small block cams

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ktcnn94

ktcnn94

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you guys are probably getting tired of my questions but I generally spend a lot of time reading and asking questions before I do anything. I've been doing a lot of reading on the forums here about 318 camshafts im seeing people recommend the comp xe268h and I seen some older posts talking about the summit sum-k6901. the comp website states adjustable valve train required and after sending them an email they replied that to run this cam I'd need adjustable rockers or adjustable pushrods, the summit cam doesn't mention that anywhere that I can find. have you guys that have used or have knowledge of either of these cams had to use an adjustable valve train? btw I've scratched the magnum idea i asked about the other night for a while anyway. my car runs right now with the stock 318 and i don't wanna have it torn apart when spring gets here i wanna be able to drive it but id like to have a nice thump in it so im gonna go with a set of long tubes probably dougs because i have my car sitting lower than stock and ive heard horror stories of the summit and or hooker headers having issues with dragging (any opinions welcome) and thought i'd stick one of those two cams in it and ride it this summer while i save some money and gather some parts to build and swap out the motor next winter. the 318 does have an edelbrock performer intake and edelbrock 1406 carb, stock 904 trans and 7 1/4 with unknown gear ratio at this point. not gonna be racing just want a nice thump and a little more power for the time being. the block has a 74 date code on it, the heads are just stock 318 heads as far as i know. again sorry for so may posts with so may questions but i just like to way my options and be well informed before i drop my dimes.
 
im running an MP 284/484 cam in my 318, using nonadjustable factory rockers(HDs from mancini racing), no issues whatsoever, I don't see any problems with those cam choices u stated.... hedman headers on my demon, no ground clearance issues, I am running at stock height though
 
Does that cam have a nice lope/thump to it? Are you using factory length pushrods.
 
Also you guys that know more about this stuff than I do, what would the compression ratio most likely be on this thing if it's in it's stock state.
 
you guys are probably getting tired of my questions
Click to expand...

LOL, that's what the forum is for.

The 268 cam is a decent cam for the 318, I run the HE268 in my teen, with a Summit 650 street/strip carb, and the Summit headers. It runs great. The stock valvetrain will work, but you must change the valve springs that is recommended for the cam.

I will tell you this though, you will still be somewhat disappointed because of the rear gear, most likely a 2.76 if it's still factory.

Once you get up into the power band, it will run good. I swapped to a 3.55 and it made a world of difference.
 
Bad Sport, does the 268 have a nice lope to it and do the summit headers drag? If no are you at stock height?
 
Here's the HE268, the XE might have a bit more.




And I don't have any drag issues with the headers, but if your car is set lower, you might.
 
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Sounds good, thanks for sharing. I'll probably use the comp 901-16 springs and a gear swap should be an easy weekend job also.
 
The XE268H works with factory rockers, adjustables are not required.
 
I also have an HE268 in a 318 and I've got 901-16 springs too. It's a pretty good cam for the 'teen. [ame="http://youtu.be/G1kUUd3i8MI"]http://youtu.be/G1kUUd3i8MI[/ame][ame="http://youtu.be/U48XNnMLgZw"]http://youtu.be/U48XNnMLgZw[/ame]
 
Just keep in mind the more "thumpy thump" @ idle the less torque you have @ the low end of the rpm range. & having apx. 8.1 ish comp raito to start with don't help @ all! I wouldn't go any larger (in duration) than the comp 268 at all! a (true) 2500 stall & 3.55's will make it a blast to drive with that cam!
 
Hipo65, thanks for the advice, yeah im not expecting a whole bunch out of it at this point, I just wanna be able to play with it some this summer and then hopefully next winter do a fresh engine build or swap, Im spending this winter doing some interior work so im running out of time and definitely money before spring hits. just want it sound nice for cruising and have a little more power, love the thump. it has what looks like (haven't measured it) 2.5" exhaust and welded mufflers on it but the guy I got it from had a failed attempt at a header install so it has little tiny twisted up head pipes coming off factory manifolds welded into the 2.5" pipes so that's gotta go.
 
bluedream, that thing sounds pretty mean, so I know what cam and springs but what about the bottom end, is it freshened up stock bore or is it machined etc, which heads etc you get my jist. thanks for the video very cool.
 
Unless you have a higher compression motor I wouldn't recommend the XE268. I'm running 9.5 comp. 318 with the XE268 and its just right at the limit of what will work with my stock torque converter. With that cam on a stock 318 I'm pretty sure you won't be happy. Dog off the line and idling problems. There are some smaller cams in the XE line that would be a lot better for a stock 318. Like the 262 or 256 cam. I had to have my carb and timing just right to keep my car from dying at every stoplight.
 
