[Gach]

Originally Posted by Steve C.

When I first put my 505 together I dyno tested with a Performer RPM intake and a Victor intake. Both manifolds were port matched to the heads in use and both tested with the same custom HP950 Holley carb. The only difference was the RPM intake had a 1/2" carb spacer and the Victor had no spacer because of the hood clearance issue. The RPM intake was a disappointment with only about 615 HP at 5800 rpm. The Victor depending on the pull made 638-642 hp at 6000/6100 rpm. This was with a custom Crower solid roller cam with 260 degrees intake duration. When I went from the previous 4.210" stroke 462 CID engine to the 4.250" stroke 505 CID combo I added 6 degrees intake duration. The 462 engine used a 254 degree solid roller cam. On both engines the RPM intake made peak power at 5800 rpm and the Victor made peak power at around 6000 rpm.

After that dyno session we decided to change the cam. I got rid of the Crower cam and put in a UltraDyne MSP solid roller cam from Bullet Racing Cams rated with 255 degrees intake duration and went from .4200" lobe lift to .4300" lobe lift. Both cams had a 110 LSA. For the most part no other changes were made except we cut the Victor intake carb flange down 0.650" to help with the hood issues and the engine was dyno tested again. This time knowing the combo thrived on the single-plane intake we never bothered to test with the RPM intake. With the new cam it made about 660 hp at the same 6000 rpm. The engine uses Edelbrock heads with about 320 cfm and it only has 10:1 compression.

.


.

So there was probably a 30 cfm drop with RPM intake so actually only saw 290 cfm, it pick up with Victor because more plenum and maybe only 15-20 cfm drop. Then going to 505 which is 43 more ci. So going to 430 lube really didn’t do much. Mostly pick up because of 43 more ci. Its like a 462 ci with what you think is a head that flows 350 cfm is not going to make 700 hp more like 660 hp.

[Gach]

Until you understand how it all works you’ll be swapping cams…intakes from now until the cows come home. And spent twice the money. Another idea going from a port matched intake to a fully port and pick up 30 more hp. So now as example that 330 intake now actually flows 330 cfm.

[Formulajones]

If it were me I'd want more cam in a 505 as the old faithful is on the small side for that engine.
With that said I wouldn't want to bother with head and intake work if a cam swap isnt in the cards.

I would however want a single plane intake on an engine that large even as it sits now, preferably with a spacer. Bottom end torque would not be a concern with an engine that size.
Other than that, without a cam change I'd be inclined to leave it alone.