I just bought a set of vortec heads and now it's time to pick a cam. I'd like to get a hydrolic flat tappet cam for the following combo:\

67 Chevelle
1972 LT-1 350 block bored 30 over
1 5/8 headers
Edelbrock 600 CFM Carb
355 gears with 5 speed
Mallory Electronic Ignition

I have not been into the engine yet, but its a 1972 LT1 and I'm guessing it has flat top pistons. The car will be a street strip machine and I'd like a streetable cam that will rev up to 5,800 or so. Cruising at 65 MPH I'm at 2,000 RPM so the cam will need to have good power at 1,500 and above with my overdrive tranny. I don't mind a lumpy idle but I don't want the car to shake too much if you know what I mean. I'd appreciate feedback from anyone with experience with a similar set up.

Thanks!
tongue.gif

Imho, a good old CC 260HE or 268HE will do you nicely..

Nothing fancy....

pdq67

UDHaroldr recommended the UD276H10 for my 350, basically the same bottom end as you and vortec heads. It performs very well with just a bit of a lope

I'm runnin a Comp Cams 268H (.218 dur. at .050 and .454 lift) with a set of Vortecs on a 355.

It think it could definatly use more cam. I'm seriously considering a swap to the CC 270H or the 268XE.

Don't get me wrong the car pulls hard with the 268H, but I think a little bigger stick would help.

Dwayne

I would use the XE 262 if you went the extreme energy route. 218/224 @ .050, 462 / .469

UDHarold has pointed this out as well, if you go to the comp site and look at the their XE dyno graphs. You don't gain using the 268 cam. Infact on the 350 in the dyno test the 262 cam made a few more ponies and had a slightly better torque curve. And the 268 cam will lower your dynamic compression over the 262.

I've used the 262 and with my old 9.5:1, .7quench, pig rich, unbalanced, plug fouled 350 it pulled pretty damn good! Ran 14.0 @ 98 in that condition 3750lb car w/ me, stock converter with a 700R4 on it's way out. Heads were a 416 casting with 202/160 valves. Vortecs are to be much better.

Just my .02

I put one together with an XE-256 and Vortecs. In a lighter car the cam really is too mild but in a Chevelle it would work great. Mine pulls fine to 57-5800 with a Q-jet.

Go with the XE series, or similar asymmetrical grind from Lunati or Crane or whoever you prefer. The Vortecs have all this killer intake flow, but the same sucky stock exhaust flow as about any other stock heads. They NEED the bigger exhaust lobe.

I know several cars in the 11.90-12.30 range with Vortecs and the XE274. Is it the best cam for the heads? Who knows, its certainly been proven time and time again to perform though.

Thanks guys for the input. Lots of choices I see? I sent in a request for recommendation to Comp Cams to see what they say. I'll share with you what they recommend. What kind of quarter mile times do you think I would expect with the XE 274 cam?

Well, If you want the best performance out of the XE274 you're gonna need to have a stall around 3000-3500RPM. 3.55 would work but 3.73-4.10's would be better, Gotta get rid of that 600cfm Edelbrock. And you're going to have to spin the motor up a little higher than you want (probably a wee bit above 6000RPM) I see you dont quite know whats in your motor so you don't know the compression ratio... I'd aim for at the bare minimum 9.5:1 with the XE274.

Now considering you do all those things along with the head/cam, depending on weight, you should have no problem being in the 12.40-12.80 range. Keeping everything the same, maybe low 13's?

Broke,

Stall will not be a problem... I have a 5 speed. I choose the 355 gears because the 1st gear of the TKO 500 is very steep. Anything over 355's would lead to a very quick 1-2 shift (like a dump truck). As it stands now I shift at 37 MPH running up to 5800 rpm.

After looking at the dyno graph I see what you mean with spinning the motor up past 6,000 to get full power. I'm a bit concerning in going much past 5,800 as I did not build the motor and can't tell you what's in there. Would 6100 RPM be pushing a stock bottom end?

I'll probably keep the 600 CFM carb until I get everthing else installed and then check at WOT with a vacume gauge. If I need more carb I'll step up to a Holly 750 Vacume Secondary. I hear this is a nice carb for my intended application (mostly street use).

I spoke to Andrew at Comp Cams today and he is recommending the Magnum 286. He tells me that the XE series cam will build too much compression for my combo and detonation will most likey result. This recomendation was based on my guess of 10 to 1 compression with the 64 CC vortec heads. Without knowing what pistons are in my block, I'm left guessing at the CR. Would it be best to take the heads off and look before choosing the cam. From what I've read the 64 cc head will produce around 10 to 1 compression with flat top pistion. But I've also read that some folks are using the XE cam in similar set ups with no detonation problems. I'm really confused now? :confused:

I am currently running COMPCAM XE 274 and this is my own personal track experience. The XE 274 cam itself will not guarantee you 13's or 12's, the truth of the matter is that every engine is different and some cars will work great with 268 XE or other cams. Pretty much any cam with a 230 and higher duration you will need at high stall at least 2500 RPM's and heads the have small runners and good flow somewhere around 260. The 274 XE cam sounds similar to the 280H and both are peformance cams, but it is suggested high stall, 650 cfm carburetor, and good exhaust.

