IRACE87

I can't make my engine past the 6000-6100 rpm range. It just hang there. I suspect that the injectors may be the cause. This happen at the same time that I reach 80% DC and my BPW is in the 9.XX range. Is it possible ??? My pressure stays in the 48 psi range so I'm pretty sure my 255 lph walbro pump is up to the task.

With my wide band I'm in the 12.7 AFR range so I can't really lean it more than that.

The engine is a 383 HSR/ 190 AFR with rev kit and AFR upgrade valve spring so this should not be an issue for valve float.

My injectors are Ford 30 lbs/hrs red top with the ECM constant set at 33.

Thanks

PAT

novass

iTrader: (1)

I know that this may sound obvious, however, what is your engine speed rpm limiter set at in the bin ?

RedIrocZ-28

I was having the same sort of problem, turns out that the chip I was using turned off fuel at 6200... sooo... Guess who couldn't rev past 6200?

IRACE87

Quote:

I know that this may sound obvious, however, what is your engine speed rpm limiter set at in the bin ?

None of the constant in my bin should keep me from reving higher than this. My speed limiter is at 255 mph and the rpm limiter is set around 10000 rpm.

Quote:

I was having the same sort of problem, turns out that the chip I was using turned off fuel at 6200... sooo... Guess who couldn't rev past 6200?

I would guess that it was the rpm limiter that was set at 6200....
Anyway like I said earlier the fuel pressure stay high when this happen so I would assume that the fuel is not turned off.

I'm clueless as to what is happening right now, on my scan on some run, the only slight thing that is different from 5900 and 6100 is that at 6100 I will see a slight increase on the map reading from maybe 98 kpa to 99 kpa and a slight drop from the O2 sensor from maybe 830 mv to 790 mv.

PAT

JP84Z430HP

Quote:

Originally posted by IRACE87
I would guess that it was the rpm limiter that was set at 6200....
Anyway like I said earlier the fuel pressure stay high when this happen so I would assume that the fuel is not turned off.

The ECM turns off the injectors when it hits the speed limiter, not the fuel pump. The oil pressure switch would keep the pump running anyway.

What is the injector pulse width just before, and when it happens?

IRACE87

Quote:

What is the injector pulse width just before, and when it happens?

I will have to take a look at my data when I'll be home tonight but by heart when it happens I'm in the 9.XX ms range. I don't see anything shutting down on my data.

When it happens it doesn't feel like the injectors are turned off, I drove an 98 Z24 Cavalier and when you hit the speed limiter it feels almost like someone hit the brakes.
On my car the engine just hang there ???? The highest rpm I saw so far is 6175.

So far I can't see anything in my bin that would cause this....

On my data logging the only clue I have is that around the same time it happens my injectors reach the 80% duty cycle range, but It may be only a coincidence.

Pressure from the fuel pump may drop 1 or 2 psi when it happens but stays near the 48 psi range.

On the machanical side the only thing I think about would be valve float but it should not happen so soon with my AFR rev-kit and there upgraded springs.

Still clueless.........

PAT

PS May try the car again tonight with someone else to get an other opinion.

John Millican

iTrader: (1)

Are you revving it in the driveway or out on the road actually driving? Sorry, had to ask.........

11sORbust

sounds like a ground strap is loose or not connected. OR the positive wire to the starter is lose. Don't think it's the prom or injectors......

IRACE87

Quote:

Are you revving it in the driveway or out on the road actually driving? Sorry, had to ask.........

?? On the road and it does it in every gear, even tried it at the track by short shifting it at 5800 rpm. Was in the 113-115 mph zone in the quarter.

Quote:

sounds like a ground strap is loose or not connected. OR the positive wire to the starter is lose. Don't think it's the prom or injectors......

Positive wire to the starter is good I checked it yesterday for something else. Why would a ground strap make my engine rev limited at around the same rpm in every gear. I didn't notice any drop in voltage on my datamaster log?????

