My 403 Build/Help
Thread Starter
Registered User
Joined: Jan 2009
Posts: 5
From: St Louis Mo
My 403 Build/Help
Well, as usual budgets change.
Mine went thru the toilet.
So I need some new suggestions.
I plan on using a set of # 6 heads.
Valve job, larger 2.07 intake, hard exhaust seats.
What is the largest cam I can use with the stock style rocker stud (5/16")?
Trying to save the $200 the machine shop wants to charge to install screw in studs.
I thought I read a .500 lift. So I was looking at a Lunati 60801. The 60802 says it needs .510 on the exhaust(I like this one better).
Both require a 1.6 ratio rocker.
COMP Cams 1242-16 meets the 1.6, but says nothing about max lift.
They suggest a "High Energy" cam.
Now, Scorpian makes a 1.6 (SCP1089BL), but still does not say anything about lift.
Will the stock studs handle the 60802 cam?
Mine went thru the toilet.
So I need some new suggestions.
I plan on using a set of # 6 heads.
Valve job, larger 2.07 intake, hard exhaust seats.
What is the largest cam I can use with the stock style rocker stud (5/16")?
Trying to save the $200 the machine shop wants to charge to install screw in studs.
I thought I read a .500 lift. So I was looking at a Lunati 60801. The 60802 says it needs .510 on the exhaust(I like this one better).
Both require a 1.6 ratio rocker.
COMP Cams 1242-16 meets the 1.6, but says nothing about max lift.
They suggest a "High Energy" cam.
Now, Scorpian makes a 1.6 (SCP1089BL), but still does not say anything about lift.
Will the stock studs handle the 60802 cam?
Last edited by 82ctls; May 18, 2011 at 12:15 PM.
Registered User
Joined: Oct 2005
Posts: 7,318
From: NJ
Well, as usual budgets change.
Mine went thru the toilet.
So I need some new suggestions.
I plan on using a set of # 6 heads.
Valve job, larger 2.07 intake, hard exhaust seats.
What is the largest cam I can use with the stock style rocker stud (5/16")?
Trying to save the $200 the machine shop wants to charge to install screw in studs.
I thought I read a .500 lift. So I was looking at a Lunati 60801. The 60802 says it needs .510 on the exhaust(I like this one better).
Both require a 1.6 ratio rocker.
COMP Cams 1242-16 meets the 1.6, but says nothing about max lift.
They suggest a "High Energy" cam.
Now, Scorpian makes a 1.6 (SCP1089BL), but still does not say anything about lift.
Will the stock studs handle the 60802 cam?
Mine went thru the toilet.
So I need some new suggestions.
I plan on using a set of # 6 heads.
Valve job, larger 2.07 intake, hard exhaust seats.
What is the largest cam I can use with the stock style rocker stud (5/16")?
Trying to save the $200 the machine shop wants to charge to install screw in studs.
I thought I read a .500 lift. So I was looking at a Lunati 60801. The 60802 says it needs .510 on the exhaust(I like this one better).
Both require a 1.6 ratio rocker.
COMP Cams 1242-16 meets the 1.6, but says nothing about max lift.
They suggest a "High Energy" cam.
Now, Scorpian makes a 1.6 (SCP1089BL), but still does not say anything about lift.
Will the stock studs handle the 60802 cam?
Registered User
Joined: Nov 2008
Posts: 8,484
From: Central Fl
Your issue with stock studs is not necessarily lift but spring pressure. Stock studs are good to about 275 or so open, but that's with the same size but better stud.
Stock heads? Don't use the VooDoo or Comp. When you're ready for a cam let me know.
Jmo.
Stock heads? Don't use the VooDoo or Comp. When you're ready for a cam let me know.
Jmo.
Registered User
Joined: May 2011
Posts: 220
You will be more than fine with the Lunati 60801 and the 60802. The lunati P/N: 31805, is a monster. Lots of duration with a moderate 520 lift. This would be the closest cam to 500 with a monster duration to help get the 403 to those high RPM's. I built a really strong 350 with this cam last year for a friend who installed it in a 67 Cutlass 4 Speed with 4.11 Posi and ran a 13.29. Nothing crazy but a very nice time for a 350 and fairly stock chassis cutlass. What stall speed are you running and what rear end. Those are always my biggest dictators on cam selection. Good luck sounds like a nice build. I think the 403 is one of the most underestimated engines EVER built. Monster bore and tiny stroke allows for both a high reving monster or you can go the route of a torque beast. Comp Cams HP estimator and cam selector program can make some scary numbers with a 403. Good luck.
email me if you want more info.
email me if you want more info.
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