Cam for torque question

[lomchivok]

Hi All,
I've got a 318 built to zero deck with forged 1.8 compression height pistons .040 over. Indy RHS heads @62cc's with about 9.5:1 compression. Eddy air gap intake and holly 650 carb. It has a comp XE268H cam and stock rockers. Very noisy valve train...don't like it. I rebuild motors...more like assemble them after machining at my favorite machine shop. I'm not too savy on cam choice. The XE268H has 110* lobe separation and 106* intake centerline. Attached is a dyno sheet of the motor after about 3000 miles.
I would like to increase the torque at a lower rpm, have less overlap so my clothes dont smell like exhaust and I need more vacuum to run my vac assist brakes. a quieter valve train would be nice too...
Any ideas as to a better cam choice. Have about .050 thick head gasket so I can put a thinner one in to raise the compression a bit and take better advantage of the quench area.

 

[Bad Sport]

I would like to increase the torque at a lower rpm

What rear gear are you running?

 

[yellow rose]

If you have idle issues with that cam, you need to fix your carb.


As for the noise, IDK what you have going but that lobe is very quiet.

Why blame the cam for other issues?

 

[rumblefish360]

YR, Because that cam line has more complaints about it than any other combined. I'm not so quick to blame his short comings as fault when many other very competent builders also have the same comment.

Lomchivox, increasing low end torque (simply) would require a reduction in cam duration. More vacuum should result. Also helping would be a wider 112 instead of the 110. The engine would have of a chop at idle.

I enjoyed this cam very much in my 318's. it is small but does delivery good torque nearly off idle and hp until about 5500 rpm.

https://m.summitracing.com/search?keyword=Crn-693941

 

[yellow rose]

YR, Because that cam line has more complaints about it than any other combined. I'm not so quick to blame his short comings as fault when many other very competent builders also have the same comment.

Lomchivox, increasing low end torque (simply) would require a reduction in cam duration. More vacuum should result. Also helping would be a wider 112 instead of the 110. The engine would have of a chop at idle.

I enjoyed this cam very much in my 318's. it is small but does delivery good torque nearly off idle and hp until about 5500 rpm.

https://m.summitracing.com/search?keyword=Crn-693941

The Crane you suggest is a SLOWER lobe for sure, but the XE lobe ain't no lifter banger either.

I have no idea what all the griping about valve train noise is. Most guys run cams that are too small, too slow, not enough lift.

And then they want more power.

You can't eat the donut and leave the hole.

Ain't no WAY 224@.050 is going to be dirty at idle if the carb is tuned correctly.

 

[Bad Sport]

I have the 268 in my 318, and it was a dog on the bottom end. That's why I was asking about the rear gear, if he is running a 2:76, then it won't have any torque down low, mine sure didn't.

I went to 3:55's and it really woke it up, I have plenty of torque now, at least for what you can expect out of a teener. Can't wait to get my 360 done.

 

[rumblefish360]

I'll leave it at this;

I read the OP'ers post. I rendered a suggestion. It also has the bennifit of having been there and done that.

Balance in the entire build is key for the target sought. This applies not only to the engine but the entire drive train AND car.

Your words on cams, is an opening to endless debate. And I am not disagreeing, but wonder if the wisdom behind the words fit the build at had.

When it comes to performance, many views of what it is and how it is done vary to widely to nut shell it.

 

[toolmanmike]

YR, Because that cam line has more complaints about it than any other combined. I'm not so quick to blame his short comings as fault when many other very competent builders also have the same comment.

Lomchivox, increasing low end torque (simply) would require a reduction in cam duration. More vacuum should result. Also helping would be a wider 112 instead of the 110. The engine would have of a chop at idle.

I enjoyed this cam very much in my 318's. it is small but does delivery good torque nearly off idle and hp until about 5500 rpm.

https://m.summitracing.com/search?keyword=Crn-693941

I like the looks of that Crane. Did you run it with headers? If not with stock or 340 manifolds?

 

[rumblefish360]

I like the looks of that Crane. Did you run it with headers? If not with stock or 340 manifolds?

