I've been looking at some cams to go with my heads that I bought and are getting ported, and this one looks good from Comp Cams:

230/236 .510/.520 110 LSA

I'd be using Crane Gold 1.6 Roller Rockers (.544/.554) and would have them grind it on a 112 LSA. My question is for guys that have run this or similar cams in 350s, at a 1000rpm idle would the vacuum be sufficient for brakes/accessories?

 

IMHO, NO. Power brakes like at the bare minimum 14 in/hg of vacuum. I ran into problems with 10 in/hg at idle (granted it was a 5,300 lbs truck). Converted to hydroboost for the brakes. I added a larger vacuum canister to run the A/C, cruise, etc.

 

I ran that exact cam for some years in a 400 (XR282HR) with 1.6 rockers (Comp 1100 series), except with the stock 110 degree centerline. It idled at 800 RPM, and the power brakes and the A/C and cruise all worked fine. No vacuum canister. Made great power.

If you don't already own the rockers, I'd suggest getting something else that's not aluminum. Either the Comp 1300 or even the 1100 series if you REALLY want the best like I did, or Crower. Aluminum ones have a bad habit of just up and breaking in street use. It's not a question of "if", but rather "when". They might go 10,000 miles, 20,000, maybe even 30,000; not too many people go much farther than that before they start to break. But steel ones will last basically forever.

 

Try the Comp Cam XFI 230/236 113 LSA

 

I'll seconded that

Agreed

 

Thanks for the input, it seems like the answers will always vary though. I've also seen some people say that the CC306 made plenty of vacuum while others said it didn't. Thanks for the heads up on the rockers too, I thought that Comp didn't make very good roller rockers?

 

Sorry to hijack the thread, but I have a similar cam (230/236* and .490/.490 with 110lsa XE274)

How would this cam work in a 350 with around 9.5:1 CR, as far as vacuum and PB are concerned at an 800-ish idle?

 

People say all sorts of things about everything. It's been real popular here lately to bash Comp for some reason. I don't know why. Their stuff is decent enough, within the limits of what it actually is, underneath the label; for example, a cast-iron roller core is risky, no matter whose box it comes out of; and aluminum rockers are prone to fatigue, same as any other aluminum part, no matter whose name is on it. The thing still is what it is.

Comp's aluminum rockers are as good as anyone's in my limited experience. Which is to say, they're aluminum, with all the properties both good and bad that go with that. Their steel ones, and Crower's, are the best you can get IMO, without stepping up to a shaft setup.

I had the XE274 in the same motor for a while, before the XR282; I liked it alot too. It ran like a bat outa hell. The XR282 ran better though. It seemed like ALOT more cam, in spite of the specs looking very similar. The XE274 will give better street manners than the XR282, rather alot actually, in the case of mine. But I think 9.5:1 is borderline too low. It might have a kind of soggy bottom end.

How much vacuum a cam makes is dramatically a function of tuning. Some of use are a WHOLE LOT BETTER at that than others; I'd like to think I'm better at it than most, but who knows. Therefore, no matter how well or poorly it worked for me, you may either be totally unable to duplicate my results, or it'll work about the same for you, or maybe you'll kick my butt. It's all up to you.

 

I agree - tuning makes a huge difference in many cases. When I first installed my 350 with mild cam, I couldn't get enough vacuum for the brakes. But I fooled with the timing (bumping it up) and then brought the idle down with the carb adjustments, and it made a world of difference. I now have plenty of vacuum for brakes, and a 750 rpm idle. There are also vacuum canisters available to hold vacuum in reserve, should you not be able to tune in sufficient vacuum.

 

I figured tuning would play an important role, I just wonder if having SD instead of MAF will hurt my chances. My friend told me that anything 230 degrees and higher (intake duration) gets tough to tune with SD. I should start some email correspondence with pcmforless I suppose.

 

Your friend has the basic idea right and wrong. It really depends on the entire setup and the cams LSA. In a 400 that cam would be real nice but toss it into a 350 and it's going to act totaly different.

