[95ramairformula]

I just picked up 73 Firebird with 3.73 gears/4speed with a 1977 400 motor with 6x4 heads.
I have Hedman headers, full exhaust. The 400 engine is .060 over with a 60916 Crower cam. I bought the whole car for 2500. The car runs really good but seems soft in the lower rpms to about 2500 rpm then pulls good. I have heard alot about the XE262 cam from Compcams. Would that be a better choice than the what I have now? If you punch the car from a dead stop it will only spin both tires about 3 ft. Rev it to 2000 and drop the clutch it will fry the tires. Seems weak on the low end even at full throttle. The previous owner told me the compression was in the low eights.
Several friends say the the crower is to much cam cause of low compression. I agree,I know this cam works better with high compression.

Have not taken the car to track yet. I want to have a low 14 sec car. 13's would be even better.
Love the look of the 73, the nose looks mean! I am going to get a Formula hood for her, she already has a rear spoiler. Originally a 350 car.

[wilcar]

You might try a set of Rhoads lifters to give you a little more bottom end or advance the cam a few more degrees to help out the low end.

[69LeMans350]

hopefully Cliff R. will chime in here, because he's a very big advocate of the 60916 cam in the 400. He routinely gets 400hp with unported heads using that cam
The only thing is, all of his 400's using this cam have at or close to 10:1 compression. If you can get your hands on some big valve heads in the 72cc combustion chamber range, you'd be sittin' pretty with your current cam.

[1971WARBIRD]

be interesting to know what was done to the motor.mine that was just rebuilt is almost like yours.78 400 block bored +.030 trw pistons,with 6X4 heads.now mine was 0 decked and the heads milled alittle.when Dave did the compression he came up with 9.2.i used the comp xe268 cam.can't say how it runs as was just finished.

[Skip Fix]

I was underwhelmed with my 262 on a 6X-8 400. First one came with the last cam journal 0.001 to big. Second one from Comp(after I ate the shipping on the first one) fit but actually degreed at 270/278 instead of 262/270. The Summit 2801 in the replacement motor pulls just as good and has a slightly smoother idle, and my 262 was on a 112 LS.

[Will]

While the 60916 is definitely suited to higher compression I'd try to see if some tuning can't pick up the low end response.

Where's the timing set? What's the rate of advance? What kind of carb is being used?

Tuning can have a large effect on an engine's responsiveness.

Otherwise, I like the suggestions of using Rhoads lifters or replacing the heads.

How do you punch it from a dead stop with a 4-speed?

[Overkillphil]

In reading the original post and the followups I kept thinking "what about tuning", then I saw Will had finally mentioned it.

Before you start making major changes, the advantages of proper tuning cannot be stressed enough. The best combo in the world will run like total crap if the tuning is way out of wack.

These 6X heads like alot of timing, and you have to play with the curve. They like it early too. If the carb jetting and other air/fuel parameters are on the money, and the timing curve is optimized for that engine, you should instantly fry the tires and burn rubber down the road on the street.

A professional musician would not buy a new Martin Guitar, remove it from the packaging and play a concert without tuning it.

Tuning makes all the difference in most cases.

[Cliff R]

Right to start with, a low compression 400 engine pushing around a relatively heavy car isn't going to have mind boggling low end torque in the first place. This doesn't mean that it woln't make good power. Small cams that will produce the most ideal low end power will have the power curve end relatively early in the rpm range. It often becomes a comprimise between salvaging enough low end torque for good starting line performance, and still having enough top end charge to make decent mph at the dragstrip.

My opinion, the cam is a bit much for the low compression engine. Even at a solid 10 to 1 static CR, the 60916 cam will not delivery any real power below about 2500rpm's in the 400 engine.

The biggest cam we have been able to successfully run has been the Crower 210/221/112 grind in engines similiar to yours. Before running out and buying a new cam, I'd consider the Rhoad's lifters. Although they will do little above about 2500rpm's, they will realy "tame" the cam below 2500rpm's, and add significant power right off idle, and improved idle quality.

