360 build

360Z28 said
the xe268h is one of those magic cams.. dunno how it works, but it does.. even with low CR engines.

eg: i toss a xe268h cam in a bone stock 400 72 Satellite once, and just like that went from 14.8s to 14.0s w/ the stock 3.55 gear.

i have never seen a 600 or 650 holley make more power then a well tuned holley 750vs carb on a 340/360/. throttle response remained excellent.

i agree with you that tube diameter plays a role in effective rpm use, but equally (perhaps more) important is the collector length.

I am running a XE268H in my 360 and it certainly is a great cam but in my build I have 10.6:1 compression. The fast ramp rate lets the cam maintain cylinder pressure like a much smaller cam but a stock LA 360 is likely closer to 7.5:1 and just won't have enough cylinder pressure for a strong low end. Since the goal is a street cruiser a smaller in the XE line would be a better choice. Also, you can't really compare how a cam works in an 400 to a 360, a bigger engine needs more cam. the XE268H in a 400 is more like an XE262H in a 360.

I have had a 600, 670, 725 and 750 VS carbs on my engine. The 725 and 750 had a noticeable to the butt dyno advantage over the 600 above 4500 rpm but the 600 had it all over the 725 and 750 in driveability and throttle response below that rpm. The 670 has as good low end as the 600 and no noticeable to the butt dyno disadvantage up top. I gave all these carbs a several 1000 mile test and spent a fair time tuning them and believe I was getting the best they had to offer.

I have run a best of 13.7 @ 102 mph with the 600 Holley and it is traction limitations (2.2sec 60' on that run) that are keeping it from the low 13's.

For a street cruiser a 4160 Holley 600 would be about perfect. The 750 would certainly work but for the maximum driving experience stay with a small carb. Carbs and cams are two of those items where it is always better to error on the small side.