More cam? Change my mind

[HotRod777]

Car:
1966 Sedan, 383 auto. 2500 Hughes converter, 3.55/grip.
383- .040, forged flat-tops (.018 in hole) .020 steel gaskets. 915 big valve heads, springs good to .550, stock rockers. DP4B, AVS2.
HP manifolds, 2.5" TTI. Light springs and limit-plate in Dist.
Cam is Comp 270H- 224* .050, .470" advanced an additional 4*.
The issue is it idles smooth like a tow-truck. The car is only a driver cruise car but I need more "sound"... not worried about overall top performance.
He is what I am considering:
1) Comp Thumper (227@50 intake on a 107cl)
2) Lunati Voodoo (226@50 intake on a 110cl)
3) Purple 484" (on the 108cl)
4) Leave cam alone and go with 1.6 adjustable rockers. (would make lift .501 and get into the overlap a bit quicker.)

The concern is my piston to valve clearance. The motor was built old-tech so I kinda need the old fashioned cams that used more duration then lift. I have scoped the cylinder and watched the overlap as the intake valve chases the piston down and there is clearance but with no scale for reference its hard to know how much clearance there actually is...

 

[67charger383]

Hughes whiplash if you want it to behave like a daily driver but sound like a hotrod.


http://www.hughesengines.com/Index/...hZnQ=&level2=V2hpcGxhc2ggTXVzY2xlIENhciBDYW1z

 

[mopar_chuck]

Are the pistons cut with valve reliefs? If not, then I would not gamble with more cam.

 

[HotRod777]

Are the pistons cut with valve reliefs? If not, then I would not gamble with more cam.

No, totally flat like stock 4brl pistons

 

[1 Wild R/T]

You can guess and gamble or you can measure what you have... Swap out the valve springs with a pair of light springs & measure valve travel at every 2 degrees across overlap..

 

[69a100]

Just bump your timing to 2*ATDC, it'll sound badass, and it's free! Go with one of these instead, bigger isn't always better!!! Good Luck
Hughes Engines
Hughes Engines

 

[HotRod777]

Unfortunately I have way too much static compression for a whiplash. I have .038 quench with closed chamber iron heads.

Hughes whiplash if you want it to behave like a daily driver but sound like a hotrod.


http://www.hughesengines.com/Index/...hZnQ=&level2=V2hpcGxhc2ggTXVzY2xlIENhciBDYW1z

 

[HotRod777]

You can guess and gamble or you can measure what you have... Swap out the valve springs with a pair of light springs & measure valve travel at every 2 degrees across overlap..

View attachment 1066902

I was thinking this is what I "should" do. What's absolute minimum with hydraulic? .075" at any point?

 

[mopar_chuck]

I did a similar build about a year ago using those type of pistons. Using a .484 cam there was only about .095" of clearance with a .040" head gasket... so pretty much at the limit. Bottom line is those pistons are not good for a performance build for this reason. I only ended up using them because they were new and i didn't want to spring for a new set. If you want more sound and performance, headers will always help.

 

[66Satellite47]

IMHO, any cam change needs to have piston to valve checked. It's not so much an increase in lift that affects the clearance as the duration and actual valve timing.

 

[1 Wild R/T]

I did a similar build about a year ago using those type of pistons. Using a .484 cam there was only about .095" of clearance with a .040" head gasket... so pretty much at the limit. Bottom line is those pistons are not good for a performance build for this reason. I only ended up using them because they were new and i didn't want to spring for a new set. If you want more sound and performance, headers will always help.

With a 383 you don't have allot of options unless you want to wind up at 8-1 or with custom pistons...

 

[4406bbl]

I would say .080 intake .100 on the exhaust. I guess it depends on how much work you want to do. You would need to be sure that is with light springs and the lifter plunger at the snap ring. I would pull a head and measure it. Your quench is perfect, you could cut reliefs deeper with an old head and bigger valve with a cutter to gain a little bit, and order the exact cam you want.