|
Num Posts
Sort Order
|
ssnova66
New User
| Posts: 4
| Joined: 06/08
Posted: 06/23/08 09:10 PM
|
|
Hi all: New to this forum so hello everyone. I have a 1966 Nova SS with a 283 stock engine, stock converter, 308 gears, 245/17 wheels, headers, Edelbrock torker manifold (I am changing to a performer EPS or RPM), Edelbrock 1400 carb and CPP power discs. I have been searching for a cam combination that will give me mild chop at idle, work with a stock converter and not have a major affect on the power booster. I have spoken to a well known cam manufacturer three times and each time given a different cam recommendation.
I would really appreciate any advice or experience any of you might have with this. Thanks in advance for your responses.
JT
|
GibTG
Moderator
| Posts: 1360
| Joined: 10/03
Posted: 06/23/08 09:56 PM
|
|
I would use about 250° of duration on a split pattern, with a 110 or 112° lobe separation angle. 4° of "ground-in" advance is VERY customary.
If the engine doesn't have headers use a 112° or even wider LSA. A more modern and "intense" hydraulic flat tappet should make about 205° of duration @.050 with the above mentioned kind of advertised duration. Don't be scared by a less intense exhaust profile. Look for 4-6° more duration on the exhaust side of the cam. Lift will probably come in around .425".
I estimate that a cam like this will pull 16-18 inches (of Hg) of vacuum with your motor - plenty for your brake booster.
|
ssnova66
New User
| Posts: 4
| Joined: 06/08
Posted: 06/24/08 08:00 PM
|
|
Thanks for the information, I can't believe how many different answers I get on this. I have been from a 218 218 @.50 112 LSA to a stock cam in recommendations. The latest one today was a 210 @.50 with a 110 LSA, they stated this would be the max they would go on a 283 because apparently most cams are rated for a 350 and the smaller displacement of the 283 makes the cam more aggressive than being installed in a 350 ci.engine. This really throws many tech help lines for a loop when I explain the combination to them.
JT
|
|
|
GibTG
Moderator
| Posts: 1360
| Joined: 10/03
Posted: 06/25/08 07:52 PM
|
|
It is true that a 350 can handle more overlap with the same or better street manners compared to a 283.
The main reason you need to cam small is because you have a small displacement engine with tall gears and very little modifications to make it "breathe" easier.
I don't think 210° @.050 on a 110° LSA is too far off. I believe that it's heavily dependent on how efficient your exhaust system is.
|
michael21
New User
| Posts: 2
| Joined: 09/08
Posted: 09/11/08 11:01 PM
|
|
can you run the .425" lift cam with stock valve springs and pushrods in the 283?
|
GibTG
Moderator
| Posts: 1360
| Joined: 10/03
Posted: 09/12/08 03:33 PM
|
|
It's never a good idea to run the stock springs and pushrods on basically any cam.
It's common for stock engines to break these components since they are likely 30 years old and were poorly manufactured (mass production 30 years ago!).
|
michael21
New User
| Posts: 2
| Joined: 09/08
Posted: 09/14/08 12:32 PM
|
|
wat all would i have to get to run about a .460" lift cam in my 283?
|
|
Posted: 11/01/08 08:14 AM
|
|
JT, Hi, I am new to this forum as well but will take a shot at it with my computer. You left out what trans and exhaust you have, and the weight of the car - - especially whether the trans is a Powerglide or one that actually has a 1st gear, T350, 200-4r, 700r4, etc.
I assumed you had a p-glide and 2" duals, and hand shift the p-glide about 200rpm over peak power, and then calculated your engine power and timeslips. Yes these are all calculated and by far it is best to go to the dyno and the strip, make one change at a time, and re-test. That is not always practical!
So on the computer, here goes. Your combo as described today, also guessing you have the "431" cam, at 0-advance: 2.73 60ft 11.31 at 66.8 1/8 mile 17.29 at 81.3
I think the Torker II is killing your low end. Does the car seem like "dog" like this? Changing to the Performer intake (I dont think you need the Perf RPM intake): 2.60 10.83 at 67.9 16.68 at 83.4 Wow, what a kick, mainly on the low end but all over. To me, for a street car, the most important time is the 1/8 mile time and as you will see, the stock cam shows the best one here, due to that 3.08 gear and 1.82 "1st gear" in the powerglide.
Anyway I did compute some other cams. The newer "929" cam, also Clevite 229-1273, computed to: 2.63 10.89 at 68.3 16.72 at 83.7 Well, nobody's computer is that good, not mine for sure, so I'd call it a tie between the "431" and the "929" cams.
Next try the Performer cam at 204-214 duration: 2.66 10.91 at 69.4 16.68 at 84.5 Slower at 60ft and 1/8 mile, not worth it.
Finally the Crane HMV-272, near copy of the "L79" cam: 2.70 10.99 at 69.9 16.70 at 85.2 Too big for your combo.
So I'd look for a Performer or similar intake, and leave the stock cam in it until you get a 3spd auto in there, then things might change.
But,
|
|
Posted: 11/10/08 02:52 PM
|
|
I agree your intake is too much for the car, look for a performer or similar dual plane intake. Cam wise look into a Comp XE256 12-234-2 or the 260H 12-206-2, for something a little lopier check out the 265 DEH 12-208-2, or N+300 12-670-4. If your carb is 600 cfm that is probably also a bit much, getting down to 475-500cfm will help improve responsiveness.
|