proryder2

can you tune a cam with 284 duration .507/.510 lift? will it be hard for a newbie?

eric305TPI

Shouldn't be to hard with a 730 ECM (SD) driving it.

87_TA

Overlap Plays a huge rule in tuning on a Speed Density car.
Not so much duration, rather combination of duration and lobe seperation.

Grumpy

Depends on the Newbie.
Some guys take to tuning EFI like a duck to water, and some of us struggle for years to **get it**

SMasterson

Yes, with the factory GM ECM you can get a really good tune. But... if you're going with "soon to be 406 tpi" you're going to have intake restrictions right off the bat.

It will take time, you'll start over several times, and you'll read these threads everynight for any clues on how to get it better.

I'm driving a SBC383 with a Comp Cams 8-306-8, .544/.576 290/306 112LC to work everyday. Very good street tune on it and it sounds awsome, but mileage in town pretty much is poor. About 11-12mpg. Highway is about 14-15 though.

I've been tuning it over two years with three different cams, three different valve train setups, three different intake systems and three different exhausts with the MAF and SD ECM's.

It just keeps getting better as I understand more. Just take time and not being afraid to experiment. Datalogging is a MUST! I use TTS Datamaster 8D but there are free data logging programs out here to use. Also, there are free PROM (Chip) editors you can use too. For the price of a PROM burner and ALDL cable and a laptop, you're hooked up!

Just keep reading and you'll find the answer to almost any question you can think of about DIY EFI.

87_TA

Must not forget the overlap as I mentioned, to much overlap will wreck havoc on your 02 reading, leaving you to tune blind in a sense. being that low rpm blm readings will mean little because of the amount of unburned 02 in the exhaust. Same goes with a WB in same situation. So carfull scaling of VE and plug reading while running car on open loop will get you there.

Answer: yes you can!
Its just if you are willing to put in the time and energy.
If you are just starting, I would start with a cam with a decent vacuum signal.

proryder2

what are the restrictions i will have? will there still be restrictions with a 58mm tb slp runners ported maniflod and 30lb injectors? also i have an msd ingition setup that i never put on the motor. it has a mallory unilite distrubter and it a a little **** you can turn to advance the timing up to 15 degrees. its the 6a. would this be good for tuning? if not what would you suggest?
thanks a lot for your help

proryder2

oooh whats the overlap thing you were talking about?

Twilightoptics

It comes down to, will your ported manifold/runners flow what the heads flow on the 406? AND do the heads on the 406 flow enough to really feed the 406?!

Doubtful. TPI runs out of huff pretty easy on a 350.

87_TA

Valve overlap is when both intake and exhaust valves are open at same time.
What that does for you is promotes higher RPM exhaust scavaging - meaning the exhaust stream is creating a vacuum while being discharged, therefor opening the intake valve during this cycle will allow the intake to utilize the exhaust vacuum to pull in new air.
But the tradoff is at low rpm the cam is very uneffecient (spelling)
at getting a clean burn because you are re burning exhaust and pulling unburned oxygen into the ex straem.
Now the problem with that is your o2 sensor makes adjustment from the amount of 02 in the exhaust, so with a cam utilizing alot of overlap the 02 will be fooled into thinking the car is lean (because of the unburned oxygen) and try to add fuel to correct therefor making the car way way rich.
You may have some people who don't understand cams try to tell you differently but those are facts.
So if you buy youself a cam with 70 degrees overlap you will basically have to throw away your o2 sensor and tune using your senses. But it can still be utilized as a tuning tool but we will get into that if needed. I just got into alot more than I wanted to here.

Twilightoptics

Friend of mine with a 383 and a pretty stout cam:

open loop was VERY rich
closed loop was very lean


kinda of backwards?

87_TA

Stout being?

MAF or SD car?

How does he know it was lean?
If it was rich in open loop thats because of his tune, open loop only gives what you tell it.
When lean in closed loop, was he going off BLM value? if so re read about the egr'ing of the cam will cause BLM to lie to you if cam has alot of LSA.

TRAXION

You can command different O2 swing points at idle and at various loads. This helps when dealing with a lower LSA camshaft and is very easy to do.

This post makes good reading:
https://www.thirdgen.org/techbb2/sho...hreadid=215238

Tim

Ronny

iTrader: (1)

advertised duration 268/280 224/230 @ .05 LSA 114 what is overlap??? thanks...

87_TA

Can you change for different RPM?
TC only has high / low for idle.

