What Type Effects Would Too Long Of A Push Rod Have On Engine Performance?
10-25-2002, 08:03 PM
#16
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Join Date: Jul 2001
Location: Ft Benning, GA.
Posts: 51
Thanks fellas on that wonderful class about how the degree wheel workr with determanning push rd length. Just one more ???
Could you actually tell that your lifters collapsed by looking at them, if so what should it looking like?
Could you actually tell that your lifters collapsed by looking at them, if so what should it looking like?
10-25-2002, 08:09 PM
#17
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Join Date: Dec 1969
Location: Sweden
Posts: 25
The spintron truly is a device of marvel.
For instance,the mer fact of watching a valvspring being the culprit more often then not of the fabled "valve float" ordeal.
Or..when you see the magic of a cogged belt streching like a rattler in heat above 7 grand.
At one time we saw the cam timing being backed down 7 degrees..
Not that it by nature is a bad thing doing so,just the mere fact of seing is believing.
Speaking of which.
Topic of turning the engine over with light springs in place came up.
Ever seen the effects of replacing those light ones with the "roller" springs that are supposed to take their place?
Puts a smile on my face every time...
For instance,the mer fact of watching a valvspring being the culprit more often then not of the fabled "valve float" ordeal.
Or..when you see the magic of a cogged belt streching like a rattler in heat above 7 grand.
At one time we saw the cam timing being backed down 7 degrees..
Not that it by nature is a bad thing doing so,just the mere fact of seing is believing.
Speaking of which.
Topic of turning the engine over with light springs in place came up.
Ever seen the effects of replacing those light ones with the "roller" springs that are supposed to take their place?
Puts a smile on my face every time...
10-25-2002, 10:45 PM
#18
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Join Date: Mar 2002
Location: NEWPORT NEWS
Posts: 158
Originally posted by arnie
Have you ever taken lite springs and actually ran the engine thru full cycle, from zero, to full lift, then back to zero B4? If you had, you'd know why roller rockers came into being. If the rocker arm tip didn't move, there would be very little friction. Talk about rocker science, LOL. But it does sound like you are not aware of the problem. It is simple math. What is pushing down on the valve stem is doing so on an arc. Do you know what that suggests?
Have you ever taken lite springs and actually ran the engine thru full cycle, from zero, to full lift, then back to zero B4? If you had, you'd know why roller rockers came into being. If the rocker arm tip didn't move, there would be very little friction. Talk about rocker science, LOL. But it does sound like you are not aware of the problem. It is simple math. What is pushing down on the valve stem is doing so on an arc. Do you know what that suggests?
MACHINIST DIE ON VALVE STEM,
VALVE FULLY CLOSED, MOVE ROCKER BACK AND FORTH TO MAKE A MARK...
VALVE FULLY OPEN, MOVE ROCKER BACK AND FORTH....
REMOVE ROCKER.....TAKE NOTE OF MARKS MADE IN MACHINIST DIE...
IF THE 2 MARKS ARE IN THE CENTER PORTION OF THE VALVE STEM, PUSHROD LENGTH IS VERY CLOSE..
CLOSE ENOUGH FOR ME...
YOU GUYS MUST BE ON THE WRONG BOARD, DONT THEY HAVE A DIFFERENT BOARD FOR TOP FUEL?
I DO WHAT I DO BECAUSE IT WORKS FOR ME, IF YOU DONT AGREE WITH IT THAT IS FINE WITH ME, DISAGREE TO YOURSELVES.
I KNOW WHAT I DO WORKS.... NUMBERS ARE NO LIE, AND THOSE I AM HAPPY WITH...
10-26-2002, 11:35 PM
#19
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,673
Originally posted by 385LT1
"CENTER IN MY WORLD"
..........
YOU GUYS MUST BE ON THE WRONG BOARD, DONT THEY HAVE A DIFFERENT BOARD FOR TOP FUEL?
I DO WHAT I DO BECAUSE IT WORKS FOR ME, IF YOU DONT AGREE WITH IT THAT IS FINE WITH ME, DISAGREE TO YOURSELVES.
