Let's talk cams/top ends

I know that this topic is probably the one talked about the most but I'll re-hash it.

Ok I have a 68 YC 400 in my 68 Firebird. It has #16 heads with a 3 angle valve job and bronze guides. I'm running an 068 grind cam currently along with a cast iron intake and a rebuilt Q-jet. Other than a Pertronix unit and a set of Hooker headers, my motor is basically a stock rebuild.

The car has an M-20 4 speed and a set of 3:55 gears with an Eaton posi unit.

The 068 is a nice cam but I believe the motor deserves more. I'd also like to add a little bit more lope to my idle than the 068 offers. I think I can get a little more power out of this motor with a more aggressive cam. It's February and I think a cam swap before cruising season is in order.

What aftermarket cams are you guys running? I'm not looking for anything radical as I have power brakes and don't want to give up vacuum or lose streetability.

I've heard good things about Comp's XE series of cams but don't have any real world feedback.

Let's hear from the experts....  

hello

i have a lot of experience with the xe series cams and like them a lot, many others here prefer the lunati equivilant. they all have more experience with pontiacs than i do.

you sound like one of those "i want my cake and eat it too" kind of guys [don't worry i am too lol]. You want good performance and good vacuum unfortunately those two terms are usually mutually exclusive.

You can search the cam specs on compcams.com and lunatipower.com

The next step up from your 068 cam in the comp series is probably an xe268h and a 60902 in lunati. lunati specs below. any thing bigger like a 274 will be too big too have adequate vacuun at idle for your brakes. it is just a bit nasty but i like this cam.

   * Advertised Duration (Int/Exh): 262/268
   * Duration @ .050 (Int/Exh): 219/227
   * Gross Valve Lift (Int/Exh): .468/.489
   * LSA/ICL: 112/108
   * Valve Lash (Int/Exh): Hyd/Hyd
   * RPM Range: 1300-5500
   * Includes: Cam Only


Cam for cam the llunati should have more vacuum slightly smoother idle more bottom end and softer, smoother acceleration feel than an equilivant comp. the comp xe268 idle will noticeable but not obnoxious. the comp xe cams hit harder not than their lunati equilivants.
 
WARNING - I could be slightly off in the comparisons. i know what the 068 specs are but never used one. others here can probably give you better advice. the cam specs are sometimes deceiving and difficult to interpret.

check out the recent "camshaft for my 428" post by chris_austria from 4 weeks ago. it has an enormous amount of cam specs and comparison info. once you get clear of the confusion from that i suggest you just throw in whatever the most popular suggestion is here. probably one of the two i listed. lol

all in good fun.

thanks  

I had a 268 in my automatic 406  it had a distinctive lope but went into gear smoothly and had good vac for power brakes. It was perfect for the auto,but of course I wanted more lope and more power. I put in a XR276HR-10 a roller. Not much more lope but low vac for power brakes at idle. Ok if your moving even 10 mph. I like the idle low so it drops in gear smooth 550. In a stick with the idle higher it might be ok?  Hope this helps you.  
Drive it before your dead!

hello formulajim

did you have a stock intake or an aftermarket one? my computer dyno says he won't gain much by doing that unless he improves his intake since it is stock. you definitely couldn't do this on a ford and realize a noticeable increase in hp but of course it isn't a ford.

PS yes rollers are definitely king if you have the money.

thanks  

Comp Cams has a free download "camquest".,. you plug in all your numbers and it recommends suitable cams.

http://www.camquest.com/

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

Maybe you should think of a 270H from Comps.. shouldn't be too big for your engine but it has a noticeable idle and will make good power.
The 268XE will be smoother and will make about the same power I guess, maybe with a little bit more vacuum if you need it.  

hello

Here’s another consideration. It’s been claimed by some that the xe series can sound a little louder than other cams mainly at idle due to the valves slamming closed so quickly due to the ramp design or because comp is running hydraulic flat tappet lifters on such steep ramps. I never noticed it myself on xe268h or smaller cams. A little on the xe274 though. These comments were on gm cars I used them on fords.

LIFTERS

I quit using all comp lifters, I had problems with their flat tappet and hydraulic lifters. The bottom surface of the flat tappets looked like they had been drug across the driveway. I sent sets back but received the same problem in return. I also had a problem with the internals not sealing on the hydraulics. They just spit oil out the push rod like old faithful geiser and wouldn’t open the valve properly. Big lifter tick also.

I switched to crane high rev hydraulics, never a problem and shiny as smooth as glass on the bottom.

Comp's other series don't have this problem and supposedly neither do lunati or isky etc.  