Thanks

PAT

Matt87GTA

Well now.... This is VERY familiar. First off, mine did (is doing) the exact same thing. Pulls great, runs great, makes good power, yada yada.... and at 6100ish it just kidn of breaks up softly and won't rev any higher.

OK, I have discussed this with a few other people and we came up with a few ideas. The first was valve springs but I had my Brodix Track 1s set up for springs that TPIS recommended for running with the ZZX cam I have ( I forget exactly but they were something like 180 seat and 355 over the nose) plus I am running a HydraRev which should help control the heavy hydraulic lifter at high RPM..... So valve springs really don't make much sense......

Then there was this idea that I might be "blowing out" the spark with too much of a plug gap as I had them set to about .050". Well that was easily proven wrong as I regapped them to .035" and it made zero difference. This was not something I had any faith in when it was brought up but I was open to any suggestions really.

The next idea is the preload setting on the lifters. I know I have at least 1/2 turn if not 3/4 turn past zero lash as I was chasing down a noise and kept bumping up the lash setting like a moron thinking it was a valvetrain issue when it was actually piston slap. So the bottom line is that I probably have too much preload on the lifters and when the engine is cranked up the pressure in the lifter is fighting my valvesprings and winning the battle. This makes sense since my springs aren't really all that crazy as far as over the nose pressure (really can't be with a hydraulic cam or it will collapse the lifter).

Basically, my setup should easily rev past 6500 and from the looks of it yours should too. I double checked every PROM setting I could think of and nothing in there is causing the problem. I tried a pull on the dyno with the TB open just to see if that was the problem and it wasn't.... So double check your lifter preload. Run as little as possible is what I have been told - like 1/16 to an 1/8th and see how it goes. I haven't gotten around to mine as I have been very busy the last month or so with certain obligations (see avatar) but I will probably be heading out to the garage some time this week to dial mine in.

Good Luck, sorry if this is a little off the PROM topic - might be useful.

IRACE87

Quote:

The next idea is the preload setting on the lifters

Well I have been thinking that the problem could be with my lifters, but the preload setting on them is only 1/4 turn pass zero lash ???

] [QUOTE]I forget exactly but they were something like 180 seat and 355 over the nose) plus I am running a HydraRev [/QUOTE

Almost identical plus or minus 5 lbs.

Quote:

I will probably be heading out to the garage some time this week to dial mine in.

Please let me know if you find anything cause it's supposed to rain for the next 3 days so I won't be able to test anything at WOT.
I triple check my PROM yesterday night and like you couldn't see anything wrong with it.
So the problem may not be reletad to the ECM after all.

Thanks

PAT

Matt87GTA

Well I haven't put a scantool on it to see what RPM I am actually hitting, but I ran it up once yesterday after I got it done through 1st and 2nd gear and it swung well past 7k on the factory tach and felt much stronger up top.... It was getting late and the car is ridiculously loud so I kept the shenanigans to a minimum....hehe.

I reset my shift light to 7k after I drove it and I will take it out again today. I'll keep you posted but I think I found my problem . Course, I probably did have around 3/4 turn past......

Oh, I set mine to about 1/16 or so past....

IRACE87

Quote:

swung well past 7k on the factory tach

Wish it was me, I guess I will have to give it a try this week end and see what happens ?????

Are you using factory lifters or aftermarket ones...

I have been told that not enough preload can get the C clip that keeps the lifters gutts inside its body flying around in the engine on high reving engine ???

Thanks

PAT

Matt87GTA

I have Comp Cams stock replacement lifters (the 63-850s). I suppose you wouldn't want to run it right at zero lash (or having clearance like a solid) for just that reason, but I wouldn't think that there would be much of a difference revving an engine high with a little preload or a lot. I mean the only force being applied to that retainer in the upward direction is oil pressure which I can't see being any different with a lot or a little preload - and in the end it seems the down side to a lot of preload is valve float, so.....

