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#21
06-12-2021, 11:38 AM
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I ran an XE274 in a 0.030" 400, stock 670 heads, 3.55 gear, 2500 stall converter, 3 tube headers in a 3858# car that did 13.0 in the 1/4, still got the motor. I think it needed a little more converter to take advantage of the cam but was an excellent all around driver and felt great on the street.
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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
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#22
06-12-2021, 12:20 PM
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The #17 heads are shown to be 72CC's and found on the 9.2 compression 350CI. They are most likely about 74-75 CC's as Pontiac added a few more CC's to take into consideration the carbon layer that would build up on the chambers and piston tops with the leaded gas of the day.
The XE cams are good with lower compression builds as they tend to build cylinder pressure, pull hard, but peak out a little early. Ran the XE274 in a 1972 400 with the 7K3 heads and those rebuild kit 8 eyebrow pistons and the engine pulled extremely hard to about 5,400 RPM's and was done - but it would rev to 6K, but it was no longer making power. Had no issues smoking tires with the 3-speed, 3.23 gears, 28" tall tires and ran on regular gas without issue. I would use this cam again on any low compression 8.2-8.5 engine. I would not run this cam in a high compression engine unless I planned on high octane gas or an additive. The concern for your friend should be the high compression. No problems in my book honing the block with a drill hone/stone if there is little wear/ridge. Have done this a couple times "back in the day" when many of us had no money and freshening up the engine to stop the high oil use with new rings and valve seals was what we did to get more miles out of the car/engine. So go ahead and hone the cylinders, just make sure to be anal at cleaning up the cylinders after the honing to get them clean. The heads will also have the press-in studs which means being reasonable on lift. If you go over a certain lift on the cam, then you will want matching springs which mean higher spring rates and this could pull studs up. So I would select a cam having a stock lift or a little more, but can use stock spring pressures. Small valves, screw-in studs, won't provide any big HP improvements, and add to that the high compression and an EX cam spec and you friend is building for disappointment. However, the heads can be upgraded at cost and that's where most will say to just go with the 6X heads and get the compression you need along with the improved upgrades - then he can go with a bigger cam and get more HP/TQ. So point out that his choice of parts are not entirely compatible and he may wind up with time/money put into the engine with disappointing results. |
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#23
06-12-2021, 12:55 PM
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In the first post it said something to the effect that KRE prepped the heads with 7/16 studs, valve job, and springs to match the cam. Should be good on that.
Only one way to find the compression for sure is to cc the heads. Pontiac’s actual head cc has some pretty large swings from what the were actually, especially on those heads that had the 72 cc rating. |
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#24
06-12-2021, 02:19 PM
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The cam has its nitche with very peppy bottom end . I have always known that. My friends' idea of 400 hp or the ability to run it on pump gas using the advertised cc numbers is very unrealistic. ...and I told him so. The only solution here is to pull a head and cc a chamber. If actual cc puts the cr in the lower 9's or so then he's good to go.
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#25
06-12-2021, 02:30 PM
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#26
06-12-2021, 02:39 PM
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Just to back pedal as I let this slip my brain, "Heads are #17 small valve with 7/16 studs and a 3 angle valve job set up by Kaufman" Ok, so your friend is good to go with higher lift cams, just match springs to lift (and they may alraedy be good to go) and then make sure plenty of valve-to-piston clearance. I believe the consensus is to keep lift under .500" and there should be no issues. Are the 7/16" replacement Big Block rocker arm studs? I am assuming so since Kaufman set them up. The heads should be using poly lock? This will allow the rocker arms to be "zero lashed." Yes, CC one of the head chambers so you know exactly what the CC's are and then you can use the on-line Wallace Compression Calculator to get a good idea of what the actual compression will be. |
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#27
06-12-2021, 07:51 PM
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You missed the five people in this thread positivity speaking about their XE cam. I know of several others here, maybe they will chime in yet. Ever consider why one member supposedly has more complaints than nearly 54,000 other members. LMAO. |
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#28
06-12-2021, 08:03 PM
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I have a set of 17’s in my pile. I cc’d them a couple of years ago and I’m almost positive that they were close to 74/75 but have a little bit of valve sink I believe. I can cc them again if you want so you don’t have to pull the heads off? I wouldn’t anyway for a question of 2 or 3 cc’s lol.
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#29
06-13-2021, 08:22 AM
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Lol, I have kind of found it is a little late to provide much helpful advise on engine internals once the heads are bolted on..
