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Author Subject: Cam timing and power loss
devere

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Location: Saxtead

Registered: 16 Dec 2008

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Post #1
Right, im having yet another god damn nightmare with the car.

Trying to get it tuned, and generally not going well at all.

Now, to fill in the details. I had the head rebuilt a while back after some bent valves. Got that all checked over and fixed. I then put the engine back together, and it ran etc. Then without doing anything else, I rebuilt the car from bare shell etc.

Now, having not run the car much since the engine was put back together, I don't know what it was like, I just know it ran. I ran it up to temperature, and revved it, and pretty much only went up the driveway with it. Then pulled the car apart.

Now its all in the new car, ready to be mapped. And its just not producing power. As well as that, the other symptom is, its not revving overly fast....

Would the cam timing being out, cause a potentially very large power loss, and also stop the engine from revving quickly?

Considering the close ration straight cut box, it should rev pretty quick anyway!

Any constructive ideas or thoughts greatly appreciated. This is getting embarrassingly annoying now.

p.s The only changes to the engine have been a satchel inlet manifold and a 4-2-1 exhaust manifold. Hence now getting the remap.
Posted 14th Oct 2014 at 18:14
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allanallen

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Location: Buxton

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Post #2
Yes, the cam timing can massively effect performance if its out. How have you set it? Is it completely standard and have you done a compression test?

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Posted 14th Oct 2014 at 18:33
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welshpug!

Capt Pedantic

Location: Bigend, Wales.

Registered: 27 Mar 2007

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Post #3
surely your mapper will set the timing and map appropriately? they always do in my experience

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Posted 14th Oct 2014 at 18:44
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devere

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Location: Saxtead

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Post #4
Well I had it set originally when I first had it mapped. The people doing the mapping fitted the verniers. Although I cant say specifically what they set the timing to.

I almost have a hunch, that they set it to the cam spec sheet, but then left it at that, rather than tweak it from there.

When I re fitted the head, I put it back together as it had come off. Id marked everything up before I took it apart, then went back to those marks.

Rightly or wrongly, I assumed that it should be fine that way. I thought if i got it wrong, id notice it would be a tooth out. But everything lined up etc. I know i should have dialled it back in maybe. But that's my fault for not doing that. As stated, i assumed it couldn't be a tooth out. Plus it fired up etc.

It had a compression test when it was put back together, and was all fine. Cant remember the readings though.

This is the engine in the rally car. So high compression, Kent PT84 cams, all head components uprated etc. So its a god spec motor. But producing nothing since ive put it back together!
Posted 14th Oct 2014 at 18:45
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welshpug!

Capt Pedantic

Location: Bigend, Wales.

Registered: 27 Mar 2007

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Post #5
Typically you wont need to stray far from the specified figures, its only when building a new combination with custom cams you'd need to play with the timing really.

3.55mm Inlet/ 3.10mm Exhaust are the listed figures.


belt tension and head skims can alter timing.

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need a part number? get on here - http://public.servicebox.peugeot.com

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Posted 14th Oct 2014 at 19:13
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devere

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Post #6
Fair enough. Im guessing if its a timing issue, then I may be a whole tooth out, maybe on both cams possibly..?!!

I know its obviously not good, but without any other first hand experience of it, I didn't know it could lose nearly all power from being out?!

He is going to look into the timing to check and see how it is.
Posted 14th Oct 2014 at 19:44
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allanallen

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Post #7
It does sound like a timing issue, he wants to be getting a dti on it and setting it properly Wink

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Posted 15th Oct 2014 at 08:59
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devere

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Post #8
Yeh I will get him to. I took it there thinking I'd done it right. So its not there fault or anything. They assumed I'd got it right!

I hope it is something like that and it's easily rectifier. At the moment I would be able to push it faster than it could drag itself along.

With big cams, would a timing issue that could be say a tooth out, have more of an effect, compared to getting a standard engine wrong? As in they have far less tolerance to being in the wrong positions? Hence a huge loss of power?
Posted 15th Oct 2014 at 10:04
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Puggitt

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Post #9
Just putting it out there, couldn't be a partially blocked exhaust? Would explain power loss and unwillingness to rev. Could have left a rag somewhere or a collapsed cat/muffler? Just cause if timing wrong on std cams tapping, bent valves and or not running/turning over are the symptoms, had any of that?
Posted 15th Oct 2014 at 10:29
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devere

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Post #10
No it makes no untoward noises. It starts and runs. And only when under a load is its reluctance to whip through the revs.