JP84Z430HP

Interesting.....I need to redo mine. I have like 3/4 or a full turn. I wouldn't feel too comfortable with anything less then 1/4, but that may help me out! The only thing that worries me is the fact that the roller rockers seem to be tapping the way they are, let alone a bit looser. Maybe it's just the nature of the roller rockers?

laiky

i'm running a similar setup, i haven't tried to rev past 6000, i shouldn't be making anymore power that high. I have 2 questions, what kind of rotating assy are you guys running? I have a cast steel crank and eagle 5140 SIR rods with KB hyper pistons. With the roller valve train i never intended to rev past 6000, that is where my limiter is set. Secondly, it sounds like your cam should peak around 5300-5500 rpm why are you trying to get it to rev so high?? Not that it shouldn't be able too.

Z69

Hyd. flat tappet circle track motors frequently run zero lash & 150lbs seat. So for short periods and testing purposes, it shouldn't hurt anything. From what I've read, with a hydra rev setup, you should be able to rev to 6500 just fine if the cam will go there.
You can also look at the valve stem tip if they are not too old. If the wear patern looks like a *, then you might have some float. You won't always hear it.

Matt87GTA

My lower end is all forged, splayed main 4 bolt, Fluidampr balancer, etc (follow link in sig for more details). It is made to handle high RPM. And, as mentioned above, with a roller valvetrain and a HydraRev kit it should pull well past 6k without a problem as far as controlling the valvetrain components goes. But with a relatively light seat pressure valve spring setup to run with the hydraulic setup without destroying lifters, it wouldn't take much to unseat the valve. Especially when the RPMs are high and the oil pressure is cranked up. Mine is a standard pressure HV pump BTW....

Quote:

Secondly, it sounds like your cam should peak around 5300-5500 rpm why are you trying to get it to rev so high?? Not that it shouldn't be able too.

Are you referring to the ZZX cam? According to the figures I have seen it should pull well past 6500 before it hits peak HP if the rest will go there. I have seen dyno numbers from a 350 with the little AFRs and a Miniram to go with a ZZX cam and it made peak power right at 6500 but hardly fell off at all until 6800 or so. It is quite clear by looking at my dyno graphs that mine is (was) being cut very short from its potential.

As for rocker noise, mine is no louder at 1/16th turn than it was at 3/4 turn from what I can tell but as I eluded to above, I have pretty decent piston slap with this current setup that drowns out any valvetrain noise. But if you have one or more actually tapping it might mean you have a bad lifter that is semi-collapsed or that you need to change the way you are setting the lash. I use the 1/2 and 1/2 method myself - half at #1 TDC and the other half at #6 TDC......

IRACE87

Quote:

I have Comp Cams stock replacement lifters (the 63-850s).

I have the stock GM ones....

Quote:

what kind of rotating assy are you guys running?

4 bolts GM block, Scat 9000 modular crank, crower 6'' stroker rods, Wiiseco flat top forged piston. Everything is internaly balance and I'm using a Fluidampr balancer.

Quote:

Secondly, it sounds like your cam should peak around 5300-5500 rpm why are you trying to get it to rev so high??

My cam is something like 240 244 .544 .537 with my 1.5 roller rockers. And on paper I should be shifting around 6500-6600 to make the most out of this combo.

Quote:

But with a relatively light seat pressure valve spring setup to run with the hydraulic setup without destroying lifters, it wouldn't take much to unseat the valve. Especially when the RPMs are high and the oil pressure is cranked up. Mine is a standard pressure HV pump BTW....

My oil pump is a Moroso high volume high pressure pump. Can it be part of my problem????

Quote:

I have pretty decent piston slap with this current setup that drowns out any valvetrain noise.

I know what you mean. When the engine is cold my knock sensor will see knock for the first 3 to 5 minutes.

I should be reajusting my preload saturday morning and be able to rev higher after hopfully.

Thanks

PAT

Grumpy

For a single coil ignition system to work at 6K, generally takes some sort of CDI. If you already have one, might try another brand. Seems like you've also rules out everything else.

BTW, fuel pressure alone is no guarantee you have enough pump. Just for giggles, I replace mine ever 2 years as a maintance item. Fuel's just too important to scrimp on, IMO.

IRACE87

Quote:

For a single coil ignition system to work at 6K, generally takes some sort of CDI.