Also if cam is that big (which we do not know yet) for instants
a 106 lsa that would be 102 degrees total overlap - forget it.
you can find yourself at 4mv. pretty quick.

102 Degrees total which is what my last cam was 286/286 @ 110
Anywhere below 1400 rpm 02 mv. where @ 4.
If your overlap is that bad , header temps will let you know in a hurry.

My current cam which is much larger duration @ .050 actually has less total overlap - 84 degrees .

With a bigger cam you will want to look for Header temps in the
280-400 degree range. (surface)
with my other cam closed loop fueling would give you 750 degree
temps and a pretty glow at night - sure it looks real neat but spark plug wires hate it.

Just picked myself up a new craftsman laser pyro on sale for $44 - very handy. Not to get more off topic but they are also a great way to check valve adjustment by comparing each tubes temp.

87_TA

74 degrees total / + 20 degrees spread @ .050 = no problems.

Ronny

iTrader: (1)

how did you arrive at that fiqure? not questioning accuracy just trying to fiquere this stuff out. with a 360 deg event the intake is open 268 and the exhaust 280 deg so they overlap each other for a period of time and both valves are open but to lesser amounts as the events happen at different times. please elaborate. i did see the post with the graph so the overlap is illustrated but how to calc with paper pencil the overlap? i never see illustrated on specs,

87_TA

Way off topic now.
360 DEGREES MINUS DURATION MINUS DURATION PLUS LSA.
Or search internet for cam overlap calculator.

http://www.rbracing-rsr.com/camshaft.html

If you have anymore cam questions this is not the thread for them.

Ronny

iTrader: (1)

thanks. makes sense.

Twilightoptics

Stout being : 60deg overlap @ .006

284/292:230/238 114lsa, 108CL

Maf car

Mostly stock ARAP openloop. Smells fat and fouls the plugs.

160blm @ idle in closed loop. Seems to idle good, cruise blms are around 126-136

We decided to leave the maf values where they are at idle because it idles good with no knock and richening the maf values will cause open loop to suck more.

Besides if it lies then?

87_TA

Well MAF is a different animal.
But as I said about the BLM value - its still rich it just thinks its not because of the raw air in exhaust stream.
He would be best to change o2 toggle setting (lower) if he can go low enough.
If not force open loop all of the time and fix MAF tables.
60degrees @ 006 is pretty good overlap, My previous had 66 @ .006. I had no choice but to force open loop.
Now if it happen to be a solid roller he can try to lessen valve lash to eliminate alot of overlap, but it may cost HP - But maybe not.
Actually you can do the same with a HYD roller long as you are using a good quality lifter. A lesser lifter will blow out C clip retainer.
Another option is to Run a solid lifter if it is a HYD cam, you may even gain some RPM and HP and still lessen overlap.

Twilightoptics

Tuning by nose and plugs, it's not to rich at idle in closed loop and idles like a kitten.

Which way do we want to turn the o2 swing? If we move it lower than .5mv, it's going to subtract more fuel, and we should more or less ignore the blm?

If we force open loop, it wont purge the CCP and it will fill up with fuel. Had that happen once.

87_TA

Hmmm,
Well you could do a couple of things - If you want and don't care disconnect ccp and vent line.

Next option is lock BLM and INT. and tune from there.

"Which way do we want to turn the o2 swing? " Lower until BLM start to raise at idle regardless you will have the same amount of fuel at this point - currently Idle BLM is 160, so right now at idle ECM is adding 25 % fuel at idle trying to correct BLM


If we move it lower than .5mv, it's going to subtract more fuel, and we should more or less ignore the blm?"
Correct, Its not going to really sutract fuel its just going to tell ecm that where you are is correct.

Remember the 02 is getting reading from the oxygen in exhaust stream. So if you are putting alot of unburned o2 in exhaust the sensor thinks you are lean - hence the 160 blm. See the sensor reads 02 content - not fuel, so if you are really rich, it does not read the extra fuel, it reads the lack of 02(normal cam)

But if you are rich and purge alot of unburned 02, the sensor thinks you are lean still because of the high 02 content.

If you lower toggle voltage its not going to start taking fuel until you get a BLM value less than 160.


Here is a question:
Are you happy where the fueling is now at idle? smell and plug wise.
Regardless of BLM where do you think idle fuel is now? rich/lean or perfect?

If it smells fat in open loop and fouls plugs then it should be just as rich in closed loop if not richer.
Its using same maf tables but now adding fuel because 02 sensor thiks you are lean.