Very true,the stock torque converters are pretty tight even with a stock cam. I just finished up a mild 383 for some friends in there 70 charger & I used the xe262 in it because I knew who ever rebuilt motor before I worked in it put in the low comp silvo lite pistons. glad I didn't go any bigger with it eather it has stock t/c & 3.23 gears. It may not have the potato,potato cam sound yer looken for but the stock 340 cam is a nice one for a mild 318 with plenty of street manners. In yer case id stay under 220 @ .050 duration & get as much lift as you can. Again wont give to much thmpy idle but will be a lot better for the street! Ive done the "too big cam blues" not cool! sounds nasty as hell but wont turn tires unless my buddys got out to lift up the rear some to get em going! no power until 2700 rpm then like a switch BOOM! se ya!
 
Most mopar cams that use the oem base circle cam spec can get away with stock hydro rockers and pushrods, but when th e elift starts to go up, the only way the camshaft will fit through the bearings is if the lower the floor of the cam base circle, and thats when you start to need either adjutable rockers, or sometimes cheaper, linger pushrods but you have to measure them very carefully as you only have about .060 max wiggle room in the final length, thats the preload tolerance. Adjustables sell for about 125 used here, get their ball/socket pushrods too!
 
If you cam a low compression engine to only sound good, only sound good is all it will do.
 
ktcnn94 said:
bluedream, that thing sounds pretty mean, so I know what cam and springs but what about the bottom end, is it freshened up stock bore or is it machined etc, which heads etc you get my jist. thanks for the video very cool.
Click to expand...

The engine is a '68 318 and i kept the stock rotating assembly and heads.. I tore it down to the bare block and the wear on the cylinders was minimal so I honed it and gave it new rings and bearings. So the bore is stock and the pistons are what came in it from the factory. For the cylinder heads I just cleaned them up and lapped the valves and put them back together with the new springs since they were redone not too long ago. 600cfm eddy carb on a performer intake and exhaust is through hooker competition headers (which I haven't had a problem with so far), 3" duals with cutouts and an H pipe. Its a good setup but I'm about to yank it out and drop in a 340 :burnout: thanks for the compliments!
 
yeah, the 284/484 cam definitely sounds raunchy, I know im overcammed, took a lot of tuning to get it right, but she sure pulls from 3000 to 6500, depends what youre looking for I guess, and yes factory length pushrods.
 
Blue dream, what gear are you running and how is your bottom end with the stock bore and Pistons.
 
Rigger what about you, what gear and trans you running
 
Camshaft Mash

The XE-268H is Comp-Cams most popular unit, and the Stock Valve train can
be retained with this Camshaft.

On a lighter-note, we just used a Comp-Cams XE-256-H on a relatively stock 1973 Dodge Dart Sport, with a 318, and with 8.70-1 Compression.

Shipping Weight > #3175 lbs.
Curb Weight ..... > #3280 lbs.

* 1970 '318' Engine
* Re-freshed > w/Chrome Oil Rings
* Stock Flat-Top Pistons {-.060" below deck}
* 2843675 Cylinder Heads {1.78" Intake x 1.50" Exhaust}
* 8 1/4" Rear ..... 3.21 Gears 'Sure-Grip'
* A-904 Automatic Transmission
* Stock Converter
* 340 Exhaust Manifolds
* Dual-Exhaust {'340' Style w/2.25" Exhaust Pipes}
* Cherry Bomb Mufflers
* Weiand #7510 Intake {Early Profile/Single-Plane > 'Torker Style'}
* Carter AVS {630 CFM}
* 1973 Breakerless Electronic Distributor

Lift ...................... .447"/.455"
Duration ............... 256"/262*
Duration @ .050" ... 212*/218"
Overlap ................. 42*

With the Comp-Cams #901 Valve Springs {Singe-Coil w/Damper}
* Valve Closed ..... #104 lbs.
* Valve Open ....... #259 lbs.

An excellent bump-stick, with Strong Torque, and with Low-End and Mid-Range Power.

Pulls solid right from > 1000 thru 5000 RPM's.

Surprisingly responsive, with a good idle.
 
Well, I know you didn't ask, but I'll pitch in again.

My engine is stock, with the exception of the HE268, a Wieand Action Plus intake and a Summit street strip 650. Initial set to around 16* and all in around 34*. Long tube headers, and a 3.55 suregrip out back. Stock converter.

It runs quite well for what it is.

The big obstacle after the engine upgrades was the rear gear, once I changed that it came alive. It still isn't quick from a takeoff with the stock converter, but it doesn't take long and it's pulling pretty good for a lazy 318.

Budget was an issue for me, AND I already had a 360 in the works, so I didn't go hog wild with it. I plan on going through the teen when it comes out, and find me an early A or an older Dodge pickup to put it in.
 
ktcnn94 said:
Blue dream, what gear are you running and how is your bottom end with the stock bore and Pistons.
Click to expand...

Rear is an 8 1/4 open diff with 3.21's.. Trans is an A-230 3 speed. I'm going to go with a 3.55 sure grip sometime this summer though once I get the 340 in. It does ok off idle but it would probably do better if I didn't go for giant dual 3" flowmasters. 2 1/4 or 2 1/2 would be better suited for it. All in all Id say it's not bad though, especially for how mild it is.. It'll outrun my friends '73 350 Omega no problem.
 
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