[scott70]

If you were using a RA4 size cam,,,would rhoads lifters make a engine more prone to detonation over using regular HFT lifters?

[PAUL K]

Originally Posted by scott70

If you were using a RA4 size cam,,,would rhoads lifters make a engine more prone to detonation over using regular HFT lifters?

Yes , Rhoades lifters work by closing the valves sooner at lower RPM's. Close the intake valve earlier and the cylinder will have more time to build higher pressure.

[Cliff R]

Rhoads lifters are well pumped up and operating as standard lifters WAY before the engine reaches peak VE and highest cylinder pressure so they really don't contribute to detonation at heavy load/WOT, etc.

I dyno tested them many years ago and we even tightened up the brake to read power (torque) below 3000rpm's and the dyno runs were identical between the Rhoads and standard lifters.

Rhoads lifters will however increase engine vacuum and cylinder pressure at idle and low RPM's which increases vacuum, power and throttle response, so you do get some variable valve timing effect.........Cliff

[Cliff R]

That explains why my XE274 was so crappy in my 10.6-1 470 a few years back. LOL

Not nearly enough seat timing for a 455 build at that compression ratio....IMHO.

The only impressive dyno runs I've seen with that cam were on a 400 build around 8.8 to 1 compression. As much as I don't like that line of cams due to their overly aggressive lobe profiles we had a customer do a pretty stout 400 build with one a few years back.

He used 6X-4 heads and had them ported to 250cfm, used the XE-274 cam, decked the block and cut the heads a bit and cam up at 8.8 to 1 compression. I really didn't think it was going to make big power way down there but it cranked out over 1hp/CID and over 450ft lbs torque, which is pretty strong for a "low" compression 400 with iron heads on pump gas.....

[firechicken]

Originally Posted by Cliff R

That explains why my XE274 was so crappy in my 10.6-1 470 a few years back. LOL

Not nearly enough seat timing for a 455 build at that compression ratio....IMHO.

The only impressive dyno runs I've seen with that cam were on a 400 build around 8.8 to 1 compression. As much as I don't like that line of cams due to their overly aggressive lobe profiles we had a customer do a pretty stout 400 build with one a few years back.

He used 6X-4 heads and had them ported to 250cfm, used the XE-274 cam, decked the block and cut the heads a bit and cam up at 8.8 to 1 compression. I really didn't think it was going to make big power way down there but it cranked out over 1hp/CID and over 450ft lbs torque, which is pretty strong for a "low" compression 400 with iron heads on pump gas.....

I built a 400 for my TA exactly the same as this many years ago. It was a lot of fun with a ST-10 4speed and 3.73 gears until it wiped an exhaust lobe...

[slowbird]

Originally Posted by Cliff R

That explains why my XE274 was so crappy in my 10.6-1 470 a few years back. LOL

Not nearly enough seat timing for a 455 build at that compression ratio....IMHO.

The only impressive dyno runs I've seen with that cam were on a 400 build around 8.8 to 1 compression. As much as I don't like that line of cams due to their overly aggressive lobe profiles we had a customer do a pretty stout 400 build with one a few years back.

He used 6X-4 heads and had them ported to 250cfm, used the XE-274 cam, decked the block and cut the heads a bit and cam up at 8.8 to 1 compression. I really didn't think it was going to make big power way down there but it cranked out over 1hp/CID and over 450ft lbs torque, which is pretty strong for a "low" compression 400 with iron heads on pump gas.....

We've made real good power with that cam in a 400 with 230cfm heads, high 11s at 113-114mph in our 73 Ventura.

[Stan Weiss]

Originally Posted by slowbird

We've made real good power with that cam in a 400 with 230cfm heads, high 11s at 113-114mph in our 73 Ventura.

Brian,
What was your CR and what octane did you run?

Stan

[scott70]

So below 3000 rpms,, say 2300,,cruising in 4th gear and moderately give it some throttle,,you could have more of chance of detonation with Rhoads compared to standard lifters?

[slowbird]

Originally Posted by Stan Weiss

Brian,
What was your CR and what octane did you run?

Stan

10:1 91-92 octane

[PAUL K]

Originally Posted by scott70

So below 3000 rpms,, say 2300,,cruising in 4th gear and moderately give it some throttle,,you could have more of chance of detonation with Rhoads compared to standard lifters?

Yes, without a doubt. If you have an engine that is octane challenged, increasing cylinder pressure is the last thing you want to do.

If you have enough octane to get the job done it will make no difference.

[Cliff R]

I supposed you might see higher cylinder pressure there, but you are reaching the RPM range where they become fully pumped-up and operating like standard lifters. You are also still well below peak VE so the pressure isn't as high as it will be a little further up in the RPM range.

The leak down rates with Rhoad's are pretty quick but not instantaneous. They make some noise at idle because the events aren't happening as many times per second. Assuming the leak down rate is around 20 seconds compared to 120 seconds you are going to get some noise and loose the full potential of the cam lobes in terms of lift and duration. This makes the cam act smaller and more effective cylinder filling with less overlap as well.

As engine RPM's increase you'll notice the valve train quiets right down and at that point your Rhoads lifters are operating same as standard lifters. We know this to be true because when I back-to-back tested them the dyno charts were EXACTLY the same.

Even when we tightened up the brake and pulled the engine down really low, or under 3000rpm's there was no difference at all with the Rhoads lifters. From what I saw with the test we did they are doing their work below about 2500rpm's.

I suppose we could have played around with lower viscosity motor oil and tried to get them to bleed down at higher RPM's but I doubt if it would make a lot of difference.......