I KNOW WHAT I DO WORKS.... NUMBERS ARE NO LIE, AND THOSE I AM HAPPY WITH...
"CENTER IN MY WORLD"
..........
YOU GUYS MUST BE ON THE WRONG BOARD, DONT THEY HAVE A DIFFERENT BOARD FOR TOP FUEL?
I DO WHAT I DO BECAUSE IT WORKS FOR ME, IF YOU DONT AGREE WITH IT THAT IS FINE WITH ME, DISAGREE TO YOURSELVES.
I KNOW WHAT I DO WORKS.... NUMBERS ARE NO LIE, AND THOSE I AM HAPPY WITH...
Fred
10-27-2002, 01:25 AM
#21
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Join Date: Apr 1999
Location: Fort Wayne, Indiana
Posts: 86
hey ZZ17IROC, I see I am not the only one running these "junk" heads. I am curious, did you also fall victom to the imfamous iron guides with teflon seals siezing the valves in the open position while the engine was running as I did shortly after I purchased these just about 4 years ago?
Anyway, on with your question. I would assume that too long of pushrod, as long as it did not cause premature wear or damage, can effect performance if a certain condition exists. This condition has to do with the arch in which the rocker arm tip travels in and the relation in which it will contact the valve. It is possible for the rocker arm tip to travel out of alignment with the valve stem in which the rocker arm tip starts to move across the top of the valve more than it is pushing down on it to open it. In other words, you want the rocker arm tip movement arc to stay as parallel as possible to the valve stem over its complete actuation. The only way to accurately measure this on an engine is by using a dial indicator and a cam degree wheel. Of coarse, another goal is to try to keep the rocker tip centered on the valve stem.
In examining my TFS Trick Flow G1 heads and using a "pushrod length checking tool" I found that there was no correct length pushrod for my heads. It almost seems like the rocker arm stud holes were drilled too close to the valves because no matter what length the pushrod was, I could never get the rocker arm tip to evenly sweep across the valve stem close to its center. I am wondering if this is your case.
I think your best bet would be to call comp or crane cams as well as TFS to get their opinions and facts concerning this matter. Good luck, and I would like to hear what flow numbers your heads yielded after the port job.
Anyway, on with your question. I would assume that too long of pushrod, as long as it did not cause premature wear or damage, can effect performance if a certain condition exists. This condition has to do with the arch in which the rocker arm tip travels in and the relation in which it will contact the valve. It is possible for the rocker arm tip to travel out of alignment with the valve stem in which the rocker arm tip starts to move across the top of the valve more than it is pushing down on it to open it. In other words, you want the rocker arm tip movement arc to stay as parallel as possible to the valve stem over its complete actuation. The only way to accurately measure this on an engine is by using a dial indicator and a cam degree wheel. Of coarse, another goal is to try to keep the rocker tip centered on the valve stem.
In examining my TFS Trick Flow G1 heads and using a "pushrod length checking tool" I found that there was no correct length pushrod for my heads. It almost seems like the rocker arm stud holes were drilled too close to the valves because no matter what length the pushrod was, I could never get the rocker arm tip to evenly sweep across the valve stem close to its center. I am wondering if this is your case.
I think your best bet would be to call comp or crane cams as well as TFS to get their opinions and facts concerning this matter. Good luck, and I would like to hear what flow numbers your heads yielded after the port job.
10-27-2002, 02:50 AM
#23
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Join Date: Apr 1999
Location: Fort Wayne, Indiana
Posts: 86
Originally posted by FilledWithFurySS
Bang Bang Bang, as the rod is Knock Knock Knocking on your motor
~Mike
Bang Bang Bang, as the rod is Knock Knock Knocking on your motor
~Mike
10-27-2002, 08:56 AM
#24
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Join Date: Jul 2001
Location: Ft Benning, GA.
