Cam for torque question

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If after your tune up and still not satisfied.
I wouldn't go with less cam probably won't gain much downstairs just lose top end.

The reason people say don't build a 318 isn't cause they can't perform. But people are barely willing to gear a 360 properly nevermind a 318. 3:55 gear is what the average guy runs that's why 408 are so popular. To me 3.91 is the minimum 318 gear unless you after an econo combo and with your parts list seems not to be the case.
 
Rear wheel power makes more sense. I thought the nubers were pretty weak.
 
Lustle said:
That XE268H should make tonnes of vacuum. 15.5 inches at 850 idle.
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FWIW, we have a Crane Z268 in a 340 and have 14-15 in idle vacuum at 850 RPM. That cam has slower ramps than the XE and a 112 LSA but 9" at vacuum is indeed low. All the comments as to tune are spot on. If you are happy with the car's performance (as it seems like) then I would not change cams before getting other items straightened out. As suggested, the the PCV may be wrong for that cam and may be opening up wide to the higher cruise flow levels at below 15" and throwing the idle setup all off. A stock PCV will have that problem so should be replaced.

Then a cam change would be in order if you wanted more MPG, for example, or more low end, and were OK with a bit less top end. But I see no reason it can't still rev to 6k+ with a step or 2 down in cam; the heads are decent flowing. Your SCR is not excessive to start with so it can stand some more DCR.
 
I agree - cam should not be a problem. I don;t consider 1000rpm as an idle - it should be less, and you might actually be too high in the transition slots and it's drawing fuel. Hard to say - but I think it's tuning too. Try a different known carb on it, or something you can get the idle down to 800-ish out of gear.
 
Ok these are all good thoughts, and if it has been covered, sorry. but i think the Power Valve is the first place to investigate! 2nt, some one ask at what altitude you live. This would help us with you combo as well..........

Now initial timing should be turned up and see what your vacuum gauge shows. This could make your vac. raise back up to were i think it sould be......But if that Power Valve is too high of vac. OR it is blown(BAD) then it will run PUG rich no matter what you do.
I think you need to know what power valve you have and if it is any good.................
 
Cudafever said:
Ok these are all good thoughts, and if it has been covered, sorry. but i think the Power Valve is the first place to investigate! 2nt, some one ask at what altitude you live. This would help us with you combo as well..........

Now initial timing should be turned up and see what your vacuum gauge shows. This could make your vac. raise back up to were i think it should be......But if that Power Valve is too high of vac. OR it is blown(BAD) then it will run PUG rich no matter what you do.
I think you need to know what power valve you have and if it is any good.................
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I'm at 300 feet...Bellingham Wa. The power valve is a 35..3.5" inches. Could maybe up it to a 4.5.
I know I am leaving something on the table. There are times when going through the gears to 6 grand that between about 5200 and 6 it pulls very hard, really lays ya back in the seat. There are other times when at the same rpms it just isn't there. It's a more lazy climb to 6000. I'm thinking it's the Distributor or more so the cheap mechanical limiter bars anyway as one of the contributing factors.
This winter with the FiTech and FBO install I should see (hopefully) better A/F control, idle control and timing control...that being said, there is then the setup learning curve for the FiTech.

When I'm done I'll post another Dyno Sheet and another run at Mission Raceway.
I'm not a 1/4 mile racer per se, I just like to go to the test and tune nights or the street legals to see what results my tinkering brings and to grudge with my buddy and his cheby luv 350...(Hehehe He's pissed off at my 318). I am however starting to get that bug again...
 
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I don't think you understand what a power valve does....so i will try and explain.
the vac #3.5(plenty low enough) is the point in which the power valve(PV) open. when the valve opens, it adds more fuel or richen the idle and main circuit. if you vac was to drop below that 3.5 it would start dumping more fuel in.
Your vac is not that low so it shouldn't open even in gear(but you should check to see) BUT if that PV is bad it will be dumping more fuel in at ALL TIMES. And would cause a stink in the tail pipe.
buy a new one, they're inexpensive, and replace it. IF it was bad you will know it when you fire it up.

