I was able to finish up the hyd roller install in the 408 motor, fire it up and take it up/down the road a couple of times on Saturday. I can tell you it is noisy and I am most likely getting valve float by 5600 - 5800. I readjusted the valves (reset them in 3/4 turn from "0" lash-will have to see how this does) and did a compression check while I was at it, while the motor was still plenty warm.

Cylinder pressure is only 165+/- a couple of lbs. - very consistant cylinder/cylinder. I am kind of surprised at the low cylinder pressure. I was expecting to see something in the 190 - 200 range. For comparison, before we freshened up the motor (which also included .012 cut off the deck and .008 off the heads) we had on average cylinder pressure of 172- with a couple of abnormally low cylinders thrown in there, hence the rebuild. This was with an old design Crane 280 cam [280/290 adver, 222/234 @.050 on 114 LSA/112ICL and a worn/loose timing chain]. I never checked it with the Crane 286 Powermax hyd flat tappet. But with the Comp NX279HR I expected it to be higher. 279/294, 230/242 on 113LSA installed at 108ICL. I know cylinder pressure is not a tell all, but I really thought it would be higher.

The plan is to pull the 408 motor and set it aside for install in a lighter car down the road {Camaro or Nova}. The cam swap was intended to do a little in car test/tune, back to back comparison.

The motor should be in the 9.5-9.6 CR range based on the measurements I have. And for what it's worth, the motor was spinning fast for the test. I ran each cylinder on a charged battery with the charger on full boost for each test.

Any thoughts?

Joe,I'm really interested in the track results of the swap,including MPH,etc.
I'm guessing maybe the longer duration has something to do with your readings

Joe,

I know the only true way to see any improvement in performance is to get some track time, but I was just curious how the H-roller compares to the Crane Powermax that you took out drving around on the street? Did it seem to be any better power-wise?

Chris, I am right with you. That's why I did this cam swap on this motor with no other changes. Same intake, exhaust, carb. It will be interesting to see just what these cam changeouts are worth. Also, later this year when I assemble the other block, I hope to have a better handle on what is worth considering.

71, Truthfully, I can't say for sure what the difference is. It was rather cold on Saturday and the gas is probably getting stale, the motor did seem to cough a little. I didn't do any real pounding on it, just wanted to see in general what the temperment was.

Two things though that I can tell you.

#1 - the 3 car garage the car sits in is built in under the end room on the house, there is a large family room over it. Probably not 5 minutes into running the motor (with all the doors opened), I was instructed by my wife to back it completely out of the garage - the entire upstairs of the house was actually vibrating. It has a very loud exhaust sound now - even with the Dynomax Hemi Turbos. A lot more sound in the headers. This is a NOX/Blower design cam and has a lot of added exhaust duration that we thought would help offest the 2.19/1.72 valve combination.

#2 - Even with the 113LSA, the motor has a pronounced idle. Compared to the cam that was in the motor the overlap is less at the seat 60.5 vs 67, but 10 degrees overlap @ .050 vs 7.

Also, forgot to mention earler, when I reset the valves, I changed out the Crane Energizer roller rockers for a set of Crane long slot stamped rockers that I had. The cam lift is only .537/.541 so this may be one of those cases where a roller rocker is detrimental. There is a big difference in weight between the two. I figured the big difference in rocker wt. may help the valve float issue. Did not restart the motor yet, mananged to break a plug while pulling it apart, didn't have a spare.

Gotta bring it over so I can hear it Joe.

I would expect to see a slight drop in cranking compression. Your new cam is longer duration so the intake valve closes later and builds less cylinder pressure.

For comparison, my 454 is about 9.5:1 with a 224/229 cam on a 115 LSA and I get about 165 PSI cranking.

/Markus

Zwede,
Actually the cam I put in has an earlier intake valve closing event than the Crane P/M 286. Crane advertises the 286 at about 72 - 73* closing, the new cam closes as 67.5*. I never checked the cranking compression with the 286 cam, the 172 numbers I posted were with the 280 cam that was in the car when I got it. But what is interesting (and I have to feel this is the shortcoming of trying to use DCR as a hardfast calculation) of the 3 cams that were in the car, I have hard compression (cylinder pressure) numbers on two of them.