I think I underestimated the power potential of a small valve head some. I got to thinking I remember Dennis Jenson ( SD455DJ) posted some dyno pulls for a 400 with small valve heads a while back. Pure stock type built, tight quench, upper 70s cc small valve head with 45* valve, summit 2801, 214/224 @.050” cam, log manifolds. 383 HP @5300 and 455 tq@3500. You can see there would be no need to jump up to the bigger 224/234 cam. FWIW..Personally, most my experience has shown heads with 45* valves can usually tolerate more compression than the 30* intake heads, especially on smaller valve set ups. If KRE did 45* seats, it will help the XE some. Hopefully the engine has the bigger cc’s than in the 70s. Last edited by Jay S; 06-13-2021 at 08:47 AM. Reason: Add |
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#30
06-13-2021, 08:23 AM
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No "supposedly" to it. My information doesn't come from regurgitating what I can Google up, the efforts of others, or trying to associate myself with big names in the industry to put some sort of meaning to useless comments on these subjects.
Anyhow, I've had them on the dyno, and scores of vehicles in here to tune using them (at least the ones that didn't wipe lobes early in life). Matter of fact there was a 455 on the dyno with an XE284 camshaft in it right ahead of me once. It was topped with ported 7K3 heads, single plane T-II intake and an aftermarket 850cfm carburetor. They pulled and pulled and pulled on that engine running around changing this and tweaking that and couldn't bust 400hp and 499tq. Finally with ALL the stops pulled out they hit around 430hp. Actually we did NOT know what cam was in it till a few days later as it was simply dropped off at the facility for dyno testing and the owner/builder wasn't present at that time. It had a "menacing" idle and sounded like it was going to do something, but didn't make the grade when they started making pulls on it. I do remember power ending ABRUPTLY at 4800 RPMs so it never had a fighting chance to use the 240-246 @ .050" duration because the valve springs gave up. I'm a quick learner with this sort of thing so after building a turd of a 400 a few years earlier with a XE268 cam and seeing that engine fall way short I've avoided them. There are simply better choices out there that do not require battleship valve springs to keep things in check at high RPM's and you don't have to deal with all the "clatter" in the valve train that I've witnessed with many of those engines. As soon as we got that "turd" off the dyno I put my own 455 on the same dyno with 6X heads, Crower RAIV cam, iron intake, Q-jet and factory HEI and cranked out 455hp on the very first pull. IF anyone reading this wants to have a good experience with an XE camshaft have the heads prepared with 45 degree intake seats and heavy porting under the intake valves. I've seen a few respectable dyno runs with the XE274 camshaft in builds where the engine builder did that, plus they use really light components above the lifters to keep them from "crashing" at high RPM's. I still wouldn't go in that direction, there are simply better choices out there these days and you woln't have to deal with potential noise, lobe failure and lifter "crash" at high RPM's....FWIW.....
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#31
06-13-2021, 09:46 AM
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T-II intake vs Iron Q-jet 850 aftermarket vs Q-jet Cliff - "the valve springs gave up." = - "power ending ABRUPTLY at 4800 RPMs" PJ - So how can the cam be the fault in this example when the valve springs crapped out? What was the engine's compression?? And your 455? Cliff - "there are simply better choices out there these days and you woln't have to deal with potential noise, lobe failure and lifter "crash" at high RPM's" PJ - Blanket statement? What RPM does lifter "crash" occur? Never experienced any of this with the XE274 I ran - ticking noise? You mean like Rhoads lifters that are promoted here, or the roller lifter ticking of certain brands that are used here? Heaven forbid I bring up solid HFT and their ticking noise. I don't recall any annoying "ticking" but then again I did not build the car/exhaust to be B-body 4-Door old man quiet so I can listen to the single speaker AM radio. No lobe failure in my experience, but I also know how to break in a cam and match parts. I zero lash my lifters, so is the "ticking" always a cam issue or maybe a lifter choice or adjustment issue just like other cam/lifter selections? Please, when posting, state this is your experience and opinion and don't discount others when their experience have had no issues with the XE cams. They have a place when used in some builds. Yes, there are better choices on cams, but that can be said on every build as cam selection IS SUBJECTIVE. I could choose one cam, but another builder might choose another, and so on and so on. I could select the "best" cam based on dyno results, engine simulators, recommendations, and then choose a different intake/carb or have different head flow numbers, or wrong timing curve, wrong gearing/converter, etc. and have a "turd" or lack luster performance and then question those who suggested the cam. I think you should know by now the difference between a street car and race car. On the street, I don't need to squeeze out every lick of HP. I am most likely not going to twist the engine to its max RPM range each and every time I row throw the automatic or manual gearing. So a cam profile that works best up to 6,000 RPM's may not be in my best interest when most of my driving is going to be around town and to car events. I LIKED the XE274 cam in my LOW compression 400 engine because it woke it up, pulled very strong (and I like power), could light up the tires, and got 16 MPG on the highway at 70 MPH. Was a great stoplight-to-stoplight cam which was most of my local driving - FUN, which is why I own the car. A RAIV cam would have never worked. Yep, power was gone by around 5,400 RPM's. So what? Isn't that what the next gear is for? So maybe the lower RPM range also protects those not so skilled at driving from grenading an engine and less wear on parts. I respect your opinions, experience, and words on this forum, so don't take this personal, but sometimes these "absolutes" just don't fly. How about building a low compression street engine with the XE cam and let us know how the seat of the pants feel is for you. Yep, it won't be 500HP and 600TQ, but I don't think it will be a "turd" either. |
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#32
06-13-2021, 09:49 AM
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#33
06-13-2021, 11:00 AM
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"Apples to oranges comparison."
