Thinking of a cam change
 

I'm beginning to wonder if my my current cam is too small for my setup.
I currently have a Comp 274XE cam with the following specs:
274/284(230-236) .519/.523 110LSA

I was thinking of going with the next size up 284XE cam:
284/296(240/246) .541/.544 110LSA

When I built my engine, I was worried about going too aggressive and I knew it's better to have a cam that's too small rather than too large so I went with the 274 cam.
In retrospect, I think I was too conservative on my cam selection.
What do you guys think?

Re: Thinking of a cam change
 

I think the cam you have is fine for your combo. you change the cm you would probly change your powerband. right now i bet it's very torquey and a fun ride around town

Re: Thinking of a cam change
 

It's an excellent combo on the streets but it's only worth a 13.36@104 on the strip. I feel I should be running mid 12's even though my converter is a little small for now.
I think my carb/intake would like a larger cam

Re: Thinking of a cam change
 

I got an X303 sitting here that's currently doin nothing! ;)

Re: Thinking of a cam change
 

I Would Go With A 3500 Stall Or Higher And 4.30's You Should E In The 11's Easy.........keep The Cam You Got

Re: Thinking of a cam change
 

A set of 4:30 gears and I will run out of gear. My current cam is only good up to 6000. I'm at 5500 rpms now, in top gear, through the traps. I have a C-4...not a T-5

Re: Thinking of a cam change
 

Thanks but I'm not setup for a roller cam.

Re: Thinking of a cam change
 

Based on what happened when you changed intakes and carbs, and the fact your buddies told you it sounded like it was bogging off the line, and the 2200 RPM you said you were getting, actual stall, I'll bet if you go up in size you're gonna get worse instead of better ?
You are in that unknown territory area right now, and it's really difficult to predict what is gonna work and what isn't until you just take the leap and try it. One good thing is, you're doing all my research for me :D
If you're in the traps at 5500 RPM, I think you're out of the power band on the low side. That is a 110 degree cam, and if you're getting your power band info from the comp cams web site, that was in a fairly mild 350 Chevy with 1.5 rocker ratio.
A quick way to find out if my theory holds water, is to borrow some shorter tires. That should be a cheap way of raising your RPM's, which barring a loss of traction, should tell you a little more about what cam that beast is wanting.
Keep in mind I could easily be way off base on this :p
Don't give up now my brotha, you're closer than you think. This is the time when, although frustrating as hell right now, will make you a seasoned veteran when you get it all ironed out. :)

Keep us informed !!

Rod

Re: Thinking of a cam change
 

So...if I change cams, I'll gain more top end power but still suffer at the 60' mark....right?
If I go to...say...a 3500 stall converter my 60' would be much better and I would have more of the power band through the traps because the converter would lock up later??

Re: Thinking of a cam change
 

Ya got good valve springs in there? Wind that beeotch up! I'm shifting at 6800. I understand I have a bit more motor than you, but you're setup should be more than capable of reaching 6500 or so. The cam is only "good" to 6000, but your entire engine might like it better at 6500 instead of 5500. Remember the engine is a system, and everybody gotta play nice together. Heads and intake may take over where the cam leaves off.

Keep us posted!

Re: Thinking of a cam change
 

Yep...all new valve springs. Based on trying different shift points, it seems to like to be shifted at 5800...any more or less and E.T drops off. Going through the traps in 3rd, at 5500rpms, I can tell the engine is running out of steam.
My 60' sucks...even with slicks so now I'm leaning towards the converter being the culprit. If I can drop my 60' by .2, I will be in the mid 12's.....make sense?

Re: Thinking of a cam change
 

Pretty bad, you can't even give that cam away.

I remember you thread from a month or so ago. I am not much of an auto guy, but I still think it's in the converter. I would call a good transmission shop and see what they recommend for that cam and gear.

Re: Thinking of a cam change
 

Bigger cam will slow you down IMO. If everything is functioning as it should be on your motor then a bigger cam is the last thing you need for your poor flowing heads.

Really man what else could it be?

Re: Thinking of a cam change
 

I wouldn't exactly call my heads "poor". They might not be AFR's but there is a lot of money wrapped up in them...porting, polishing. oversized valves...etc.
Anyhow, it almost HAS to be the converter. There's still some fine tuning that needs to be done on the carb. but not enough that's going to gain me 3 tenths.
I figure if my 60' times are only in the 1.9 range with slicks and gears then it's either the carb or converter.....but then again, I was getting the same 60' times with the carter 625 and performer intake.....so it's back to the converter again.

