Since i'm considering a Swap toa more practical cam, i thought it would be a good idea to get some facts from board members. I would like you guys to state your cam specs plus displacement, CR and most importantly VACUME at a given idle rpm. I'll go first.

383, afr190, 9.85 cr, HSR,950 1.6 rockers
224/230 @ .050 114 LSA (lift is about 540-550) Hydraulic Roller
idling at about 1000 rpm i get 12 inches of vacume and average 12 mpg

Idle is choppy, and uneven, mileage is dismal at 12 mpg average.

 

You've got problems then if your idle is choppy, with that cam in a 383 it should be really smooth especially with that 114* lsa.

 

Actually it should be choppy thats a stout cam, about 280 advertised duration. It's a little too choppy for my tastes, and it's killing me on emmissions. I will be going over the motor soon to be sure but it's been that way since built. not rough anywhere else though just idle and very low rpm.

Besides i think it would be great to have a list with actual cams and realworld opinions on them.

 

I have a '71 Camaro with a ~ 9.5 compression 350, stock Vortec heads, Performer RPM intake, Holley 650 DP, headers and a Comp Cams Magnum 280.

It's not very choppy at all. Even with it's 110 LSA and 230* duration @.050" lift it still pulls ~12"Hg @ 700 RPM with that carb and intake.

With a TH-350 trans, 2400 stall TC, 3.42 rear gears, 245/50/16 tires I still get about 15 MPG out of it (3,000 RPM @ 65MPH).

Oh. And with my G-Tech I recorded 14.12 ET @ 104 MPH with horrible traction. Figure .2 tenth higher and ~2 mph slower at a real dragstrip, based on the average "overatures" of the G-Tech.

The Performer intake is hurting my high RPM range a little, but gosh it's fun to drive.

 

Thanks! thats the kind of info i'm looking for.

 

I still think your motors not running right at all. Thats a pretty tame cam for a 383. I am almost certain you have plenty of vacuum leaks.

My 305 has a XS262S-10 solid lifter cam with 224/230 duration and a 110 lsa. And its not overly choppy or uneven like your saying.

 

its good to know people are sucessfully running that duration, I have no vacume leaks that i know of, its been like this for 2 edelbrock maniolds and the HSR, i have checked many times.

I think i might have mis-stated my problem. The idle is choppy and i seem to have reversion problems. I can get a decent idle if i dump fuel into it but that causes emmission headaches. What i'm looking for is the biggest cam i can run with a smooth idle and a reasonable amount of fuel. I also want better mileage and no reversion.

I figured that this would be a resource for anyone building a motor, who expects certain things from their cam choice. My car pulls like a tractor in any gear at any rpm but it could be better, and i want it better.

 

You might want to try the LT4 hot cam.It should still pull to 5800-
6000.Lots of people have had made good power with that cam.

 

I agree w/ ME leigh

I had a 224/234 cam in my old Trans Am which had a junkyard, 7.8:1 compression, oil buring 400 long block in it. I slapped that cam in it, some roller rockers, and my ported CFI intake and bored TB's. It pulled 15" of vacuum at 7000' elevation and idled like a completely stock engine, at 6-700 RPM. Also got 24 mpg on the highway. I agree that something seems amiss w/your combo.

For further refference, I now have another poor combo(that I didn't put together!);
A 350, TFS heads, RPM intake and RPM cam (234/244 @ .050 and 308/318 @ .006). Hurting that combo, are dished pistons resulting in about 8.5:1 compression. With some time tunning last summer, I got the vacuum to about 11" at 7000' at 1000 RPM, and it is just slightly rough at that idle speed. At 600-700 RPM it's pretty rough and I only get about 8" of vacuum. I drove the car from Mass to UT last summer and averaged 18.6 mpg on that entire 2300 mile trip. And I wasn't going slow.

 

This is interesting, the car is now a second car it's basically going to get a full once over. I'm going to pull a header to repair a broken air tube, might as well pull both to make a leakdown and compression check easy.provided thats good i will dive deeper. The cam is a comp grind, i have it installed strait up. if leak down doesn't reveal a problem, i'll check that next. Other than cam timming i do not know of anything else that will cause reversion. My hsr is stained brown and had a nice coat of oil on it. All vacume lines are dry. PCV was especially clean. There are deposits on the backs of the intake valves as well. I can't remember what kind of seals the AFR's came with, i guess i'll know when i pull the valve covers. Anyhow i really wan't to get to the bottom of this. It's driving me nuts that the car makes great power even idling! but i'm having these issues. I have no problem going to a smaller cam for drivability but i wan't to know it's not somthing else.