I have an ACCEL 300+, I tought that it could have been the source of the problem so I tried the stock set up with no change in my symptom.

Quote:

BTW, fuel pressure alone is no guarantee you have enough pump. Just for giggles, I replace mine ever 2 years as a maintance item. Fuel's just too important to scrimp on, IMO.

I guess pressure doesn't guarantee that I have volume. And that's one of the the reason I now have a quick access panel to my fuel pump. I can change it in 15 minutes now.

Thanks

PAT

Matt87GTA

Yeah, when we first heard/saw mine doing its thing on the dyno, ignition was the suspect. But I have a pretty stout setup with an MSD 6A, MSD Pro Billet distributor, MSD Blaster II coil, Taylor 10.4mm wires, AC FR3LS plugs (allbeit gapped pretty big at the time) - and the plugs, wires, and dist. were brand new with the motor build up. The coil and box have about 8k on them. Just didn't seem likely and we checked for crossfiring in the wires and they were fine so we started to think valvetrain.....

I am running a Walbro 255 high pressure pump with a hot wire kit..... In case anybody is wondering. I don't remember exactly, but I think I have my pressure set to 48psi (vacuum-less). Mine seems fine on fuel so far but with more RPM available it might be getting close on injector.... I have 30lb SVOs and with the 6k "false" peak of 420 RWHP it was at about 87% DC......

laiky

you know, it sounds like the injectors might be suspect. A couple of guys are starting to find that the 30lb injectors aren't enough over around 425 hp. i have mine almost maxed out and i have 30's. if you have an adjustable pr i would try cranking up the pressure for a run or 2 to see what happens. it might be that simple. are you both running 30lb injectors?

Matt87GTA

I am using 30lb SVOs right now. It is(was) not the injectors on mine as of right now, as I logged data on all of my dyno runs and was seeing 87% DC max with 420 RWHp so they are definately good for well past 425 at the crank (20% loss is the norm for accessories and drivetrain). I think if mine is pulling what I think it is now that I have another 1k or so usable RPM it might be pretty close to maxing out the 30lb SVOs...

On a side note, I was out messing around with the car last night and happened across an 03 Cobra on the freeway..... Was a damn close run - too close to call by all accounts from both cars. I talked to him afterwards and he has a smaller pulley, a chip, and full exhaust. He said he dyno'd at 450 RWHP two weeks ago...... Needless to say he was quite surprised that a thirdgen was right with him...hehe....

laiky

not to get off topic but, you guys are making the sort of power i feel i should be making, my car hasn't been dynoed, and i run a cat but i feel i'm quite a bit off what it is capable of doing. I have slp 1 3/4 headersto a 4 bolt cat and 3" slp exhaust. i think i could gain a lot more if it wasn't for the restrictive exhaust. What exhaust and cats (if applicable) are you guys runing, my setup is in the sig.

JP84Z430HP

What exactly makes you think that exhaust is so restrictive? The only thing that may even be remotely restrictive is the cat. I have the same headers and exhaust you have, and let me tell ya, not restrictive. Maybe your cat is going bad?

laiky

i think it is restrictive, because compared to a set of long tubes with a crossover and dual 2 1/2 or 3 " exhaust it is restrictive. the shortie headers are a disadvantage(how much is hard to determine) the y pipe is small (2 1/4"?? i think) and the y pipe lengths are very uneven, one side is very long and the other short. on top of all that it enters a single cat at a 3" inlet and a 3" outlet. I would like to know what a similar combo to mine dynos with this exhaust. if someone is making realy good numbers and has proof i would feel better. But i have no hard evidence. I really do not want to run without a cat, it goes against my environmental science degree, and i prefer to be clean.

IRACE87

Just to let you guys know that I could't try the car this week-end it rained all day on saturday and I had family matters to attend on sunday.

Quote:

Yeah, when we first heard/saw mine doing its thing on the dyno, ignition was the suspect. But I have a pretty stout setup with

Myself I have an accel 300+ box and coil, with moroso 8 mm wires and stock distributor with accel cap and rotor.

