Jump to content
SAU Community

Dialling in cams

MonstaS4

By MonstaS4,
in Engines & Forced Induction

 Share

Recommended Posts

MonstaS4 Collaborator

MonstaS4

Posted
Posted

I'm after some advice on dialling in cams on an RB30DET. Due to the positioning of the belt tensioners, the cams do not line up with the marks on the back plate when at TDC. My guess is they are 5 or so degrees out. It's an R33 head so the VCT gear is adjustable from behind, and i have an adjustable exh. gear.

I've made up a degree wheel which is bolted on the crank, but there dosn't seem to be alot of room on the lifter to place the dial guage on. Is there a trick to this? There's no way a dial guage can sit perpendicular to the lifter as the cam gets in the way. Help!

Link to comment
https://www.sau.com.au/forums/topic/73332-dialling-in-cams/
Share on other sites
Warpspeed Experienced

Warpspeed

Posted
Posted

I have been all through this myself. You need to take a bit of time and do it properly, otherwise it's a complete waste of time.

The first thing you need is a decent dial indicator with the little screw in ball in the end, and it must also have enough travel to work over the full valve lift (obviously).

Next get a small flat metal strip, and drill a suitable hole in one end and fit it under the screw in ball on the end of the dial indicator. It should stick out a right-angles, like a foot sticks out from a leg. That way, the projecting metal "foot" can sit on the very edge of the cam follower without the lobe hitting the stem of the dial indicator as it rotates past. Until you have tried this, you will not realise how little room there is.

The last, and most important thing is to make up a very solid mount for the dial indicator. It absolutely MUST be mounted parallel with the axis of the valve stem, otherwise the metal "foot" will slide around on the follower and the readings will be all over the place. I made up a special fixture that bolts on top of the camshaft bearing saddles. It requires a couple of longer bolts, but it is extremely rigid, and mounts the dial gauge exactly true. If you are clever, it can be turned around and used on both inlet cam and exhaust cam.

Another handy little gadget I fabricated from an old spark plug body, is a fixture for very accurately finding TDC. It has a long threaded bolt that hangs down inside the combustion chamber, and it stops the piston coming up at exactly 90 BTDC.

With the degree wheel fitted, the engine can be turned both ways to hit the stop, and it should show exactly 90 BTDC one way, and 90 ATDC the other. If the bolt length is not exact. both readings should still be identical. When they are, remove the spark plug fixture and TDC should be exact on the degree wheel.

If you take the time to set it all up and make some special tools, cams can be dialed in very quickly and accurately. This might be important if you are trying a few different cams and have adjustable pulleys.

A really convenient way to turn the engine over is to place the car in fifth gear and just roll it backwards and forwards. It is the easiest way.

Link to comment
https://www.sau.com.au/forums/topic/73332-dialling-in-cams/#findComment-1349771
Share on other sites

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

    • LaurelPWR
      Forced Performance Hta Turbos

      By LaurelPWR · Posted

      Placing bets on my stock oem RB25 rods, orrrrrrr........?  😂💀 for anyone interested, Insta is : @genuine_rb13 https://www.instagram.com/genuine_rb13?igsh=MTR5dGh4NWh0NHg3cA==
    • LaurelPWR
      Forced Performance Hta Turbos

      By LaurelPWR · Posted

      Hahahahah, look, your not wrong 😂😂 and thank you brother 🙏🏼 jokes aside, I haven't driven the car in 6+ years and it's like I'm starting all over again, and furthermore the car is wayyyy more powerful and it's characteristics are night and day different now compared to what I remember. So I'm slowly easing myself back into the groove, the car is literally scaring me a bit tbh.....it feels like it has 200hp more than it does on paper and responds like a cammed Ls v8, and-some! 😅 every single bit of throttle pedal travel and input has instant response all the way to the floor, zero flat spots or labouring feelings, it's nuts. Im shooketh, go easy on me hahahaha or don't 🤙🏼😊      
    • MBS206
      NC MX5

      By MBS206 · Posted

      If the house has ever been sold before too, they have photos from that etc.
    • GTSBoy
      NC MX5

      By GTSBoy · Posted

      I used to do that, but then I got savvy. The benefits of having your phone photos geotagged outweigh the negatives. I just don't publish any photo straight off the phone/out of the gallery/off google photos, etc. If I'm going to use a photo, other than for SMSing to fam, I will always open it on the computer, copy it/otherwise edit it and save down without the original metadata, before using it. For example, posting photos of my engine bay into a thread on here, to show someone a plug or something - I will just screen-cap the section I want to use and paste that section direct from the clipboard into the post. No metadata goes along with.
    • GTSBoy
      NC MX5

      By GTSBoy · Posted

      Yes, so it won't work for places with no photos on the net. I would have said that there are no photos of the inside of my house on the net, but....then I realised that my kids' parties would have had bazzillions of photos of the living spaces, kitchen etc put on insta and other shitmedia. So... you can see how insidious it is.
×
×
  • Create New...