In that description there isn’t much to there for comparisons sake between the KG7 and the KG8. Which one would be preferable or even manageao in traffic and parking lots? Considering .060” thou shave and thin gasket to boost CR, and chipped LH 2.4 with the b21f intake and a worked head with 40/46 valves? Stock bottom.
It says that the KG7 has 304? of rated duration and the KG8 has 315?, that's quite the change! Neither would be preferable in traffic and parking lots, but the KG7 is obviously the less aggressive and likely the more "manageable"(loosely used in this scenario!). If you aren't using LH then the Swedes say these high duration camshafts are happier at lower rpm if you are using individual throttles(carbs or ITBs).
If you ARE using LH, the k-jet/B21F intake manifold is supposedly a much better match for these camshafts than the B230F intake manifold because of the runner diameter and length being better. The B21F intake manifold's runners are large enough to support 240hp according to a flow bench and calculations, and their runner lengths are good for a power peak of around 6500rpm. Erland Cox suggests adapting it to have a larger throttle body on the front of the plenum as opposed to just putting a larger one on the bottom in the stock location, and others suggest the factory location is better(evenly distributed). Regardless, you'll want larger than the stock throttle body for optimum flow and power. The larger you go on the throttle, the more sensitive and a pain in the ass it is to drive around at low speeds though! The General Leif has a B21F manifold with the 90 degree elbow adapter Nathan used to make(or someone) and a 960 throttle body. It's not fun to drive in first gear at all! If we adjusted the ignition timing at low load to be lower once you get off the idle timing map, it wouldn't be quite as bad, but that will take some time.
With .060"(1.5mm) off the head you will be close enough to the right compression to run the camshaft if you're using a thinner headgasket. Make sure you don't have any piston to valve clearance issues, though.
Why the 40mm exhaust valves? Is this a 530 head?
We had a poor result with a wide lobe separation KG7 in a 10.9:1 B230F with a couple other supporting mods (no cat, free air filter element) and we ran that cam no more than maybe an hour on a dyno. LH2.4, but we can tune to application. It sounded awesome, like a 2 stroke, but from the first pull it was totally flat (torqueless). Put the K back in it. We probably could have made more power down low if we'd REALLY put the fuel to it, but then fuel consumption would have been an issue, and we endurance race this particular engine, so poor economy is undesirable.
It seems like because of the long overlap period, the MAF is getting a reversion signal that is "stalling"(?) the incoming air, making it think it's using less air than it is? I don't know. I'm sure that something like this is why the GM TPI engines of the late 80's aftermarket cams all had lobe sep of 114, maybe 112 at the tightest.
It's all very possible! When you guys installed the cam, did you set it to a certain lift at TDC like most of the aftermarket cam guys suggest(I haven't seen a value listed for this camshaft, though!)? If not, and even if you did, I really think you missed out on trying different camshaft timing. There's the possibility that it needed to be advanced a few degrees to get closer to the desired result, or even retarded! We don't know at this point, but that would've been an easy thing to try first, and then trying to add fuel down low and removing some up top to flatten out that torque curve some and keep it afloat even more up top. I'm sure the ignition timing would've preferred to be different as well once you got the cam timing and fuel where you wanted it. Sorry!
Here's the dyno chart of your best K vs the best KG7 run with the AFRs shown as well. The KG7 was basically making more power from 4900rpm all the way up, but with an odd, early HP peak of 5300rpm(torque peak at 5150). The K cam had a HP peak at 5680rpm(torque peak at 4550). I'd maybe try retarding the K cam a couple degrees next time the car is on the dyno and see where that gets it, actually...! You don't need the torque under 2500rpm that it obviously has, but if it moves the torque across the board lower(except above 6000rpm), then it doesn't make sense.
Well in reading the original post. I would think you want something like a enem V15 or maybe V16. I run the V15 on a B230F LH2.4 with just chipped ezk and simons sport exhaust. The engine has torque all around even up to redline. Everyday driven. still gets about the same mileage with our crappy fuel. 420k miles. cam installed since 275k miles.
V15 has about the lift of the K with the duration of the B cam. 109 lobe angle. Easily passes emissions testing if necessary. Use the mildest cam that accomplishes your goals is what I was taught and it's been a good rule to follow in my small amount of experience.
I'd say a V16 would be a great DD cam with more pep than the K if you have the funds to get one. Even in a completely stock engine! It'd probably benefit from being advanced a bit if you have an automatic, and having a thinner headgasket is always preferred as well, but ENEM even says in the description that it's a sport cam for a non-turbo motor, stage 2. If the valve adjustment with the factory camshaft was good, it won't need adjustment when swapping it in and it's optimal for a fuel injected engine with a good idle!
Thanks for chiming in, and that post summed up your first very well. I’m considering a cam as part of a staged build. I have a while before I choose between ITBs or Weber’s (48ish) on a purpose built shortblock. I have on hand all the bits I stated above. Ultimately I need to set it up so that she’s livable on the street in SoCal. Considering meth injection to get around kaligas and knock.
1975 chassis or something? If you're going to that extent, then the KG7 or a similar/better(more modern) cam from another supplier starts to make real sense!
