RPM for a 440?

[694spdRT]

I have a new project that I want to build now. 

I am building a 440 up to go truck pulling next year with my '78 Dodge W250 4 speed. The class is for street driven trucks and the shortblock is already built with TRW 2355's and six pack rods. It was balanced and set up right for sled pulling already by a friend of mine. He pulled in a class limited to stock intake and exhaust manifolds and ran about 6000 to 6200rpm down the track. I am planning to use a tunnel ram with 2 660 Holley center squirters, ported 346 heads, Crane 1.6 rockers, headers, and a cam of undetermined specs right now. The engine is going to be right around 10.75 to 1 compression. Is somewhere in the 6000rpm range "safe" or can I run up to 6500rpm? This will be a wide open blast for approximately 15 seconds pulling 30,000lbs and you need maximum ground speed. I know this tunnel ram setup would easily spin to 7000rpm before on a 8.5 to 1 compression 440 and I think that is too much. I fear that with 4.10 gears, running in 2nd gear, and low range(2:1 reduction) on the transfer case this thing is going to really want to rev.

Also, I have never used a rev limiter and was wondering how they work. When you "bump" the rev limiter does it hurt the power or just limit it? In other words is it best to not hit the limit at all?

Thanks

[SeattleCharger]

  I don't know much about all this,  more of a question here I guess, but isn't the 30000 lbs. of weight being pulled going to significantly load on the motor? even in 2nd with low gears, the weight of the sled is basically making you come to a stop and eventually stalls the engine.   Is the revving really high rpms happening at the beginning of the pull before the weight has moved very far forward on the sled?   Am I even talking about the right sport here?   

   I believe a rev limiter  just prevents from going over the set rpm, you want it at 6500, that's as high as it will rev, doesn't affect anything except that.    If you want your peak power at 6500 and you set it at that, you can run full out, which will be 6500, it won't go past that, but if you have more power above that, doesn't matter, you can't go past 6500, but it doesn't hurt it to run at the high setting point, I run mine right at the limit on one engine I have the entire time, (not a car engine), but I don't want to go past the set rpm or I can mess up the pump the engine is running (cat pump),  so I turn up the throttle full blast and don't have to worry about free spinning  my pump (or cavatating it) when I have less restistance in the pump, because the engine can't go past the rev limiter, its a direct drive to the pump.  Very helpful to have in an engine IMO.   I don't know if this helps at all,

[694spdRT]

  I don't know much about all this,  more of a question here I guess, but isn't the 30000 lbs. of weight being pulled going to significantly load on the motor? even in 2nd with low gears, the weight of the sled is basically making you come to a stop and eventually stalls the engine.   Is the revving really high rpms happening at the beginning of the pull before the weight has moved very far forward on the sled?   Am I even talking about the right sport here?     

The sled is set up with a sliding weight box that moves forward as you go down the track. Depending on traction and how "fast" the operator sets up the sled box speed will control how far you go. There is a pan under the sled that once the weight is dropped on usually stops the trucks rather quickly. Most of the trucks in the street class seem to either run out of traction, run out of power because they simply don't have enough, or break something. 

Thanks for the info on the rev limiter.

[firefighter3931]

The 6-pack rotating assembly is heavy but having it balanced will help. I would say 6500rpm is a maximum if you want to keep this thing together. If it were mine.....i would be going with a solid cam to keep the valvetrain stable at higher rpm. The tunnel ram will be excellent for this type of application....they make killer torque at higher engine speeds.

The rev limiter that MSD uses is called a "soft touch" which is gentle on the engine....basicly it just stops fireling the cylinders at random so the engine will not RPM any higher than the chip being used is designed for. One thing i've noticed is that the chips actually come in 200rpm before their rated limits. A 6200 chip will have the engine bouncing off the limiter at 6000. Something to keep in mind when picking chips for your application.


Ron

[694spdRT]

Thanks for the advice. I have adjustable rockers but I would need different pushrods for a solid cam.

I listed the wrong pistons...they actually are the 2295 High domes.

