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Camshaft instalation probs! HELP!

bbenny

By bbenny,
in Engines & Forced Induction

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Jay95R33 Grand Master

Jay95R33

Posted
Posted

Bbenny - I think the RB20 motor has a non-interference head/valve set up. So I really don't think it'd be a bent valve (thank god !!)

Have you run the diag's on the ECU to see if it finds any faults?

I'd go around all the plugs/sockets around where you worked and give them a wiggle and crimp them tight if they look a bit sus. Could just be a dodgy connection....

J

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mabru Enthusiast

mabru

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Ok, swapped in a good water temp sensor and that didn't help much. I'm starting to think it's the brackets of the cam's themselves, ie. not enough clearance compared to the stock RB20 cams.

My engine sounds like its laboring pretty hard to idle and runs ok above 3k rpm. At first I thought maybe I had put the timing belt on too tight but I've redone it and seems fine, there isn't much left for me to check at this point but the cam's and/or the bearing clearances.

-Matt

DoughBoy Veteran

DoughBoy

Posted
Posted

Have you guys checked the timing with a gun? I had the same problems, turned out the timing was way out (and yes I marked everything clearly to put it back in exactly the same, but it still got knocked out by a fair bit anyway)/

mabru Enthusiast

mabru

Posted
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Have you guys checked the timing with a gun? I had the same problems, turned out the timing was way out (and yes I marked everything clearly to put it back in exactly the same, but it still got knocked out by a fair bit anyway)/

Yeah I've run the gun on it, but with no steady idle to speak of it's pretty hard to get a decent reading. It bounces between 20 and 30 degrees BTDC near 1000 rpm. I have attempted to adjust the CAS with almost no positive results.

I might be forced to put the stockers back in just to make sure everything is ok in there.

-Matt

mabru Enthusiast

mabru

Posted
Posted

Ok, I'm wondering if I should be using a different torque spec for the cam retaining bolts other than whats listed in the R32 engine shop manual. I'm starting to think that maybe the clearances are too tight and it's causing the low rpm problems.

SK, what torque setting do you guys use when doing this swap? I'm just about out of ideas.

Thanks for any input, not trying to hijack your thread Bbenny, just trying to achieve the same end result :rofl:

-Matt

Chris32 Veteran

Chris32

Posted
Posted

You guys had any luck fixing your problem?

Mine are on hold until I hear the outcome of how it all works out

Good thing is I have a spare motor to play around with, I am thinking of swapping therm into that just as practice, then doing the real thing on my car............

Chris

mabru Enthusiast

mabru

Posted
Posted
You guys had any luck fixing your problem?

Mine are on hold until I hear the outcome of how it all works out

Good thing is I have a spare motor to play around with, I am thinking of swapping therm into that just as practice, then doing the real thing on my car............

Chris

My cam probs are on temporary hold, I'm in the middle of my work days at the moment so time for car repair is virtually non-existant. I'll start my break on Sunday, doing a friends auto > manual conversion that day then hopefully I can sort my probs out after.

I am anxiously awaiting more info from Bbenny though :)

-Matt

Chris32 Veteran

Chris32

Posted
Posted

by the sounds of it the stock ecu idle settings are unable to cope...........

Both of your installations sounds like a sucess, but maybe the factory computer was holding it all back?? S/K, what are your thoughts...........

Sydneykid Grand Master

Sydneykid

Posted
Posted
Ok, I'm wondering if I should be using a different torque spec for the cam retaining bolts other than whats listed in the R32 engine shop manual.  I'm starting to think that maybe the clearances are too tight and it's causing the low rpm problems.  

SK, what torque setting do you guys use when doing this swap?  I'm just about out of ideas.

Thanks for any input, not trying to hijack your thread Bbenny, just trying to achieve the same end result :)

-Matt

Hi Matt and others, no way it is torqque settings, the cams would have seazed in the head by now if the clearances were so tight that it affected the idle. Plus it would not be possible to rotate the camshaft by hand at all.

The torque setting is low, 8-10 ft lbs from memory.

Our RB20 has a Power FC on it, and I did a few things at once when I changed the cams. Ignition timing is critical, I marked the crank pulley before I pulled it appart and then reset the CAS so the timing was exactly back on that mark. I was confident in my work so I just drove it around for a day or so, it was a bit rough but it settled down. I had to fiddle with the idle rpm aim table on the Commander, I don't remember adjusting the fuel until we stuck it on the dyno.

It wouldn't hurt to try taking mucking around with the fuel via your SAFC or ecu if you can. It should need leaning out at low rpm, if anything. So I would start there. You can test this theory by trying it without an airfilter or intorduce a leak in one of the vacuum pipes. Just stick your finger over the open end and gradually open the gap, if the idle improves then leaner is the go.

Hope that helps

bbenny Mentor

bbenny

Posted
  • Author
Posted

like youi Mabru, my weekend is mon tue. so i am slowly getting in an hour of dissasembly every night, im going to tripple check everything again, and if i still have the same prob i will have to revert to standard camshafts... maybe throw a set of adj pulleys instead.

i just thought it would work easily as there is only about 1.8mm difference in lobe height between the std and GTR shafts...

its just so frustrating because theoretically it makes alot of sense and should work well!

one thing i was wondering, would it be possible to maybe sort out iddle issues with adj cam pulleys?

Roy Grand Master

Roy

Posted
Posted

Get a cheap valve meant for automatic watering systems and disconnect the carbon canister lines that run from the manifold. Put the little cheap and nasty valve on those lines and throttle the inlet leak...

If it turns out you need to richen the idle mixture, then grab an adjustable pot from Jaycar and wire it up to the water temp sensor, by fooling the ECU into thinking the car is cold it will automatically run a little richer.

Anyone have an SAFC you can borrow...?

mabru Enthusiast

mabru

Posted
Posted

I am currently running an SAFC II, so I'll give the low RPM low throttle settings a little tweak and see how it runs after.

SK- I was basically grasping at straws with the whole torque settings thing since I was running out of ideas.

I'm guessing the extra lift has put the lean/rich condition over the top and the ECU can't keep up.

-Matt

bbenny Mentor

bbenny

Posted
  • Author
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SK im also running an SAFC II but am having the ecu rechipped next week.

i cant check the timing as i cannot hold idle at all.

as i am already half way to the cams, please let me know what happens when you play with the SAFC at low rpm and idle Marbru!

i would love to know before i pull these babies out and re-fit the standard items!

thanks!

Also, all my mechanical timing is spot on as is torque settings on clamps, as SK said i didnt think it was clamps after i went around the block and didnt see my timing belt snap as the cam seized! few! that would have been messy!

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