Both times I ran this cam was with headers on stock 318 & 360 heads furtherly equipped with;

Open air cleaner
4bbl. (600 - big TQ's)
Dual and single plane intakes. Dual highly suggested.
1-5/8 headers
Low compression @ 7.8-1 up to 9.25-1.
Low and high stall OE converters
4spd manuals
3.21 gears up to 4.10's

An old member here used this cam in his gutted track only Duster and ran 12's.
I ran the best of high 13's in a heavier Enbody.

 

[lomchivok]

What rear gear are you running?

running an 8.75 3.23 sure grip now. it was an AMC 20 with 2.87's and it was a dog...it's much better now with the 3.23 and 2200 stall.
If you have had a 318 with an xe268 hydraulic with stock rockers, I'm, sorry but you cant tell me your valve train is quiet.
I ran it once at Mission Raceway in BC Canada and it ran a 12.92 at 102mph.

In gear at idle it pulls about 9" of vacuum, out of gear about 15". I've got a vacuum can that is all in at 8" and limited to give me 24* advanced at out of gear idle on manifold vacuum. 18* initial with mechanical all in at 3200 and 40* total...the dyno showed that any less timing was a loss in torque and hp. more quench and I might be able to run a tiny bit more advance before detonation. I have no detonation issues at all with 92 E10.

It's a good strong motor but because of the duration and overlap, it stinks and the vacuum is low.
All I want to do is find a cam that will give me a little more acceleration (Torque) at a lower rpm, a more pleasant breathing experience while cruising and a little more vacuum so I can stop after smokin a cheby 350....which it does....smoke 350's.

I know the teen doesn't have the displacement to make a ton of torque short of a massive overbore or a stroker and by it's nature likes to run at high rpm's but I should be able to move the powerband down in rpm a bit...if by no other means than an adjustable timing gear set (which it has) and is as close to 106 as I could get it at 105.5 intake centerline.

 

[crackedback]

Tune it is what I would do. There is no reason an engine as described should be puking exhaust that smells like a leaking fuel truck.

What is the idle rpm in park and in gear? If it's dropping a lot, that could be not enough initial timing or a tight converter. Give the engine as much initial timing as it can handle and still start when warmed up. Alter the mechanical advance to hit your total number.

 

[AJ/FormS]

If it stinks it due to the tune,plane and simple, it ain't the cam by itself.

I couldn't get any sense out of your timing spec, other than it seems all messed up to me.
The #1 thing is to stop trying to use the Vcan on manifold vacuum; this is nonsense on this size of cam.Go back to the drawing board.
Assuming the cam timing is close, and that there is nothing wrong with your carb, that the ignition system is up to snuff,and that you have fixed your noisy valve train;
Disconnect the vcan and plug the carb-port. Then set the idle-timing to 18*max. Then reset your curb-idle screw to about 750rpm. Then get your T-port sync worked out.(see link below). Once the sync is set, you can limit your power-timing to 36*max. After all this is done, You have to prove that there are no vacuum leaks anywhere,namely; external,internal and including any devices operating off manifold vacuum,Such as the power-valve system. And now begins the fuel tuning.And the rate of advance tuning.
Then, after all that is done, THEN you can hook that Vcan back up to PORTED vacuum,and adjust it's rate of advance.
By this point, the vacuum disparity between in/out of gear should be, with a 2200TC,very minimal.The exhaust should be dripping water during warm-up (off choke). And when fully warmed up and idling, you should be able to hold a rag in the exhaust stream, and afterwards hardly smell any exhaust on it at all.If not, sit down and figure out where you messed up. There are at least four different kinds of stink that can come out that pipe; raw gas,NOx,burnt oil, and normal.Each is distinctly different.
But you gotta get to the bottom of the noisy valve train first! It's gotta be the set-up, the adjustment, or the lobes are going away! Option 4 is as rumblefish says, and I cannot comment as to that.
As to the set-up, well, there are a few things to look for. Obviously valve lash is #1. #2 would be rocker-arm orientation. #3 would be pushrods rubbing in the tunnels, and #4 is geometry. and #5 is crummy springs or crummy spring pressure. So pop the covers and sort it out.