[694spdRT]

Ron

Would the Mopar 296/557 or 312/590 solid be a decent cam for my set up? Listed operating ranges of 3000-6700 vs 3400-7000 respectively.

Thanks

[firefighter3931]

Ron

Would the Mopar 296/557 or 312/590 solid be a decent cam for my set up? Listed operating ranges of 3000-6700 vs 3400-7000 respectively.

Thanks

I don't think you have enough compression for the 590 and you might run into piston to valve clearance issues with that cam and the pop ups. The 557 is just about right for that combination.....or something similar. A solid in the 250*-255* @ .050 range is where you should be looking. I'd prefer to see it on a tight lsa (108) so that it hits harder at the torque/hp peak. 


Ron

[694spdRT]

The Engle KV-3 looks like a decent cam with 250 @ .050 and a 108 lsa. Do you think the lift of .383" or .575"(1.5 ratio) is pushing the limit with 1.6 Crane gold rockers? I remember you saying they actually run about 1.65 which would put me at 0.632".

I could go with KV-2 and have it ground on a 108 lsa also.

[Todd Wilson]

I'm no expert on pulling or engines by any means but arent we thinking oposiite of what we should be thinking here?   Dragging 30,000# on a sled?   High RPMS?   Doesnt it take torque to pull and HP to go fast? Isnt sled pulling determined in how quickly you get things moving and momentum built up (IE. Low end torque)?    I also wonder if that 440 will even be able to turn 6500rpms  with it lugged down pulling. Any other engine I have ever seen working hard pulling a trailer will barely spin RPMS/s out of its power band when pulling hard and working?!  Will your setup be putting out good power at the 5000+rpms range (needed in a drag car)  but at the same its being lugged down to 3000 rpms or less pulling and not be putting out maximum power?!?! Should you determine the RPM range the 440 will be sitting at when pulling hard and build a cam and intake around that?



Todd

[694spdRT]

This will be a learning experience for me but I have been around truck pulls for over 15 years. The gear reduction will spin the engine hard going down the track. If you think about a 4.10 gear reduced to 8.20 through the transfer case and then using 2nd gear on the tranny will be quite low and rev the engine at any speed. I will be using a slipper clutch and launching at approximately 3000rpm. Some of the weaker trucks like stock Chevy 350's have all they can handle just getting going but the worked big blocks whether Chevy, Ford, or Dodge are coming down the track fairly fast which will rev the engine past 3000rpm.

Depending on traction some of the trucks will bog out on the top end but most lose traction on the end or break. You are right that getting momentum going is the key and for that you need speed. My friend would run down the track at 6200 rpm pulling the same sled. I have another friend that would pull his 1998 V10 and he was bumping the factory rev limiter all the way down the track.

[Blown70]

This will be a learning experience for me but I have been around truck pulls for over 15 years. The gear reduction will spin the engine hard going down the track. If you think about a 4.10 gear reduced to 8.20 through the transfer case and then using 2nd gear on the tranny will be quite low and rev the engine at any speed. I will be using a slipper clutch and launching at approximately 3000rpm. Some of the weaker trucks like stock Chevy 350's have all they can handle just getting going but the worked big blocks whether Chevy, Ford, or Dodge are coming down the track fairly fast which will rev the engine past 3000rpm.

Depending on traction some of the trucks will bog out on the top end but most lose traction on the end or break. You are right that getting momentum going is the key and for that you need speed. My friend would run down the track at 6200 rpm pullng the same sled. I have another friend that would pull his 1998 V10 and he was bumping the factory rev limiter all the way down the track.

AHHHHHHHHHHHHhheeeeeeeeeeeemmmmm PICTURES

[firefighter3931]

The Engle KV-3 looks like a decent cam with 250 @ .050 and a 108 lsa. Do you think the lift of .383" or .575"(1.5 ratio) is pushing the limit with 1.6 Crane gold rockers? I remember you saying they actually run about 1.65 which would put me at 0.632".

I could go with KV-2 and have it ground on a 108 lsa also.

