Best Vortec Heads / Cam Package - Chevelle Tech
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  #1  
Old Jul 6th, 04, 1:00 PM
trimless trimless is offline
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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!
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67 Chevelle with 350 LT-1 (1972 vintage, Tremec 5-speed. 13.29 @103.5
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  #2  
Old Jul 6th, 04, 2:16 PM
pdq67 pdq67 is offline
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Paul
 
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Imho, a good old CC 260HE or 268HE will do you nicely..

Nothing fancy....

pdq67
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  #3  
Old Jul 6th, 04, 2:30 PM
blumont blumont is offline
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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
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  #4  
Old Jul 6th, 04, 3:42 PM
New68SS New68SS is offline
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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
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  #5  
Old Jul 6th, 04, 5:44 PM
Twilightoptics Twilightoptics is offline
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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
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  #6  
Old Jul 6th, 04, 6:32 PM
Mike Feudo Mike Feudo is offline
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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.
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  #7  
Old Jul 6th, 04, 8:38 PM
RB69SS396Conv RB69SS396Conv is offline
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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.
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  #8  
Old Jul 6th, 04, 9:02 PM
broke broke is offline
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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.
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  #9  
Old Jul 7th, 04, 10:59 AM
trimless trimless is offline
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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?
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  #10  
Old Jul 7th, 04, 1:33 PM
broke broke is offline
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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?
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  #11  
Old Jul 7th, 04, 2:17 PM
trimless trimless is offline
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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).
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  #12  
Old Jul 7th, 04, 2:43 PM
trimless trimless is offline
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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?
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  #13  
Old Jul 7th, 04, 2:47 PM
Spawn22 Spawn22 is offline
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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 [img]graemlins/thumbsup.gif[/img]
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  #14  
Old Jul 7th, 04, 5:55 PM
broke broke is offline
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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.
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  #15  
Old Jul 7th, 04, 6:14 PM
trimless trimless is offline
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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?
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