Thread: Uh-Oh!!!!

The shim clearance on the kelford spec sheet will not provide the lift and duration numbers on the spec sheet.

My motor has a much tighter shim clearance than factory because i didn't measure when i first got the motor and at the time i was putting it together there was no known information being shared about factory clearances.

So to be clear from degreeing the cams they do not appear to be on factory base circles.

The cams were degreed on a motor that was on a stand not the motor in my car.

seperate issue
I want to loosen the clearance on my motor to factory specs in hopes of gaining more power on every set of cams i test on my car.

The latest set of Kelford cams are not quite what i would call "correct". The base circle on the cams is smaller than stock by almost .25-.5mm small lobe and big lobe.

These cams were degreed into another motor and the last was set to the specs as given by kelford on the spec card. The intake cam duration was pretty close to what they said, but the lift was way off. This set of cams can not be run on stock rocker arms. they must be modified to clear the rotation of the cam lobe because the lift is .521" (13.23mm). the most that will clear stock rockers is .498" or 12.65mm. The exhaust cam is the problem. The valve lash for the exhaust i believe is .40mm spec (.016") The exhaust cam was then degreed and checked and the exhaust valve opening at .004" lift is 104 deg BBDC. that means the exhaust valve is opening before the piston is 1/2 way down the bore. Then the max lift was .486" or 12.34mm which will clear the rockers so that is ok, the exhaust valve closing was 65 deg ATDC which was way too late. So that means the exhaust cam has 349 deg duration at .004" lift. Something seem wrong to anyone?

Exhaust (.016" lash)
349 @ .004"
303 @ .015"
255 @ .050"

109 C/L

Intake (.008" lash)
318 @ .004"
291 @ .015"
256 @ .050"

105 C/L

The exhaust was way over spec on duration. After checking the opening and closing ramps I measured the base circles and found them to be smaller than stock. 32.20mm I think for the exhaust. That is a .30mm difference from the factory. I decided to set the exhaust valve lash to .025" (.635mm) and try it again. this time I got more "normal" numbers

313 @ .004"
284 @ .015"
249 @ .050"

109 C/L.

The exhaust valve opening went from 104 BBDC to 86 BBDC. Almost 20 deg just from loosening the valve lash. These numbers are very close to what is listed on the spec sheet ( if that is what they are supposed to be).

After seeing these results, I would love to try loosening up the valve lash on the N1 exhaust cam to see if it gains power by not opening the exhaust valve so soon.

Well thats disappointing, I would have thought better of kelford especially as they have a cnc cam grinder.
I've never had any problems with any of their cams before they have always degreed up as per spec, These weren't sr cams though so I can't comment on these as i'm yet to build an sr.
You mentioned you were going to talk to them?
I'd be interested to hear what they have to say.
Are you going to dyno the n1's with looser lash, that would be an interesting test.

yes we are going to talk to Kelford
this weekend im reshimming the head for looser lash and then we will dyno

cool cool cant wait.
Which are you dynoing?
Kelfords, N1's or both?

Re dynoing the N1's with the looser ( correct) valve lash, then the kelfords.

Hey Bro, have you jumped on the dyno yet & if so, what were the results? We should be heading to a dyno in the next 2 weeks but I've hit a snag in that my engine builder didn't notch the pistons when the block was open (I think to keep costs down) so when playing with cam timing I've only got 2mm piston-to-valve clearance to work with.

On the bright side I did save $100 on a $4,000 short-block prep.

Yay

Mine are currently set -2 -2 & I'll be gutted if you find these cams make best power at +4 -4 or something like that.

This morning I am going to get the shims I need.

We degreed the cams in a bone stock 16ve and found that stock the lash is too loose on the exhaust side. We are going for .20mm intake and exhaust lash.

Speaking with Kelford the spec sheet we got was incorrect with the cams. apparently the sheet we got was for new yet to be released cams.

Once i get the shims in we will degree the cams again and then dyno.
Just like my old custom kelfords these look good on paper but my old cams didn't make N1 power.

Once we find the centerlines on these in a properly shimmed motor we will be able to determine the cam gears.

Clint what shims are you currently running in your motor and did you have any headwork done?

Yep, I did have headwork done by Kelford who also did the original shimming. Cook Motor Racing re-shimmed it when the head was put on the rebuilt block & then again after I had run the engine in. Sorry but I don't have any idea what sizes were used. I went to CMR because they build quite a few competition VEs & have about $8,000 worth of shims in stock so I didn't have to worry about that side of it.

Here is the porting, Kelford retained the standard valves.

we are going to have to wait a little while longer, the shims i need have to be ordered