Jump to content
SAU Community

Timing On Rb25/30

Black R32

By Black R32,
in Engines & Forced Induction

 Share

Recommended Posts

Black R32 Experienced

Black R32

Posted
Posted

Sooooooooo....

I'm having trouble setting the timing on my freshly slapped together RB25/30....

Tensioner has been relocated to above water pump.... 152 Tooth belt...

Lined up everything but and the first time engine started fine, idled fine, but no power AT ALL!!!

played with the timing a lot and thought it might have been one or two teeth out but couldnt get it to run any better.... actually made it worse.

So i'm starting again, and need to know the count of teeth required between each mark.....

I know that its supposed to be 38 teeth between the two cam gear marks, but what is needed from crank mark to exhaust cam gear?

I have searched many forums but to no avail!?!

Help!!

NEED IT DONE BY AUGUST WINTON!!!

Link to comment
https://www.sau.com.au/forums/topic/405385-timing-on-rb2530/
Share on other sites
KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

I think my relative lack of power might be timing related too. Does anyone know if the timing belt is absolutely symetrical on a stock RB engine i.e. the same length (same number of teeth) on the left and right side?

It occurs to me that this could be upset by the relocated second tensioner. Is it possible that this could mean that even though all the timing marks appear to be in the correct place the timing is out?

I know that Guilt Toy and others have said that valve timing is critical to getting the full power from the RB30.

Well just had a look at this thread

http://www.skylinesaustralia.com/forums/topic/73824-adj-camshaft-pulley-new-cam-belt/

and it sems to me that if the crank timing is set at TDC and the cam gears line up with the backing plate it should be correct. The marks on the belt (if there are any on a belt for a twin cam RB30) probably won't line up as the belt will not have been made for that purpose.

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

great thread but unfortunately that is for a standard rb25... i need one for the extra height of the 25/30!

Help!

I don't think so! I've got a 30/25 too and the main information should hold true and I will check mine this weekend. I reckon that if the crank is set at TDC and the cam gears align with the dots on the backing plate (not on the belt) - as per the illustrations in the thread then the timing must be correct regardless of how many teeth there are either side. The height of the block is neither here nor there. Have you found the timing marks for the crank?
  • 1 year later...
GTRPSI Mentor

GTRPSI

Posted
Posted

I don't think so! I've got a 30/25 too and the main information should hold true and I will check mine this weekend. I reckon that if the crank is set at TDC and the cam gears align with the dots on the backing plate (not on the belt) - as per the illustrations in the thread then the timing must be correct regardless of how many teeth there are either side. The height of the block is neither here nor there. Have you found the timing marks for the crank?

Exactly....

Stop counting teeth.

Find TDC by finding the top of the piston travel on Cyl 1 by removing a plug and feeling down the plug hole (if you dont have a dial indicator), then check your harmonic balancer mark to make sure the balancer outer wheel has not slipped and is lining up where its supposed to be.

Then look at your cam gears, intake side cam gear dot should be at the 9 o'clock mark and lining up with the mark on the cover, exhaust gear dot should be at 3 o'clock and also lining up with the dot on the rear cover.

If they are adjustable cam gears, the scales should both be at 12 o'clock.

  • 1 month later...
iruvyouskyrine Grand Master

iruvyouskyrine

Posted
Posted

So the extra deck height of the RB30 won't throw out the timing marks on the cam backing cover?

Looking to start my engine soon and i was worried about the timing being out. I have aligned everything perfectly (cam gears to backing plate and crank sprocket to oil pump markings) but just want to be absolutely sure that i have it correct.

Thinking about getting a professional mechanic to degree my (stnadard) cam gears just to make sure timing is 100% spot on.

  • 2 weeks later...
r33_racer Grand Master

r33_racer

Posted
Posted

Easiest way is to setup number 1 on TDC with a dial indicator down the spark plug hole and get that bang on and then line up the cam gears with the backing plate using the backside of the dimpled tooth on cam gears. Once that is lined up your belt should go on quite easily and your timing should be pretty close to right.

I have found that some backing plates have a little bit of slop in them and can rock left and right which can throw out your cam gear alignment, so try to get that centred. I haven't seen enough slop before that it throws it all out by a tooth when fitting the belt.

