Joe I got this right off Chevrolet.com. Shows slightly higher duration on the 720 hp. Possibly a typo. Seems like I've seen some variations on specs with this engine before. What's deal on the heads also. When I looked up the part number on the heads they show a 310 int runner left intentionally smaller for porting. Just wonder if the heads are untouched on the 720 or if they are cnc' or what. Head P/N 88961160. Are these edelbrocks and are they rec or oval port. They come up as oval port 310 cc however as you can see the specs show rec port for the advertised on the site. I would think there is a bunch of power left on the table especially with the CR and cam used. Just in the heads alone. Intakes appear to be the same on each 620/720. Look pretty similar to edelbrocks.

Just some conversation.

good call . If you look the cam part # from the 720R up on some sites, it shows the durations I mentioned earlier. But in the GM literature for the 720r, it shows 278/282 @ .050

ill bet the 720 heads are as cast , just different part numbers due to the 720 having different valve springs than the 620hp version.

[QUOTE=endeavour32;4657921]I'm changing the direction of my 572's. They started life as Keith Eickert 1000s that had 10-71's on them. Sold the 10-71's due to hatch clearance issues with the 38 KV Scarab I was building at the time. I then purchased a set of Whipple quad rotors. So I began to buy all the parts to build around the whipples.

Then last week I threw in the towel on the 43 Scarab I was rebuilding, and now it looks like I'm going back to a 38 Scarab Thunder. With all that said, I do not need 1300 hp a side in a 38 Scarab. So I sold the Whipples and I'm wondering what else I may need to change. I'm thinking the cams may be a touch large for N/A so that is the real question here.

First the specs of the engines:
Dart Big M blocks with steel caps
Callies Magnum Cranks 4.375"
Carrillo Rods 4.56"
CP Pistons (these will be changed)
350 Canfield heads. Worked over by Valako flow 385/308 @ .65
TD Shaft Rockers
.903 Morel Ultimate Solid Lifters
Then the new cams I bought for this set up are 262/268, with .663 lift, 112 lope separation

The 6 degree split may hold a lot of heat in the motor.

I really don't think so. The guy that designed the cam knows what he is doing, and this cam has run well in all his engines he's used it in, lol and no- it's not a Marine Kinetics cam. The Eickert cam that they are replacing, only had a 4 degree split.

Just my opinion by what I saw on the EGT gauges in the boat while trying different cams,

I was running wideband 02 sensors, it was EFI.