With the 1.65 rockers i'd be looking at something that wasn't as agressive as the Engle grinds to keep you from pounding the valvetrain into oblivion. Something along the lines of a Comp 294 S would be reliable and low maintenance. You won't have to go with killer spring pressures to keep it stable. It's a double edged sword with the fast rate grinds ; they make great power but you need lots of spring to keep the valvetrain from floating at high rpm....but that high spring pressure can wipe out your cam. Add a 1.65 rocker into the mix and the problem is only magnified. The alternative is to run a Schubec lifter but those are $700.00 so the costs add up quickly.

Inmo, a better approach is to run a grind that is (more) compatible with the 1.65 ratio and easy on parts.  The 294 S will make peak torque around 4200 rpm and pull strong to 6200-6500. This would be a good off the shelf cam for your build, inmo. Another part worth looking at are the "Howards" lifters which have a small hole lasered into the lifter face. That hole is there to pressure feed the cam with oil through the lifter bores instead of the usual "splash" lube that the factory designed. Of course you'd want to run a good racing oil like Valvoline VR-1 20/50.


Sounds like a fun project. Post some pics when you get a chance. 



Ron

[SeattleCharger]

The Engle KV-3 looks like a decent cam with 250 @ .050 and a 108 lsa. Do you think the lift of .383" or .575"(1.5 ratio) is pushing the limit with 1.6 Crane gold rockers? I remember you saying they actually run about 1.65 which would put me at 0.632".

I could go with KV-2 and have it ground on a 108 lsa also.

With the 1.65 rockers i'd be looking at something that wasn't as agressive as the Engle grinds to keep you from pounding the valvetrain into oblivion. Something along the lines of a Comp 294 S would be reliable and low maintenance. You won't have to go with killer spring pressures to keep it stable. It's a double edged sword with the fast rate grinds ; they make great power but you need lots of spring to keep the valvetrain from floating at high rpm....but that high spring pressure can wipe out your cam. Add a 1.65 rocker into the mix and the problem is only magnified. The alternative is to run a Schubec lifter but those are $700.00 so the costs add up quickly.

Inmo, a better approach is to run a grind that is (more) compatible with the 1.65 ratio and easy on parts.  The 294 S will make peak torque around 4200 rpm and pull strong to 6200-6500. This would be a good off the shelf cam for your build, inmo. Another part worth looking at are the "Howards" lifters which have a small hole lasered into the lifter face. That hole is there to pressure feed the cam with oil through the lifter bores instead of the usual "splash" lube that the factory designed. Of course you'd want to run a good racing oil like Valvoline VR-1 20/50.


Sounds like a fun project. Post some pics when you get a chance. 



Ron

That is good to know about the engle cams.     For a basically stock 440 with forged pistons, and a holley 870 avenger, 2500 stall, would that comp 294 S be a good cam for street/hot rod use?  would it be lumpy sounding?  I have manual brakes.

[694spdRT]

I think we will be running 4.88 gears now. I have a Dana 70 front axle and IH RA-15 rear(equivalent to a Dana 70) from a 1 ton International that are going in once the locking differentials are installed. Top speed will be 29mph at 6500rpm with 33" tires in 2nd gear. 

[694spdRT]

Ron

I just talked with my friend that had this engine before. He has an older Comp Roller cam new in the box that he was going to use in the engine but didn't. Grind number is 300-5/306-5. It is pretty wild with 264/270 duration @ 0.050 and .420/.421 lift(.693/.695 at the valve) on a 108 LSA. I already have the heavy double valve springs for this because they came with the heads when I bought the engine. I would need to buy roller lifters though.

It will be more or less nothing to buy it but it probably is not going to work will it...especially due to valve lift issues? 

Thanks

[firefighter3931]

Ron

I just talked with my friend that had this engine before. He has an older Comp Roller cam new in the box that he was going to use in the engine but didn't. Grind number is 300-5/306-5. It is pretty wild with 264/270 duration @ 0.050 and .420/.421 lift(.693/.695 at the valve) on a 108 LSA. I already have the heavy double valve springs for this because they came with the heads when I bought the engine. I would need to buy roller lifters though.

