Who knows what this is? Dyno vid included.
04-26-2014, 12:34 AM
#1
11 Second Club
Thread Starter
Who knows what this is? Dyno vid included. We seem to be chasing valve float, but don't know where.
History
Bought car 4 months ago.
LPE 346 shortblock with diamond pistons
PRC 5.3 stage 2.5 w 3 angle and milled .023
Had PRC springs
TSP 233/239
LS7 lifters
Fast 92 intake
92 mm tb
We dyno'd the car right off the bat and got 428/382, but the graph showed what looked like valve float over 6000 rpm.
So, we installed Brian Tooley .660 Titanium valve springs. During install, discovered 2 of the PRC springs were sitting on top of mismatched seats or shims (washer looking things) and was told this could throw off the seat pressure and cause the valve float we had seen. A bad spark plug wire was also found at this time and replaced. Another realization was that the Mass Air was a stock one, which was choking the intake setup.
Fast forward a couple of months...Mass air removed and the car was switched to speed density tune. Cutouts were also installed.
New Dyno was run...468/414 with the cutouts closed.
Cut outs were then opened and at 5800 rpm the graph was showing another 15 rwhp and climbing just from opening the cutouts. But...there was a sharp drop after that and it only made 471. It looked a lot like the valve float again but we were suspicious of our converter anyway so decided it was pushing thru the converter.
We ditched the re-stalled Vig 4000 that was flashing to 5200 in favor of an Edge 4000 (which drives amazing on the street compare to the Vig), and lost the 60 lb each Boyd Coddingtons and their accompanying 315/35/17 Mickey Thompson et street II's in favor of 15x8 Race Stars and 275/50/15's. The diameter has remained pretty close to the same at 25.8 to now 26.0 inches.
Today it went back to the dyno because I raced it last weekend on the old wheel and tire setup, but with the new converter, and it was falling on its face right about 5900 rpm in 2nd gear. I managed an 11.66 at 119 even though 1st gear was useless on 4 or 5 year old 17 inch Mickeys, and it was running out of steam early in the rpm.
Today's dyno results..
450/402
It peaked right at 6000 and stayed dead flat to 6400. No rise at all. At 6400 it was falling on its face again, and we could see the drop from last dyno was starting as early as 3000 and then was more pronounce by 5800.
Tracey says it's valve float still, which might be caused by the wrong lifter preload, weak lifters, wrong pushrods, the cam, or maybe just the combo not being 'happy'. It looks to me like it's getting worse, because it is dipping more suddenly and farther. We plan on racing this car for the opening night of Friday Night Lightz, along with our other car. I'm really nervous about it because the shift points are still 6900 rpm, and that seems like we're just begging to trash a perfectly good LPE block and all of it closest friends, like Mr. Cam, Mr. Crank, etc.. lol
A friend told me I might need short travel lifters and suggested some aftermarket rockers too. My rockers are stockers without the trunion upgrade.
I'm just lost and really don't want to keep throwing parts and money at this, hoping the next guess is right. The point of the Brian Tooleys and Converter changes was to fix this issue. It would suck to lose a great engine in the process too.
Any ideas?
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History
Bought car 4 months ago.
LPE 346 shortblock with diamond pistons
PRC 5.3 stage 2.5 w 3 angle and milled .023
Had PRC springs
TSP 233/239
LS7 lifters
Fast 92 intake
92 mm tb
We dyno'd the car right off the bat and got 428/382, but the graph showed what looked like valve float over 6000 rpm.
So, we installed Brian Tooley .660 Titanium valve springs. During install, discovered 2 of the PRC springs were sitting on top of mismatched seats or shims (washer looking things) and was told this could throw off the seat pressure and cause the valve float we had seen. A bad spark plug wire was also found at this time and replaced. Another realization was that the Mass Air was a stock one, which was choking the intake setup.
Fast forward a couple of months...Mass air removed and the car was switched to speed density tune. Cutouts were also installed.
New Dyno was run...468/414 with the cutouts closed.
Cut outs were then opened and at 5800 rpm the graph was showing another 15 rwhp and climbing just from opening the cutouts. But...there was a sharp drop after that and it only made 471. It looked a lot like the valve float again but we were suspicious of our converter anyway so decided it was pushing thru the converter.
We ditched the re-stalled Vig 4000 that was flashing to 5200 in favor of an Edge 4000 (which drives amazing on the street compare to the Vig), and lost the 60 lb each Boyd Coddingtons and their accompanying 315/35/17 Mickey Thompson et street II's in favor of 15x8 Race Stars and 275/50/15's. The diameter has remained pretty close to the same at 25.8 to now 26.0 inches.
Today it went back to the dyno because I raced it last weekend on the old wheel and tire setup, but with the new converter, and it was falling on its face right about 5900 rpm in 2nd gear. I managed an 11.66 at 119 even though 1st gear was useless on 4 or 5 year old 17 inch Mickeys, and it was running out of steam early in the rpm.
Today's dyno results..
450/402
It peaked right at 6000 and stayed dead flat to 6400. No rise at all. At 6400 it was falling on its face again, and we could see the drop from last dyno was starting as early as 3000 and then was more pronounce by 5800.
Tracey says it's valve float still, which might be caused by the wrong lifter preload, weak lifters, wrong pushrods, the cam, or maybe just the combo not being 'happy'. It looks to me like it's getting worse, because it is dipping more suddenly and farther. We plan on racing this car for the opening night of Friday Night Lightz, along with our other car. I'm really nervous about it because the shift points are still 6900 rpm, and that seems like we're just begging to trash a perfectly good LPE block and all of it closest friends, like Mr. Cam, Mr. Crank, etc.. lol
A friend told me I might need short travel lifters and suggested some aftermarket rockers too. My rockers are stockers without the trunion upgrade.