I had a very similar cam in my 360; 223/230/110 with lift of .538/.549 and the advertised was 270/276. It was a zero deck,10.9Scr. I had three different carbs , and two different intake manifolds on it, and after the tune, not a one of them stinked other than normal. That cam made the most torque of any of the three that have been in that engine. It really sucked when it dropped three lobes immediately after an oil-change. I remember it fondly. The cam was dead quiet and went willingly to over 7200rpm.Admittedly it quit pulling a lot sooner,but I just like to hear those dual 3"pipes screaming.
I wish you every success in your search

 

[lomchivok]

If it stinks it due to the tune,plane and simple, it ain't the cam by itself.

we did fatten up the secondaries 2 jet sizes as it was getting lean at about 3500 rpm but left the primaries alone.
I do have a FiTech 600 power adder sitting here in the box yet. I will install it this winter along with an FBO ignition system...you're most likely right AJ...that will more than likely clean up the smell. I've considered a remote vacuum pump for the brakes but haven't yet done it.

 

[lomchivok]

it idles at 1000 and drops to 850 in gear

 

[Lustle]

That XE268H should make tonnes of vacuum. 15.5 inches at 850 idle. And it's a known torque maker. Lots of guys drop those in 360 truck engines to make good bottom end torque.

I'm surprised at the power you're making. Your DCR is 7.85. That cam's not bad. Decent heads. Yet you're only making 280? Usually that cam is good for 1hp per cube. You should be making way more torque as well. That cam is a torque over horsepower maker.

I'd say you need a good tuneup. Check ignition, timing, carb, etc etc. You should be making more power. And shouldn't have a problem running vacuum anything.

As reference, I run the XE274H in my 340. And have no problem with power brakes and steering.

 

[AJ/FormS]

As said that cam will have no trouble with operating the booster.
And it should idle just fine at 600 in gear, 700 in P/N.Your 1000 rpm idle-speed points directly to an error in the tune, and I'm guessing it starts with timing and the T-port sync. But it could just as easily be sucking air somewhere, and you have compensated for that with carb adjustments. Forget messing with mainjets until you get this idle-business sorted out.
Start with a new PCV valve.You do have one installed now,right? There is no simple test of those guys. Well there is but I'm not telling just yet. Ok, you twisted my arm, I'll tell. On a well-tuned near stock combo; Remove the hose from the PCV. Plug the end with whatever fits. Drill a hole in there about 3/32.Start up the engine, adjust the idle speed to about 650 in N/P, adjust the mixture screws as may be required to achieve best idle. Shut off engine, re-install PCV, start her back up. Changes to the idle speed and mixture screws should be minimal. Bigger cams like more air.Your cam might like a 1/8 hole to come up even. Unfortunately, those valves are non adjustable, so you have to give them air elsewhere;NOT the curb idle screw.The T-port sync will reveal the deal. But if you start with a defective PCV, well that just throws a whole big monkey wrench into the tuning regimen!

Now holdonasec
As to the low, idle, in-gear vacuum; A while back, there was a fellow here that had a similar idle issue in/out of gear, and it turned out his TC had gone sour, and it was dragging the idle down. Now don't confuse this problem with anything so far said, by anyone; but if, after putting a decent tune into it and it still drags the idle speed down,THEN this is something to consider.
OOps I see cracked post#11, already mentioned the TC idea

Ok one more thing; what elevation are you tuning at?

 

[lomchivok]

That XE268H should make tonnes of vacuum. 15.5 inches at 850 idle. And it's a known torque maker. Lots of guys drop those in 360 truck engines to make good bottom end torque.

I'm surprised at the power you're making. Your DCR is 7.85. That cam's not bad. Decent heads. Yet you're only making 280? Usually that cam is good for 1hp per cube. You should be making way more torque as well. That cam is a torque over horsepower maker.

I'd say you need a good tuneup. Check ignition, timing, carb, etc etc. You should be making more power. And shouldn't have a problem running vacuum anything.

As reference, I run the XE274H in my 340. And have no problem with power brakes and steering.