I still think you need to grab that dist and give it a turn. bet the vac goes up when you turn it the right way.............
check the idle timing and give it a twist!
one more thing, you said that you are idling at around 1000 rpm. if your centrifugal advance is starting to open at 1000 rpm and your initial timing is at say 15. If you turned you idle down you may find that it is not at 15 but maybe only twelve. so when you put it into gear you loose timing........something to think about:poke:
 
Cudafever said:
I don't think you understand what a power valve does....so i will try and explain.
the vac #3.5(plenty low enough) is the point in which the power valve(PV) open. when the valve opens, it adds more fuel or richen the idle and main circuit. if you vac was to drop below that 3.5 it would start dumping more fuel in.
Your vac is not that low so it shouldn't open even in gear(but you should check to see) BUT if that PV is bad it will be dumping more fuel in at ALL TIMES. And would cause a stink in the tail pipe.
buy a new one, they're inexpensive, and replace it. IF it was bad you will know it when you fire it up.

I still think you need to grab that dist and give it a turn. bet the vac goes up when you turn it the right way.............
check the idle timing and give it a twist!
one more thing, you said that you are idling at around 1000 rpm. if your centrifugal advance is starting to open at 1000 rpm and your initial timing is at say 15. If you turned you idle down you may find that it is not at 15 but maybe only twelve. so when you put it into gear you loose timing........something to think about:poke:
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I know what a power valve does...had a 6.5 in it out of the box changed it to a 4.5. did the vacuum/2 calculation and put a 3.5 in
 
Cudafever said:
K so do you think it might be.. bad?
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Don't think so...Never had a backfire...the older carbs would blow out power valves on a backfire, the newer ones have a check ball that is supposed to prevent that from happening still could though I suppose. Could have some debris causing it to not fully seat but the fuel tank, filters and lines are all new, about ten months old. Fuel filters have been changed 5 times already, not because of problems but because it's a new installation. I only change the fuel filters now at oil changes.(2500 miles)
 
Yup, would be worth a check if you pull that front fuel bowl off.
Like i said above, think it need more initial timing. do the twist and find out.:D
 
Cudafever said:
Yup, would be worth a check if you pull that front fuel bowl off.
Like i said above, think it need more initial timing. do the twist and find out.:D
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Ill do that.
I have to take it truck shopping today so I'll pop in a new power valve and do the twist of fate before I leave...My dumb *** Ram 1500 thought it would be a good idea to send water into the oil through a crack in the head...now it's got water in the oil and oil in the water...time for a new truck. This one has been good, 325000 miles and not a problem until now...it's fully worn out.
 
Don't let them talk you out of your ride in the process:poke::D
 
Okay, New 35 power valve, test drive = no difference. Brought the initial timing up to peak vacuum then back off 2". That brought the initial up to 33*, my smallest limiter is 12* that brought it all in at 3200 and 45* total and caused detonation. brought it back down to 21* initial with the 12 bar and 3200 all in at 33* = no detonation but not as much power. Changed limit bar to 16, now it's all in at 3200 with 37* total test drive = More power and no detonation. Brought initial up to 24*. with the 16* limiter bar it is now all in at 3200 and 40* total test drive = more power.
Back on ported vacuum. and all in static, mechanical and vacuum at 3500 rpm I get 48* total with the moroso vacuum advance limiter stop still installed. Idle is 950 neutral and 800 In gear. Need to check the transfer slots yet too but don't notice any stumble off idle
Will be leaving for about a 150 mile truck hunt drive in a few min. will share results when I get back.
 
Tight converter or a vacuum leak somewhere is my guess.

If you have any power items pulling vacuum from the manifold, block them all off and see if the engine rpm changes.
 
Well, it runs great... as it did before. I do notice the hard pull between 5200 and 6 grand is still there and it seems to pull a little harder mid range as well...it went a little sideways at a 50 mph shift from 1st to 2nd...first time that has happened.
I think yes, a vacuum leak. With the initial issues I had with the new carb and the fitment issues with the intake... it raises suspicion. I need to get rid of the pertronix dizzy too. Those mechanical stops just suck...period. The FBO approach is much more positive. Lots of work to do...never enough time but it'll get there. Should be able to tune it much better and faster on the Dyno after the TBI install...I hope so anyway...it's 125 bucks an hour for the Dyno and 100 bucks an hour for the tech to run it.
 