468 my car has performer RPM. Sealed power forged pistons 670 heads unswroded to 80cc 9.5:1 comp. my car isn't louder I put flow master 40 series mufflers it's still to quiet. It's got a 2400 stall converter too.  
Drive it before your dead!

gmw68bird and formulajim

jim your motor set up sounds killer. WOW, That's unbelievable about the sound though. i guess if you have the original 40 series and not the flow technology 40 series than the next step up would be the round flowmaster straight through outlaw series or dynomax straight through ultra flows. or just run straight pipes. your xr cam is probably quiet due to the roller lifters and/or cam profile.

i still think his stock intake is still going to limit him from seeing a significant improvement over the xe268h plus his vacuum requirement for p/b

thanks  

oops  

gmw68bird

someone else just posted a header recomendation question. perhaps you coild tell him exactly what yours are ie comps or supercomps and if you had to hit them and dent them to make them fit!

thanks  

Hope someone can enlighten me on my 74 TA cam Choice.  I have a 74 TA that has the following:  Factory 3.42 gears, 4 speed, Rochester 750 cfm w/vacume secondaries, Edelbrock Performer intake, Summit HEI blueprint distributor, Hooker 1 5/8" ceramic coated headers complete with x pipe with 3" Collector and 2 1/2" Exhaust out to the tailpipe, Comp cam 1.52 Roller tip Rockers and factory 4X heads. The car has power brakes and came from factory with NO air conditioning.

I am going to install a Cam this spring.  I have two new ones.  

One is a Comp Cam with a LSA of 110 degrees, 218° duration on both intake and exhaust with .454 lift on both intake and exhaust.

I also have a Crane Cam with 114° LSA and .458 lift on intake and .473 lift on exhaust.  Duration is 226° on intake and 234° on exhaust.

The car is going to be used as a weekend warrior with maybe an occassional trip to the strip.  Its not a grocery getter.  What are your opinions on these two cams, and which one would you use with the combination above.  Other than the modifications to the engine, the car is completely stock and has only 56000 miles.  

Hello bradshdj

This might have been better for you posted as a new topic. you would recieve more suggestions that way. it's not too late to do that.

1.It really depends on what you want so more info would be helpful.

2. Do you need vacuum for pb?

3. Do you want a rough or smoother idle?

4. What is the other code on your heads 1h, 3h, 7h, 4c, etc. this will help determine compression?

5.What size is your motor, it’s 40 years old so who knows what someone might have stuffed in it by now?

Your comp cam is a 268h, 1500-5500,  the crane is an h-288-2, 2400-6000 rpm. I can’t find crane valve timing specs. My guess is the intake valve closes late.
There is not enough info without these valve specs to speculate on idle vacuum however by their rpm range the comp has more idle vacuum if you care.

The comp will be pretty mild, the crane is as large as you might want to go especially with your gears.

Always look at the rpm range and performance description of the cam. No matter what the specs say this is the easiest way one can compare the difference in performance between different cams. When the cam mfg says it starts at 2200 rpm they mean it and 2200 is near the fringe for a moderate street car. 2400 would be max with your gears.

Don’t be committed to either cam. You can buy another cam that’ might be better suited for you and sell the others on ebay for $100.00 easily.

All this info is on their online sites.

Hope this helps.  

I'm no expert but I'd pick the crane and put in a billet roller timming chain. A cheep chain stretches in about  two weeks and your timming jumps around causing poor performance. Cam timming makes all the diferance in hot motor or not. Read all you can and make a informed decision. I've learned a lot from the experts on this forum,cam choce is the tuffist  thing for us non experts. Read all the threads on this website and you'll learn a lot!  The price of a cam is cheep so put in one that is best for your car, the work is the hard part and having to do it over is a pain!!!  Jim  
Drive it before your dead!

OK I had a busy week so I wasn't able to log on until now. Yes I have the factory cast iron intake but I'm not married to it. If I'm tearing into the motor to swap cams, I can always slap on an Edelbrock Performer RPM intake too. This car will NEVER see a track as I have way too much time and money invested into it to risk any kind of damage. Not to mention that I haven't raced the car since I was 19-20 when I used to street race illegally. I'd be afraid of blowing my clutch or worse...

Basically it's a weekend cruiser that sees cruise nights, some car shows, and frequent trips out with the kids to grab ice cream in the nice weather. Personally I just want to add a little more lope to the idle because it sounds badass. I actually like the 068 cam with my combo, but I feel like a slightly more aggressive cam might simply make the car more fun to drive.

I have Hooker Super Comp's and they fit fine with no clearance issues.