Is there a downside to (Reground Camshaft)

[ForcedFirebird]

Hmm, mystery regrinds? Old pic of my turbo Firebird regrind cam card.

[AndrewBird]

Do you lose lift with a re-grind? I can't imagine how you would not if you didn't add material before grinding.

[ForcedFirebird]

Do you lose lift with a re-grind? I can't imagine how you would not if you didn't add material before grinding.

No. Lift is determined by subtracting the base circle from the high point of the lobe. To get more lift on a regrind, leave the highest tip of the lobe and make the base circle smaller. The smaller base is taken up by the valve lash adjustment (why over size eccentrics was mentioned).

[digger]

a regrind is probably not going to have much extra lift over stock and less than a new cam

[pantelones]

If the cam is a cast piece, then it is casehardened (Not too sure of billet cams). I forget the usual amount, but generally a case is between a few thou and .050" Machining a casehardened material is going to work-harden the remaining case, and possibly contribute to uneven ware. In addition to work-hardening the material while machining, the case itself is also not perfect, meaning that the case depth varies throughout the piece. So in-order to know if it is safe or not to regrind a cam you must: test the depth of the case/consistency, and determine it's Rockwell consistency both pre and post-machining on a test subject (preferably subjects...)

Personally, I would NEVER weld material onto a caseharden cast materiel. Way too much inconsistency in the crystal structure and too much risk for distortion. You would need to restructure the piece though heat-treating and at this point, you are putting too much time and effort into half ass something that needs to be done the right way, the FIRST time...

A reground cam is not a bad thing if it is quality candidate for being reground; when you start getting into adding material, risking breaking the case, and uneven hardness it could be more hassle than it's worth...

[digger]

my welded MM cam hasn't fared anywhere near as well as my Catcams in terms of durability. it is barely any cheaper (IIRC) but i got a complete head so used it......my new setup with catcams that uses VAC double valve springs which are alot stiffer than the MM beehives and still looks like a new cam after coming upto 5 year...same oil to with plenty zinc

[ForcedFirebird]

Most cam re-grinders test after grinding, and some do post-treating. Lift after grinding will depend on geometry, with the m20, not much more lift or duration.

Even when we buy new cams made from blanks, they are cast, ground, treated. A lot of companies that offer "billet" cams are just made from new cast blanks, a real billet cam is very expensive.

[essi1553]

Essie, check out the 280/274 from bimmerheads. It'd go nice with a chip and #17s. If i was gonna get another one i'd get this.

I was actually thinking about getting the 285/285 duration cat cam from vac motorsports.

[ForcedFirebird]

I was actually thinking about getting the 285/285 duration cat cam from vac motorsports.

Hope you don't plan on stock compression with a cam that big. You won't make much useable power.

[essi1553]

Hope you don't plan on stock compression with a cam that big. You won't make much useable power.

I would hope you elaborate on this, spending close to 2k for a rebuilt head and MILLER MAF and war chip. So i'm expecting some fooking useable power. Can't afford to mess with the bottom end.

I was quoted at a gain of about 50 hp, after the valve job and the above items from Vac.

[SkiFree]

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I was quoted at a gain of about 50 hp, after the valve job and the above items from Vac.

Please elaborate on the details of your quoted hp increase, you must be misunderstanding what they are saying. Its the only thing that makes sense.

[ForcedFirebird]

Large duration cams require increased compression, or they will only be effective at very high RPM. 272 is more adequate with stock compression.

Also a cam that large requires valve springs and you should use new rockers on any new cam - expect over $1k in just head parts.

Personally, I would get a Megasquirt P&P for less than the Miller MAF, plus upgradable to MAP easily. If you want to tune your Motronic, get an Ostrich emulator.

[essi1553]

Large duration cams require increased compression, or they will only be effective at very high RPM. 272 is more adequate with stock compression.

Also a cam that large requires valve springs and you should use new rockers on any new cam - expect over $1k in just head parts.

Personally, I would get a Megasquirt P&P for less than the Miller MAF, plus upgradable to MAP easily. If you want to tune your Motronic, get an Ostrich emulator.

The head repair and upgrade includes thier stage two:

http://store.vacmotorsports.com/vac---m20-stage-2-performance-cylinder-head-p983.aspx

• Complete Disassembly & Cleaning
• Comprehensive Leak, Crack & Pressure Test
• Inspect All Components For Irregular Wear
• Our Superior Max Performance Multi-angle Intake, Radius Exhaust Valve Job Using Serdi Equipment
• Unshrouding of Valves
• Attention to Potential Hot-spot Areas and Chamfering
• All New VAC Uprated Valve Guides
• Reconditioning & Blueprinting of Your Valves
• Trueness Checked & Resurfaced Mating Surface
• VAC High Performance Valve Springs, Balanced
• VAC Performance Steel Alloy Retainers (Ti On Request)

From CatCam's they state that the 285/285 is a drop in upgrade:

http://store.vacmotorsports.com/cat-cams---m20-camshafts-p2291.aspx

285°in/ 285°ex - 11.55mm/ 11.55mm [Hot Street & Sport](drop in upgrade)

My estimate also includes new OEM rockers, rocker shafts, miller MAF + chip, and some adaptor. The war chip would be extra, and im not sure its really something i'd want, at this point I feel a chip, and new injectors would be money better spent.

I know nothing about megasquirt other that its tune-able and I do not have the resources/time to spend paying someone, or trial and error teaching myself. I will look into it, like now...

[digger]

ive seen a 3 or 4 catcam 285/285 2.7/2.8 stroker dyno plots and there is a common theme they make less torque than a healthy stock engine at 2500rpm and come on cam pretty hard and make good Hp. you will want a much higher CR and even then you will sacrifice alot of bottom end over a schrick of similar advertised duration but make more peak hp

i would avoid a 285/285 unless it is a track car with a decent bump in CR.

err on the small side, the car will feel faster and be more streetable but maybe wont make as pretty numbers on the dyno


ask VAC to tell you what their stage 2 flows CFM vs lift

[essi1553]

ive seen a 3 or 4 catcam 285/285 2.7/2.8 stroker dyno plots and there is a common theme they make less torque than a healthy stock engine at 2500rpm and come on cam pretty hard and make good Hp. you will want a much higher CR and even then you will sacrifice alot of bottom end over a schrick of similar advertised duration but make more peak hp

i would avoid a 285/285 unless it is a track car with a decent bump in CR.

err on the small side, the car will feel faster and be more streetable but maybe wont make as pretty numbers on the dyno


ask VAC to tell you what their stage 2 flows CFM vs lift

I didnt understand much of this? I need to understand why i would be asking them a questions I understand the purpose of. The bottom end will stay stock, even though the price is the same for either duration, im better off with the 272. I don't care about numbers, I want reliability and to be minivans, or at least give them a run for their money.

Just thinking out loud here, but should shaving the head be considered to improve CR even with a 272 cam.