Unlikely to be the exhaust, as it's a 4-2-1 manifold to a straight pipe all the way to the back box. And that was fine previously.

Any opinions always gratefully received!
Posted 15th Oct 2014 at 10:41
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welshpug!

Capt Pedantic

Location: Bigend, Wales.

Registered: 27 Mar 2007

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Post #11
inlet and exhaust changes can also affect the mapping required massively.

got a fixed FPR or an adjustable one? worth checking the pressure either way, and if its an adjustable reg bin it for a far more reliable fixed unit.

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need a part number? get on here - http://public.servicebox.peugeot.com

Bring on the Trumpets.

Posted 15th Oct 2014 at 10:57
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devere

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Location: Saxtead

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Post #12
3 bar fixed regulator that has always been on there since I put the throttle bodies on to it.

The more that's said makes it seem likely that it's just not timed right and hence the big cams just aren't doing anything...

Getting proper p**sed off with it now. Interest in the car is at an all time low...
Posted 15th Oct 2014 at 13:21
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welshpug!

Capt Pedantic

Location: Bigend, Wales.

Registered: 27 Mar 2007

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Post #13
just throw it on a trailer and get it mapped Thumbs up

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need a part number? get on here - http://public.servicebox.peugeot.com

Bring on the Trumpets.

Posted 15th Oct 2014 at 13:23
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devere

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Post #14
That's what we have been trying! Lol.

Obviously I took it to be done and they thought it was ready to do, but now this problem has surfaced I obviously need to get them to time it up again and do it. But it's all money out the door at the moment!!
Posted 15th Oct 2014 at 13:42
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welshpug!

Capt Pedantic

Location: Bigend, Wales.

Registered: 27 Mar 2007

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Post #15
why didn't they just time it up?

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need a part number? get on here - http://public.servicebox.peugeot.com

Bring on the Trumpets.

Posted 15th Oct 2014 at 13:56
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devere

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Location: Saxtead

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Post #16
They have timed it up. And have moved them about to the best place. Still massively down on power, although it is an improvement on previously!

The only major change is the satchel inlet and trumpets.... are they really likely to cause a problem compared to the jenvey inlet!?
Posted 15th Oct 2014 at 18:02
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allanallen

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Post #17
Hang on, have they played with the timing since you fitted the head then?

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Posted 15th Oct 2014 at 18:26
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devere

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Location: Saxtead

Registered: 16 Dec 2008

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Post #18
Well I refitted it and times it up. Thinking it was right. Appears I was possibly out with the timing.

So now he has adjusted the timing today, and made more power. But it is way way down on power still. And it tails off at about 6k rpm. The cams power range is 3-8 and it made power all the way up to 8 previously.

The only changes apart from the head rebuild were the 4-2-1manifold and the satchel inlet and trumpets on my bodies....
Posted 15th Oct 2014 at 18:50
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welshpug!

Capt Pedantic

Location: Bigend, Wales.

Registered: 27 Mar 2007

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Post #19
what manifold is it?

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need a part number? get on here - http://public.servicebox.peugeot.com

Bring on the Trumpets.

Posted 15th Oct 2014 at 19:51
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devere

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Location: Saxtead

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Post #20
Torque technique. Identical to the maniflow competition stuff.
Posted 15th Oct 2014 at 20:01
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Puggitt

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Location: New Zealand

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Post #21
Checked plugs and coils? Just thinking of some solutions for me in the same situation with other cars.
Posted 18th Oct 2014 at 06:11
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welshpug!

Capt Pedantic

Location: Bigend, Wales.

Registered: 27 Mar 2007

Posts: 25,817

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Post #22
bung the old exhaust on and try it?

________________________________________

need a part number? get on here - http://public.servicebox.peugeot.com

Bring on the Trumpets.

Posted 18th Oct 2014 at 11:59
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welshpug!

Capt Pedantic

Location: Bigend, Wales.

Registered: 27 Mar 2007

Posts: 25,817

Status: Offline
Post #23
bung the old exhaust on and try it?

________________________________________

need a part number? get on here - http://public.servicebox.peugeot.com

Bring on the Trumpets.

Posted 18th Oct 2014 at 11:59
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pete_rallye

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Registered: 12 Dec 2002

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Post #24
Any updates on this Martin? Be interested to find out whats causing it? I assume you have done compression and leak down checks etc?

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Posted 23rd Oct 2014 at 20:52
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