BBC cam selection

[Bill Eveland]

Hi, I'm working on brothers 454, 81 Camaro, and were changing the cam.
How similar are Pontiacs to BBC for cams, were putting in a 2800 stall, 3:42 Posi rear end, headers and was thinking of using the Comp XE274. Anyone use this cam in a BBC?. Thanks, Bill.

[mrrat1]

In my LS-6 I used the L-88 cam, matching springs,titanium retainers, ordered from GM High Performance Catalog. Runs like a bear. I have to dig for specs if you want them. Dave K.

[Skip Fix]

A friend made 550HP with a Comp 294-S with factory rectangle ports and intake on a 454.

[Mr. P-Body]

We've used the XE274H in BBCs. It does act simlar to the Pontiac when used with oval port heads. Rectangular ports need more cam, such as the L-88 grind mentioned. It's very "dated", but still a good one.
Rectangular ports also need more gear than 3.42. They tend to make no power at all until over 3,500 RPM. You could consider one of the solid versions of the XE grinds.

Jim

[JSAauto]

Bill??

What are the specifics of your engine? Compression, heads (alum or iron and which aluminum head) usage, etc. Is this a 454 or a 468? Makes a big difference in the power since a .060 overbore BBC unshrouds the valves alot.

Typically canted valve Chevies enjoy a wide lobe center because of the valve angle arrangement. Be careful not to overcam a Rec port motor as you will loose a ton of velocity (power) down low in the RPM dept. The rec port motors DO NOT require as much camshaft as the comparable oval ports in a moderate street application and do not make the same torque numbers lower in the RPM band. It's really easy to overcam a rec port set up for a street/strip motor. And unless you want to be spinning your BBC at speeds over 7000 rpm, I'd concentrate on making as much "low end" power and trying to keep the velocity (air speed) up in the cylinder heads.

The XE274 is almost exactly the same cam we use on our oval port/street combos. 9.5 to 1 compression, mild stall around 2600-2800, but we put them on a 114 lobe center. Although the 110 lobe center will be more "peakish" in power, the 114 lobe center will allow the car to behave really well on the street and have a much broader power band. Now if you're not concerned with street behavior, then get the XE274 and install it at on a 102 intake lobe center. The thing will be explosive out of the hole with a 3000 converter, oval port heads, and the show will be over at around 6000 rpms.

For rec port motors, to make some REAL POWER we prefer more compression (11.5-12.5) and like this Crane camshaft #H-262/353-2S-14. It's basically 322/330 adv duration, 262/[email protected] duration, and .600/.615 lift on 114 degree lobe centers. But would require more converter and more gear to make work. But hold onto your socks!! This mother will put you in the seat like nobodies business.

It just really depends on what your going to be using the car for primarily and what components are you running (i.e. heads, nitrous, etc.)

[JSAauto]

Skip... you should be able to make that number with much less cylinder head (i.e. oval port) and the same cam and end up with more torque down low in the RPM's.

[Bill Eveland]

I've been so busy, I almost forgot about this thread.
I don't know too much about the engine, it is a rectangular port head, there has been some work done to the heads including machining them for the plastic looking valve seals. It also had a steel crank. I went thru the engine 3-4k miles ago, had to have the rods all resized and crank turned etc... but now my brother wants to step it up a few notches.
It has a performer cam, don't remember the intake -maybe TII. I don't know the compression either . I'm thinking 9-10: 1 .

[Skip Fix]

I know the oval ports are a better street strip head. This was on a VERY conservative dyno.It usually reads the same HP as the Moroso slide says for the weight and mph. Enough to get himin trouble for norollbar in a heavy ragtop 69 Camaro(lotsof factory subframe bracing.

I'll keep that cam in mind and compression ratio for when I ever get around to using my Bowtie Rectangle port aluminum heads.

Used a Crane 310/320 F-Nitro solid cam in my old 409 Impala years ago that performed well, with the 250/260 @ 0.050 and .580/.590 had a pretty rowdy idle,didn't smooth out til 2000!

[JSAauto]

Bill....

What are you plans for the car?? Street? Strip?? Both?? What kind of performance are you trying to get out of this?

For the street, something around the 230-240 range @.050. Single pattern, no split because you have such big heads with low compression and small cam. I'd look for something around .550 lift and on 114-116 lobe centers. That way this thing will still make power down low and behave nicely on the street. Look for a Victor Jr. and a Holley 850.

Get rid of those teflon valve seals as they will suck oil in no time. Have someone install some viton seals. Much better for the street.

Did you say this was a 454, 460, or 468??

If you want help with the set up, once you get the specifics about what parts you have and final compression, call me at the shop.
(818) 772-1737

[Bill Eveland]

460 .030" over. I went thru the engine because of a rod knock. The rings and main bearings looked great, but the rod bearings and crank journals didn't. The backside of the bearings didn't look like they were making full contact, thats why I had them resized. And the champers?spelling - were opened up and rough but cleaned up with having the crank turned.

Teflon-viton? I don't know, but they were a real PITA with those springs on the seals to install. They were white and had metel springs on them.

Just building a hot rod, I'll have to step up my car now LOL to keep up with my brothers. This may seem some track time, he still needs subframe connectors and at least some slapper bars etc.. for traction.

[Bill Eveland]

I found out these are oval port heads, it's been awile since I did the engine.
I'll probaly go with the xe284h 240/246 at .050" , .574/.578" lift. But how do I change the centerline to a 112*, or should I just leave it at 110*?

[Skip Fix]

Only way to change lode sep is to have one ground that way.Although Comp has the same cams in the marine and tow/pull section with wider lobe seps.

[Bill Eveland]

They had 4 x 4 cams on a 111* and marine at 112*. How much of a differance would those actually make opposed to a 110*. The engine had an Edelbrock Performer which was on a 114* cl.

Also with the bigger cam change, what do I need to do as far as a Power valve in his 3310 carb(750 vac sec) so it will idle and respond correctly?

[Skip Fix]

1 degree isn't going to be much change, hard to even see on the degree wheel. You can have Comp grinf it on a 114 if you want. Still be cheaper to order the custom ground from someone than getting it direct.