First cam was 280/290 224/234 114LSA, 112ICL produced 172PSI on average, this was a well worn engine with a sloppy timing chain.
Second cam 286/296, 226/236 112LSA, 110ICL Don't know the cranking compression - never took it.
Third cam 279/294, 230/242 113LSA, 108ICL produced
165 PSI on average. This cam has the shortest advertised seat timing and the most advance ICL at 108.

Kind of tells me that the .050 numbers may have more to do with it then seat duration.

Vince,
Doubt it will get driven much past the end of the driveway for a while now. Pulled the hood off yesterday (before the Eagles Game). I am going to try and pull the rest of the front end along with the trunk deck next weekend to send out for media blast. That will only leave me with the 1/4 panels and the 2 doors to have to sand out. Prepping the body for a re-paint was really all I wanted to accomplish though February. Changing the cam out just kind of fell in there. If there's one thing that has really changed for me in the past year or so is the availability of free time. Thank goodness for having a car hobby - I would go bored out of mind if I had nothing to work on.

Don't forget Crane and CC use different specs for their seat duaration numbers. I beleive CC is .007" and Crane is 0.004".

Comp uses .006" as their advertised numbers. Crane is either .004 or .0045 . So the 280 crane really is more like 276 (at .006")

You might want to try loosening up them rockers a bit, If you run it at closer to zero lash it will rpm higher, with the 3/4 turn preload it may be pumping up and hanging the valves open. Just a thought.

I ran it first with 1/2 turn from "0" with the roller rockers (Crane Energizers). Motor was breaking up at 5600+. The Energizers are a little on the heavy side, especially compared the stamped steel ones. Now whether that weight is in the shaft and fulcrum or in the rocker itself, I don't know for sure. Comp says 1/2 turn, Crane says 1 full turn (especially for hyd rollers). The other issue is that it may not even be valve float, but I could have a lean full throttle condition. So until things warm up a bit and I get to really play with it, I installed the stamped rockers. I will leave it go at that for now. It is excessively easy to change rockers out that I would rather start with a baseline of simplest parts for tuning purposes and add on/change as I go.

I wonder if Vizards trick of lashing almost all of the plunger travel out would help you? It would certainly reduce the mass of the oil under the plunger.

hmmm...louder exhaust usually means higher cylinder pressure

Grn69chv,
Don't be discouraged by the cranking pressure. My 410 cranks at 170psi. The valve float, now that is another issue.

I tend to think that is what Crane is eluding to with the 1 full turn after "0" lash. I have to be honest, because this is a street car and not a race car, I like many, kinda enjoy the tinkering and experimenting aspect of all this. Would be a lot easier is it were warmer here though.

I assume the louder exhaust is being motivated by the aggressive exhaust timing. The exhaust lobes on this cam are the same as from the Comp XR288HR cam 294/242/.541. With the cam set at 108ICL and a 113LSA, the exhaust is probably blowing off cyclinder pressure at a higher pressure peak. I tend to think that may also have aggravated the top end break up that I immediately noticed with the install of this cam. I assume it is feasible that the secondaries may need a significant jump in Jetting. I still am running the Holley Avenger as it came out of the box. Plugs on the old cam had a nice even tan color with about 500 - 600 miles on them in a nice mix of driving so I never messed with it.

Dave, the cam specs are similiar to your's but of course HR. The exhaust sound reminds me of how your motor has been described. Real knarly agrresive under full throttle. After digesting things, I am thinking that all of the breakup may not be from valve float, but aggravated by too lean a mixture. Either way, we'll get it figured out. One of the reasons I stayed with a lower lift cam was to allow some room for increasing the spring pressure if need be. I have the springs installed right at 1.900 for a seat pressure of 122 and 330 over the nose. I could step these up .030 and move things to like 135/350 or .040 to something around 140/355.