Help me build a 509ci Big Block
10-25-2017, 08:50 PM
#121
Le Mans Master
I received the camshaft. I went with a custom hydraulic roller from Bullet Cams. The cam is on a billet core with an Everwear distributor gear. It's a Gen VI step nose core and I've got the GM Performance cam retainer plate. I did not want to deal with cam buttons and end play on this build. I also started pulling the heads down. Overall they look really good. Guide clearance measured .0014 - .0017 on the intakes and .0015 -.0017 on the exhausts. Valvespring installed height was in the ballpark at 1.950(+ -), but I may re-shim a few of them.
On the heads, I think I'm going to just do a light cleanup. The plan is to take out any ridges at the valve seat/bowl area. I'm going to smooth out the CNC blend on the short side radius and also extend the CNC blend at the port entry. If I get brave, I might lightly profile the valve guide where it meets the bowl. I may also take out the small ridge between the CNC chamber and the valve.
On the heads, I think I'm going to just do a light cleanup. The plan is to take out any ridges at the valve seat/bowl area. I'm going to smooth out the CNC blend on the short side radius and also extend the CNC blend at the port entry. If I get brave, I might lightly profile the valve guide where it meets the bowl. I may also take out the small ridge between the CNC chamber and the valve.
That’s a nice cam choice.. should make some jam with that.
10-25-2017, 09:10 PM
#122
Thank you for the pics. That is very helpful. Looks like I focused on the proper areas, but I was a little more aggressive on the plenum to port entry roof area for the corner cylinders. I did that trying to equalize the cross-sectional area of each cylinder. It looks like yours has a bit more taken out of the rear plenum area where Holley added a boss for a vacuum port. I left the boss but smoothed and shaped it in case my carb doesn't have a port for the brake booster. I'm gonna keep the Weiand Stealth intake and do a back to back comparison on the dyno. I'm gonna try a spacer too.
10-26-2017, 03:12 PM
#123
Thanks. Before calling Bullet I had picked out lobes for a 246/258 .629/.615 108 LS grind. Mark at Bullet picked out a very similar spec without me telling him what I wanted, so I figured that was a good sign. He wanted 110 LS and talked me out of a 108. I think he settled on 109.5 just to humor me.
He said these bigger motors just don't like the real tight centers even though there's a lot of conflicting info out there. Mark is extremely knowledgeable and the cost was comparable to a shelf grind. I still think that Crane 244/256 shelf grind would be a great choice too.
He said these bigger motors just don't like the real tight centers even though there's a lot of conflicting info out there. Mark is extremely knowledgeable and the cost was comparable to a shelf grind. I still think that Crane 244/256 shelf grind would be a great choice too.
Last edited by Neil B; 10-26-2017 at 03:12 PM.
10-26-2017, 04:18 PM
#124
Le Mans Master
Can't believe how close we came on motors coming from 2 totally different directions..
I've got a 496, 10.5:1 compression, Comp solid roller that's .671/.671 254/260 110* centerline, but I also did the 7-4 swap. Ended up with Brodix RaceRite rectangle port heads, 294cc intake ports and 115cc chambers. I did add on T&D Shaft Rockers.
I've got a 496, 10.5:1 compression, Comp solid roller that's .671/.671 254/260 110* centerline, but I also did the 7-4 swap. Ended up with Brodix RaceRite rectangle port heads, 294cc intake ports and 115cc chambers. I did add on T&D Shaft Rockers.
10-26-2017, 04:52 PM
#125
Can't believe how close we came on motors coming from 2 totally different directions..
I've got a 496, 10.5:1 compression, Comp solid roller that's .671/.671 254/260 110* centerline, but I also did the 7-4 swap. Ended up with Brodix RaceRite rectangle port heads, 294cc intake ports and 115cc chambers. I did add on T&D Shaft Rockers.
I've got a 496, 10.5:1 compression, Comp solid roller that's .671/.671 254/260 110* centerline, but I also did the 7-4 swap. Ended up with Brodix RaceRite rectangle port heads, 294cc intake ports and 115cc chambers. I did add on T&D Shaft Rockers.