Posts: 51
Well madmax350,
I got those heads from a friend of mine in Tenn. that had a 383 w/superram. I took the heads striaght to Bryan Tolly @ Total Engine Airflow in Bowling Green, KY just 50 minutes from Ft. Campbell and had them shaved down to 58cc, stage 2 port job, and new 2.02, 1.60 valves installed with TF .550 valve springs. It took him about two weeks to get to them, but when I picked them up I was very happy with the flow numbers. Try 309 cfm on int @ .600 lift and @ .400 lift 278cfm. On the exh. 258 @ .600 and @ .400 lift 236cfm. So you see I only went 12.83@ 108 with messed up valve geometry. Who knows alot of friends of mine are saying I have a lo 12's sec car or maybe even hi 11's.
I'm fairlly new to the performance engine building and I'm learning from my mistakes. That is why I', posting on this board for answers. THANKS agian for your help.
I got those heads from a friend of mine in Tenn. that had a 383 w/superram. I took the heads striaght to Bryan Tolly @ Total Engine Airflow in Bowling Green, KY just 50 minutes from Ft. Campbell and had them shaved down to 58cc, stage 2 port job, and new 2.02, 1.60 valves installed with TF .550 valve springs. It took him about two weeks to get to them, but when I picked them up I was very happy with the flow numbers. Try 309 cfm on int @ .600 lift and @ .400 lift 278cfm. On the exh. 258 @ .600 and @ .400 lift 236cfm. So you see I only went 12.83@ 108 with messed up valve geometry. Who knows alot of friends of mine are saying I have a lo 12's sec car or maybe even hi 11's.
I'm fairlly new to the performance engine building and I'm learning from my mistakes. That is why I', posting on this board for answers. THANKS agian for your help.
10-27-2002, 12:12 PM
#25
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Join Date: Apr 1999
Location: Fort Wayne, Indiana
Posts: 86
Those flow numbers sound impressive and not beyond the capabilities of the G1 heads according to a tech I spoke to from TFS. The only thing I am wondering about besides your valvetrain issue is that perhaps that your heads are stalling airflow at lower RPMs. How does the engine feel? I used to have a 350 with my TFS TF G1 heads and the MiniRam II and the engine didn't feel like it started pulling real good until about 5000 RPM. Is this the case with yours?
As far as your valve train issue goes, GM Performance Parts sells "hi performance" hydraulic roller lifters that feature a higher integral spring load than standard hyd roller lifters that supposidly help with larger cams. I installed a set of these to replace my brand new stock ones and the power gains were noticable.
As far as you "rocker arm noise," the roller rockers are not at fault. I too, have that annoying valvetrain clatter which comes and goes depending on RPM. I am running 1.5 Roller Rockers and have tried roller tip and standard rockers to no avail. Still had the noise. My friend put the LT4 head-cam-rocker kit on his LT1 and has no valvetrain noise whatsoever, so I don't think its fair to blame to rockers.
It is worth mentioning that the knock sensor will pick up this valvetrain clatter and register it as knock and pull timing accordingly. I actually had to desensitize the knock sensor and do some work with the chip to limit the amount of timing the computer can pull out on the top end to allow the engine to run at its full potential. If your ECM is seeing knock, it is a safe bet that it is pulling timing and killing your 1/4 mile performance.
As far as your valve train issue goes, GM Performance Parts sells "hi performance" hydraulic roller lifters that feature a higher integral spring load than standard hyd roller lifters that supposidly help with larger cams. I installed a set of these to replace my brand new stock ones and the power gains were noticable.
As far as you "rocker arm noise," the roller rockers are not at fault. I too, have that annoying valvetrain clatter which comes and goes depending on RPM. I am running 1.5 Roller Rockers and have tried roller tip and standard rockers to no avail. Still had the noise. My friend put the LT4 head-cam-rocker kit on his LT1 and has no valvetrain noise whatsoever, so I don't think its fair to blame to rockers.
It is worth mentioning that the knock sensor will pick up this valvetrain clatter and register it as knock and pull timing accordingly. I actually had to desensitize the knock sensor and do some work with the chip to limit the amount of timing the computer can pull out on the top end to allow the engine to run at its full potential. If your ECM is seeing knock, it is a safe bet that it is pulling timing and killing your 1/4 mile performance.
10-27-2002, 12:39 PM
#26
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Location: Ft Benning, GA.