With the help of people like Pat Kelly I was able to get my car running 13.2's at 106 MPH with a 60 foot time of 2.0 best. Performance wise I think your combo will be a great street machine. 12's for a small block is hard let me tell you, espically a 350 or 355.

My advise is don't get caught up in all the times people estimate for your car, because I think most of it is crap and chances are it will not be to your expectation but your combo sounds like it will be a damn good street machine graemlins/thumbsup.gif

I wouldnt quite listen to Comp Cams detonation theory. Yeah, every motor is different, but I know cars running as much as 10.8:1 with Vortecs and the XE274 running perfect on 93 octane pump gas. The 3-4 cars I know running this setup are all in the 3300-3600lb range and they're ALL 12.6's or better.

With 1 5/8" headers your powerband should come down a little so you'll probably be fine only spinning to like 5800-6000RPM. XE274 also has a pretty clean idle - Hardly noticable to the untrained ear with the idle RPM turned up a bit.

The thing I hate about Comp Cams (or any other big cam manufactorer) is that everytime I call them and talk to someone else about recommendations, they give a different recommendation.

Yeah, I hear ya. Depends on who answers the phone I guess. I'm going to choose between the Comp Cams XE-262, 268 or 274. Can anyone tell me what the CR and DCR will be for these cams assuming I have stock flat top cast pistons, 64 CC vortecs, and .041 head gasket. I'm certain the block has been rebuilt, so assume a .030 overbore. I'm looking to stay at 8.25 or less on DCR so which cam will get me closer to this goal?

" XE274 also has a pretty clean idle - Hardly noticable to the untrained ear with the idle RPM turned up a bit."

Are you serious a cam with .480/.490 lift with aggressive valve opening and closing has a hardly noticeable idle? Maybe in a 454 big block but you will hear the cam very well in a small block even a stroked 383 guaranteed! The XE274 is a great PERFORMANCE cam with a noticeable idle!

Again the RPM range for the 274 cam is 1800 - 6000 but it will almost always depend on your heads and CR and DCR, ask PAT KELLY. That being said your torque curve maybe 2000 - 6000 and thats perfect for a street vehicle, my car which ran 13.2 with a bad 60 ft time power band is 2800-6400 which is not ideal for street even though it is 100% street driven. I have to compensate for this by a 2800-3000 stall 10 inch converter. If your want to get into the 12's or whatever then you will be purchasing yourself a 3000 or so stall with a small block because SB don't have the low band torque that BB have so SB have to be rev up!

posted by Spawn22: If your want to get into the 12's or whatever then you will be purchasing yourself a 3000 or so stall with a small block because SB don't have the low band torque that BB have so SB have to be rev up!Believe it or not i have seen 350's run into the 12's on a stock converter and something like 3.31 gears. One that I know of also had a mild cam that idled like a stocker BUT it had great heads. This was in a late model Malibu.

Rod

With the bigger head gasket, assuming you are .025 in the hole, and 64cc heads, the XE 262 will put you closest. Followed by the 268 then the 274. Bigger the cam, lower the DCR.

This is my DCR calculator specs using a .015 Head gasket.
Bore: 4.030
Stroke: 3.48
Rod Length: 5.7
ADV Intake Closing Angle: 61
Dynamic Stroke Length: 2.79
CC: 64
Head Gasket: .015
Head Gasket Bore: 4.1
Deck Height: .025
Flat Pisons: 8.65 (4 reliefs)

Quench: .04
CU IN: 355
Static Compression: 9.96
Dynamic CR: 8.19

Don't get me wrong I am not saying a small block can not get into 12's because
I have seen small block run those time a couple in our club, but none with your
friends or a friend of a friend set-up. a small block run's 12's with a stock stall
1800-2000 RPMs and gears lower 3.42 and assuming this is all motor and no Nitros or
superchargers than I don't see happening and I guess I would just have
see it. I am assuming that the cars you are referring to have slicks? Anyhow
I believe that a smallblock that runs good you will hear it with the exception
of stroker motors.

Heads are important and the most critical factor in determining performance, but if
you have a high flowing head then it is useless with getting into the High RPM
power band. So my question is what is the exact times your friends are running because
if they are running 12's with stock converter and pretty much stock gears then how are
they getting good 60' times?

