland and building a 460 based motor for my'73 Mach-1 (street driven and never tracked). When it comes to a stroked windsor (427 inches), a hydraulic roller cam 232/240 @ .050" would be a healthy yet very streetable cam. Is it fair to say a similar cam would perform similar in a 427 inch bigblock?

​

Click to expand...

Displacement is displacement.

Match the cam to the heads, gearing and intended usage.

As in 427 inches is 427 inches, regardless of how you get it?

As in 427 inches is 427 inches, regardless of how you get it?

Click to expand...

For the purpose of anticipating the behavior of a specific duration camshaft on the street, yes.

Certainly people will argue that an engine with a long stroke and small bore vs shorter stoke/big bore will present different torque curves (and they would be right). But on the street I don't think there would be a significant difference or even a detectable difference in drivability between either combo with the cam duration you propose.

I think gearing/head/induction and intended usage would have a greater influence on selection.

You could test this by calling a cam company and giving them the specs for two different engine combos at the same displacement and see what they say.

Just keep in mind that as displacement increases, a cam becomes more tame.

A 280 advertised duration cam in a 351 is a pretty healthy street cam. In a 408 stroker, it's much less so.

There is a 200 lb weight penalty for going big block, so don't overlook that one either. The 427W will not rev out like a 460 can either. The long stroke wheezer will have a ton of torque down low, but it's not going to be a screamer at high RPMs.

I understand it won't rev but to be honest, I don't really need it to. For a start only car in the California bay area (traffic and over zealous Highway Patrol Officers) , I really don't need to wind it up past. 6000rpm. The reason for my question, I have a 393w with a healthy cam 232/240 @ .050". For a similar cam for a 460 big block from Comp Cams, it says it has a lopey idle. I just would have expected a milder cam description with a larger engine..

I believe the biggest cubic inches you can get out of a 351 block with a bore and stroke is 408 ? And that requires some grinding for rod clearnce at the bottom of the bores. Unless windsores have a lot thicker walls?

I have a Dart block. It allows for 4.125+ bore. With a 4" stroke (408w) you would end up with a 427. But I was comparing similar cam profiles in different displacement motors (small block and big block), not the same exact can. I was trying to figure out why: a cam that was described as "radical idle" for a 460 inch motor, was healthy, yet very streetable in my 393 inch motor.. Everything I have read and been told days that the additional cubic inches should "absorb" some of that cam..

I have a Dart block. It allows for 4.125+ bore. With a 4" stroke (408w) you would end up with a 427. But I was comparing similar cam profiles in different displacement motors (small block and big block), not the same exact can. I was trying to figure out why: a cam that was described as "radical idle" for a 460 inch motor, was healthy, yet very streetable in my 393 inch motor.. Everything I have read and been told days that the additional cubic inches should "absorb" some of that cam..

Click to expand...

I've heard of 435 cid Wheezers using the stock block. Coast High lists a 454 Wheezer using a different block, too. I'd be concerned with excessive sideloading with super long strokes like that. The torque would be ridiculous, though!

My experience, thru seat of the pants testing and confirmation using computer simulation has been that using the same cam in 2 different displacement engines, keeping all other variables the same, is that the power/torque curve moves closer to idle as displacement increases. I'd be glad to run some numbers for you in the Dyno2000 simulation and provide numbers and graphs. I've found it to be reasonably accurate.

4.125+ bore? Well there you go !

Well my new motor has a 3.850" stroke (393w) with the 4.125" bore which gives me about 411 inches. With a set of AFR-205 heads,a paxton Novi-2000 supercharger and an intake (I have the Trick Flow box intake as well as the Edelbrock EFI intake), it should make great power. But I was really considering a 460 based stroker motor. I just can't figure out the camshaft. By the way, I have two older mustangs, I'm not just building motors..lol

I love my 393w and would like a 520 inch version of it. My 393 has a 3.850" stroke with " rod. With a hydraulic roller cam: 232/240 @ .050" 545" lift-112'. It has AFR-185 heads, edelbrock air gap intake with a Demon 750 with vac 2nd. What I am interested for my '73 Mach-1 is a 520 bbf: 4.3000" stroke and 6.800" rod Air gap intake and aluminum cobrajet heads. As for the cam, I'm thinking hydraulic roller 242/248 @ .050" about .540/.550-112'

I like the characteristics of my 393, but would like more power and have always been interested in a big block..

