Reground Cams?

H

heretic

Registered User
Can someone explain to me how reground cam work?

I'm so lost:confused:

I bought a reground cam and the lobes are smaller than the stock cam but its advertised as being larger and having more duration.

How does this work?
 
heretic said:
Can someone explain to me how reground cam work?

I'm so lost:confused:

I bought a reground cam and the lobes are smaller than the stock cam but its advertised as being larger and having more duration.

How does this work?
Click to expand...


Longer pushrods
 
sorry let me specify..

How can it be a more agressive cam with smaller lobes?

How do they Change the actual profile of the cam?:confused:
 
The size of the lobe is somewhat proportional to the diameter of the base circle of the cam. Smaller base circle = smaller lobes.
 
heretic said:
sorry let me specify..

How can it be a more agressive cam with smaller lobes?

How do they Change the actual profile of the cam?:confused:
Click to expand...

For a regrind, the increase in duration and lift is accounted for by exponential radii which can only be increased by grinding the base circle of the cam.

Otherwise, the ramp speeds and near max lift, on both sides of the lobe, can only get smaller.
 
cam.gif


Assuming the above picture works... B is the base circle of the cam, and C is the lobe. If you make B smaller, it actually makes the lobe bigger.
 
92sclikenew said:
were do you get longer push rods???
Click to expand...

You can use pushrods for a 5.0l but you have to figure out how long you need them they come in different sizes. Who reground the cam, they should be able to help you out with the size. Other here can elaborate on it.
 
ricardoa1 said:
You can use pushrods for a 5.0l but you have to figure out how long you need them they come in different sizes. Who reground the cam, they should be able to help you out with the size. Other here can elaborate on it.
Click to expand...

i was just wondering because i really didnt know what a regrind was all about

now i do and seen that you said longer push rods and then just wonder'd were you would get thos from
 
Like Scott Long said a couple posts back, you can get many sizes of pushrods at Summit Racing Equipment or Jeg's. Both have websites. Or you can talk to an engine shop in your area and they can probably get them too.

I think that the length you would need would be the original pushrod length (I have no idea what that is) plus the difference between the original camshaft base circle and the reground base circle. Now, whichever company ground this cam should know what length you need. It may be as simple as just calling or sending an email to them.
 
Normally 7.200 pushrods will take care of the problem but there are many variables starting with what core was used to grind the cam and what lobe separation was specified. Cam base circle WILL vary and each engine will add it's own variables to the equation so in the end you'll have to measure and see what you come up with.

SC people assume that this is a unique problem that we have with reground cams but I assure you this is a common problem with ALL engines and it is SOP to check pushrod length after a cam swap of any kind.
 
I ended up using 7.250's with shims in order to get the preload to come out right.

With a new cam, 7.200's were too short.
 
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