I'm just lost and really don't want to keep throwing parts and money at this, hoping the next guess is right. The point of the Brian Tooleys and Converter changes was to fix this issue. It would suck to lose a great engine in the process too.
Any ideas?
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<div class="fb-post" data-href="https://www.facebook.com/photo.php?v=706263226082492" data-width="466"><div class="fb-xfbml-parse-ignore"><a href="https://www.facebook.com/photo.php?v=706263226082492">Post</a> by <a href="https://www.facebook.com/profile.php?id=100000964625488">Jerry Buckamneer Jr.</a></div></div>
04-26-2014, 01:37 AM
#3
11 Second Club
Thread Starter
On a side note...
60 lbs oil pressure cold at 65 mph, 50 at idle.
45 lbs oil pressure hot at 65 mph, 40 at idle.
After a couple of hard pulls...
40 psi at 65 mph, 25-30 psi, but comes back up as temps come down.
60 lbs oil pressure cold at 65 mph, 50 at idle.
45 lbs oil pressure hot at 65 mph, 40 at idle.
After a couple of hard pulls...
40 psi at 65 mph, 25-30 psi, but comes back up as temps come down.
04-26-2014, 09:24 AM
#5
What is the installed height of the springs?
The first thing I would do would be to shim the springs to 1.750" installed height if you suspect valve float.
If that doesn't fix it then go for the lifters. Something like the Morel 5206, Comp short travel or Johnson lifters, we have all of them in stock.
BTW, those springs installed at 1.750" height using a .630"ish lift cam have gone 7800 rpm without float. However the cam was one of ours that used super stable lobes.
I hope this helps!
The first thing I would do would be to shim the springs to 1.750" installed height if you suspect valve float.
If that doesn't fix it then go for the lifters. Something like the Morel 5206, Comp short travel or Johnson lifters, we have all of them in stock.
BTW, those springs installed at 1.750" height using a .630"ish lift cam have gone 7800 rpm without float. However the cam was one of ours that used super stable lobes.
I hope this helps!
04-26-2014, 10:37 AM
#6
11 Second Club
Thread Starter
Thanks guys. The rockers are stock and do not have the trunion upgrade. I would assume the valves are the ones PRC was using in their 5.3 heads 4 years ago.
Brian, I do not know what height Tracey Scott installed your springs at. I did not see him measure. He may have just torqued the rockers down to a given ft pound. I will check with him.
Thanks again.
Brian, I do not know what height Tracey Scott installed your springs at. I did not see him measure. He may have just torqued the rockers down to a given ft pound. I will check with him.
Thanks again.
04-26-2014, 01:00 PM
#7
TECH Fanatic
Had a very similar issue, fell on its face at 5800rpm & it was the springs, then went to 6400rpm & it was the aftermarket rockers, changed back to OE rockers with Truunion upgrade which helped, now goes to 6700rpm but believe now it's the stainless valves.
I need to try LS3 turned down valves & see if that works but that'll be sometime in the future now.
I need to try LS3 turned down valves & see if that works but that'll be sometime in the future now.
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04-26-2014, 04:29 PM
#8
What is the installed height of the springs? The first thing I would do would be to shim the springs to 1.750" installed height if you suspect valve float. If that doesn't fix it then go for the lifters. Something like the Morel 5206, Comp short travel or Johnson lifters, we have all of them in stock. BTW, those springs installed at 1.750" height using a .630"ish lift cam have gone 7800 rpm without float. However the cam was one of ours that used super stable lobes. I hope this helps!
04-27-2014, 12:58 AM
#9
I'd look at lifter preload and the pushrods as well as shim the springs. The TSP 233/239 is ground on XE-R lobes, so it does need some attention to detail.
If you can't get it sorted, might be worth it to pull the cam, inspect, and replace it and the lifters if necessary. I'd also try some 11/32 or tapered 3/8" pushrods.
If you can't get it sorted, might be worth it to pull the cam, inspect, and replace it and the lifters if necessary. I'd also try some 11/32 or tapered 3/8" pushrods.
04-27-2014, 04:31 PM
#14
11 Second Club
Thread Starter
Ohhhh, and this might make sense to someone out there:
On the last dyno pull, we opened the cut-outs and it Did Not fall off at 6400 rpm in the same way. That run it looked like a gradual drop all the way to 6900, when the tuner let up.
That run was still 30 hp down from what it looks like it should do, if something goofy wasn't hurting it from 3000 on.
On the last dyno pull, we opened the cut-outs and it Did Not fall off at 6400 rpm in the same way. That run it looked like a gradual drop all the way to 6900, when the tuner let up.
That run was still 30 hp down from what it looks like it should do, if something goofy wasn't hurting it from 3000 on.
04-27-2014, 06:10 PM
#16
11 Second Club
Thread Starter
We thought it was blowing through the last converter. Then Andre at Edge Converters spec'd us a custom 4000. It just went in the car and does not appear to be the problem. It was locked for all dyno runs.
05-09-2014, 11:40 AM
#17
11 Second Club
Thread Starter
So, it looks like it had 7.4 push rods and Tracey measured and said it needs 7.35's. He also shimmed the valve springs another .030 to bring installed height to 1.75
Does it sound like that could have explained things?
Brian Tooley?
Thoughts please.
Thanks all!
Does it sound like that could have explained things?
Brian Tooley?
Thoughts please.
Thanks all!
05-09-2014, 12:49 PM
#18
Hopefully a little more spring pressure fixes your issues. The shorter pushrods could help also. Anytime the valve train gets into loft or separation the lifter plunger can pump up which holds the valves open. The shorter pushrods will help that situation if you are getting into loft/separation.
Keep us posted.