Keep in mind that some folks absolutely HATE the Rhoad's lifters, as they sound much like a solid lifter cam, with a noticable audible "clicking" at low rpm's. I've used them and don't mind the noise at all, and they are very easy on the cam. We ran a set of Rhoad's in our 455 engine for nearly 5 years and over 1200 track runs. When the cam was removed, it was in mint condition, nicely polished with no measurable wear anyplace. We gave the cam away, and it ended up in a fresh 400 RAIV engine!

We have never tested the Comp XE262 cam, but did run an XE268 grind in a 400 engine at apprx 10 to 1 static CR. I was not overly impressed with that engine, other than it idled nearly dead smooth, which was surprising considering the .050" duration numbers from that cam. The XE268 cam in the 400 we tested, made decent power, very strong mid-range, but power ended early, it was all done by about 5000rpm's......Cliff

[95ramairformula]

Will- I push in the gas and let off the clutch real quick, If i rev her up at 2000 + and dump the clutch she will fry the tires.

Looks like I need to stay with the Crower and try to tune the motor. Then if it isn't any better try some early heads.

[68FireBird]

I'm running the xe262 in my 68 Firebird convertible. 400, trw pistons, 6x-4 heads, 1.77 ex valves. It's got a TH 350 and a stock torque converter, 3.55 posi.

I was extremely disappointed with the performance when I had a Edlebrock Performer 750 cfm carb on the car. I switched to a Q-Jet from Cliff and the car really woke up.

It's been down the strip once (with the Q-Jet), and ran a 13.88 at 100 mph with a 2.25 60' time. I expected low 14's so I'm happy.

[95ramairformula]

Originally Posted by 68FireBird

I'm running the xe262 in my 68 Firebird convertible. 400, trw pistons, 6x-4 heads, 1.77 ex valves. It's got a TH 350 and a stock torque converter, 3.55 posi.

I was extremely disappointed with the performance when I had a Edlebrock Performer 750 cfm carb on the car. I switched to a Q-Jet from Cliff and the car really woke up.

It's been down the strip once (with the Q-Jet), and ran a 13.88 at 100 mph with a 2.25 60' time. I expected low 14's so I'm happy.

Those are good numbers. First post I have seen with 1/4 mile times with the XE262 cam.

[95ramairformula]

All
Its been a awhile since I posted and performance never really improved with the 60916 cam, in the low compression 400. I don't like the 3.73's and I am planning a change. Going back to factory exhaust manifolds and mufflers. No more headers. Exhaust will still be true duals.
I am taking a different route. Looks like I will be going to either 3.08 or 3.23 gears.
Looking at either a XE 256 cam or a Summit 2801. Which would be the better of the 2 cams. I beleive I can stay with the stock valve springs with either cam. Will these cams pull to 4800 rpm?
Remember low compression 400 with 6X4 heads, 4speed BW super T10 , 73 firebird as a Formula clone. Thanks

[vertbird]

If you're dumping the headers, try to get the Ram Air manifolds, they'll work better than logs for sure. Also I'd run the 3.23 rear.

As far as cam choice, you know how it goes everyone has their preference. My low CR 400 has the Crower 60240 that Cliff referred to. It's ok with my 2.73 rear, ram air exhausts, Cliff Qjet......running mid 9's in the 1/8. I'd like to try the XE262 for comparison but I've got other projects at the present. The XE series of cams, have earlier intake closing which helps build cyl. pressure for lower CR engines. Pretty much exactly what you're looking for. Negatives seem to be a slightly noisier valve train and a higher risk of wiped lobes/lifter problems. Loads of people are running the 2801 with good results, it's pretty close to the Crower I run. Both the cams you mentioned should pull to 4800, the 2801 will go higher.

Hope this helps some,
Garth

[speedshopmike]

skip, the XE cams are ground with 110 LSA, not 112.
your advertised duration check coming up bad:
at what lift did you check this spec?
crane and comp, for example, do not rate theri advertised duration at the same lift, so those figures are not comparable directly.
this is why the .050" lift standard is the standard - it gives a common reference point to check among different manufacturers.

pursuant to the XE series cams - as Will noted, they do close the intake early.
so, they make better bottom end then their duration would suggest, and sign off earlier up top, too.
the 262 won't pull past 5k rpm in a 400.
as noted by others, rhoads lifters work great.
however, HIGHLY recommend not changing lifters lifters on a used cam!!