Okay AJ, Tomorrow i'm gonna pull the valve covers and look for loose rockers and shiny push rods then adjust em back up myself...at least then I know.
The timing setup I was using earlier today was a collaborative effort between myself and the machine shop. The pertronix dizzy was recommended as part of the process because of the ease of adjusting the mechanical advance limits...not working out...and the low vacuum actuated can was chosen for the low vacuum at idle. The moroso vacuum advance stop was chosen to limit the vacuum advance.
The idea for the vacuum advance was to run on manifold vacuum so at idle the can would advance the timing from 18* to about 24* to help smooth out the idle and run a bit cooler in traffic. Then at WOT the vacuum source would be lost allowing the motor to run on initial and mechanical curve timing then at cruise vacuum to provide more timing, about 48* through the can for better cruise fuel economy. it seems to work...I am open to a different approach.
Got my new truck but cant pick it up till monday so I don't want to tear in to it too far. I still need to get to work on monday but... this weekend I will try some of what you suggested.
 
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It's hard to overadvance a hi-compression aluminum headed SBMer, with this size of cam,and,operating under cruise conditions at 2200 to 2600ish. My 360 has not complained with over 60*. I am currently running about 50*/57* at 2800. Which is 80 mph with my gears.At 65 my gears get me 2236rpm, and the timing is about 44*/51*. The plus 7* is from the dash-mounted dial-back timing gizmo.
To be honest tho, the plus 7* makes very little difference. Sometimes it will pull up the mph 1 or 2 miles an hour, or, on the tach 50 or 60 rpm; on the exact same throttle opening. Other times not so much.
I only fiddle with it now, on long trips.
My engine is currently running a 276/286/110 Hughes cam (230/237@050), and runs rock-solid at 205*, with just 14* idle-timing,so overheating is not a concern for me.
And I like a tuff sounding idle, so I run only the 14*. I installed the DB gizmo as a tool for finding out instantaneously what advance the engine wanted under various loads and throttle openings. And also to retard the timing even more from the 14*,to weaken the power-pulses so the car would not be so jumpy, when parading it around the parking lot(stick-car). The cruise benefit was secondary.
On another topic;
IIRC my 230* cam makes a tic over 10" of vacuum at 750rpm. But the vacuum rises rapidly with rpm. I run my PV to open pretty early. What I did was to install a block-off plug in the PV hole and took the car for a drive. Then I rolled into the gas-pedal and figured out at what vacuum the engine wanted more fuel. Then I put the vacuum pump to every single PV I had, and lined them all up from earliest opening to latest. I pulled one out that seemed like a good match, and installed it. My engine wanted PVgas at about 10 inches vacuum. Since it idled at a tic over that, I couldn't put a 10 in there. But I discovered that the numbers stamped on my PVs bore little resemblance to what the valves were actually doing, so I just re-labeled mine from 1 to 8(IIRC), I forget which direction; maybe 10 fastest opening. It took a couple of tries to get one just right. If it opens too late, I could really feel the sag on tip-in, before it started pulling.Too early is hard to tell, so I aimed for too-late and backed up 1. But you will never know too early unless you have several to chose from and you calibrate them yourself.
I bought one of those adjustable PVs but I couldn't get it to work right, and eventually abandoned it.
 
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AJ/FormS said:
The plus 7* is from the dash-mounted dial-back timing gizmo.
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Yah, I been watchin you...you got some pretty cool stuff, dial-back timing gizmo...I want one!! Gear vendors I thought I read....I've been thinking about that option too for a long time...I would get quick and fast in 1 package...eh...prolly not sounds like split shifting em is troublesome for most.
 
Yeah there's a trick to splitting. I think it would work better with an automatic. The TC would absorb the shock better.That thing shifts like lightning, when off the computer, and likes to tear out the clutch hubs or spit out the springs,when I shift it without clutching it. But chirping the tires going into 2od,at 80mph is kindof cool.
 
GV are tuff! with just a little maintenance, it WON'T be the weak link! If i could afford it, i would have another one!!!
 
A power valve on a properly set up, tuned engine has ZERO effect at idle. I have cars that pull less vacuum than the PV rating and the idle doesn't change when a PV block off is installed.

If the throttle plates are open too far, a PV will richen the mixture, BUT, that means the carb/tune up is way off.
 
interesting....so what you are saying is that the PV is Not part of the idle circuit. I just AssUmE that it did. Really no reason that it should, now i think about it for a minute. :BangHead:
 
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