Quote:

I don't remember exactly, but I think I have my pressure set to 48psi (vacuum-less). Mine seems fine on fuel so far but with more RPM available it might be getting close on injector.... I have 30lb SVOs and with the 6k "false" peak of 420 RWHP it was at about 87% DC......

My pressure is set in the 48-50 psi range depending on wich gauge I use to check it. I have 30 lb SVOs also and I saw around 84% duty cycle at 6100 with an AFR of 12.7 on WB.
Matt87GTA do you know what was your AFR on the dyno ???

Quote:

A couple of guys are starting to find that the 30lb injectors aren't enough over around 425 hp.

I'am pretty sure that I will have to upgrade when I will finally be able to rev higher. My set up should be able to make around 490 hp at the crank.

Quote:

What exhaust and cats (if applicable) are you guys runing,

SLP 1 3/4 headers, SLP cat back, no cat and was able to be in the 113-115 mph in the quarter. And was short shifting at 5800 rpm.
When I will be able to rev higher I will try some pass with the exhaust on some with open headers and will see how restrictive it is.

PAT

laiky

I think i will be building a good test pipe in the near future.

correct me if i'm wrong but i believe you can't expect an injector to run at 100% duty cycle. As i understand it if your over a certain duty cycle you will have problems getting enough fuel. I do not know what amount of time constitutes 100 duty cycle, i assume as RPM increases it gets smaller. I have spoken to a member of chevytalk.org who is currently in the very low 12's on 30lb injectors but he is maxed out with his commander 950. he can't give it any more fuel. Just a though that as your RPM increases the available on time for the injector gets smaller.

IRACE87

Quote:

I do not know what amount of time constitutes 100 duty cycle, i assume as RPM increases it gets smaller.

There is a formula to calculate this, if I'm right the injectors have like 10 ms at 6000 rpm to do there job. Right now I recheck my data and I'm like 8.73 ms at 6000-6100 rpm with something like 80-84 % duty cycle. All of this with an AFR of 12.7.
So basically I style have some juice left but it would be better if I had something like 36 lbs injectors.
So yes with my set up I' am borderline with those injectors I'm pretty sure that I won't be able to rev more than 6500 rpm even if the engine wants to, because the injectors won't be up to the task.

PAT

laiky

i need to get some dyno numbers for my car. i just haven't had the time. i need to do alot more tuning since i bought the wideband. but again time is an issue. i am really curious about what is preventing you from spinning higher

Matt87GTA

I agree about that exhaust being a bit restrictive on these types of setups. My setup is Hooker LTs (1 3/4") into a custom 3" Y-pipe that flows into a 4" Mufflex cat-back with a 30 series Flowmaster single in/out muffler. The only thing that I can see upgrading at some point on mine would be the muffler since there are better flowing ones in existance (as in one that is more straight through and not a chambered muffler). But I really like the way mine sounds and it probably isn't really hurting me that much as of right now.

As for power levels, I guess I just don't see the AFR 190s hanging with my larger and better flowing heads - especially at high RPM and with the extra cubes (over a 350 I mean). But then again I am pretty sure my current setup is not fully utilizing the potential of my heads either.......

OK, on injectors..... On the last dyno run of the day I saw 8.65 ms PW which is 89% DC (per Datamaster at 6100RPM) and I was at about 13.2-13.3 AFR. So I would have to say that I actually am probably VERY close to going static with these injectors now that I can pull well past that mark..... Hmmm.... Gonna have to invest in some 36s or 42s now I think. Thanks for bringing that up as I hadn't really given it that close of a look after the dyno session as I was too concerned with what was making it fall on its face right at 6k. I'm no expert on injectors, but from what I understand the ECM is no longer really in control of fueling once the injectors get much over 90% DC as they start to not close between pulses (or go "static" as it is referred to).

I also noticed my MAP signal goes down gradually above about 4500RPM so maybe my 52mm TB is lacking a little with this setup.... Geez.... I wonder what this thing is really capable of!!!..lol Too bad I'm broke as heck right now.....

