What do head problems look like on the dyno?
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14 Second Truck Club
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From: Bossier City, LA
I'm asking because my power is dropping very quick after 5500rpms for the mods I have, 383 LS1 with F13, Patriot stage II 5.3 heads, Vengence ported 90mm F.A.S.T. intake/UMI 90mm TB.
Here is the graph, Converter was locked btw:
Futral told me in a 383 with the F13 my power should be peaking at 6200 rpms, especially since I have a ported FAST 90/90 setup. What do ya'll think?
Here is the graph, Converter was locked btw:
Futral told me in a 383 with the F13 my power should be peaking at 6200 rpms, especially since I have a ported FAST 90/90 setup. What do ya'll think?
Wow, you should be way over my results. My F13 peaked at 5900 rpms, but I don't have the flow like you do. What length pushrods did you use, your preload could be way off. You could be a tooth off as well.
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From: Bossier City, LA
I used the stock length pushrods (7.400") and stock MLS head gaskets. I've been told that I might have too much DCR by my tuner. He said he thinks my heads might not be supporting that much flow, considering they are stock casting 5.3s and all. I'll be done with school for month after friday, so I'll have a little bit of time to check some things. Just don't know what to check first.
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TECH Junkie
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With peak power at 5500 I was thinking maybe the cam was advanced to much. That was the reasoning behind the question. The way it noses over at 5500 that might still be the case. It does not even try to hang on to say 6000 or so.
One more question? What is your exhaust system made up of?
One more question? What is your exhaust system made up of?
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From: Bossier City, LA
1 3/4" midlength LaPole headers, 2 1/2" True Duals with cut-outs, stock cats, Dual in/out Magnaflow (w/internal X-pipe) run out the back with 4x22" crome tips.
The run in blue is through the full exhaust. The run in red is through the cut-outs.
The run in blue is through the full exhaust. The run in red is through the cut-outs.
If he said he just popped the cover and fixed it he didn't do ****. You still have to take off all the rockers to take the pressure off of the cam, otherwise it will break the adjustable part of the timing set.
It could be worse. At least you gained power. 
I went from a 346 to a 383 and lost power everywhere. Plus the 383 peaked a lot earlier. I can't say that I would recommend a 383 stroker to anyone. Way too many disappointing results I've seen over the years on this website. Below is my graph. The higher curve is the numbers my 346 H/C put out. The lower curve are the numbers after installing a 383 stroker.
I went from a 346 to a 383 and lost power everywhere. Plus the 383 peaked a lot earlier. I can't say that I would recommend a 383 stroker to anyone. Way too many disappointing results I've seen over the years on this website. Below is my graph. The higher curve is the numbers my 346 H/C put out. The lower curve are the numbers after installing a 383 stroker. 
I think it is a preload problem. Get an adjustable "measuring" pushrod and take a measurement. All you have to do is pop off a valve cover, unbolt a rocker or two, and go. It will probably take less than one hour. You can't know if you are OK without measuring. That cam probably has a smaller base circle than stock. Plus your heads are probably milled. You just don't know what size pushrod you should have.
-Geoff
-Geoff
Not a spring issue.
The cam could be installed off or maybe the cam was ground incorrectly. The setup should not peak that early, and even if it did should carry the power further.
Good Luck,
The cam could be installed off or maybe the cam was ground incorrectly. The setup should not peak that early, and even if it did should carry the power further.
Good Luck,