How big of a cam can i go with stock pistons???

[Pbum5]

stock size rods also??????

My whole bottom end is stock so Yes, stock Rods..

I was not running nitrous though. a 100HP shop should be ok but if you use it a lot it can be rough on Cast (stock) pistons.

Be sure to get the valve springs to match your cam.
Screw in studs and guide plates are also a good idea with a bigger cam!!!

 

[D.Hearne]

My God, this thread sounds like the blind leading the blind

 

[mustangman70]

We all have to learn some how

What is required to use screw in studs? wouldent i have to tap the heads or something????

 

[D.Hearne]

For screw in studs, you really should remove the heads and have them milled, drilled, and tapped by a competent machine shop. The stud pedestals on pre-78 heads need to be milled .300 for studs and plates, on pre-rail rocker heads you can leave off the guide plates and mill the pedestal, less the guide plate thickness ( about .200) as the heads have guide slots in the head already. Now, Nitrous and blower cams have a wider LSA to reduce the overlap, apparently you need less overlap with either, not more. Less overlap will also help your motor perform without the juice by helping to build more cylinder pressure with low compression pistons. Generally you can get away with up to about a .525 lift x 290 degree ( advertised) duration cam with stock pistons. But as has been already advised, it's a good idea to check the clearances before firing it up.

 

[mustangman70]

Thank you for answering my question sir

You have been very helpful as evreybody has, THANKS GUYS, I decided on the comp cams 280H, Thats the direction i want to go with the motor and car, How much about would it cost to get the screw in studs put in if i bought the studs

 

[D.Hearne]

One more thing, you've chosen the Comp Cams 280H, Better check your compression ratio first. With dished pistons, I doubt you'll have the recommended 9.5 to 1 minimum ratio needed for that cam. If that's so, then you're going to be very disappointed in it's performance. With dished pistons you're likely to have something in the low to mid 8's as far as comp ratio, if that's so, you need to make a better cam choice, something with a wider LSA to boost the dynamic compression with a low static ratio, you'll be a lot happier with the performance. Comp's cams like the Nostalgia plus ( part #31-670-4) or the XE250H-14 ( part #31-255-5) or a High Energy grind are what you'll want with a low compression small block.

 

[mustangman70]

How can i test the compression ratio? reason i ask is the last owner of the motor said it had 9.5:1 (at least thats what he thought) Also they arent dished, we found a picture of the build up in progress, and they are flat tops with some small cuts in them for valve clearance.

 

[D.Hearne]

Best way to know for sure is to remove the heads, and measure how much deck clearance there is with the piston at TDC. Then measure the head gasket thickness. Also see what heads you have there to determine what size the combustion chambers are. It doesn't take many cc's difference to make a huge difference in the static ratio in a 289 or a 302. Too little compression with too big a cam will net you a motor thats a dog on the street or at the track. Too small a cam(overlap we're talking here) with a high static ratio will net you a very responsive motor on the street, but maybe one that will require premium pump gas ( or race gas) to keep it from pinging, and with today's gas prices, most people ( like me) don't want to spend anymore on gas than they have to. In short, do your homework, before choosing a cam, you'll be that much ahead of the curve when you're done.

 

[iskwezm]

Thank you for answering my question sir

You have been very helpful as evreybody has, THANKS GUYS, I decided on the comp cams 280H, Thats the direction i want to go with the motor and car, How much about would it cost to get the screw in studs put in if i bought the studs

Rember the bigger the cam,the rest has to go with it,gears,T/C,heads and springs.It might sound mean,but its gonna be a big dog off idle.

 

[mustangman70]

I plan on doing all of that stuff