My Turn for a Cam question - 318 Build

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MileHighDart

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Ok, I know this has been beat to death, and I have read thread after thread and I think I have a pretty good idea what cam I should run, just want to bounce it off you guys. I'll give you my engine/car specs and intended use, and the two cam choices I've narrowed it down to

Engine:
1971 - 318, .030 over so its actually 323cu in.
Weiand Stealth 4bbl intake manifold
Edelbrock 1406 Carb
Heads are Late 70's 318 with 1.88 and 1.60 valves, Mild porting job following 318willrun's post. Heads cc at 65
Pistons, unknown brand but sit .030 in the hole.
I figure with the thin head gaskets I'll be at 9.0 static compression
Rotating assembly with be balanced.
Doug's d453 ceramic coated headers in to 2.5" exhaust, with H pipe

Car is 1968 Dart, with 904 auto, stock converter, 8-3/4" rear, pegleg with 3:23 gears
25" tires.

Intended use: Cruising on weekends, the occasional commute to work, and maybe a once a year trip down the 1/4 mile. Would like plenty of low end torque. I will be staying with my 3:23 gears as I do a lot of Highway driving, like 90% highway, 10% in town.
Will stick with stock converter, or possible factory high stall, (although I don't know what stall the factory high stall converter is).

Cam choice after doing research here, and using Comp cams cam selection simulation program, I've got it down to these 2

XE256H operating range 1000-5000, peak tq at 3500rpm, peak hp at 5000 recommended stall 1600 - 2600. Comp's simulation show 322hp at 5000 and 379tq at 3500

XE252H operating range 800-4800, peak tq at 3500rpm, peak hp at 4500 recommended stall 1400-2400 Comp's simulation show 293hp at 4500 and 377tq at 3500

Both have about the same torque at 3500, 29 less hp with the xe252 but makes it at 4500 instead of 5000rpm.

Discuss
p.s. I am at about 5200 ft altitude
 
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Anything but comp.

Nothing over a 108 LSA.

Can't you afford a few dollars more for a custom ground cam?

Cam Motion.
Racer Brown.
Bullet.
Sig Erson.
Jones.
Controlled Induction.

That is 6 of the best cam grinders I know of, off the top of my head, in no particular order, though I get on with Jim at RB very well.

Any one of those will be better than an off the shelf deal.

Spend once wisely or many time foolishly.
 
Oregon cam grinders was great to work with.

Address: 5913 NE 127th Ave #200, Vancouver, WA 98682
Phone: (360) 256-7985
 
TrailBeast said:
Oregon cam grinders was great to work with.

Address: 5913 NE 127th Ave #200, Vancouver, WA 98682
Phone: (360) 256-7985
Click to expand...


No offense to OC, or Delta, or any other cam regrinder. It's a tough way to make a living.

But I have a hard time buying a cam from a guy who can't design a lobe. They only copy a lobe. So you are really buying a copy of a copy.

Don't step over a donut to pick up a dog turd.
 
yellow rose said:
No offense to OC, or Delta, or any other cam regrinder. It's a tough way to make a living.

But I have a hard time buying a cam from a guy who can't design a lobe. They only copy a lobe. So you are really buying a copy of a copy.

Don't step over a donut to pick up a dog turd.
Click to expand...

It wasn't just that I needed a cam in my case, as I wanted a short snout split duration hydraulic roller regrind for my Magnum and didn't want to spend 300 on a daily driver cam.
It was right $125
Shhh, I don't think the valves noticed it was a copy of a copy yet. :D
 
TrailBeast said:
It wasn't just that I needed a cam in my case, as I wanted a short snout split duration hydraulic roller regrind for my Magnum and didn't want to spend 300 on a daily driver cam.
It was right $125
Shhh, I don't think the valves noticed it was a copy of a copy yet. :D
Click to expand...

There are times where a regrinder is invaluable. Kennys work is impeccable. He has repaired many lobes for me. He can only copy a lobe. Which is a copy of a master. You are getting a copy of a copy. He has to reverse engineer the lobe. It is what it is.
 
Nice cam for that little 318 Lunati "voodoo"10200701..
 
I love it. Which of these two cams you ask, and you get suggestions for everything but......XE256H
 
Of those two I vote xe256h, the xe250h will be too small, IMO
 
Dartboy52 said:
Of those two I vote xe256h, the xe250h will be too small, IMO
Click to expand...

If his static compression is 9.0 to 1 the 256XE will have a dynamic compression of about 6.68 to 1 at his altitude. The 250XE would be at 6.8 to 1. The altitude kills the compression and power output. I would recommend getting the heads milled some to increase the static compression for use with either cam he chose.
 
One thing you got to remember is the quoted powerband numbers are based on 340/360 so a 318 would be a little higher buy shouldn't make much difference at this level. The 250 cam is about equal to the stock 340 cam and the 256 is a step up. If you were willing to go with a bit of an converter I'd step up to the 262 cam but since your not the 256 should fit the bill.
 
I ran the 256 in my truck and loved it. Ran it auto stock converter and then clutch 4 speed. Started with Carter Competition carb and when secondaries opened sounded like a muscle car but a little rich. Went to a 625 Street Demon and ran great, breakaway was instant. I put a 2bbl BBD, cats and retarded timing to pass emissions test here in Ontario Canada. I used Comps recommended springs, retainers and cut down guides with there tool for safe clearance and positive seals, stock rockers. Wanted extra clearance for more lift in future if I changed to a bigger cam.

I do like the look of the Howard's more than the Lunati. The 256 Comp has loads of grunt on the bottom and surprised me on the top end.
 