BRAIN STORM
What size inj is he using and fuel pressure? stock/stock?
If not that may be the problem with open loop.

Twilightoptics

typically it is smelling rich and fouling the plugs in the lower temperatures of open loop. I've been slowely changing the

Open Loop AFR ratio % change vs coolant temp.


I've been lowering that table and it's been getting better. After about 2min of idling in open loop from the first startup of the day you can't SMELLL the richness anymore.

I assume thats the right table to adjust only Open loop fueling other than the maf tables.

Fuel pressure is about 43, 30lb injectors.
383 Miniram.

87_TA

I was going to suggest that as well, and yes you are ok to do
that. I wasnt seeing that table on my version. Though it has not been updated for years.

The reason I asked about the inj. is to make sure constants matched - That can throw open loop off quite a bit.
But back to closed loop, try locking BLM/INT to 128 and see how it idles. if its still good start working the O2 Swing tables down till BLM (Unlocked now) get into range.
If constants and FP are correct and its very rich closed open loop, its going to be rich closed loop as well. And as you say his BLM are max lean which is where the overlap comes into play.
Keep us posted.

Twilightoptics

It's hard to tell a difference in idle with whatever we do its so smooth. We either smell fuel and foul the plugs, or don't if it's warmed up enough.

I'll try moving the O2 swing,

It's set at:


0 gm/sec .575mv
8 gm/sec .610mv
16 gm/sec .628mv


He idles right about 8-9gm sec.

So is moving it to .350 mv too much to start?

(Wish I could afford a romulator)

Even with moving the o2 swing, I've got to bring the open loop down with that table some more.

Thanks!
-Paul

87_TA

Also ! If the car has a Cat on by any chance that will kill the rich smell when warmed. It should also be smoking hot.

Twilightoptics

Cats are gone (ruined them with the rich idle LOL so they were hollowed).

There is quite a bit of carbon that comes out the first WOT or two from the richness.

proryder2

ok i found the specs on the cam im using they are posted here:
http://www.compcams.com/Technical/Dy...84H-10_001.asp
please let me know if it will be very hard to tune. the engine is a 406, 11.6 to 1 compresson, double hump fuelie heads (ported and polished) 2.02 intake valves, 30 lb injectors, 58mm tb, slp runners, port matched plenum and manifold. thanks for all your help just wanted to know what im getting into.

BIRD91ZRAG

iTrader: (1)

I see plenty of one or both of these in your future....

1-Detonation
2-Race fuel with 100+ octane.

Your static compression ratio is waaayyyy too high for street pump gas and cast iron heads. With the cam you spec'ed you'll have a Dynamic Compression Ratio (DCR- The running compression your engine actually sees.) of 9.06:1 You want to be below 8:1 with cast iron heads, and below 8.5 with Alum. I suggest you use a dished piston and a head with a chamber of at least 70 cc's, if not 72 cc's. THis will put your static CR at 10.1:1 with a 12 cc dished piston. (I have a set if you need them)
Changing to a cam with a 112 or 114 LSA will require even less static CR.

Dave

proryder2

that engine is already in my truck it has 64cc heads and i run it on 91 octane now pings or detonation. the timing is at 16 degrees intial. i was just wondering how hard it will be to tune it when i put the tuned port on it.

proryder2

that engine is already in my truck it has 64cc heads and it runs on 91 octane no pings or detonation. the timing is at 16 degrees intial. i was just wondering how hard it will be to tune it when i put the tuned port on it.

87_TA

Yes!
That cam has a huge amount of overlap. You can easily run a big overlap cam long as you force open loop.
The problem with that is you are tuning blind - even if you have a w/b.
Its also kinda of a mismatch, a cam like that wants to build high RPM HP that you cannot give because of the long runner setup. and heads that I am sure are not flow very well - even ported.
If you were to do maybe a LT1 converted intake or switch to a MIni Ram/ Stealth Ram you would be much better off.

Not saying it can not or will not work well, but with the current setup you may want to focus on torque more than HP. Get a cam with less overlap to use cyl. pressure to build more torque, be alot more new tuner friendly, and you could make a monster that will break things with ease

Twilightoptics

My Static is 10:1 My Dynamic is 8.19 and I can run 87 octane all day and my AFR is 14-14.5:1 at WOT according to the dyno wideband. No knock.