IRACE87

Went for a ride yesterday after work (no I didn't have time to reajust the preload setting on my lifters before the ride).
But I have new data from my datamaster and WB and I'm not sure what to make out of it.

First pass on second gear I reached 6000 rpm with a DC of 78.1% and PW of 7.81 ms. The weird thing is from my WB when the engine stop reving higher I see the AFR go from 12.97 at 4.59s on the session to 11.55 at 5.24s ????

On the second pass second gear Data are in RPM
5950-6075-6000-6100-6025, had at 6075 rpm a DC of 81.7% and a PW of 8.07 ms. The AFR goes from 12.38 to 12.98.
On third gear I see RPM 5525-5675-5775-5875-5825-5925 and had at 5925 rpm a DC of 79% with a PW of 8.00 ms. The AFR goes from 12.52 to 13.07 and when it stop reving any higher the AFR dropped to 11.85.

Questions:
So if the pressure in my lifters is fighting my valvesprings like suggested by Matt87GTA is it the kind of pattern I would see, or only when it is related to a weak ignition like suggested by Grumpy???

Is there anything in the BIN , PROM, ECM that could cut the ignition ???

Quote:

I agree about that exhaust being a bit restrictive on these types of setups.

I agree and will find out at the track when I will try the car with open headers.

Quote:

As for power levels, I guess I just don't see the AFR 190s hanging with my larger and better flowing heads - especially at high RPM and with the extra cubes (over a 350 I mean).

Agree again, by your higher DC and PW that you have compare to me at 6000rpm with about the same AFR that I have I think your making more power on top than me.

Thanks

PAT

JP84Z430HP

It sure sounds more like ignition causing your problems. Not enough spark? I think it has already been mentioned, but that is something I'd really be looking at.

IRACE87

Is there any way to test the ignition without swapping parts, I really don't feal like buying new parts just to see if they are the cause of my problem.

PAT

boost creep

I'm a little late here, but maybe missed something. When you say you can't rev past 6000, does the engine just quit (like shutting of the ignition)? or does it miss and pop and fart at 6K? Or is it just down on power but hits on all 8?

Paul

laiky

you need some one with an oscilliscope, preferable with a datalogging feature. My friend has an OTC genesis that has a digital scope with datalogging. You could look at the primary and secondary wave forms to see if its breaking up. Snap on used to make one too but it was huge and not suited for test drives, unless your dyno guy has one.

IRACE87

Quote:

I'm a little late here, but maybe missed something. When you say you can't rev past 6000, does the engine just quit (like shutting of the ignition)? or does it miss and pop and fart at 6K? Or is it just down on power but hits on all 8?

No fart no pop, the nice rumble of the engine when you are at WOT goes away and just stop from reving any higher. It doesn't feel like I hit a wall (the way it felt when my stock bellows was collapsing at 4800 rpm) it just stay there for like the 2 seconds I keep my foot to the floor until I upshift.

It's not like the engine quit at 6000 and come back to life at 5800 it just stay there.

Quote:

you need some one with an oscilliscope

Gonna have to make some phone call today.....

Thanks

PAT

boost creep

And this just happened all of a sudden one day, or you have never been able to make this thing rev that high?

Paul

IRACE87

Quote:

And this just happened all of a sudden one day, or you have never been able to make this thing rev that high?

It never went higher than 6100
The engine is only 1300 miles old, I've been tuning the BIN and now felt confident that I could rev it higher safely and found out about the problem.

Like I said earlier my first problem with the engine was my intake bellows that was collapsing at 4800 rpm and preventing me from getting higher rpm. Now that I got ride of that problem (new custom dual cold air intake) something else is wrong.