Extra height wont throw anything out if you are setting it up with number 1 at TDC. If you are counting teeth like a 25/26 then you will run into issues.

The way I outlined it and others have already is pretty well the only way to fit your timing belt and have it aligned correctly on an RB30det.

Degreeing your cams properly is a far more involved practice, which you need a degree wheel, cam card information, adjustable cam gears and dial indicator with usually a custom made indicator rod so you can do the job correctly. But for most basic builds this is not required and in most cases cannot be done because people don't have the required parts fitted or tools to do it.

iruvyouskyrine Grand Master

iruvyouskyrine

Posted
Posted

This is exactly the situation I was in. I understand how to set up timing following the backing plate and crank timing marks, which I have done correctly. Was just wondering if they would be out due to the extra height if the block, but if it doesn't matter then it should be all good.

Like you say I don't have the tools/knowledge to properly degree my (standard) cams, and was wondering if it is worth getting a workshop to do it properly.

Thanks

r33_racer Grand Master

r33_racer

Posted
Posted

If you have it done that way then you should be fine. Once you get the car going you will know if its out a tooth.

After I fit the timing belt and then set the belt tension I will turn the motor over a couple of times and make sure its all settled in and then re check that it all lines back up. Always a good practice to double check things, even more so when its a pretty critical part.

XKLABA Grand Master

XKLABA

Posted
Posted

Using the marking on the crank belt gear against the oil pump and cam gears agaisnt maykings on cam backing plate is the best way, then turn by hand a few times ( as michael said ) then recheck they are lined up

Then while still set at TDC install crank gear cover and balancer and check theose markings line up for later when setting ignition timing with timing light

jiffo Mentor

jiffo

Posted
Posted

Once you've fitted the belt and test rotated a few times, I suggest you prove TDC on the balancer.

Make a suitable piston stopper such that when it's screwed into No 1 spark plug, the crank stops slightly off TDC.

Rotate the crank clockwise until No1 piston hits the stopper. Mark the balancer referenced against the TDC pointer.

Rotate the crank anti-clockwise until No1 hits the stopper again. Mark the balancer referenced against the TDC pointer.

Remove piston stopper and re-fit spark plug.

TDC is now halfway between those 2-marks you scribed on the balancer.

That's sorted the crank but I feel there's so many variables associated with building these engines that as a minimum, you need an adjustable exhaust cam wheel.

iruvyouskyrine Grand Master

iruvyouskyrine

Posted
Posted

I was pretty sure I had the timing sport on with the cam gears and the crank sprocket, but I took everything off and double checked it all and it was all perfect :) turned it over and everything lined up again.

I just want to get the thing started at the moment so I know it's going to run. First engine build so I'm hoping for the best but expecting the worst haha. Will get everything spot on with a piston stop etc once I know it's not going to explode into a million pieces on start up :)

  • 5 weeks later...
Easto Apprentice

Easto

Posted
Posted

RB25/30's ain't that hard I just recently threw a big end on mine and replaced it with one I had under the house.

If you have the right belt and line all the marks up, providing the tension is correct, confirm they meet up again after a number of rotations. No problem.

You then need to tune the thing,

Stock 25 computer needs a fuel reg to bump the fuel pressure up.

If you haven't touched the fuel pressure you don't have enough juice for the thirsty 30.

I have never used an adjustable cam wheel on either cam other than the standard oil activated one(which has a blocked off oil feed of course)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • oHBoy.
      Starter motor replacment teeth count.

      By oHBoy. · Posted

      I had 3 counts over the last couple of weeks once where i got stranded at a jdm paint yard booking in some work. 2nd time was moving the car into the drive way for the inspection and the 3rd was during the inspection for the co2 leak test. Fix: 1st, car off for a hour and half disconnected battery 10mins 4th try car started 2nd, 5th try started 3rd, countless time starting disconnected battery dude was under the hood listening to the starting sequence fuel pump ect.   
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      This. As for your options - I suggest remote mounting the Nissan sensor further away on a length of steel tube. That tube to have a loop in it to handle vibration, etc etc. You will need to either put a tee and a bleed fitting near the sensor, or crack the fitting at the sensor to bleed it full of oil when you first set it up, otherwise you won't get the line filled. But this is a small problem. Just needs enough access to get it done.
    • suko
      J50 clock date suddenly reset to January 1

