Power problem after cam and intake swap

[mchyphy]

I recently did a cam and intake swap on my 72 with a pretty much stock 350. I put in a Summit 1102 cam, about .421 lift on the intake and .442 on the exhaust, nothing really radical. The intake I put on is an Edelbrock Performer, again nothing crazy, the intake that was on there before was an Edelbrock Torker II, which didn't really fit the rest of the engine combination. I reused the stock valve springs, which I suspect is my problem. I've got nearly no power after about 2600 rpm. Before the swap it pulled well past 3000 rpm all the way up to 4000. Other things in my combo are mid length headers, true dual exhaust with magnaflows, 600 cfm Edelbrock carb, HEI, a TH350, and 3.08 gears. I just swapped the metering rods in the carb to see if that was the issue, but it didn't help. It pulls pretty well up to 2500 rpm, just falls flat after. Anyone got any ideas? Is it the valve springs like I suspect?

[geezer#99]

What’s your timing like?

[mchyphy]

I don't know anything about the timing curve, the weights and all that are untouched in the distributor, I've got about 16 degrees base timing.

[geezer#99]

Is that 16 set with the vac advance plugged off?

[mchyphy]

Yeah that's with the vac advance plugged off.

[geezer#99]

When you adjusted your valves before you fired it up for the cam break in, how far did you adjust the rockers. And when you adjusted them did you use the twist the pushrod method or did you use the wiggle the slack out of them method.
And how long and at what rpm was the cam break in done?

[mchyphy]

Originally Posted by geezer#99

When you adjusted your valves before you fired it up for the cam break in, how far did you adjust the rockers. And when you adjusted them did you use the twist the pushrod method or did you use the wiggle the slack out of them method.
And how long and at what rpm was the cam break in done?

I adjusted the rockers so they had some slack and wiggle room before firing it up, and while it was fired up we adjusted them until there was no more ticking, then maybe half a turn more. What we might have done wrong was when we adjusted the valves when it was fired up, we let it idle at maybe 700 rpm for maybe 5-10 minutes while doing the final adjustment. After that I kept the rpm above 2500 and varied it for 15 minutes. I used the cam lube, 4 quarts of Rotella T5 15-40, and a quart of Comp Cams break in oil.

[geezer#99]

Pop the valve covers off, check for rockers that aren’t moving enough.
You mighta flattened a lobe or two.

You needed to be at high rpm and stay there for 20 minutes. The high rpm ensures the lifters rotate and wear in to the lobes. Any initial idling is a lobe killer.

[mchyphy]

Man, I really hope that's not the case. I'll check em out tomorrow when I got the time.

[hjewell2]

Originally Posted by mchyphy

Man, I really hope that's not the case. I'll check em out tomorrow when I got the time.

Keeping the rpms up at fire up is to keep oil splash on the cam from the crank.
by letting it idle the cam does not get the splash and it gets dry in a big hurry during this all so important time. I dare say you wiped a couple of lobes if not all.