People like to bash comp cams because all we hear is how a lobe or two got wiped. I had one go flat before. There cams are just so popular it seems when 1 out of a 100,000 goes flat the news spreads, especially over the net. ISKY is the way to go I'm personally much happier with ISKY products but that has nothing to do with the topic.

 

Thanks for all the replies guys, it seems more than a few people have run the XR282HR without vacuum troubles, even at 800rpm idle speeds.

 

Mabey I missed a post, Has anyone ran this cam or similar roller in a 350?

 

I'm running it now, 13" of vacuum at 800rpm idle with a stick, brakes work fine. It will all come down to your combo and tuning. Might want to consider a 112 or 113 LSA as suggested above to play it safe.

 

Exactly, if I had the cash for a 383 setup I'd leave it on a 110, but since it is going in a 350 I'm going to go on a 112 just to be safe.

 

What type of intake set up are you planning on running. TPI Mini ram or carb?

 

Oops, missed the part that he had a T-56. With an auto, the vacuum at idle would be too low in gear with this cam for power brakes, with a stick, it maybe good though.

 

I have a 280 XFI (230/238) and its more to the radical side for a 350, but not bad. You wont need 1000 idle though, I think around 850 is fine, below that it gets a little unhappy.

I dont know what my idle vacuum is, but the brakes work ok.

 

I have a Stealth Ram that I'll continue to use.

 

I posted in your thread because I can't find any XFI grinds on Comp's website, how do the lobes compare vs Xtreme Energy lobes?

 

Guess I'll reply in both places

Probably pretty aggressive. 230/236@ .050, 280/288 @ adv. (I think comp uses .006 for adv), .576, .571 lift, 113.0 LSA. Thats off the box. I dont know if the info in the box listed the timing events, but in any case I have that information somewhere. I checked it for myself as well so I can post that too.
Summit racing also has that general info, if their website is working. Was down yesterday. Look up cams, comp cams, 350 small block, etc., and isolate 113LSA cams and that should get you close. All the XFI's are 113LSA or at least they have been since they came out.

 

Did you use the conical springs with that?

 

No, used what was on the AFR's but they may not have been stock. Double spring with damper. I think the guy that set them up said they were 130 on the seat, 340 open.

Checked the vacuum today, 8psi at idle (850rpm).

 

I'm suprised your brakes work with vacuum that low.

 

They seem to work fine. Dont ask me.

Car was cold, I dont know if a nice warm idle affects it any. Maybe tomorrow I will check that, going to be toying around with it again.

 

Lo-tech told me he pulled 13 inches with his XR282HR, and that cam has a 110 LSA and the same duration. I figured the 280XFI would have a bit more vacuum than that. It seems that there isn't much info on these cams out there, Comp doesn't have any info on its page nor can I find any articles or other users of these cams. They've been out since late '04, I would think more info would be available on them now. I'm now convinced I'm going to run the 280XFI.

 

I might be able to mess around with timing and whatnot and pull some more vacuum at idle, I havent gotten that far into it as of yet. Thats just what its reading currently. I'll post up some warm numbers later if they are any different.

 

Madmax, is your app carbed or FI?

 

He is using TPI. He has another thread about his dyno numbers on here with that cam, AFR195s, and TPI.

 

It should be read in inches...I hope you don't have 8psi at idle.

Need to work on the tune, b/c there is a lot more in there if tweaked correctly.

 

Ok, 8 in then (vacuum), no pressure in there obviously. Its running 11 warmed up. Obviously the car isnt happy cold.

WOT its pretty close, its the idle and part throttle stuff that still needs work, neverending battle right there.

 

What is the difference between the 1300 and 1100 series? I looked on Comp's site and couldn't find a description on the 1100s. For 150$ more they better be significantly better. I was thinking about getting the Pro Magnum 1300 series but now I've been told they may not clear the centerbolt valvecovers that my ZZ4 came with.