Well, A little more information and in retrospect... I bought this holley carb from summit. Installed it at the time of rebuild...the engine had never ran. Broke it in on that carb. It never really ran right at idle and needed to be at 1200rpm idle to stay running in gear. Sprayed carb cleaner around the carb base and it stalled the engine. I took the carb off and found that all the throttle plate mounting screws were loose except 1. When I turned them, they let out a "snap" as if they were installed with a thread locker but they all turned in after that about 1 1/2 turns each. I put it back on and the idle settled right down to where it is now.

Now you've got me re-thinking this carb. there may still be a vacuum leak somewhere. I do see fluctuation on the vacuum gauge but I attributed that to intake and exhaust pulses. Also, due to the Indy RHS heads height, the air gap manifold doesn't fit perfectly. I had to use 340 intake gaskets to make it work. cant detect a leak with carb cleaner or propane there.. Perhaps a trip to the machine shop with the intake in hand is in order along with a carb teardown.

 

[lomchivok]

That XE268H should make tonnes of vacuum. 15.5 inches at 850 idle. And it's a known torque maker. Lots of guys drop those in 360 truck engines to make good bottom end torque.

I'm surprised at the power you're making. Your DCR is 7.85. That cam's not bad. Decent heads. Yet you're only making 280? Usually that cam is good for 1hp per cube. You should be making way more torque as well. That cam is a torque over horsepower maker.

I'd say you need a good tuneup. Check ignition, timing, carb, etc etc. You should be making more power. And shouldn't have a problem running vacuum anything.

As reference, I run the XE274H in my 340. And have no problem with power brakes and steering.

Should clarify that the dyno sheet is hp and torque at the rear wheels but yes, it should be making more power.

 

[yellow rose]

I'll leave it at this;

I read the OP'ers post. I rendered a suggestion. It also has the bennifit of having been there and done that.

Balance in the entire build is key for the target sought. This applies not only to the engine but the entire drive train AND car.

Your words on cams, is an opening to endless debate. And I am not disagreeing, but wonder if the wisdom behind the words fit the build at had.

When it comes to performance, many views of what it is and how it is done vary to widely to nut shell it.

Wasn't meant to prove an argument Rob. Just pointing out his cam is not big for any build.

As I suspected, his tune up is diametrically opposed to what I would do, but that's up to the OP. I'm not a big fan of comp, ever and love to bash them every chance I get. But that bashing needs to be based in fact and that lobe ain't ****.

So the OP needs to look at his tune up and work on that for a bit and see where he gets as far as stinking up his clothes.

As for the noise, I rarely address this because I get bashed for being anal retentive, but I can tell you in had a .509 on stock rockers and it sounded like solid lifters. Since it was 1982, I don't remember why I even had the valve covers off, but I noticed there was a good bit of slop between the rockers, and the rockers and the hold downs. So I did some checking and not one place told me it was normal to shim the rockers. That I was crazy to waste my time. I went ahead and bought the shims and closed up the slop. All the noise went away. All of it. It was the rockers making the noise, not the cam.

To this day, I don't do a set of head without the rockers. I number them all and shim them so they are correct.

BTW, some of the later replacement OEM style rockers measured a bit narrower than the OE rockers.

 

[lomchivok]

Wasn't meant to prove an argument Rob. Just pointing out his cam is not big for any build.

As I suspected, his tune up is diametrically opposed to what I would do, but that's up to the OP. I'm not a big fan of comp, ever and love to bash them every chance I get. But that bashing needs to be based in fact and that lobe ain't ****.

So the OP needs to look at his tune up and work on that for a bit and see where he gets as far as stinking up his clothes.

As for the noise, I rarely address this because I get bashed for being anal retentive, but I can tell you in had a .509 on stock rockers and it sounded like solid lifters. Since it was 1982, I don't remember why I even had the valve covers off, but I noticed there was a good bit of slop between the rockers, and the rockers and the hold downs. So I did some checking and not one place told me it was normal to shim the rockers. That I was crazy to waste my time. I went ahead and bought the shims and closed up the slop. All the noise went away. All of it. It was the rockers making the noise, not the cam.

To this day, I don't do a set of head without the rockers. I number them all and shim them so they are correct.

BTW, some of the later replacement OEM style rockers measured a bit narrower than the OE rockers.

