68Satellite440
Well-Known Member
Can you explain how the rear gear and cam work in relation? I don’t exactly understand how a cam decides what gear is best. I didn’t know if maybe there is a general rule or formula?
440 camshaft question
- Thread starter greycharger
- Start date
As you probably have seen...All cams have a power band and make compromises. A bigger duration cam moves the rpm range higher while sacrificing the lower rpm hp to make higher rpm hp.
Torque is a function of hp at a certain rpm... torque is what does the work to move the car. More torque moves the car faster. The gears and transmission multiply the torque. If you install a cam that makes its peak torque at a higher rpm you can compensate by using a rear end gear that gets the car in its power band sooner. Choosing a convertor is similiar.
Torque is a function of hp at a certain rpm... torque is what does the work to move the car. More torque moves the car faster. The gears and transmission multiply the torque. If you install a cam that makes its peak torque at a higher rpm you can compensate by using a rear end gear that gets the car in its power band sooner. Choosing a convertor is similiar.
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68Satellite440
Well-Known Member
Oh okay! That makes perfect sense. Thank you for explaining that
gtxrt
Well-Known Member
i posted a video in general discussion on c-body forums with my 67 Newport. watch the tach and see how the cam performs
68Satellite440
Well-Known Member
I had another question about the Lunatic 703, with it being 494/513 lift, I need to change most of the valve train and they sell the kit with the necce
I have some more questions.
If im gonna upgrade basically the entire valve train to handle the 494/513 lift of this cam, they sell this kit with the necessary springs and keepers etc.
would it be better to just also buy whats missing from this to replace rest of valve train, or should i just get the cam and lifters and pick my own replacement valve train?
Also, do I need to replace factory rods with shorter ones since this cam lifts higher?
The length of the pushrods is not affected by the lift of the cam. Stock length should work fine. Upgrading to 5/16 chrome moly pushrods is always a good idea.
The lunati kit doesn't break down the individual parts numbers. I would be most concerned about what lifters come in the kit. The better ones from lunati are called micro-trols. You can tell the difference by looking at the snap ring. Cheaper quality lifters have a round clip. Micro-trol has a snap ring. We have always pieced it together so I can't say what is in the kit from experience.
Also look at delivery dates. That is often a factor.
The lunati kit doesn't break down the individual parts numbers. I would be most concerned about what lifters come in the kit. The better ones from lunati are called micro-trols. You can tell the difference by looking at the snap ring. Cheaper quality lifters have a round clip. Micro-trol has a snap ring. We have always pieced it together so I can't say what is in the kit from experience.
Also look at delivery dates. That is often a factor.
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68Satellite440
Well-Known Member
Do you have any preference on rockers? Are roller tip or roller rocker necessary over stamped rockers?
Parts list so far:
- undetermined rockers
-5/16 chrome moly rods
-hylift johnson or micro-trol lifters
-undetermined heavier springs
-possible bigger stall conv
Did I forget anything?
gtxrt
Well-Known Member
there not affected by the lift but are affected by the base circle of the camshaft. it effects your preload on a hyd cam and lash if running a solid lifter cam.
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68Satellite440
Well-Known Member
So they’re generally all the same standard length, you just change rockers than can handle certain amounts of lift?
Or is there a certain amount of lift before you have to have shorter rods?
gtxrt
Well-Known Member
no they have different lengths. even with adjustable rocker arms you can only go so far up or down with the adjustment nut or arm to be in the right position and geometry being right.
Stamped steel rockers are the only ball/ball pushrods run in a mopar, that I am aware of.
If you want adjustable valvetrain you will need ball and cup pushrods. At that point I would do a solid cam. At least that is always my preference. Then use pushrod length checker and order the correct length.
A lot of hydraulic cam engines don't get the pushrod length checked. The lifter is expected to compensate. Which it does...but it has its limits.
Mancini aluminum rockers and shafts are good value for what they are. We don't run any of the cheaper rockers. Seen to many fail. Crane and isky ductile rockers haven't been made for some time. But they come up for sale used frequently. Crane roller rockers and mp rockers (made by dove) were good back in the day.
If you want adjustable valvetrain you will need ball and cup pushrods. At that point I would do a solid cam. At least that is always my preference. Then use pushrod length checker and order the correct length.
A lot of hydraulic cam engines don't get the pushrod length checked. The lifter is expected to compensate. Which it does...but it has its limits.
Mancini aluminum rockers and shafts are good value for what they are. We don't run any of the cheaper rockers. Seen to many fail. Crane and isky ductile rockers haven't been made for some time. But they come up for sale used frequently. Crane roller rockers and mp rockers (made by dove) were good back in the day.
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With a lunati 703, I would just run stamped steel and better push rods can be had pretty cheap. Have some extra rockers laying around in case one pokes through. May never happen, depends on the shape they're in. Stamped steel run less then 1.5, actual lift will be nearer to .484/.499.
These are about the cheapest decent pushrods I have seen.
for MOPAR 440 Chrome-Moly PUSHRODS Plymouth Dodge Chrysler 440-6 Challenger R/T+ | eBay
These are about the cheapest decent pushrods I have seen.
for MOPAR 440 Chrome-Moly PUSHRODS Plymouth Dodge Chrysler 440-6 Challenger R/T+ | eBay
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68Satellite440
Well-Known Member
Okay so i dont necessarily need to upgrade to roller rockers, Just some new stamped would be okay. I figured i might as well replace them because i have no idea how many miles is on this motor when they swapped it.
I really dont wanna poke one thru.
Does the cam manufacturer usually say how heavy of springs I need? I dont wanna go too big and be killing hp.
I guess i also need to order some light springs and the pushrod checker
Older catolog page but Lunati recommends spring part 73100. 125lbs @1.85. 333 lb spring rate. It's a bit fuzzy...zoom in. LOL
It's a dual spring. You have to cut the guide and update the seal to run these. There are single springs out there as well. Dual spring you can brake it in wo the inner spring installed which is nice if it's what you considering. I would call it optional this cam isn't that big nor are the springs. But It's never a bad plan.
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73815 is the spring they recommend in the current book. It's a single w damper.
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Grabbergreendream
Well-Known Member
2 things to point out here based on my own personal expierience with the kit I purchased with the 703.
1st-call Lunati. They beat a package kit price by $100 over Summit.
2nd-call Lunati. If I'd have baught the kit through summit, it would have came with the wrong springs and valve keepers.
I'm following along.
Good luck.
68Satellite440
Well-Known Member
Thank you for taking the time to let me know! Appreciate it
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