Not my intent at all, info sharing thread.

For what it's worth I put a KC SBF 427 with a Dart aluminum block in my cobra. Reasons: 1) Roush is BIG - the good is a very good "we'll fix your problem" record and dealers are close by (everywhere?). The concern is that they have many "certified" builders vs. KC who does it all in his shop - I assumed this meant more control by Keith over the quality/who's building it, etc.part. 2) Price: got essentially the same quality parts plus upgraded to the DART aluminum block and it still cost less (including shipping). While the downside of a KC engine is that you have to deal with Arkansas instead of a local dealer I have to say that I had a shipping problem that damaged the oil pan and carb and with no questions asked KC immediately shipped replacement parts at KC's cost. The engine has run flawlessly so far (only 3000 miles and not racing) but it is definitely strong. I ordered a slightly de-tuned version of the KC 580HP motor. KC measured it at 554 HP at 6000. After installation I put it on a chassis dyno (inertial dyno in 4th gear - 140mph max) and got ~425HP so the KC dyno number seems to be reasonably good. By the way, torgue was something just north of 580. Given that this motor is lighter than the original 289 and ~12% more powerful than the original FEs I'm guessing Carol would have given his eye teeth for this motor in '65. Not only does the 554 HP keep the power to weight ratio ~the same as the original (slightly heavier SPF still behaves like an original) you can drive it to breakfast or in heavy traffic with no problem. By the way, I get 16 mpg (freeway) with a carb. <{:>))

Looking at a few with Roush, kind of like the 427R, and one with a KC 482
with Pond Al block. I have always heard good things about KC until last week
when I learned of a low mile, 350ish, that had to be shipped back with a
vibration and oil using problem. But I'm sure that happens to them all every
now and then, hell the 997.1 Turbos have a few issues.

Going to check out the KC Cobra next week in Vegas, was at Hillbank last
week, nice tour and test drive, they go through all the used cars they get
in before they turn them.

Herc

I drove a Roush 427R when I was looking and found it to buck too much. I got a lot of comments about a simple carb adjustment to fix that. My Roush 427 SRTW bucks a little, but not so much I can't keep it smooth. Just an FYI on the 427R model....

Yes. My KC also does a little bit of bucking at low speed when cruising at a constant speed. It's totally tolerable but for that and a few other minor reasons (more stable idle, better gas mileage, eliminate issues with fuel sloshing like stumbling during hard braking and just better over-all control of the required A/F ratio) I'm switching to fuel injection. Not so much the engine but the fuel delivery/ignition control.

Matt

For those of you with a light surging (bucking) at cruising speed, that usually is the result of a slight lean condition. Try opening up the idle air screws a quarter turn and see if that helps. If it does, then screw them back in until the surge returns and then back them out slowly till it disappears. If it doesn't, take your primary jets up a size or two and re-test. Light cruising is generally on the main jet system.

Have to give this two thumbs up, best post, thanks for the laugh!

Re the revving thing, I've had two similar engines, one 406 3.80 x 4.125, and a 408, the 406 had a solid roller, the only difference, except for the 52# crank in the 406 and I'm sure a heavier Eagle crank in the 408, guessing closer to 60#. I could tell the difference in revving, the 406 was much quicker, maybe because of the solid roller but wouldn't bet on it.

I've heard the 347's are quick revvers and wouldn't bet a similar 351 against one, they use what, a 43# crank?

Just my experience.

I'm curious to know what CobraEd, Brent and AL427SBF think about this "quick revving" concept. We really haven't broached this subject much around here. :LOL::LOL::LOL:

In my next engine, I am going to have a custom crank made out of tungsten or maybe depleted uranium. After all, I don't want it to rev too quickly or high!!!! :-)




.

Not sure if I've already responded here as I'm not going to read all the posts to see if I did.

I have a Roush 427 SRTW powered SPF. At 12,000 miles, it was using a quart of oil every 250 miles. Did a leak down test. Readings all over the place, from 10-35%. Pulled the heads. Scratches in a couple of bores. No cross hatch showing in the cylinders. Blow-by was coming out the breathers and dipstick. Sent the heads out. Guides worn, valves had ridges in the stems, seals were shot. Tore down the block. Cracked piston ring land. Rings shot. Damaged lifters. Cam going flat. Broken inner valve spring. Rods and crank were fine, whew! Replaced the anemic street avenger with a ProSystems dp and the sidepipes to 3" a long time ago so the thing could inhale and exhale better.

Remember, this is a street only engine. No race time and few runs to 6000 rpm.

Now, after a complete rebuild and dyno tune it scares the living crap out of me. Get into the throttle a little too hard in third gear and it will step out right now! And that's with sticky nitto 315's.

So, now I'm letting brent build me a slightly detuned engine as a backup in case I decide to part with mine.

Personally, I don't think a Roush engine was worth the money.

If she is still a little zippie for ya, add a little stroke, that will calm her right down ;)