It will be more or less nothing to buy it but it probably is not going to work will it...especially due to valve lift issues? 

Thanks

Wow, now that's a cam !  I like it but it's a bit much for the proposed combo. Nearly .700 lift at the valve with the pop up pistons won't work unless you cut reliefs for the valves. You would also want to bump the compression up to 12:1 or it would be a pooch at low engine speeds. That would be a good cam for a 500ci 10.5:1 stroker build though.

The other issue is the cylinder head flow and where it stalls or goes into turbulance. Opening the valve too much can actually reduce power so it's something you need to be careful with. I don't think that i'd run that cam with a 1.65 rocker and expect it to have valvesprings last very long. The other issue is the Crane Golds....they are not designed for roller spring pressures.  My buddy just broke his crane golds with a milder roller cam than the one you're contemplating....and upgraded to Harland Sharps. That's another $600.00 so it adds up quick.

Roller cams are a whole other ballgame and everything needs to be "right" or you'll break stuff. They are a higher maintenece item with more frequent valvespring swaps and roller lifter rebuilds...you have to be prepared for the extra maintenance and cost when considering a full roller valvetrain.


Those are my thoughts on it, fwiw.


Ron

[firefighter3931]

That is good to know about the engle cams.     For a basically stock 440 with forged pistons, and a holley 870 avenger, 2500 stall, would that comp 294 S be a good cam for street/hot rod use?  would it be lumpy sounding?  I have manual brakes.

Nate, that opinion was based on using a fast rate cam with an agressive 1.65 rocker ratio. I wouldn't have a problem running a fast rate cam on the street with the standard 1.5 rocker ratio. Hope that clears things up.


The 294S is a solid cam so you need an adjustable valvetrain to make it work. You would need more converter and gear to make it work well. At least 3000 stall and 4.10 gears, inmo. The idle is rather nasty and can be a pain to tune so i'd say it's a bit much for a basicly stock 440. When you decide on gears and stall we can throw some cam ideas around.


Ron

[694spdRT]

Ron

I just talked with my friend that had this engine before. He has an older Comp Roller cam new in the box that he was going to use in the engine but didn't. Grind number is 300-5/306-5. It is pretty wild with 264/270 duration @ 0.050 and .420/.421 lift(.693/.695 at the valve) on a 108 LSA. I already have the heavy double valve springs for this because they came with the heads when I bought the engine. I would need to buy roller lifters though.

It will be more or less nothing to buy it but it probably is not going to work will it...especially due to valve lift issues? 

Thanks

Wow, now that's a cam !  I like it but it's a bit much for the proposed combo. Nearly .700 lift at the valve with the pop up pistons won't work unless you cut reliefs for the valves. You would also want to bump the compression up to 12:1 or it would be a pooch at low engine speeds. That would be a good cam for a 500ci 10.5:1 stroker build though.

The other issue is the cylinder head flow and where it stalls or goes into turbulance. Opening the valve too much can actually reduce power so it's something you need to be careful with. I don't think that i'd run that cam with a 1.65 rocker and expect it to have valvesprings last very long. The other issue is the Crane Golds....they are not designed for roller spring pressures.  My buddy just broke his crane golds with a milder roller cam than the one you're contemplating....and upgraded to Harland Sharps. That's another $600.00 so it adds up quick.

Roller cams are a whole other ballgame and everything needs to be "right" or you'll break stuff. They are a higher maintenece item with more frequent valvespring swaps and roller lifter rebuilds...you have to be prepared for the extra maintenance and cost when considering a full roller valvetrain.


Those are my thoughts on it, fwiw.


Ron

Thanks for the advice...I figured that roller cam was going to be a bit much. The price was right so it was worth a shot.  Although, a 500 Cube Eddy head "street" truck would still qualify rule wise.   

[Chryco Psycho]

I ran my 440 shifting at 7200 RPM with the Speed pro 2355 piston for 9 years , no Problkems at all , the assy was properly machined & balanced & used the 6 pack rods as well
I missed a shift once & my memory tach showed 9200 , still no damage ...Thankfully