[Tim Corcoran]

This has been a very interesting conversation and you may flame me for butting in to this post but since we have all the cam experts here I have a question. Here it is, a 400 engine with a 4.193 bore and a 4" stroke, 6.625 length rods, 6X heads with 2.11/1.77 valves flowing 265@ 28" water and 9.0:1 static compression using custom Ross flat top pistons about .003 below the deck. The exhaust is RAM Air/HO exhaust manifolds and a full 2-1/2 exhaust system using Walker turbo mufflers. The car is a 67 LeMans TH-400 trans full weight power steering, power brakes, air conditioning. Will need a strong stable idle with good vacuum with good drivability good street manners and want a broad power band with a 2,500 RPM stall converter. This engine will have a hydraulic roller with 1.65 rocker arms. Needs to run on 93 octane pump gas and needs to run high 12's in the 1/4. Pick my cam.

[400 Lemans]

https://butlerperformance.com/i-2936...tegory:1272239

Originally Posted by Tim Corcoran

This has been a very interesting conversation and you may flame me for butting in to this post but since we have all the cam experts here I have a question. Here it is, a 400 engine with a 4.193 bore and a 4" stroke, 6.625 length rods, 6X heads with 2.11/1.77 valves flowing 265@ 28" water and 9.0:1 static compression using custom Ross flat top pistons about .003 below the deck. The exhaust is RAM Air/HO exhaust manifolds and a full 2-1/2 exhaust system using Walker turbo mufflers. The car is a 67 LeMans TH-400 trans full weight power steering, power brakes, air conditioning. Will need a strong stable idle with good vacuum with good drivability good street manners and want a broad power band with a 2,500 RPM stall converter. This engine will have a hydraulic roller with 1.65 rocker arms. Needs to run on 93 octane pump gas and needs to run high 12's in the 1/4. Pick my cam.

I think this is about perfect for your build.

[ekancler]

Originally Posted by Tim Corcoran

This has been a very interesting conversation and you may flame me for butting in to this post but since we have all the cam experts here I have a question. Here it is, a 400 engine with a 4.193 bore and a 4" stroke, 6.625 length rods, 6X heads with 2.11/1.77 valves flowing 265@ 28" water and 9.0:1 static compression using custom Ross flat top pistons about .003 below the deck. The exhaust is RAM Air/HO exhaust manifolds and a full 2-1/2 exhaust system using Walker turbo mufflers. The car is a 67 LeMans TH-400 trans full weight power steering, power brakes, air conditioning. Will need a strong stable idle with good vacuum with good drivability good street manners and want a broad power band with a 2,500 RPM stall converter. This engine will have a hydraulic roller with 1.65 rocker arms. Needs to run on 93 octane pump gas and needs to run high 12's in the 1/4. Pick my cam.

What does the exhaust flow? And guessing 6x-4?

[Tim Corcoran]

shaved 6X-8 around 70% of intake

[Tim Corcoran]

What about this
Lunati Voodoo Hydraulic Roller Cam LUN-20510711
(0) Reviews: Write first review
Description: Advertised Duration (Int/Exh): 270/278 Duration @ .050 (Int/Exh): 219/227 Gross Valve Lift (Int/Exh): .515/.530 LSA/ICL: 112/106 Valve Lash (Int/Exh): Hyd/Hyd RPM...
custom ground on a 114 LSA with 1.65 rockers

[Cliff R]

Complete WASTE of time looking at camshafts that are done making power by 5000rpms when you have 265cfm of head flow available, IMHO.

One of the last 428's I did here used unported KRE aluminum heads. They got a port match to a stock intake gasket and a little "clean-up" under the valves. I used a custom ground Comp Cam with XFI lobes with .361" lift, 236/242 @ .050" with 1.6 ratio Crower Enduro rockers. With a factory iron intake and Q-jet w/o a spacer it cranked out 497hp/540tq. Made peak HP at 5800 rpm's and peak torque at 4200.

The 4" stroke is a very good way to go with one of these engines, IMHO. They never disappoint anyplace but you need to put some cam in them as they like to rev............Cliff

[Stan Weiss]

Originally Posted by Tim Corcoran

What about this
Lunati Voodoo Hydraulic Roller Cam LUN-20510711
(0) Reviews: Write first review
Description: Advertised Duration (Int/Exh): 270/278 Duration @ .050 (Int/Exh): 219/227 Gross Valve Lift (Int/Exh): .515/.530 LSA/ICL: 112/106 Valve Lash (Int/Exh): Hyd/Hyd RPM...
custom ground on a 114 LSA with 1.65 rockers

I don't think that is enough cam.

Stan

[i82much]

Originally Posted by Tim Corcoran

This has been a very interesting conversation and you may flame me for butting in to this post but since we have all the cam experts here I have a question. Here it is, a 400 engine with a 4.193 bore and a 4" stroke, 6.625 length rods, 6X heads with 2.11/1.77 valves flowing 265@ 28" water and 9.0:1 static compression using custom Ross flat top pistons about .003 below the deck. The exhaust is RAM Air/HO exhaust manifolds and a full 2-1/2 exhaust system using Walker turbo mufflers. The car is a 67 LeMans TH-400 trans full weight power steering, power brakes, air conditioning. Will need a strong stable idle with good vacuum with good drivability good street manners and want a broad power band with a 2,500 RPM stall converter. This engine will have a hydraulic roller with 1.65 rocker arms. Needs to run on 93 octane pump gas and needs to run high 12's in the 1/4. Pick my cam.

i would do some searching here for other 4" stroke combos to see what works. i have heard that longer stroke engines tend to like a wider lsa, but i honestly have no idea. i went with old faithful in a 4.25 stroke combo under the theory that it makes more sense to learn from others than to try and reinvent the wheel.

[ekancler]

How many folks use this for cam selection:

http://davidvizardperformanceseminar...oftware.phpolk