All good information and taken to heart. I have been going around and around with the timing on this thing. right now it has a pertronix hall effect points eliminator on it. The pertronix dist came with mechanical limiter bars that are cheesy at best. They have jammed the mechanical advance several times by dislodging from the locating pin under the springs. That's why I now have an FBO ignition sitting here in the box ready to go in in about 2 weeks.
I'll do as AJ suggests and try the timing and ported vacuum setup again.

Yes, I think the valve train noise is the rockers not the cam. Being unfamiliar with mopar and uneasy with setting up the rockers after having to get longer push rods to accommodate the taller indy heads I took it to the machine shop where I had the block and crank work done and had Ed set the valve lash up for me...is it correct??? i don't know, i just trusted someone with much more knowledge than me.

 

[AJ/FormS]

I do have a FiTech 600 power adder sitting here in the box yet. I will install it this winter along with an FBO ignition system...you're most likely right AJ...that will more than likely clean up the smell.

No, I don't think so! Your ignition system for this cam does not need to be fancy. It will run on points if it has to.Well a dual-point system anyway.It just has to be stable and reliable.Your stink is not likely caused by a faulty ignition system. At idle, this is purely a mixture issue.And since the transfer ports are your #1 low-speed fuel delivery circuit, augmented by the adjustable mixture screws; this is the place to start.So the T-PORT sync is job #1, after the valve racket is fixed.

Earlier, someone reported a low Dcr with that 9.5 Scr and I verified that it looks to be around 7.8/155psi at sealevel. IMO that's not so bad, certainly far better than the stock Scr.It might be a little soft with your TC and gears, so;normally I might suggest to toss that 2200TC in favor of a 2800 at least.But the dyno chart shows that this engine is making pretty good torque by 2400, so Ima thinking the slight improvement might not justify the expense.And 3.23s ain't so bad.Your timeslip says the engine is pretty strong.I'm betting you short-shifted it to trap in third/Drive. Second with 3.23s is about 6450 plus slip, so maybe 6700/6800.Your dyno sheet shows a peak around 5800, but the test was stopped before we see where it crashes. We can see tho that the fall off looks to be real slow and gradual.A third gear trap mightabin 4400 plus slip,say 4600.At this rpm it looks like the engine finishes about 60 horsepower down.But worse is if you outshifted second at 6000 rpm to drop into third at about 4100, where power has fallen to something like 180. There's a good chance that holding second through the traps, the power might have fallen to the same 180, but you saved a shift.The result of that would be a little quicker ET. The correct gear for your speed might be 4.10s,depending on tire choice, to allow a full 3-gear pull, trapping at something like 6200. These 4.10s will make your car greased lightning to about 45/50 mph,again depending on tire choice. Of course now it's a city car

 

[rumblefish360]

That ought to be a nice package!

 

[lomchivok]

It can be very frustrating when tuning your baby. There are so many variables that the load can be quite overwhelming for a guy who doesn't do this every day especially when you have to try fix the new parts that you're supposed to be able to trust right out of the box...Yea right. Hopefully someday soon the good stuff will be made in America again.
I know it's blasphemy to mention a Cheby but I have built more of them than I can count on 2 hands and haven't had the issues I'm having now, well except for the 396 I destroyed in tech school. (I learned a lot about oil pumps and drive shafts on that build)...I like to be an optimist and believe that better things come from hard work. For my first mopar build I must say that I am impressed with this motor and how well it runs and handles rpm's. I'll get it dialed in. My success will be large in part from the input from you who have much more experience than I.

 

[AJ/FormS]

Those heads seem to be doing their job!....12.92@102 is moving pretty good for that cam,in a teener, in I'm assuming, that notchy.

 

[Lustle]

Should clarify that the dyno sheet is hp and torque at the rear wheels but yes, it should be making more power.

280 at the wheels is not bad. That should be what? 325-350 at the crank? Depending on transmission/rear end? Torque doesn't really surprise me. Bore = HP. Stroke = Torque.

But if you are having vacuum and idle problems. Then it still needs a tuneup. And you'd be amazed how much power is in a tune up. If you do go to a smaller cam, you might make more torque but you will make less power.