      By suko · Posted

      The time is always correct. Only the date is wrong. It currently thinks it is January 19. Tomorrow it will say it is January 20. The date and time are ( should be ! ) retrieved from the GPS navigation system.
    • MBS206
      Mistakes were made, my R34 Story

      By MBS206 · Posted

      Buy yourself a set of easy outs. See if they will get a good bite in and unthread it.   Very very lucky the whole sender didn't let go while on the track and cost you a motor!
    • Kinkstaah
      Mistakes were made, my R34 Story

      By Kinkstaah · Posted

      Well GTSBoy, prepare yourself further. I did a track day with 1/2 a day prep on Friday, inpromptu. The good news is that I got home, and didn't drive the car into a wall. Everything seemed mostly okay. The car was even a little faster than it was last time. I also got to get some good datalog data too. I also noticed a tiny bit of knock which was (luckily?) recorded. All I know is the knock sensors got recalibrated.... and are notorious for false knock. So I don't know if they are too sensitive, not sensitive enough... or some other third option. But I reduced timing anyway. It wasn't every pull through the session either. Think along the lines of -1 degree of timing for say, three instances while at the top of 4th in a 20 minute all-hot-lap session. Unfortunately at the end of session 2... I noticed a little oil. I borrowed some jack stands and a jack and took a look under there, but as is often the case, messing around with it kinda half cleaned it up, it was not conclusive where it was coming from. I decided to give it another go and see how it was. The amount of oil was maybe one/two small drops. I did another 20 minute session and car went well, and I was just starting to get into it and not be terrified of driving on track. I pulled over and checked in the pits and saw this: This is where I called it, packed up and went home as I live ~20 min from the track with a VERY VERY CLOSE EYE on Oil Pressure on the way home. The volume wasn't much but you never know. I checked it today when I had my own space/tools/time to find out what was going on, wanted to clean it up, run the car and see if any of the fittings from around the oil filter were causing it. I have like.. 5 fittings there, so I suspected one was (hopefully?) the culprit. It became immediately apparent as soon as I looked around more closely. 795d266d-a034-4b8c-89c9-d83860f5d00a.mp4       This is the R34 GTT oil sender connected via an adapter to an oil cooler block I have installed which runs AN lines to my cooler (and back). There's also an oil temp sensor on top.  Just after that video, I attempted to unthread the sensor to see if it's loose/worn and it disintegrated in my hand. So yes. I am glad I noticed that oil because it would appear that complete and utter catastrophic engine failure was about 1 second of engine runtime away. I did try to drill the fitting out, and only succeeded in drilling the middle hole much larger and now there's a... smooth hole in there with what looks like a damn sleeve still incredibly tight in there. Not really sure how to proceed from here. My options: 1) Find someone who can remove the stuck fitting, and use a steel adapter so it won't fatigue? (Female BSPT for the R34 sender to 1/8NPT male - HARD to find). IF it isn't possible to remove - Buy a new block ($320) and have someone tap a new 1/8NPT in the top of it ($????) and hope the steel adapter works better. 2) Buy a new block and give up on the OEM pressure sender for the dash entirely, and use the supplied 1/8 NPT for the oil temp sender. Having the oil pressure read 0 in the dash with the warning lamp will give me a lot of anxiety driving around. I do have the actual GM sensor/sender working, but it needs OBD2 as a gauge. If I'm datalogging I don't actually have a readout of what the gauge is currently displaying. 3) Other? Find a new location for the OEM sender? Though I don't know of anywhere that will work. I also don't know if a steel adapter is actually functionally smart here. It's clearly leveraged itself through vibration of the motor and snapped in half. This doesn't seem like a setup a smart person would replicate given the weight of the OEM sender. Still pretty happy being lucky for once and seeing this at the absolute last moment before bye bye motor in a big way, even if an adapter is apparently 6 weeks+ delivery and I have no way to free the current stuck/potentially destroyed threads in the current oil block.
×
×
  • Create New...