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Yeah Bryan tolly did some good work on the heads. I did notice the power band change. I really noticed the power lost do to excessive lenght on the push rods at 5000 rpms plus. It just felt like the car took a crap went it hit 5500rpm. Last week before I tore it all apart I heard those lifters.
I saw a set of lifters in summit from comp cams for factory roller rockers. ? Are those lifters heavydutybecause they cost $240.00 and the factory replacements cost $160.00 from TPIS.
I saw a set of lifters in summit from comp cams for factory roller rockers. ? Are those lifters heavydutybecause they cost $240.00 and the factory replacements cost $160.00 from TPIS.
10-27-2002, 04:49 PM
#27
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Location: Fort Wayne, Indiana
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Good question. I think that is a question better directed towards the manufacturer of the lifters. I know that GM offers a "non-stock replacement" high performance lifter specifically for higher lift cams. Perhaps you should price these out at Pace Chevrolet Performance Parts on the net. Might be cheaper than Comp or Crane.
I would hook up a scan tool and watch your knock retard deg under full throttle conditions near the RPMs you specified to see if the ECM is pulling a bunch of timing. The ECM can pull enough timing to make the engine fall on its face if it "thinks" it is picking up detonation which could be your valve train clatter. Good luck.
I would hook up a scan tool and watch your knock retard deg under full throttle conditions near the RPMs you specified to see if the ECM is pulling a bunch of timing. The ECM can pull enough timing to make the engine fall on its face if it "thinks" it is picking up detonation which could be your valve train clatter. Good luck.
10-27-2002, 04:52 PM
#28
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Join Date: Mar 2002
Location: NEWPORT NEWS
Posts: 158
Originally posted by MadMax350
Good question. I think that is a question better directed towards the manufacturer of the lifters. I know that GM offers a "non-stock replacement" high performance lifter specifically for higher lift cams. Perhaps you should price these out at Pace Chevrolet Performance Parts on the net. Might be cheaper than Comp or Crane.
I would hook up a scan tool and watch your knock retard deg under full throttle conditions near the RPMs you specified to see if the ECM is pulling a bunch of timing. The ECM can pull enough timing to make the engine fall on its face if it "thinks" it is picking up detonation which could be your valve train clatter. Good luck.
Good question. I think that is a question better directed towards the manufacturer of the lifters. I know that GM offers a "non-stock replacement" high performance lifter specifically for higher lift cams. Perhaps you should price these out at Pace Chevrolet Performance Parts on the net. Might be cheaper than Comp or Crane.
I would hook up a scan tool and watch your knock retard deg under full throttle conditions near the RPMs you specified to see if the ECM is pulling a bunch of timing. The ECM can pull enough timing to make the engine fall on its face if it "thinks" it is picking up detonation which could be your valve train clatter. Good luck.
i have cast aluminum valve covers which seem to intensify the noise..
going with LT4's.. ill post my results... after we do a data log
10-27-2002, 08:55 PM
#29
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Location: Ft Benning, GA.
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Well I'll put it this way. When I had the mass airflow on the car I wasn't getting any knock, but I just put the car back together with new factory replacement lifters, the new cam, and better flowing head and I ran around town fine until about july time frame then the performance started to drop slowly before I installed SD in august. With the SD on the car I was getting knock count all the time and it got worse all the way up until now, so that brings us up to speed on my cars current condition. On the blocks with intake off and waiting for parts from summit.
I've already ordered the correct push rods which are 6.950 lenght on the exh. and 7.000 on the intake. and also I ordered a set of Comp Cams heavyduty lifters that cost $240.00 part # CCA-850-16. Oh my I almost forgot to order my 1206 felpro intake gaskets.
I've already ordered the correct push rods which are 6.950 lenght on the exh. and 7.000 on the intake. and also I ordered a set of Comp Cams heavyduty lifters that cost $240.00 part # CCA-850-16. Oh my I almost forgot to order my 1206 felpro intake gaskets.
10-27-2002, 09:01 PM
#30
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Oh yeah. I did go to Raceway Park during a EFI shootout that GMHTP was holding and I meet Johnny hunkins. I only ran one time because of the slow pass which was 13.83 @92 mph. And on that pass I had 15 degrees retard so thats how I know something was wrong.