If your asking between the 252 or the 256, they both will give you good service. If your going to do a little more playing around than what you think, then I'd say the 256. If you truly believe that you'll hardly ever step into it, then the 252 would do just fine.
I also know that altitude (I have family in Colo), and it's a killer on low end torque. There have been some good suggestions as well from others on cam choices.

You'll make the right choice for you, because I from what I've read from a lot of your post, you are no rookie at this hobby :)
Sounds like a tough teener, I like it!
 
Torque wise I don't think your gonna fine much difference down low could even go a could steps up before it drastically changes.
The 252 cam will give you a couple of inches of vacuum more and maybe a slight mpg advantage. When picking the cam for my 400 bronco i went with the 255deh cam even though I could of easily went with the 268 and picked up 30-50 hp. But I figured it was a truck and the 255deh would easily double the factory hp with what I was doing with it.
And figured I wasn't willing to sacrifice even 1 mpg for 30-50hp. In your situation there might be a 15-20hp difference but I doubt there would be much of an mpg difference I'd still go with the 256 but that is up to you.
 
As above....... Keep in mind with the 5200' altitude, you're gonna lose a lot of DCR. Going to the 250 at 5200' won't even equalize the DCR loss at 5200' versus the 256 at sea level. So the Comp calculator numbers are going to be overly high, and if you want low end torque, it might be best to keep to the smaller cam.

Or, put in some more cam advance, maybe another 3-4 degrees. Or consider a cam with a narrower LSA, with the 250-ish durations to close the intake even sooner. (As suggested.) The altitude is going to be your biggest headache for cam selection and maintaining low end torque IMHO; your DCR's will be down below 7 with the altitude, and cranking pressures will be close to that of a stock /6 at sea level. (Assuming the .028" head gaskets.)

I would very strongly consider milling the head about .040-045" each to get the chambers down to around 58 cc's. That will push the DCR up around 7.4 and get the cranking pressures up around 145 psi with the XE250 cam, and around 7.25 and 141 psi with the XE256 cam. Good for the torque you are seeking....
 
BTW, thanks for making it clear what yo want to do with the car... I wish everyone could be that clear!

And if you do mill the heads, you'll need to think about changing the pushrods. It's always sumpthin'.....
 
BTW, OP, are you sure about the pistons being .030" in the hole? And what number of eyebrows are there? .030" would not be the case for any stock pistons. Just trying to see for sure what SCR you have; if the pistons are really .030" down, then 9:1 is what I get too. Just trying to be accurate here...
 
nm9stheham said:
BTW, OP, are you sure about the pistons being .030" in the hole? And what number of eyebrows are there? .030" would not be the case for any stock pistons. Just trying to see for sure what SCR you have; if the pistons are really .030" down, then 9:1 is what I get too. Just trying to be accurate here...
Click to expand...

They are indeed .030 in the hole. They are not stock pistons. They were replaced the first time I built this engine about 17 years ago. At the time, I let the machine shop get all the parts, they told me they couldn't find a "mopar" piston the right size, with full floating pins. So what they put in it is pistons that have 2 valve reliefs, but they are in the wrong place to actually do any good as valve reliefs. I don't know if the're chevy pistons or what. I'll post a pic later to show what I mean.

IMG_20160525_115839504.jpg
 
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MileHighDart said:
Ok, I know this has been beat to death, and I have read thread after thread and I think I have a pretty good idea what cam I should run, just want to bounce it off you guys. I'll give you my engine/car specs and intended use, and the two cam choices I've narrowed it down to

Engine:
1971 - 318, .030 over so its actually 323cu in.
Weiand Stealth 4bbl intake manifold
Edelbrock 1406 Carb
Heads are Late 70's 318 with 1.88 and 1.60 valves, Mild porting job following 318willrun's post. Heads cc at 65
Pistons, unknown brand but sit .030 in the hole.
I figure with the thin head gaskets I'll be at 9.0 static compression
Rotating assembly with be balanced.
Doug's d453 ceramic coated headers in to 2.5" exhaust, with H pipe

Car is 1968 Dart, with 904 auto, stock converter, 8-3/4" rear, pegleg with 3:23 gears
25" tires.

Intended use: Cruising on weekends, the occasional commute to work, and maybe a once a year trip down the 1/4 mile. Would like plenty of low end torque. I will be staying with my 3:23 gears as I do a lot of Highway driving, like 90% highway, 10% in town.
Will stick with stock converter, or possible factory high stall, (although I don't know what stall the factory high stall converter is).

Cam choice after doing research here, and using Comp cams cam selection simulation program, I've got it down to these 2

XE256H operating range 1000-5000, peak tq at 3500rpm, peak hp at 5000 recommended stall 1600 - 2600. Comp's simulation show 322hp at 5000 and 379tq at 3500

XE252H operating range 800-4800, peak tq at 3500rpm, peak hp at 4500 recommended stall 1400-2400 Comp's simulation show 293hp at 4500 and 377tq at 3500

Both have about the same torque at 3500, 29 less hp with the xe252 but makes it at 4500 instead of 5000rpm.

Discuss
p.s. I am at about 5200 ft altitude
Click to expand...
This won't make much power with those cams and compression, at 5200ft. The big thing is the heads and compression.
unless a decent throat cut is made and you really know how to port, the heads are going to be weak in low/mid lift flow and probably would be better off porting with stock valve sizes with such small cam and limited porting ability, and if you do use the 1.88...open the runner to 360 sized port window. You are gonna be foot deep in iron dust fyi
 
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