16 total mech and vac sounds really low. What distrib you running and 16 total at 2500?
Slightly disappointed in performance
- Thread starter DSMRossi
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I don't think he's counting vacuum, and that is correct. Vacuum advance should not be counted when setting up a distributor curve. It's initial, plus mechanical. Vacuum is sometimes adjustable, but only as to the "when" and not "how much". Even the MP engine book says to let vacuum just "end up" where it is.
nm9stheham
Well-Known Member
That's the compromise you have to hit. You can step up at least one cam size and it will still be quite a good driver since you have started with good CR. I'd get into the mid-upper 270's for advertised with that static CR and not expect to miss the minor loss in the low RPM torque. You have plenty of rear gear to start with.
I would be looking at a 262 with a low CR 318 to not lose too much low RPM torque for daily driving. Not need to stay that small for your engine.
I asked earlier what the total of both is. Let me find my crayons so I will shut up.
Not counting vacuum, I’m not even sure what I have for part throttle. I had some rattling at first and took some of the vacuum advance out (adjustable vac can), but I’m only talking WOT performance at the moment.
As far as part throttle driving, you’d think the car was bone stock besides the noise. It drives great
LMAO. It's not uncommon to see 60* total including vacuum advance. It's really not important because the vacuum can only works at part throttle. On accel, vacuum drops out, so it's not working then. Likewise at idle, IF it is connected to a ported vacuum source.
mopowers
Well-Known Member
Have you had it on a dyno or drag strip? What performance are you disappointed in??? Give us some numbers.
PRH
Well-Known Member
I get the feeling it’s the butt dyno that’s not happy.
hemi446
Well-Known Member
My 2 cent the cam is on the small size and the dual plane intake may not be helping on top end at all. Like other have said what was the engine built for and what numbers do you have. We are just guessing without knowing what is hurting is it 60 foot or top end. The really answer is in those number and what you are using the car for.
goal was to have a street night monster capable of low 12’s high 11’s, but also a car that Im able to cruise with to regional shows.
It comes out of the hole great, but it just doesn’t shove me in the seat like I expected, especially into 3rd
Sometimes you can't have it both ways.
yellow rose
Overnight Sensation
PRH
Well-Known Member
Honestly, with how poorly many street oriented cars are set up to get good track times, I would have waaaaay overshot what I needed in terms of HP.
If the goal was to truly have shot at the 11’s, with a “street” car........ a 408 with some mild reworked RPM heads and a solid cam would have been a wiser path imo.
I’d have gone for 500ft/lbs and at least 450hp.
Can a 360 get you there? Obviously yes....... but not likely without giving up some(probably more like a lot) of that street friendly demeanor that you’re currently enjoying.
At this point, my recommendation is to go make some passes and/or a trip to the chassis dyno to see what you really have.
A 100 shot is probably the easy solution here.
That’s what’s on there now
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Just for comparison;
Back in about 2002, my 360 equipped 68 Barracuda went 106@12.9 with 3.55s and street tires at 3650 pounds and ~715ft elevation. One run only, then went home. Hyup the 750DP was quite rich, didn't care. My 360 was also close to zero-deck with KB 107s, OOTB aluminum Eddies, AG-intake ,TTIs (full exhaust), 10.9Scr,and a 223/230/110 Hughes-cam, with .538/.549lift. The 60ft was in the 2.4zone. Oh yeah this is a clutch car and the tires were 245/60-14s@25.6 tall. So 106 was 6900 in third,about same as 1-2 and 2-3 shifts.
IIRC the Wallace calculator makes that 335 hp. I was disappointed in the number, but not at all with the trapspeed.Nor with the engine in general, great streeter.
This combo, IMO, had phenomenal torque and power. If the cam hadn't lost lobes, I'd still be driving it today.
MOPAROFFICIAL
Oogliboogli
The exhaust ports could flow more. That's with a 1 3/4 pipe. Intake is pretty good.
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Yes and no.
Set up the mechanical curve and initial, then tweak the vac advance for the part throttle load and can get better part throttle response and power.
And do it wrong with too quick on the mechanical and get the part throttle ping.
Small block Chrysler with factory type heads should be around 50* - 52* while cruising on highway.
But the mechanical being all in at 2500 is a problem with vac advance. Makes it too easy to detonate at moderate to heavy part throttle.
Dead nuts at top end of the timing curve is proven at the track.
WOT AFR same thing.
But you can get close on the chassis dyno.
IMO the important thing to do on the dyno is make the WOT AFR flat. Then at the track you just make jet changes.
Later you can tinker with enrichment restrictions vs main jets if needed and you want to dial in the highway mixtures.
Get that all done and check if slight changes in timing make difference.
All depends how dead nuts you want it.
Time to burn and mixture density are related, so thats why testing requires many iterations if you want the best out of what you got.
Most people are happy with pretty good.
QuickDart360
Well-Known Member
Just stick a 292 mopar purple cam in and make some power!
Let the bashing begin!!
Oh the 108° lobe separation version.
Let the bashing begin!! Oh the 108° lobe separation version.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Just stick a 292 mopar purple cam in and make some power!
That's what I did. With 3.55s. I thought with a clutch I could get away with it. I was wrong. That cam even at 11.3Scr didn't even wake up until over 3000 rpm... which with 3.55s and a 2.66 low gear, comes at 25mph. So wrong gears for the cam, or wrong cam for the gears. I got rid of it. Not for the above reason alone mind you, but because with a clutch, the engine is married to the rear tires, and slipping it out like a grain-truck was was not very Mopar-like.
The minimum driving speed was about 750 rpm so 6.25 mph, making parades and car-shows impossible. Yeah I advanced it, but at 11.3Scr,she already had a ton of torque, just not at 750 rpm..., So yeah, I advanced it some more, with predictable results.So I retarded it to straight-up, installed a A833od, and 4.88s Oh Yeah.
And I'll tell ya, she was a ripper after 5000, all the way to 6500 and I usually shifted her at ~7000; but 65mph was 6800 in second; now yur talking.
Well sorta. First gear at 3.09x4.88=15.08 starter gear was ignorant. But the silver lining was 750=3.9mph; walking speed, horrah. The bad was 30mph was 5750 in first 3100 in second, and you can see how ugly that was.
I think I pulled it out in late summer. I don't miss it.
After that is when I installed the Hughes 270/276/110 (223/230@.050).. That's 3 cam sizes,if yur counting. And IMO was just right. I loved this cam. Out with the 4.88s and in with 4.30s, and got a GVod and started splitting gears; badaBoom. 3.09-2.41-1.67-1.30-1.00-.78-.54 hyup 7 nicely spaced gears. A couple of gear changes later And she was wearing 3.23s, and then back to 3.55s.
For a streeter it's all about having the right amount of torque at the right time. If you got that, then you don't need absolute power, cuz you can only use it once at the top of first, and usually the tires are spinning anyway. If you have a TF, the 1-2 shift is where things get cranky, cuz the split is 59%. If you short shift into second, well your engine better have some juice down there. Most guys don't build to spin very much past 6000, so if you shift there, then 59% is 3540...... way below peak torque of a 292 cam, so she's gonna struggle to maybe 3800/4000 to find some pull, and with 3.55s that will put you right around 65mph.So you hit the speed limit right when the cam is waking up the second time. Bad news you lose, to the guy who's been on the powerpeak already for 200/300 rpm, even tho he might have way less power, Ima thinking a cam up to about 3 sizes smaller.
That 292/108 had a great top-end rush, and woulda made a great race-combo with the right gears. For me, the 292 was just all wrong.
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