MP 509 Cam Replacement Recommendations

[Charger_Dart]

I have a MP 500 crate engine that came with a MP 509 cam. I have lost a lobe on the cam so it needs to be replaced. I have not been a huge fan of this cam so i am hoping to replace it with something that is a little more streetable.

Currently my Charger is setup with 3000 stall converter with 3.91 gears. I am running a Proform 950 DP on a Edelbrock RPM intake. I also am using 68 exhaust manifolds. I know the engine is really designed to run a single plane intake and headers, but I want to maintain a stockish look. I drive the car only on the street and its setup to shift at 5500 rpms.

Currently the engine runs on pump gas and I would like to keep it that way. Cranking compression is 160 psi in the good cylinders.

Since I need to replace the cam I hope I can find something that has good torque from 1000 - 5500 if possible. HYD, soild, or roller? suggestions?   

[BSB67]

I have a MP 500 crate engine that came with a MP 509 cam. I have lost a lobe on the cam so it needs to be replaced. I have not been a huge fan of this cam so i am hoping to replace it with something that is a little more streetable.

Currently my Charger is setup with 3000 stall converter with 3.91 gears. I am running a Proform 950 DP on a Edelbrock RPM intake. I also am using 68 exhaust manifolds. I know the engine is really designed to run a single plane intake and headers, but I want to maintain a stockish look. I drive the car only on the street and its setup to shift at 5500 rpms.

Currently the engine runs on pump gas and I would like to keep it that way. Cranking compression is 160 psi in the good cylinders.

Since I need to replace the cam I hope I can find something that has good torque from 1000 - 5500 if possible. HYD, soild, or roller? suggestions?    

Custom ground solid lifter cam.  Comp XTQ lobes.  274°/280° advertised (244°/250° @0.050") ground on a 114°, installed at 112°.  You'll be shifting higher than 5500 if you want to get everything out of it.

[c00nhunterjoe]

The comp xs282s grind would fit the bill here nicely in my opinion. That is similar to what was just suggested. There is no reason a good dual plane could not be used either. If usuimg stock port window heads, run the performer rpm intake. Its the best of both worlds until you get into max wedge ports.

[BSB67]

The comp xs282s grind would fit the bill here nicely in my opinion. That is similar to what was just suggested. There is no reason a good dual plane could not be used either. If usuimg stock port window heads, run the performer rpm intake. Its the best of both worlds until you get into max wedge ports.

Sure.  On paper, it looks like it might boost cylinder pressure and could effect using pump gas.  The MP .528 would work well too and would be my first choice for something off the shelf.

The thing I don't like about the xs282s off the shelf for this application is the idle won't be as clean, and the larger overlap won't work as well with the manifolds.  I wish they made a couple of other XS lobes.  They do have a 280° lobe, but the next size after the 282 is the 290.  I think it would be happier in this motor with a wider LSA.

[c00nhunterjoe]

Ooo, i missed the part about running the 68' manifolds. Good call.

[Charger_Dart]

Thanks for the suggestions. I thought I might also ask Hughes and see what they suggested.

They came back with a hyd cam with 232/236 duration at .050 with 110* LSA and .357/.364" lift.

Seems maybe a little mild to me, what do you think?

 

[firefighter3931]

Thanks for the suggestions. I thought I might also ask Hughes and see what they suggested.

They came back with a hyd cam with 232/236 duration at .050 with 110* LSA and .357/.364" lift.

Seems maybe a little mild to me, what do you think?

 

That is definitely too small for a 500in motor and the LSA is too narrow for the restrictive (manifold) exhaust.

Listen to Russ (BSB67) because he has a lot of good experience with pump gas street builds using factory exhaust manifolds. 

Cam choice is critical and reducing overlap helps a lot with reversion. A wider lobe separation is preferable....the narrowest LSA you should be looking at is 112* 

The XTQ is a nice profile for the street and makes excellent torque 

This will be a custom order so you should have the cam nitrided while they're making it and use an EDM style lifter with priority oiling.



Ron

[Charger_Dart]

Thanks Ron, that makes a lot of sense. With a solid lifter cam I assume I would need adjustable rocker arms and need to set valve lash - correct? If so, any suggestions that would clear stock valve covers?

[BLK 68 R/T]

Thanks for the suggestions. I thought I might also ask Hughes and see what they suggested.

They came back with a hyd cam with 232/236 duration at .050 with 110* LSA and .357/.364" lift.

Seems maybe a little mild to me, what do you think?

 

My thought is this is lobe lift and not total lift. The rocker arm ratio would determine total lift correct?

Also, not trying to hijack this thread. But could someone explain what LSA is and why it matters when choosing between manifolds and headers? I did a search and did not come up with much.

[firefighter3931]

Thanks Ron, that makes a lot of sense. With a solid lifter cam I assume I would need adjustable rocker arms and need to set valve lash - correct? If so, any suggestions that would clear stock valve covers?

