| FAQ |
| Members List |
| Social Groups |
| Calendar |
| Search |
| Today's Posts |
|
#1
|
|||
|
|||
|
Rebuilt my engine and my car does not scream like it used to. have a comp cam 268. Met a guy who told me he was the one who restored this car and said he put a goat cam in it. Having problems with tuning on this cam. Should I get the ram air 3 cam?
|
|
#2
|
||||
|
||||
|
Ace770, Please post more relevant info about your setup;
1) cylinder heads - stock casting, or ported 2) Comp ratio 3) intake and exhaust 4) Axle ratio 5) manual or auto (if auto - converter stall speed) 6) Desired rev range 7) car usage (cruise, drag race, etc) |
|
#3
|
|||
|
|||
|
I will give you what I know
1 "7k3" stock casting now ported and polished (hardened exhaust valve seats for the intro to unleaded) 2 8.5 to 1 3 stock intake and exhaust with carter 4bbl 4 not sure but think it is a 3.73 or less 5 automatic TH400 with a hurst dual gate shifter 6 old one ran real strong around 2500-3200 rpm 7 street mostly |
|
#4
|
||||
|
||||
|
A recommedation can be somewhat straightforward except that you mention that the heads have been "ported and polished". A little clean up won't matter much, but if the flow potential has been increased alot, say from 200 cfm up to 240, this may impact your cam selection.
Based on your repsonses I would suggest any of the following; - a factory 068 grind (the RAIII auto) with 1.65 rockers - a summit 2801 with 1.5 rockers - a comp cams xtreme energy 51-222-4 with 1.5 rockers These combos result in approx .450-.460 lift and around 215 intake and 225 exhaust duration at .050" They will not kill your low-end torque with 8.4 CR and still rev to 5200 rpm, with a torque peak around 2500 rpm. The comp cams choice will probably give you a bit more dynamic CR for throttle crispness, but at the expense of a little top end power. If you go to lifts beyond .470 you won't gain anything, and if you go to durations in the 230/240 range you will push your torque peak to 3000 rpm and lose that good low-end "feel" which is necessary for street driving. Way too many people over-cam their engines, kill their low-end torque and actually make a slower car all for the sake of a cool rumpity idle! I don't claim to be the "cam-doctor" so if anyone else has a suggestion please post! |
|
#5
|
|||
|
|||
|
Thank you for the help. I have 1.6 roller rockers in it now and when I had the old cam it was stock rockers. Sounds like the RAIII is best for me. Another important piece of information I left out was this cam was set a 4 degrees in advance (the guy that did it for me said it would run better) Should I run the new cam straight?
|
|
#6
|
||||
|
||||
|
Advancing or retarding cam timing generally does not make more power or torque, it just moves the peak torque and hp rpm around a bit. Jim Hand claims in his book "How to build max performance Pontiac V8s" that advancing 4 degrees will lower the peak torque and hp speed by 200 rpm. Based on the description of your car and my experience with the RAIII manual (744) cam I would certainly consider the four degree advance. If you are going to use the RAIII auto cam (068) I would not advance the cam timing.
|
| Reply |
|
|