DOHC Cam Information...

[Dave]

so like 3 or so years ago, I contacted Mantapart about cams and portwork, this was the email I got back from them...

Unless you can find cam blanks there isnt much we can do with the 3.4 cams, grinding them is very limited. We can only give you about a 212 duration with about .400 lift for performance and still be safe for the valve train geometry on a stock cam regrind. Our porting is very backed up here, it would be around $400 for the heads and then you would need valve work and special valves and springs, which we can provide. You would have about $1000 invovled in doing a set of heads, a 50% deposit and about 4 weeks to get through our shop right now. Let us know, thanks
MP

I dunno if they still offer this service, but thought I'd share this info with everyone...

--Dave.

[Dave]

RE: DOHC Cam Information...

I just sent the guys this new email...

Hello, I contacted you guys several years ago about doing some cam regrinding on a 1992 3.4 DOHC V6 engine (LQ1) (VIN-X engine) and was wondering if you still offered this service, and if so, how much per camshaft would I be looking at spending,

Thank you in advance for your response,
--Dave P-----

Hopefully I'll get a response and can put it up for everyone to see.

--Dave.

[your_I.D.]

Re: DOHC Cam Information...

Unless you can find cam blanks there isnt much we can do with the 3.4 cams, grinding them is very limited. We can only give you about a 212 duration with about .400 lift for performance and still be safe for the valve train geometry on a stock cam regrind.

212 duration? Correct me if I'm wrong. Dont stock cams have alot more then that?

[bszopi]

RE: Re: DOHC Cam Information...

212 is most likely the 0.050" duration, not the 0.001" duration. I'm pretty sure the stock 0.050" duration is less than 212... most likely less than 200 even.

[Dave]

RE: Re: DOHC Cam Information...

Hey guys, here's the response I got from the guys at Mantapart (they are very quick, and nice)

WE HAVE SINCE CHANGED CAM GRINDERS, SO WE WOULD NEED TO KNOW JUST WHAT
PROFILES YOU HAVE IN MIND AND WE CAN FIND OUT IF THEY CAN (OR WILL?) DO THEM FOR
YOU, OK? GIVE US MORE DETAILS,
MP

if anyone has an idea of what would work for a regrind, lemme know so I can contact 'em again.

--Dave.

[your_I.D.]

Whats mantapart charge? Crower will do it for $100.00 a peice.

here's aqoute from sappyse107:

Looking through my excel files I found the worksheet I made with the stock specs, 13 degree retard, and the regrind specs that were recommended by alan johnson. Ill dig up the regrind specs after I copy paste this mofo.

http://60degreev6.com/Sappy/DOHCCam/34DOHCcamtiming.xls

Intake lift: .372
Exhaust lift: .384
Seat to Seat Specs
IVO: 23 BTDC
IVC: 67 ABDC
EVO: 71 BBDC
EVC: 29 ATDC

Those are actual specs that they can do. Thats 270 intake duration and 280 exhaust duration seat to seat. They did mention advancing one cam a few degrees and retarding the other a few, 2 and 3 or 3 and 4 I think. Someone else can play around with that if they want. That should give you a general idea of how far the regrind can go though for duration and lift, give some duration, take some lift and so on. Quick comparison, stock is 242 degrees duration for intake and 253 duration on the exhaust. Thats 28 degrees more for intake and 27 for exhaust. Thats "advertised duration" though, its the .050 specs that really matter. I dont have those for the regrind though so I dunno what that info is worth to anyone playing with DD2K and wondering what the .050 specs on a regrind could be.

Prolly have to run lash caps or deck the cam carriers to comopansate for lobe base being ground smaller.

[Kohburn]

where do you buy lash caps?

[Q]

You can buy lash caps from valve manufacturers or valve train companies, such as Manley, Crane, Comp Cams, Etc. Just specify the stem diameter and the thickness.

For what it's worth:

You can deck the cam carriers to make up the difference in base circle after a re-grind, understand that you will be shifting the geometry which changes the cam timing. It's simple geometry, but the results must be doubled, since all cam timing and duration measurements are based on CRANK degrees (except LSA). The valve train geometry is based on camshaft position relative to valve centerline.

If you do so, you will be advancing one intake and one exhaust cam, while retarding the other intake and the other exhaust cam, and they are on opposite ends of the motor. (Front intake/rear exhaust and rear intake/front exhaust.) You will have virtually no choice other than to degree EACH cam independently. I don't know the base circle diameter of the cams off the top of my head, otherwise I'd be able to advise exactly how many degrees of advance/retard you'd get for each .010" of decking. The included angle is 22 degrees, so use the sine of 11 degrees in your calculations.

Personally, I'd vote for lash caps. What effect they have on the lash adjuster position in the head I can't tell you, but that will change, too. Probably less of a big deal than decking the cam boxes.

[Kohburn]

that doesn't sounds too bad then.. you can pull the cams and lifters - install the lash caps put lifters back in then put int he reground cams.. then time them accordingly

I recieved a spare cam cog from sappy this weekend and looking at it I believe I can mill adjustable center hub and modify the cogs to act as a ring gear on the new aluminum hub.

as long as people turn over a core then its a lot cheaper than full custom adjustable cam cogs.

[your_I.D.]

I received a spare cam cog from sappy this weekend and looking at it I believe I can mill adjustable center hub and modify the cogs to act as a ring gear on the new aluminum hub.

as long as people turn over a core then its a lot cheaper than full custom adjustable cam cogs.

? There already fully adjustable. Or did I misunderstand you.

[Kohburn]

adjustable without removing valve covers