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Neon Camshaft Swap - Cranks like no compression

 
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Old 17 Jun 2017, 12:00 pm
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Default Neon Camshaft Swap - Cranks like no compression

Jumped in and swapped Neon twin cams into my '05. Looked like a good option while refreshing head, but....

Won't start and cranks like there is little compression. Gassy smell out the tailpipe so thinking low compression or spark.

Head was checked, decked an complete valve job by trusted shop. No other changes other than, what I thought would be, a direct replace during reassembly. What did I miss?
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Old 17 Jun 2017, 12:06 pm
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Default Re: Neon Camshaft Swap - Cranks like no compression

It's likely that one of both cams are not timed right. You may have installed one of your cams (likely intake) upside down. That is the reason why your motor has no compression. You likely need to install them with the #1cyl at TDC and both holes in the cams between cyl 1 and 2 straight up. On many setups like this, it will mean that the stock intake cam sprocket has to be upside down while aligning the marks.

Won't affect compression, but you do know that the cam sensor magnet has to be reclocked 180 degrees, right?

I predict this thread will soon develop into a heated discussion of how adding the Neon cams is of little or no benefit unless properly timed with variable cam sprockets. But for now, let's get that sucker timed right. If me, I'd go back with the PT cams.
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Old 17 Jun 2017, 12:07 pm
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Default Re: Neon Camshaft Swap - Cranks like no compression

Finding out what the engine compression is for every cylinder would help diagnose the problem.
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Old 17 Jun 2017, 12:16 pm
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Default Re: Neon Camshaft Swap - Cranks like no compression

Okay. Will check the cams for position. When I put the belt back on, I felt 4 good spots in my 2 spin check, thinking I was okay.

Reclocking cam position sensor? New to me. What do you mean?
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Old 17 Jun 2017, 12:44 pm
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Default Re: Neon Camshaft Swap - Cranks like no compression

Quote:
Originally Posted by RCSnyder View Post
Okay. Will check the cams for position. When I put the belt back on, I felt 4 good spots in my 2 spin check, thinking I was okay.

Reclocking cam position sensor? New to me. What do you mean?
Cam timing can ultimately be checked since with the #1cyl at TDC, both holes in the cams between cyl 1 and 2 should be straight up. So if the intake cam turns out to be upside down, you may have to install the timing belt with the intake cam sprocket upside down. And when you do that, the cam sensor magnet is now upside down. So you clip off the plastic dowel on the back of the timing magnet and tighten it up turned 180 degrees.

This stuff gets all confused on the internet because many folks used to install only the 2.0 exhaust cam which is good to go as is. Also, aftermarket camshafts often have extra dowel holes in the front to work on either 2.0 or 2.4 cam sprockets.

In summary, just make sure both holes in the cams between cyl 1 and 2 are straight up when #1 cyl is at TDC. And then if it has compression but doesn't start, rotate the cam magnet as described.

Also, there is no good reason to use the Neon cams. If you read though the SRT4 forum, you will find that they are only beneficial when properly advanced using variable timing sprockets. According to the SRT4 guys, you may lose power using them with stock cam sprockets.
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Old 17 Jun 2017, 01:00 pm
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Default Re: Neon Camshaft Swap - Cranks like no compression

could you just lay the new cams next to the old cams to see if the lobes, dowel holes, etc, line up?
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Old 17 Jun 2017, 01:09 pm
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Default Re: Neon Camshaft Swap - Cranks like no compression

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Originally Posted by rob302 View Post
could you just lay the new cams next to the old cams to see if the lobes, dowel holes, etc, line up?
Did that and cams looked identical. Going to compression test and dig from there.
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Old 17 Jun 2017, 01:12 pm
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Default Re: Neon Camshaft Swap - Cranks like no compression

There is a lot of hyp and myth then facts for the use of neon camshaft in the PT. My suggestion save your self all the trouble and reinstall you original cam set.


Butt Dyno reports are the most amazing part of Hot Rodding, everybody always claims "feeling" more power but almost never when actually tested on a real loive DYNO!


Quote:
Originally Posted by Handy_Cruiser View Post
I predict this thread will soon develop into a heated discussion of how adding the Neon cams is of little or no benefit unless properly timed with variable cam sprockets. If me, I'd go back with the PT cams.
Then why even mention it?
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Last edited by NitroPT; 17 Jun 2017 at 01:19 pm.
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Old 17 Jun 2017, 03:10 pm
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Default Re: Neon Camshaft Swap - Cranks like no compression

Okay, so zero compression on all 4.

Lifted cover and spun to TDC. Exhaust cam's next move is set to open. Intake already open. Hmm. No good. Fresh cylinder fill to be pushed right out the exhaust does not sound like one of the four cycles I remember.

Intake clearly 180 off.

That answers the million dollar question.
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Old 17 Jun 2017, 03:52 pm
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Default Re: Neon Camshaft Swap - Cranks like no compression

Quote:
Originally Posted by Handy_Cruiser View Post
I predict this thread will soon develop into a heated discussion of how adding the Neon cams is of little or no benefit unless properly timed with variable cam sprockets.
are you implying that he should buy cam gears, or that neons are not race cars?



i would listen to nitro..at least 50%...go with the PT intake cam. and try again.
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Quote:
Originally Posted by Handy_Cruiser View Post
So you clip off the plastic dowel on the back of the timing magnet and tighten it up turned 180 degrees.
do you really expect a random person to be able to clip off pegs, rotate something exactly 180, and secure it in such a way that it will be accurate for the next 100k miles? i just bought a $100 cam degreeing kit for my ford because i don't even trust the people that made my cam to be accurate to the degree.
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Last edited by rob302; 17 Jun 2017 at 03:59 pm.
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