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355 SBC cam recommendations-425hp

5K views 6 replies 4 participants last post by  BogiesAnnex1 
#1 ·
I will be rebuilding my 350 which is my first build and looking to produce about 425hp.

I'm starting with a 1996 .030 over block, forged scat rods, scat crank, speed pro pistons 10.1cr using pro comp aluminum angle plug heads 64cc 2.02 intake/1.60 exhaust. 1.6 roller rockers with girdles.

Current cam is LT4 Hot Cam duration at .050" tappet lift (intake/exhaust) is 218/228; and maximum lift with 1.6 rocker ratio (intake/exhaust) is 525/525. Roller lifters, Summit dual plane intake.

While i have the motor apart i think i would be better served with a bit more radical cam, looking for recommendations/part numbers, I'm assuming i have to change out the valve springs also.

TH350- 2600 stall
Rear gears-3.42 posi (Possible future upgrade to 3.73
Rear tires- 275/60/15
 
#3 ·
The recent versions of those heads are not that bad. They're not afr quality but they're better than anything oem. A port clean up and maybe valve job should be enough on them. Didn't mention the headers or exhaust, there's a lot of power there. And lastly the tune, dyno time will help you tune for peak numbers. The cam should be adequate if you clean up the heads run a good exhaust and get the tune dialed in.
 
#6 ·
going to at least a 750 will help peak power numbers, and get the damn thing dialed in (this doesn't mean just swapping out jets either!) Getting your carb tuned in makes a hell of a difference- the problem with a carb is that keeping it dialed in is damn near impossible when the weather changes. May want to consider going to EFI instead of a new carb if this is driven on the street. For a track only car a carb is easier to tune as you're always at WOT, and can just tune it every time you go to the track for current track conditions.
 
#7 ·
What you have with an Edlebrock Performer RPM intake or a Victor Jr with a 750 Holley or Holley clone in place of the Summit intake and 625 CFM carb should go to an easy 425 on an engine dyno. I'd keep a half set if 1.5 roller rockers in my tool box, often on these split intake to exhaust duration cams the use of 1.5's on the exhaust has the effect of bringing the power band down a few hundred RPM with no sacrifice in the top end power. just widens the peak curve over more RPMs. So this is a useful tuning item as are carb spacers.

The Comps are an OK head especially the latest go around. They like a lot of lift on the intake. They also respond to a back cut of 30 degrees on both the intake and exhaust valves more than most other heads, this will pick up the Comp's rather weaker mid lift flow as well.

Valve springs should be a decent quality beehive. These things really keep the valves under control without having to go to exceptionally stiff springs.

Other than that this should be good to go where you want.

Bogie
 
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