Is a regrind cam as powerful as a billet cam

[AC sports]

Something I've heard differing opinions on for years.
Let's take 2 fast road cams for a dohc engine.
290* advertised
245* @ 0.050"
0.415 lift
Ones a steel billet on slightly smaller than oem base circle.
The other is reground off an oem cam. Not welded up, just reground off the same profile as the first. Base circle is obviously a little smaller.
Assuming they are set up correctly in the same engine, will they perform identically? Why?
Let's hear it.

[gunt]

completely dependent on the engine / geometry , aggression of the cam , most regrinds end up speeding up the valve

but aside , ive posted this before

k20 head , a particular company stated that they could make a new cam didn't have to be billet as they did it right and others got it wrong thtas why they went to billet , so i used them , made the power , but had issues in as time went on , the lobes twisted on the shaft , a cxxt to actually find the fault of power loss , so in this case billet is a must ,

but there a lot to consider ,

iv'e had serious issues with cams from a lot of companies , i in particular 1 never guessed i'd dial it in and it was well shy of what they sold me , 3 attempts later , i just accepted it

[panic]

Regrinding is limited to within 2-3 degrees of the original LSA.

[CamKing]

If these are for a bucket type follower, there will be no difference between the two.
If this is for a finger follower, or rocker follower type system, then a change in base circle will effect the lift curve at the valve.

[AC sports]

Bucket follower.
Appreciate the clarification camking.

[naukkis79]

Regrinding is limited to within 2-3 degrees of the original LSA.

Beauty of DOHC-engines is that timing for intake and exhaust cams can be set separately - so LSA isn't tied to cam profile at all.

[naukkis79]

If these are for a bucket type follower, there will be no difference between the two.
If this is for a finger follower, or rocker follower type system, then a change in base circle will effect the lift curve at the valve.

Only if geometry is left as it is, finger and rocker arm geometry could be corrected for smaller base circle. For finger followers as easily as with lash caps - but usually every rocker arm geometry could be set with shaving either head or rocker arm assembly.

[Nut124]

What happens if the customer provided cam core does not have the material needed to make the reground profile? Cannot make lobe nose profile wider by regrinding.

[AC sports]

What happens if the customer provided cam core does not have the material needed to make the reground profile? Cannot make lobe nose profile wider by regrinding.

Good point. That's why cam grinders will only make re grinds of mildish profiles. Take a look at the pipercams listing we were looking at. They will reprofile up to 285* 10.4mm with the fiat tc. The 300 and 310* with 11mm + is billet only.
You will struggle shimming anything with a much smaller base circle also. I've used 2mm lash caps on occasion, but shaft also becomes too thin for strength.

[CamKing]

What happens if the customer provided cam core does not have the material needed to make the reground profile? Cannot make lobe nose profile wider by regrinding.

The width of the nose doesn't have anything to do with the duration.
You can have a wider nose on a cam that's .300" lift, and 280 duration, them a lobe with .350" lift, and 300 duration.

[naukkis79]

You will struggle shimming anything with a much smaller base circle also. I've used 2mm lash caps on occasion, but shaft also becomes too thin for strength.

With Fiat TC you could shave cam trays instead of lash caps and save weight. With bucket follower regrinds there's usually no strength effect on cam as grinding base circle is limited to cam bearing surface, grinding any lower won't have any effect as cam bearing surface stops bucket travel.

[Nut124]

What happens if the customer provided cam core does not have the material needed to make the reground profile? Cannot make lobe nose profile wider by regrinding.

The width of the nose doesn't have anything to do with the duration.
You can have a wider nose on a cam that's .300" lift, and 280 duration, them a lobe with .350" lift, and 300 duration.

Mike, I did not see anyone suggest it.

I have seen a few regrind profiles offered that I think could not be ground from my OEM cam cores due to the profile having a wide node profile vs narrow in the OEM cam.

I was literally wondering what the grinder would do.

Do they check the core before starting to try to assess whether it can produce the profile?

Or, would they just run the grind and end up with a profile where parts of the lobe were not touched by the grinder?

Total duration and ramps would be OK by LATDC and nose profile could be short of spec.

[CamKing]

Mike, I did not see anyone suggest it.

I have seen a few regrind profiles offered that I think could not be ground from my OEM cam cores due to the profile having a wide node profile vs narrow in the OEM cam.

I was literally wondering what the grinder would do.

Do they check the core before starting to try to assess whether it can produce the profile?

Or, would they just run the grind and end up with a profile where parts of the lobe were not touched by the grinder?

Total duration and ramps would be OK by LATDC and nose profile could be short of spec.

We would measure the existing profile, and make sure we could grind the new profile on it, and calculate who much we would need to reduce the base circle. If the new profile would require lowering the base circle too much, we would tell the customer what profile we could fit on it.