I have a Dart block. It allows for 4.125+ bore. With a 4" stroke (408w) you would end up with a 427. But I was comparing similar cam profiles in different displacement motors (small block and big block), not the same exact can. I was trying to figure out why: a cam that was described as "radical idle" for a 460 inch motor, was healthy, yet very streetable in my 393 inch motor.. Everything I have read and been told days that the additional cubic inches should "absorb" some of that cam..

Click to expand...

Because duration is only one of the determining factors in how a cam idles.

Ahh.. I didn't realize that.. what are some other factors? Or is it everything combined? I didn't think heads Gould affect idle, but I could imagine intake manifold design would (dual plane vs single plane)..

Ahh.. I didn't realize that.. what are some other factors? Or is it everything combined? I didn't think heads Gould affect idle, but I could imagine intake manifold design would (dual plane vs single plane)..

Click to expand...

Overall duration (and resulting overlap), intake centerline, and lobe separation determine idle quality. Narrower lobe sep results in a rougher idle. For example, you'll find the idle manners of a 112* lobe sep cam much better than a 110* or numerically lower.

If you have two cams of the same specs but one with 112' LSA and the other with an LSA OF 110'' the 110 will have a rougher idle? I had planned on a 112 lsa anyways due to the broader power band.

If you have two cams of the same specs but one with 112' LSA and the other with an LSA OF 110'' the 110 will have a rougher idle? I had planned on a 112 lsa anyways due to the broader power band.

Click to expand...

Yeah, the 110* LSA will sound more lumpy and probably have more punch at some specific RPM. I like the 110s, especially the sound of them. 112s are for EFI cars.

I love my 393w and would like a 520 inch version of it. My 393 has a 3.850" stroke with " rod. With a hydraulic roller cam: 232/240 @ .050" 545" lift-112'. It has AFR-185 heads, edelbrock air gap intake with a Demon 750 with vac 2nd. What I am interested for my '73 Mach-1 is a 520 bbf: 4.3000" stroke and 6.800" rod Air gap intake and aluminum cobrajet heads. As for the cam, I'm thinking hydraulic roller 242/248 @ .050" about .540/.550-112'

I like the characteristics of my 393, but would like more power and have always been interested in a big block..

Click to expand...

I would go for a higher lift cam for the big block. Cobra Jet heads will support higher lifts. Big inches will tame the cam for sure, I would go even something like this:

Howards, Hydraulic Roller Camshaft, Ford BB 429-460

243655-10

Ford BB 429-460 1968-1995

Advertised Duration: 300/300

Duration @ .050": 247/247

Valve Lift w/1.73 Rockers: .623/.623

Lobe Separation Angle: 110

Intake Centerline: 106

Valve Lash: Hyd./Hyd.

3000-6800. Lopey idle, street/strip, good mid range horsepower. Best with 3500+ stall.

or with the bigger one:

Howards, Hydraulic Roller Camshaft, Ford BB 429-460

243545-10

Ford BB 429-460 1968-1995

Advertised Duration: 302/308

Duration @ .050": 249/255

Valve Lift w/1.73 Rockers: .652/.652

Lobe Separation Angle: 110

Intake Centerline: 106

Valve Lash: Hyd./Hyd.

3200-7000. Rough idle, hot street/bracket, good torque & upper mid range. 11.5:1+, 3800+ stall.

Take minimum of 500 rpm off the max rpm are you're close to the true rpm area. Big inches will tame these beast's out.

One very good possibility is to use some good reputable engine builder to spec you custom camshaft for your exact needs.

What comes for the same degree & lift cams sbf vs. bbf, I would say as the Tommy does, but o dyno won't nessecary notice the diffrence. You can though notice it too, since the head layout = wedge and bigger borespacing can give advantage.

Thanks, and you recommend a single pattern cam over a dual pattern cam?