Yep, an adjustable valvetrain will be required to run a mechanical cam. I like the crane ductile iron rockers....they fit nice on the RPM heads, are compact and durable. 


Ron

[firefighter3931]

My thought is this is lobe lift and not total lift. The rocker arm ratio would determine total lift correct?

Also, not trying to hijack this thread. But could someone explain what LSA is and why it matters when choosing between manifolds and headers? I did a search and did not come up with much.

Yes,

The lobe lift x rocker ratio = valve lift 

Cam selection with restrictive exhaust is very important ; it all boils down to scavenging. Headers do a much better job at scavenging the cylinder vs restrictive manifolds. With too much overlap (tight LSA) you get too much intake charge dilution which hurts power & efficiency. Widen out the lobe separation and you reduce overlap and this helps compensate for a weak design exhaust and allow the engine to exhale better.

The exhaust system as a whole should scavenge the cylinders as opposed to having the motor try to push the exhaust out back. Matching the cam profile to the exhaust system is therefore very important.


For example ; the "factory" HP cam was designed with a 115* (wide) LSA for a reason. The engineers recognized the limitations of the factory exhaust and adjusted the cam profile to accommodate those limitations. The factory heads also have a poor flowing exhaust port (relative to the intake port) and compensated for that by adding additional duration into the factory grind. This was done to hold the valve open longer to allow the engine to exhale more efficiently.



Ron

[Charger_Dart]

Thanks Ron, that makes a lot of sense. With a solid lifter cam I assume I would need adjustable rocker arms and need to set valve lash - correct? If so, any suggestions that would clear stock valve covers?

Yep, an adjustable valvetrain will be required to run a mechanical cam. I like the crane ductile iron rockers....they fit nice on the RPM heads, are compact and durable. 


Ron

I went ahead and ordered the custom cam Russ spec'd out. Seems like a real good solution.

I have MP Stage V heads and Crane's ductile iron rockers show they will not work with stage IV or V heads.  http://www.cranecams.com/312-313.pdf

Any other suggestions on rocker arm assemblies and push rods? They need to fit under stock valve covers.

Thanks for all the help!
Mike

[BLK 68 R/T]

My thought is this is lobe lift and not total lift. The rocker arm ratio would determine total lift correct?

Also, not trying to hijack this thread. But could someone explain what LSA is and why it matters when choosing between manifolds and headers? I did a search and did not come up with much.

Yes,

The lobe lift x rocker ratio = valve lift 

Cam selection with restrictive exhaust is very important ; it all boils down to scavenging. Headers do a much better job at scavenging the cylinder vs restrictive manifolds. With too much overlap (tight LSA) you get too much intake charge dilution which hurts power & efficiency. Widen out the lobe separation and you reduce overlap and this helps compensate for a weak design exhaust and allow the engine to exhale better.

The exhaust system as a whole should scavenge the cylinders as opposed to having the motor try to push the exhaust out back. Matching the cam profile to the exhaust system is therefore very important.


For example ; the "factory" HP cam was designed with a 115* (wide) LSA for a reason. The engineers recognized the limitations of the factory exhaust and adjusted the cam profile to accommodate those limitations. The factory heads also have a poor flowing exhaust port (relative to the intake port) and compensated for that by adding additional duration into the factory grind. This was done to hold the valve open longer to allow the engine to exhale more efficiently.



Ron

Thank you for the explanation on the LSA and its importance.

[firefighter3931]

Thanks Ron, that makes a lot of sense. With a solid lifter cam I assume I would need adjustable rocker arms and need to set valve lash - correct? If so, any suggestions that would clear stock valve covers?

Yep, an adjustable valvetrain will be required to run a mechanical cam. I like the crane ductile iron rockers....they fit nice on the RPM heads, are compact and durable. 


Ron

I went ahead and ordered the custom cam Russ spec'd out. Seems like a real good solution.

I have MP Stage V heads and Crane's ductile iron rockers show they will not work with stage IV or V heads.  http://www.cranecams.com/312-313.pdf

Any other suggestions on rocker arm assemblies and push rods? They need to fit under stock valve covers.

Thanks for all the help!
Mike

Mike,

The stage IV and stage V have the same offset as a factory head (906/346/452) as well as the Stealth/RPM/Indy SR/EZ etc.... 

Not sure why that information is posted on Crane's website but it's wrong. The aluminum stage VI heads have a larger offset requiring different intake rockers. Maybe it's a misprint ? 

The Crane's come up for sale used often so keep an eye on e-bay and other classifieds. You should be able to get a descent set for $150-$200 

For the pushrods I would go with Smith Brothers. Mock it up first and get the exact measurement you need. They will most likely not be an off the shelf length due to the custom cam lobe design (smaller base circle) and an aftermarket EDM style solid lifter which has the cup in a different location vs the factory lifter.


Ron

[BSB67]

I went ahead and ordered the custom cam Russ spec'd out. Seems like a real good solution.