You are correct.......with all those aftermarket "high performance" parts the engine ahead of us should have made a BUTT LOAD more power, at least if you are buying into all the excellent advertising the companies making them tell us about them.....FWIW...... I'm not into "seat of the pants" feel or testing, and avoid parts that don't make the grade or have issues associated with them. The XE cams are simply a direction I will not go with these engines. Right to start with they recommend too much spring pressure, which is hard on everything above the lobes. They also throw the valves around with a lot of authority. Fine for reducing overlap and getting better .050" numbers but with Pontiac heads and flat chamber floors and 30 degree valves/seats you are NOT taking advantage of the excellent low lift numbers. Comp and other cam companies tell us that we will make "more power" with fast-ramp designs, better vacuum, improved throttle response, fuel economy, etc, etc. That sells parts but the reality of the situation is that shorter seat timing and greater .050", .200" and more lift is easily trumped by the valves being off seat longer. Folks are quick to look at .050" number but fail to realize that "time" in milliseconds adds up quickly to more opportunity to move air as the engine increases RPM's and the cycles are happening more times per second. If you really want to make more power with shorter seat timing move to a roller profile instead. When you take the limitations of the lifter diameter OUT of the equation, what they tell you becomes possible. I actually have a customer who used an XE cam in a 455 build and made excellent numbers. To get them he changed to 45 valves and seats, and HEAVY porting under the valves and short-turn in the heads. He installed ultra light parts above the lifters, including pushrods, rockers, and titanium valves/retainers. The dyno results were actually quite impressive. Even so having to do all that with your basic "street" engine doesn't make it from a business standpoint and why jump thru all those hoops when you can make the same power with slower ramp cams, lighter springs, less expensive valves, retainers, etc.......
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#34
06-13-2021, 03:34 PM
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Thanks for all the responses, Larry |
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#35
06-13-2021, 08:12 PM
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Ok I dug out the 17’s and cc’d them. They came in at about 83cc’s. The valves sit better than I remember but I’m sure they’ve had at least one valve job so I’d say out of the factory they were 80cc’s. Hope it helps you out.
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#36
06-13-2021, 08:14 PM
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Here is a pic after I cc’d them to show you how the valves are sitting etc. Im confident they are 80cc new.
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#37
06-13-2021, 11:31 PM
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I used a XE 262 on a 112 on my 78's low CR 400. Did OK. Used a 2801 Summit in the low CR 400 in the 81 about the same as the XE 262. Click over a stock cam.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
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#38
06-14-2021, 01:02 AM
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#39
06-14-2021, 03:42 AM
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If someone says "I ran 'X' cam and it ran fine" you have to realize that this is only one single data point. What does that person consider "running fine?" Did they try any other cams? Did they do any dyno or track testing?
Most guys build an engine, decide on a cam and as long as it makes the rear tires smoke and sounds good at idle, they're happy. they'll tell you the cam in their engine is great, even if the engine would make 50 more HP with a different cam. How would they know? I ran an XE274 in a 9.2:1 400 with stock ports (just matched to the gasket, nothing more), headers, 2.5" exhaust, 3000 stall "tight" converter, 3.23 gears, 27" tires, and it ran mid 13s @ 101-102. I got best times shifting around 5000-5200 RPM. No idea if the carb was tuned optimally. Probably a lot of tuning I could've done to get a little better times out of it. Would it have run better/faster with another cam? Maybe. If all I wanted was a decent running street engine with some attitude, it fit the bill just fine. I wish I could've tried a few different cams in that combo. Also wish I could've put a wideband on it to see what the carb was doing.
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---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
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#40
06-14-2021, 06:17 AM
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Those valves shown in post 36 are indeed at stock height in the chamber!
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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