[68azbird]

FWIW the smaller bore of the 350 is less prone to detonation. Not saying it can't happen but not like in a 400 - 455

[ponyakr]

The XE 274 cam is a bit bigger than the RA4 above .050 lift, because it has a very aggressive ("steep") ramp, and more lift. And I know for a fact, the RA4 cam is a bit nasty in a 350, without Rhoads lifters.

So I would not try to run the XE 274 in a street 350. That's just my opinion, and that's all I'll say about it.

[ponyakr]

Originally Posted by BubbleTops

I seen a pic of the pistons they don't have the black coating on the skirts so I assume they are the cast version. They are flat with dual valve reliefs as i said earlier.

The old TRW L2339F forged pistons did not have the black coating. But the part number and oversize should be stamped on top of each piston, whatever brand they are.

[Cliff R]

The XE 274 cam is a LOT smaller cam than the RAIV. RAIV cams have 308/320 seat timing and 113LSA with over 80 degrees overlap. A 350 build, even high compression isn't going to fair well with a RAIV cam in it. Even in the real RAII and RAIV 400 engines they REQUIRE a lot of gear and converter to be effective. I get more complaints from folks who have installed the RAIV cam in 400 engine builds than any other.

I have next to zero experience with Pontiac 350's, as we skip right by them and build 400's, 428's and 455's. Even so, I've built GOBS of SBC 350's over the years, and typically use cams around 214/224/112 in them at 10 to 10.5 to 1 compression.

My two favorites are the old 327/350hp cam and the newer LT4 "Hot" roller cam. Both are a home-run in 355 SBC builds provided you have at least 10 to 1 compression, tight quench and good flowing heads. A Pontiac 350 build wouldn't stray to far from the same cam requirements. The Pontiac 350 has the disadvantage of much heavier internals and smaller bore, so it's not going to run with the SBC trying to do the same thing. I'd still cam it appropriately for the CID and static compression ratio, and the XE274 would NOT be on my list as a cam choice for one.....FWIW.....Cliff

[steve25]

Do not forget in terms of compression that a stock what we call 350 is really 354 cid!

[Formulajones]

Like Squidward said, I'd talk to Glenn. If you're local to AZ here, then hit one of the pontiac monthly races and have a face to face with him.
Get your answers right from the horses mouth that built the engine and see if he can answer your questions as to why he did this or that. If you are satisfied with what he has to say then run the engine as is and see how you like it before you go spending more money. You can always change things later if it doesn't perform to your liking.

[PunchT37]

Originally Posted by Cliff R

The XE 274 cam is a LOT smaller cam than the RAIV. RAIV cams have 308/320 seat timing and 113LSA with over 80 degrees overlap.

Thank you. Big difference on seat timing. Can`t build cyl. pressure till both valves are closed.

The Pontiac 350 has the disadvantage of much heavier internals and smaller bore

It does but, it has a better/fatter torque curve than a SBC. So, it can do what the SBC does on the STREET better with less gear in heavier cars.


While the whole Comp XE line is not my favorite, the 274 is one of the better ones. 274 degrees on a 230 at 50 lobe will still have a rough idle but, not as bad as some might expect. It all happens in 274 degrees so it has a "smoother" idle and higher vacumn than most other 230 lobes with longer seat timing. And, he already has the cam.

As I said earlier, he will need 3.73`s or at least 3.55`s to use it well. And in post 16, that 340 ran well with that cam. Rough, but not that bad. Lots of mid range as one would expect.

[PunchT37]

Once again, the higher compression will save the day. How many here build a 350 with more than 7.5 to 8.5 to one compress? Not many. And they run 2.78 gears in a heavy car with no extra stall. 90% of the 350`s are built that way. No wonder a cam larger than 204 to 214 at 50 hurts them.

Build a SBC that way and see what a nutless wonder you will have.







A `67 Firebird with a Pontiac 350, with a 4 speed and 3.73 gears, that 274 cam, 13 heads, factory intake with Q-jet, or regular Performer intake with Q-jet or 650 Holley DP would be a fun drive that would surprise many. Maybe a Performer RPM with the "larger" cam.

[ponyakr]

So, there you have it. Typical cam debate. Some say don't use it. Some say it would be great.

So, the only way you'll know for sure what's best in your car is to run it, and then run something a little smaller and see the difference for yourself.

Then you can report back to us with the results, to help somebody else down the road.

One thing is for sure, there are enuff people who love these 274 cams so that you will have no trouble selling it, in new condition.

[77 TRASHCAN]

Originally Posted by Formulajones

Like Squidward said, I'd talk to Glenn. If you're local to AZ here, then hit one of the pontiac monthly races and have a face to face with him.
Get your answers right from the horses mouth that built the engine and see if he can answer your questions as to why he did this or that. If you are satisfied with what he has to say then run the engine as is and see how you like it before you go spending more money. You can always change things later if it doesn't perform to your liking.

X2,
Until the volume of the chambers are known, what the deck height is, it's all a waste of brain power. Would be nice if it had forged pistons, but will still be a good runner w/ a proper bore/hone job on a new build.

Could still run nice w/ correct parts...

[chiphead]

I had the XE256 in a 9:1 350 and the XE274 in a 9.3:1 400. Short answer is the XE274 is WAY too much cam for a 350 without a big stall or 4 speed and 3.73 or deeper gears. No way it would work power brakes. Higher compression may yield more detonation than power.

The XE256 in the 350 ran pretty good. Stock converter and 3.23s would run mid-14s in a 3700lb Lemans. Street performance was solid. It wanted just a bit more gear or converter but I was happy for what it was. It did detonate out the head gaskets when I advanced the timing beyond 36 degrees with 93 octane.

The XE274 was lumpy in my 400. I can't imagine it in a engine 50 cubes smaller, as it is 3 steps larger than the XE256.