I have MP Stage V heads and Crane's ductile iron rockers show they will not work with stage IV or V heads.  http://www.cranecams.com/312-313.pdf

Any other suggestions on rocker arm assemblies and push rods? They need to fit under stock valve covers.

Thanks for all the help!
Mike

Wow. Nobody does what I suggest, not even the wife, kids, or the dogs.  I feel honored.

So, this is the cam that I would try if I were in your shoes.  It sould make really good power with your combination.  For this application it is a balance with cylinder pressure, lobe sizes and low speed characteristics.  You will have some control of these with the lash.  If you were to track tune this, I would probably suggest trying a looser lash (0.024 - ish) if you don't have a ping issue.

Good luck and report back.

[BSB67]

Thanks for the suggestions. I thought I might also ask Hughes and see what they suggested.

They came back with a hyd cam with 232/236 duration at .050 with 110* LSA and .357/.364" lift.

Seems maybe a little mild to me, what do you think?

 

Dave and his son know a thing or two about cams.  A couple of points though: 1) you cannot compare solid cam and hydraulic cam 0.050" durations directly.  Every solid cam is different, but as a general rule, you subtract about 8 degrees from the 0.050" for a solid cam's duration to match it to a hydraulic (it is a lash thing, and what the valve actually sees verses what happens at the lobe).  So the cams are probably not that much different ( I would guess that Dave's 3236 has an advertized duration 276/280), and  2) I probably would have gone a little smaller too if I was not concerned about ping.  If the cam is a little too small and you have ping, there really is no living with that.

The 160 psi cylinder pressure with a no quench iron head is already close in my book.

[Charger_Dart]

I wanted to post an update on my cam change from the MP 509 to a custom spec cam provided by Russ.

I could not locate any good sets of Crane iron rockers, so I ordered a set of PRW stainless 1.5 roller tip rockers. These seem to be well made and fit nicely on the stage 5 heads. Everything lined up nicely using the provided spacers.

Over the past weekend I had a chance to break-in the cam so I started it up and I can't express how nice it sounds now. With the old cam I ran a 950 rpm idle with 7-8" of vacuum - with the new cam I can run a much stronger 850 rpm idle and 12" of vacuum. I set the dizzy to the same specs - 21 degrees at idle with a max of 35 degrees. I can't really drive it because its so darn cold here in New England, but so far I am very happy with the setup. Looking forward to spring!

A huge thanks to Ron & Russ for their valued input!!!! 

 

[fizz]

Watch the prw rockers. Just pulled a set with 3-4 hrs run time and shafts showed significant scoring. The bottom loaded side of the shaft would catch on the rocker as I slide it off. Us with roller bearings going on mine

[BSB67]

Sounds good so far. Keep us posted. Get a cylinder pressure check when you can.

[Charger_Dart]

Sounds good so far. Keep us posted. Get a cylinder pressure check when you can.

I checked one cylinder today and it came up to 160 psi. This was on a cold engine with 7 plugs installed so its not a perfect measurement. I do have a high torque mini starter that can spin the engine just about the same with plugs in or out though. It should be close. 

[Charger_Dart]

Watch the prw rockers. Just pulled a set with 3-4 hrs run time and shafts showed significant scoring. The bottom loaded side of the shaft would catch on the rocker as I slide it off. Us with roller bearings going on mine

Thanks for the info. I will periodically check them for wear. The ones I installed seemed to fit really well on shafts with wide brass bushings. The oiling system looked like a very good design also, so I wonder how you had such quick wear with your set. I did a bit of research on these and generally found they should be very good for a street car, but for racing you should consider moving up to a more expensive set. I did not want to install China made stuff, but don't really need anything real expensive either so it seemed to be a good choice. I guess time will tell....   

[justcruisin]

I have been running the PRW stainless in a 1.5 for four years, I have inspected them periodically and found some brass coloring on the bottom of the shaft but nothing that you would catch a nail on. My experience is that they are fine - at least with street friendly spring pressures.

[Charger_Dart]

I have been running the PRW stainless in a 1.5 for four years, I have inspected them periodically and found some brass coloring on the bottom of the shaft but nothing that you would catch a nail on. My experience is that they are fine - at least with street friendly spring pressures.

Good to know, thanks!

[firefighter3931]

Nice work....congrats on the install and break-in 

It's not surprising that the idle cleaned up....that was predictable with the reduced overlap and wider LSA. I like the manifold vacuum increase. That will make tuning easier. Throttle response will be significantly enhanced as well. This is a win/win scenario all around. The car is going to be a blast to drive. 


Ron

[Charger_Dart]

Well I took her out for a spin over the weekend and it runs really good. Everything is much smoother and the engine definitely has more get-up-and-go !! I am very impressed with this cam grind so far. 

Of course the engine now has that solid lifter tick which is not so bad.

The thing that really struck me was how the exhaust sound has changed in the cabin. I have been running TTI's 2.5" X system. It kind of hard to describe, but the engine has a different exhaust sound to it now when going down the road. Wide open sounds about the same as before. Not complaining or anything, just posting what I have found. Do you think this is normal?