PAT

boost creep

OK! Being that your engine does not pop,miss,fart, you can rule out the valve train, injectors,and ignition. What is happening here is that you are not making any power at this high rpm. Here's what to look for. An intake restriction....you found one already, but you need to double check this by hooking up a vacuum gauge to the intake. Don't simply rely on what a scan tool says for now. An exhaust restriction. Hook up a pressure gauge to the exhaust and measure the backpressure. It shouldn't be more than a few pounds. Ignition timing. For some reason, your ignition timing may be getting retarded, and don't relay on the scan tool or what you think is in the .bin. You need to put a timing light on it and see if it is really correct. Most likely this will have to be done on a dyno..... that is to say the the engine is under load when reading the timing. New engine??? Possibly the wrong cam installed? Or maybe installed wrong....to far advanced??

There is no particular order in what to test first. And for all I know, you may be running open headers, so you probably won't have to check the backpressure

Hope this helps.

Paul

laiky

Have you read the whole thread?

Matt87GTA

Well I can only speak for myself/my engine but I assure you that altering my lifter preload released another nearly 1k of usable RPM and mine was doing, from what I understand, the same thing as Pat's..... Just kind of softly breaking up and not revving any higher. It didn't have a real "misfire", never dropped a cylinder, nor was it backfiring in our out of the engine.... It just hit a wall. Upon further inspection I possibly have a few other issues to check out (TB size, injectors), but mine is definately making more power now than the 420 RW that it pulled with too much lifter preload so I don't see how you can flat rule out things like lifter preload for Pat at this point.

My $.02

IRACE87

Thanks for all the inputs. I have someone who I can trust on this that will help me on saturday (if there is no rain, hopefully) to reajust my preload on my lifters (down from the 1/4 of a turn I have).
And if the problem don't go away he has an oscilliscope so we will check my ignition.
Hopefully it's nothing expensive......

Thanks

PAT

laiky

good luck! keep us posted.

boost creep

Here's a link that may be of some interest. It was just posted today. Read what goftsbuick has to say about his 383..........


http://www.turbobuick.com/forums/sho...065#post885065


HTH

Paul

IRACE87

Thanks to everybody and specialy to Matt87GTA. Finally it didn't have anything to do with my bin. or PROM etc...

I reajusted the preload on my lifter from 1/4 of a turn to slightly more than 1/16 and gained around 300-400 rpm depending on wich gear I'm in. So I still have the problem but at a higher RPM. I should probably have went solid in the first place ???

In first gear it now revs up to 6300 and in third up to 6375 and stay there until I lift the trottle. I would reajust them some time this week and see what happens (ran out of time for the car this wee-end already).

For those interested about the injectors I see around 87.7% DC at 6375 and 8.26 ms PW.

By the pattern I see on my WB the problems with the lifters begins at around 6100 rpm and i can feel it to.

PAT

Matt87GTA

No problem, glad I could help . But I wonder what else is going on if the engine is still hitting a wall of sorts.....

Did you do the 1/2 and 1/2 method while adjusting the rockers, or??

Maybe the high pressure spring in the oil pump is making yours even more finicky on the lifter preload than mine.... or maybe those stock lifters act a little different than mine...

Either way, it is clear to me from situations like mine and yours that if you want to run high RPM with a roller it needs to be a solid or it will have problems with preload or end up having too strong of a spring that will wipe out the lifters or wear the cam prematurely.....

IRACE87

Quote:

Did you do the 1/2 and 1/2 method while adjusting the rockers, or??

Not sure what you mean by that ?????

I may try compcams Pro magnum hydraulic roller lifter #875-16 if they can convince me that the problem will go away.

Quote from there site... COMP Cams Pro Magnum Hydraulic Roller Lifters are specifically designed to perform at higher engine speeds.
When engines are equipped with a hydraulic camshaft, high RPM is limited by the improper position of the internal piston as the lifter inevitably "pumps up". This improper location results in open valves and therefore leads to lost power or sometimes even engine failure. Unquote

If this doesn't work I will probably go solid.

PAT

11sORbust

You want the lightest springs possible. The most important thing is for the springs to match your cam. AFR's spring rates MUST match your cam specs (open and closed),check the cam card and call AFR.... IMO,just go solid. You can't really rev hydraulic lifters high. Solid lifters don't need adjusted all the time if you have polylocks. The lifters will make a difference, for sure ..