Yes 8.1 is on the high end, but you don't have to be under it if you have good cyl heads and tuned right. Hot spots cause the detonations alot as do old style chambers. (Not sure about the camel humps though)

That cam has a huge amount of overlap and you'll be fine. Just have fun tuning it!

TRAXION

I still disagree. You can run closed loop with a cam with lots of overlap ... ESPECIALLY now that some of us are using the O2mV swing points to tune the closed loop idle for a higher AFR.

My cam has TONS of overlap.

Tim

87_TA

True you have much more ability with the o2 swing points - But they are still only at idle correct? Not 900 - 1400 and so on.

Also when you have a cam that purges soo much raw air that 02 constantly reads 4 mv at idle - Where are you going to swing from there?

What is the Total overlap of your cam Tim? Not at .050 but total?

TRAXION

Tom,

Yes, there ARE O2 constants for regular part throttle driving. There are constants for idle AND for regular driving. However, I haven't had a need to touch normal part throttle driving conditions yet.

I would put forth that if the O2 was reading 4mV then there is a problem ... and that it is not the cam. 4mV is absolutely insane. I am not going to say that it is impossible. I have a feeling that it probably IS possible with drag-only cars that are running 300+ duration cams with very low LSA numbers. FWIW, with my CC306 cam I had to change the injector constant from 33 to 40lb/hr in order to get 20mV at idle.

I don't know my total overlap offhand. However, didn't we already do the 'whos bigger' game previously with 0.050 overlap? Mine was bigger ... AND in a 350 as compared to a 400. My cam pulls ~75kPa at idle ... dude, that is some serious overlap.

Everyone who has taken a drive in my car can't believe how driveable my car is. It's extremely driveable and has great street manners for a car with such a 'no-no' EFI cam and for a car with a 3600 stall. I honestly believe that you can do closed loop ... IF you wanted to. However, I think others (like Grumpy) would possibly say "WHY" would you want to. I like it - some don't. Where there's a will there's a way. It's just a matter of what you want to do and HOW MUCH TIME you are willing to put into the tune.

Tim

87_TA

Well yes Tim, Everybody knows yours is HUGE!!!!!!!!
But total overlap is a different story from overlap @ .050..

The other cam I had my problem with was a 230/230 @ 50 ls110
my new is 242/242. ls 112
But the first cam actually has 20 more degrees total overlap
even though it has 30 less @ 50.
I kinda think that may be an issue.... 102 old cam vs. 84 current.

Back in the day overlap below .050 meant nothing to carb guys
because there is no big flow happening below there, Nor did it matter becasue a carb works much like a MAF in terms - it only gives what the air ask for.
But in EFI world where there are 02's involved things change.

As for you car driving great, Thats cool. So does mine! as it did before. actually drives extremely well and gets pretty good milage
as it also did before.
Header temps were the issue, alot of people could go and still are going on forever without knowing they have excessive exhaust temps.
Do you know what yours are? You should.

That was my point before, had I not happen to look under my hood in a dark garage to try and find an arching plug wire I would have never known.

Dude you cam is big, My old cam pulled 68 at idle in a 406.
That would probably be more than yours in a 350
Thats also may be where alot of my problem was, If we both run the same cam in out engines I will be purging 25% more air than a 350 - you agree that would also be an issue?
Its not about whos KPA is bigger, its about pushing more air (unburned) out the exhaust.

TRAXION

Performance Trends' Engine Analyzer is showing 82d of total overlap for my cam.

I don't know what my header temps are. I agree that I would like to know I guess I gotta get one of those IR Point and Shoot thermometers. Is that what you are using?

I agree with what you said about the 400. That could definitely be an issue ... but I am just curious if the code in the binary allows for O2 changes with regard to displacement? Not sure - I haven't looked at it that in depth.

Tim

87_TA

See now we are getting somewhere, Your cam has 82 degrees total. Mine had 102! Pretty hefty overlap.
My current has 84


Yeah Tim for the Pyrometer I just bought at sears 1 week ago on craftsman day. $44 dollars scans -20 to 520 degrees +/- 2%.
Prior to that I had a borrowed snap on (very nice), did not want to give back

As for code changes for displacement, I doubt it. Stock applications never have enough overlap for that to be a concern.
But you never know.

Twilightoptics

What header temperatures are you after, why, and what effects them?

I have a pyrometer that I use for tire temps and it would work great for header temps. Do coated headers give different readings?

Why do you think total overlap has so much more to do with closed loop problems? I think lobe shape has alot to do with it. Some cams being a-symetrical and all.