Spawn:

I see lots of car with nice 350 motors running high 11's with 3.23/3.42 gears, 2600+ stall, and drag radials with 1.6-1.8 60ft times.

It's doable. If your setup can put out the horsepower.

The XE274 and vortec heads runs 13.50's in my sons 355 powered 81 chevy peekup w/3.73 gears...and his best 60ft is 1.94....so I'd think you could get in the 12's easily with traction and something a little more aerodynamic smile.gif


posting from Glade Park,Co....Gods country in the middle of nowhere smile.gif

Originally posted by Spawn22:
Don't get me wrong I am not saying a small block can not get into 12's because
I have seen small block run those time a couple in our club, but none with your
friends or a friend of a friend set-up. a small block run's 12's with a stock stall
1800-2000 RPMs and gears lower 3.42 and assuming this is all motor and no Nitros or
superchargers than I don't see happening and I guess I would just have
see it. I am assuming that the cars you are referring to have slicks? Anyhow
I believe that a smallblock that runs good you will hear it with the exception
of stroker motors.

Heads are important and the most critical factor in determining performance, but if
you have a high flowing head then it is useless with getting into the High RPM
power band. So my question is what is the exact times your friends are running because
if they are running 12's with stock converter and pretty much stock gears then how are
they getting good 60' times? It's OK that you don't believe my statement. It's your perogative. graemlins/waving.gif

The combos I speak of were built for lower rpm torque so "High rpm" as you say was not necessary in order for them to produce mass moving power. Yes, they were on slicks or BFG drag radials and they were not trying to do it on a hard, stiff, road racing suspension. They were on all motor.

I'll leave it that because I'm not the type of person who's going to argue the point over the internet.

Spawn:

I see lots of car with nice 350 motors running high 11's with 3.23/3.42 gears, 2600+ stall, and drag radials with 1.6-1.8 60ft times.

It's doable. If your setup can put out the horsepower.Weight is key too. That ain't gonna happen in a 4000 lb Chevelle ragtop or something like that (unless we are talking about using a little spray). Now a 2900 lb Chevy II? Sure! smile.gif

BTW, There are lots of LT1 (93-97) f-bodies running in the 12's with this sort of combo (maybe a bit more stall). They are still 350s, even thought they have reverse flow cooling.

Rmchevelle

Yo man I am just trying to make sense of what you said, please understand that when someone post a topic or statement like my friend runs 12's all day and have a stock converter with some non performance gear like 3.31's and the only modification is heads then someone should questions the source of your statements. I don't care if you don't want to argue or not that not what I am about either, I just believe that its more to your friends motor than you know. I basically think you leading someone to the wrong conclusion because lack of information.

Twilightoptics- mentioned sixty foot times which at least give someone the ideal of if its a dead hook or not, I think its necessary information that the person who started this topic needs to know. I sixt foot time of 1.6-1.9 is really darn good if you ask me.

Going back to the orginal statement of vortec heads and 274 cam I think it can be a sweet street machine and the time will vary depending on chassis and suspension, stall and other factors. Overall I think it will be a great street machine that will be a blast to drive. I think we can all agree on that!

Originally posted by Spawn22:
Rmchevelle

the only modification is heads then someone should questions the source of your statements.I don't remember saying the ONLY mod was the heads. I DID say it had a stock converter. I also said it idled LIKE a stocker but NO where did I say it WAS stock. When I said mild cam I meant a mild aftermarket cam. Just to clarify: '79 Malibu, 350 +.030, TFS heads, small Delta Cams hydraulic cam, TH350 trans, STOCK converter, 3.23 gears, 7.5 rear, 16" Drag Radials, rebuilt but stock suspension, 12.80 E.T.'s.

My original point is that you don't need a 3000 rpm conveter to do 12's with a small block.

Sorry to the original poster of this topic for getting off track. Build it for torque!

I realize my car is not as heavy as a Chevelle, but with stock 3.23 gears, a 2800 stall speed Vigilante Converter, stock LT1 shortblock with a Comp XE 224/230 roller cam and ported stock heads I run 12.20's all day long at 110mph. Car is incredibly consistent too. This is a fully optioned Trans Am with no weight reduction done at all.

I have 3.73s in now looking for 11s, but have not had a change to race it again yet. I was running 12.90s with a smaller cam and a whole lot less cyl head 2 yrs ago as well. Big blocks and big gears are far from necessary for 12.99 timeslips.

:D

Hmmm...I'm going to have to dig up our cam specs. We're running a 355 with Vortecs and a Holley 600, 4spd, and 3.73 rear gear. To date our best has been a 12.5ET. My brother shifts at 5800RPM. If he revs it more than that it goes slower.

I know the lift on our Comp Cam is .050 on both sides.