Cam selection help for destroked 7M project

bigaaron

bigaaron

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I'm supposed to pick up my 85mm stroke 7m crank tomorrow, so I'm thinking about the cam selection now. I have an opportunity to have a set of cams made to my specs at a good price, but I don't have any real experience with upgraded cams other then just cam gear adjustments. I was talking to X-Man today about his experience with the 7m because he has made some seriously huge power with basically stock 7m engines, and he has first hand knowledge of what different cam selections can do to the powerband etc... So after talking it over the best setup for me seems to be a 264 duration with 8.5mm lift, using the same center line as stock turbo cams. The goal is to improve the midrange up to the top end. I would like to be able to rev the engine to 8k if it will keep making power that high. I'm going to use upgraded valve springs with stock valves. I was just wondering if anyone has any input on this subject. I don't want to spend a fortune on the head, I just want to get a little better performance then stock.
 
supra90turbo

supra90turbo

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You can get away with a fairly stock head (i.e. shim over bucket still) using 264's with a mild lift over stock.

However, if you wanted to go with shimless or shim under bucket, you would be able to run more lift, and inevitably be able to breathe harder at higher rpm's.


here's the stock cam specs:
256° duration
7.54mm lift

It seems that your 8.5mm lift cams would be a bit lofty for the stock shim/buckets, and thus, you would indeed spend a fortune on the head.
 
jdub

jdub

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The 8.5mm lift will work fine for the stock shim/bucket set-up. You can start spitting shims at 9.0mm lift or so. Consider getting a mild port on the head for better flow.
 
U

upgradedsupra

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The cams you mention are a good all around cam. This is similar to what I have custom made for my set-up. 8.5mm will also fit in the stock base circle therefore no need for major head work. Basically, you take old cams out and the new in. (of course the shims will need replacing and no shim under buckets needed :))
As far as power, I have not yet dynoed the car (on the dyno today!) but my reason for choosing the cam I did (which again is similar to the one you want.) is for more top end power. It might sacrifce the low end but the mid and high are again where you will see this gain. We will see results soon enough. :biglaugh:

I had mine custom made by TED

What cams you go with?

HTH
Duane
 
bowsercake

bowsercake

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So a 8.9mm lift at 272 duration cam will really be pushing/exceeding the stock valve train. However, with Brian Crower or Ferrera valve springs and retainers the stock head will be able to handle these cams, correct?
 
aljordan

aljordan

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bowsercake said:
So a 8.9mm lift at 272 duration cam will really be pushing/exceeding the stock valve train. However, with Brian Crower or Ferrera valve springs and retainers the stock head will be able to handle these cams, correct?
Click to expand...


Incorrect. The problem isn't the springs/retainers, the problem is the shim over bucket configration. A high lift cam will grab the edge of a shim, and kick it out. When this happens, you get to purchase a new cam. Also the head may need to be modified in order for the high lift lobes to rotate.
 
U

upgradedsupra

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aljordan said:
Incorrect. The problem isn't the springs/retainers, the problem is the shim over bucket configration. A high lift cam will grab the edge of a shim, and kick it out. When this happens, you get to purchase a new cam. Also the head may need to be modified in order for the high lift lobes to rotate.
Click to expand...

Like he said in regards to the big lift cam. Anything over 8.65mm, you will have to modify the head to accommodate the cams to move.

Duane
 
suprarich

suprarich

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I will chime in here, you can run up to nearly a 9.7--9.52 lift with out cam lobe clearance issues. You can run up to a 10.2 to 10.5 mm lift with a 272 duration with the standard shims. You can not however just throw them in. They must be shimmed pretty tight and the edge needs to be knocked off with a bit of emery. a high 7mm lift with a 272 duration will yeild about a 40hp gain over stock cams on a 350-400 hp 7m. Your 8.5-8.6mm 262-264 duration will yeild approx a 45 to 50 hp gain on the same motor but peak higher in the rpm range. If you are going with the 8.5 264 cams on stock centerline, you will be a happy camper Aaron.

IJ - Every head will have a slightly different clearance, I know you are aware of this, but needed to be said for the general population. some heads will take a 10mm some will only take a 9.7 Casting.....
 
S

suprahooked

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Jun 20, 2006
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suprarich said:
Aaron, call me, I will send you a set of cams at my cost.
Click to expand...
Arron give him a call he's a great guy and gives great deals ,I bought a lot from Rich and plan to a lot more.:icon_razz
 
suprarich

suprarich

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aljordan said:
Hmm. Those not yet released brian crower 272 degree cams have 9.52mm of lift.

I wonder if the head needs to be modified for that....
Click to expand...

I don't think they are 9.52, he list them as a 8.53 and a 8.68mm lift.

Both of which are actually a small cam, and I think will only make you want a larger one.
 
bigaaron

bigaaron

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Well I found out last night that my cams were already done and I didn't even know about it. :biglaugh: There was some miscommunication between Jose and I, Jose had already dropped off a set of cams a few weeks ago. I guess they are using a special process of welding the lobes and then grinding, using a welding rod that is exactly the same metal at the stock cam. So when it's done, it is a bolt in cam that doesn't require a makeup shim, has the same centerline as stock, but has more lift and duration. I guess this is nothing new, they make these cams for all the high performance Honda engines including the NSX (read:high reving), Porche engines, and for drag race motorcycle engines. I'll have more info soon.
 
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