Re: Thinking of a cam change
 

I have no doubt the converter is at least part of the problem. Whether it's all of the problem or not is a different story ? I know for sure, that motor should not be falling on it's face, on the other end at only 5500 RPM, not unless somebody shoved a potato up one of your header pipes :o

You're 60' is not good, are you spinning the tires that much, or does the car just not have the power to get you there any faster ???
With that motor, in that light a car with 4:10's, if you're hooking up, it should come off the line like a bull frog off a hot rock.
If it isn't ign. timing and it isn't valve timing and it isn't rocker ratio and it isn't valve lash and it isn't a carb thats way out and it isn't restricted exhaust and it isn't a vacuume leak?????

If I were you, i'd go back to the beginning, with an open mind (must have the open mind, otherwise you'll keep walking right past a mistake without ever catching it) and recheck the ign. timing the cam timing, check for a major vaccume leak, check that you really have the rockers you think you have, reset the lash, check the exhaust for restrictions, get another torque converter ! lol then if it's still falling on it's face on the big end at 5500 RPM I'm gonna have to ease over next to Dark_5.0 and start questioning your heads, because there ain't much left other than that :(

Keep us posted, this is the kind of thing we all learn from. It's just to bad it has to be from your misery :(

Rod

Re: Thinking of a cam change
 

Your mph tells the story a 10.5 to 1 351 with decent heads and cam should be going about 5-7mph faster than you are.

Ive been there man I had my stock heads ported,polished.milled, bowls blended valve springs etc... and I was running high 13's. I went to a bigger cam and got lower gears and ran about the same. I finaly got some decent heads and picked up 5-6 mph and now run in the 12's in this crappy altitude.

Re: Thinking of a cam change
 

I don't get any tire spin off the line. It just doesn't leave hard. The fact that I only get 2000 foot brake of stall speed doesn't help either. I have a 3000 stall converter that was loaned to me to use.
I did find out Saturday that my friend, who sold me the 750, installed a 37 shooter in the carb. I think that's too much for my application and would like to try a 31 or 33 shooter. It may be the reason my one friend said my car appeared to be bogging.
So, I do still have some carb. tuning to do but I doubt it's going to net me 3 tenths.
As far as how the car feels throught the traps at 5500, it just feels flat to me but who knows? I've had the engine up to 6500 rpms before on the street in 1st and 2nd but I think I was way beyond the power band.
There is a guy on another forum, that I visit, that owns a dyno jet and has the same cam I do on his 393 stroker and he said the 274XE cam made 385 hp at the wheels. That's with aftermarket heads and higher compression that I have. So, it may be very well that I'm running out of power at 5500 rpms.
But still, I guess that proves that this cam is good enough to run 12's.
I guess the only thing to do now is try the 3000 stall converter I have and tweak the carb. some more.
Hell, I'm ready to try putting the car in neutral after I'm staged, rev her up to 5000K and drop it into 1st and see what happens...provided I don't scatter tranny parts all over the track :D
That would tell me if the engine wants more stall speed....right...in theory???
As far as valve lash, I have rail type rockers and the book said to tighten the nuts until there is drag on the pushrods and then torque to 24 ft/lbs. They are non-adjustable
I could also forget the 60' times and just install a NX Hitman system that would drop my E.T about a full second and have a low 12 car.

Re: Thinking of a cam change
 

I think you should figure out your problem...so you can install the nitrous and run 11's.

Have you looked into your timing at all? Have you put a timing light on it to see if it is advancing?
Ryan

Re: Thinking of a cam change
 

Yeah, I pretty much have the timing sorted out. It's set at 34* total all in by 2500. Yes, it does advance.

Re: Thinking of a cam change
 

Yeah, a mild 100 shot of nitrous at the correct pressure via a bottle heater, would probably get you into the 11s now. But it's your 60' that is killing your time right now. Ever thought of getting a transbrake? I know that can cost some bucks...but if you could launch at 5,000-6,000 rpms...you'd be turning 1.7s or 1.6s coming off the line...which would obviously put you into the 12s.