The cam I'll be running on a 112lsa/106cl, has 47deg overlap at .20 and 19deg at .050 (I think I am using the DCR calculator right). 267/275 at .020, 239/247 at .050. Some cam manufactures don't pay so much attention to the advertised at .00 because of the lobe shape and ramp.

It all depends on how fast the ramp is, if you ramp faster you have that big overlap faster, if you ramp slower at first at least, then you really don't have as big a overlap. (among other things I'm sure.)

87_TA

Overlap: Most performance cams want their overlap @ 50 and above because thats where it counts for performance .
Overlap beforehand is not really wanted or needed but used because it has to be. Reason being that you see less Total overlap in mine and traxxas cams compared to my previous (HYD)
roller, A hyd needs a slower ramp to not compress lifter and not float valves due to weight. It does not need the massive overlap (total) but is forced to because the slow ramp.
A solid can use a much faster ramp to obtain its desired duration/lift after .050 - so it does in our aplication.

That is where the total duration comes into play when being used in an EFI application. - That overlap does not really hurt a carbed car as much other than vacuum loss and response due to vacuum loss which is why you have those monster HYD rollers for people Who want the GO without the noise/maintenance.
Your right about lobe shape to - But is that not where the overlap before and after .050 com into play? Sure their is more to it than that but it is a good place to start.
Look at almost any advertised EFI performance cam out their and their total duration figures . You might see a pattern.
I can tell you the cam in my car now is much easier to tune compared to my Previous HDY roller despite having more O/L @ .05 but much less total. (Because it could) Being a solid roller.

Now don't think you can't or will not be able to get away with it their are more factors. If you have smaller valves low flowing heads/intake , restrictive exhaust you will hide alot of the overlap
issues and the WOT performance associated.
Start talking to cam manufacturers , you will be surprised How little alot of them know about EFI. They need to start getting more TRAXION's and Grumpy's and Rob's to work for them.
Also call Comp for a cam recomendation, then call again and talk to another tech. You will be really surprised that 2 techs will give two totally different cams.
Header temps depend on the Cam. A near stock type cam you will see 400 + degree temps at idle. A performance cam with healthy O/L will see 300 and below because of the Unburned air cooling the charge as it gets pulled from intake tract.

Twilightoptics

I had called comp for a recommendation for the hell of it and they recommended the 268 cam. 224/230 on a 114LSA. Thats one step above the 262 cam they recommended that I used for TPI and almost stock heads.

268 for Pro heads and a Stealth Ram? I don't think so.

That's why I'm going with the 239/247 on a 112 Solid Tappet.

I'll have to check out my exhaust temps with the 262 in there and after the cam swap.

TRAXION

Who is TRAXXAS????

Tim

87_TA

Some jerk, You would not like him.

LOL, My bad.
Honestly my brother in law has one of those gas powered remote trucks and its made by traxxas. Think I had that on the brain.

11sORbust

FYI, I had not trouble tuning my 406ci engine with 242/250*duration,114*lda....but then again I don't have tons of overlap.

87_TA

Did you tune for 128? If so then you probably have more trouble than you think

11sORbust

I have not hooked up the wideband(part throttle or idle). Not sure it can even be used for idle, with my cam? But I do know the car will start warm or cold just like a stocker. The gas mileage is 20+. There is zero part throttle flat spots. I tried to command 14.2 a/f ratio at idle with the o2 constants. Everything seems to be fairly good.

What kind of trouble are you talking about? I'm always open for suggestions. Now that we "locked horns" again, maybe you can explain why you swapped heads? I really wish you had a site for your car.

87_TA

Actually read through this post and you will see, My car ran perfect with the other cam, idle,start,wot,mpg. ect.
The problem was excessive header temps. Did not really smell that bad but... WB 14.7 / BLM 128.

Wish I had a site too don't know how to make..
Swapped heads cause I always wanted AFR's, since after I bought my first set of darts years ago. Always settled for less because of money.
There was alot of things I did not like about the Canfields - Well talk off board. Sorry keep getting thread sidetracked.

11sORbust

sounds good. I'm really curious how much the AFR gave you over the canfield?



It's hard to check header temps because I have heat wrap on em. I can always tell when headers are too hot though. The paint on my the heads would smell a bit This cam I have now doesn't get the headers hot, like your old one did.

My tune is starting to get real sharp @ wot. I'm breaking traction at 85mph shifting into 3rd. I'm ALWAYS open for advice/suggestion though. thanks!