Jump to content
SAU Community

Hi Lift Camshafts And Base Circles And Lifters..

R32 TT

By R32 TT,
in Engines & Forced Induction

 Share

Recommended Posts

R32 TT Mentor

R32 TT

Posted
Posted

Hi guys,

I am in the process of an RB26 rebuild.

I am looking to buy some Tomei Procams with 260degree duration and 10.8mm lift on both inlet and exhaust.

A couple of questions:

1. I know I need valve springs to suit. Tomei have "Type A" valve springs which are said to be good for up to 10.85mm lift. Does this mean they are "right at their limit" if using a 10.8mm lift cam? OR are they exactly what I need? ie do they have appropriate clearance - I don't want them coil binding obviously. Has anyone had any experience with these? Can you run that "Type B" 11.5mm lift springs with a 10.8mm lift cam for some 'extra piece of mind' or is this unnecessary...?

2. Tomei seem to suggest that they reduce the base circle of their cams to get this lift. And they have lifters made for the job to most of this up. But of course this adds a further $500 minimum to the job. Has anyone successfully shimmed the stock lifters for these type of cam?

3. Lastly, if I DO need new lifters etc, then it may be better to back off the lift a little and go to say HKS 264 degree cams with only 10.0mm lift... (but I'd prefer as much lift as I can get).

Can anyone comment if HKS/Tomei have reduced base circles and how they go about resolving these problems?

Cheers!

M

CruiseLiner Mentor

CruiseLiner

Posted
Posted
Hi guys,

I am in the process of an RB26 rebuild.

I am looking to buy some Tomei Procams with 260degree duration and 10.8mm lift on both inlet and exhaust.

A couple of questions:

1. I know I need valve springs to suit. Tomei have "Type A" valve springs which are said to be good for up to 10.85mm lift. Does this mean they are "right at their limit" if using a 10.8mm lift cam? OR are they exactly what I need? ie do they have appropriate clearance - I don't want them coil binding obviously. Has anyone had any experience with these? Can you run that "Type B" 11.5mm lift springs with a 10.8mm lift cam for some 'extra piece of mind' or is this unnecessary...?

2. Tomei seem to suggest that they reduce the base circle of their cams to get this lift. And they have lifters made for the job to most of this up. But of course this adds a further $500 minimum to the job. Has anyone successfully shimmed the stock lifters for these type of cam?

3. Lastly, if I DO need new lifters etc, then it may be better to back off the lift a little and go to say HKS 264 degree cams with only 10.0mm lift... (but I'd prefer as much lift as I can get).

Can anyone comment if HKS/Tomei have reduced base circles and how they go about resolving these problems?

Cheers!

M

my jun cams, 272/11.35mm lift, have smaller base circle and use thicker shims under the stock buckets to get the correct clearances (plus hd valve springs, titanium retainers). not sure about the other info sorry.

N I B Grand Master

N I B

Posted
Posted

Large cams on RB26 needs machining of the head to clear the cam lobe,the springs are correct but need to be setup right mostl needing shims under the springs to get the correct seat pressure.You could get a custom made set of shims but at about 13mm you would have trouble.

Valve guides also become an issue.

GTR heads must be setup by a machine shop that knows what their doing.If you are not going for 700hp+ look to Pon cams.

R32 TT Mentor

R32 TT

Posted
  • Author
Posted
my jun cams, 272/11.35mm lift, have smaller base circle and use thicker shims under the stock buckets to get the correct clearances (plus hd valve springs, titanium retainers). not sure about the other info sorry.

Cheers! Sounds from what you're saying then that I shouldn't have too much trouble shimming them.

mmm... big cams you have there!

CruiseLiner Mentor

CruiseLiner

Posted
Posted
Cheers! Sounds from what you're saying then that I shouldn't have too much trouble shimming them.

mmm... big cams you have there!

also requires the machining of head for large lift (over 10.8mm i think) and shims were around 5mm thick compared to stock 3.5mm ones i think (all set up by a head specialist for exact clearances on all buckets)

yes cams are big and they sound nice too :thumbsup: a little annoying in traffic with the shacking of the car at lights, vrmm vrmm vrmm at idle but they sound sooo tough, and will be worth it when i can put some boost into the motor after run in. almost sounds like a rotary when idling, but alot deeper.

R32 TT Mentor

R32 TT

Posted
  • Author
Posted
Large cams on RB26 needs machining of the head to clear the cam lobe,the springs are correct but need to be setup right mostl needing shims under the springs to get the correct seat pressure.You could get a custom made set of shims but at about 13mm you would have trouble.

Valve guides also become an issue.

GTR heads must be setup by a machine shop that knows what their doing.If you are not going for 700hp+ look to Pon cams.

Hi mate,

Yup - I knew about the machining to clear the cam lobe - but thanks for pointing it out nonetheless.

Wow - are you saying I need 13mm shims??

Don't you think getting as much lift as possible is going to help with engine efficiency and spool up even at 500-550hp? (my target)

Its been recommended to me to go as higher lift as I can get in the duration I want and I thought it made good sense - I thought Poncams (as good as they are) were easier because you didn't have to worry about other valve train components. I don't mind mucking around a bit though to get the result I want... If its only shims and valve springs I am prepared to do it.

If its special lifters, modifications to valves guides and more hoo-hah, then I might not go that far.

What do you think?

proengines Rising Star

proengines

Posted
Posted

Personally, I would go for hks cams, you do need to machine the head to fit them with the higher lifts but they use the standard base circle which means you can use shims in the standard range. The cams with the smaller base circle are made so you can fit them without having to remove the head from the engine as they can give the same lift without having to make the top of the lobe sit higher and hit the head. It will cost you to have the head milled to clear the cams but means you can use the standard buckets and shims. We assemble the head with the standard shims, check the clearance and tip the ends of the valves to set the clearance. Usually by the time the seats are cut and the valves faced the clearance will close up by .005-6" which isn't much to remove from the end of the valve.

R32 TT Mentor

R32 TT

Posted
  • Author
Posted
Personally, I would go for hks cams, you do need to machine the head to fit them with the higher lifts but they use the standard base circle which means you can use shims in the standard range. The cams with the smaller base circle are made so you can fit them without having to remove the head from the engine as they can give the same lift without having to make the top of the lobe sit higher and hit the head. It will cost you to have the head milled to clear the cams but means you can use the standard buckets and shims. We assemble the head with the standard shims, check the clearance and tip the ends of the valves to set the clearance. Usually by the time the seats are cut and the valves faced the clearance will close up by .005-6" which isn't much to remove from the end of the valve.

Hi Greg, glad you stopped by on this one!

Tell me, is there a 'disadvantage' to running smaller base circles (other than the cost for new buckets?).

ie the HKS do a 264 duration cam up to 10.0mm lift. But Tomei do a 260 duration cam up to 10.8mm.

I am trying to get as much lift as possible. Would the extra 0.8mm lift of Tomei still be worth while?

Or would you go the 10.0mm lift HKS cams and save the money and extra hassle...

ylwgtr2 Grand Master

ylwgtr2

Posted
Posted
Personally, I would go for hks cams, you do need to machine the head to fit them with the higher lifts but they use the standard base circle which means you can use shims in the standard range. The cams with the smaller base circle are made so you can fit them without having to remove the head from the engine as they can give the same lift without having to make the top of the lobe sit higher and hit the head. It will cost you to have the head milled to clear the cams but means you can use the standard buckets and shims. We assemble the head with the standard shims, check the clearance and tip the ends of the valves to set the clearance. Usually by the time the seats are cut and the valves faced the clearance will close up by .005-6" which isn't much to remove from the end of the valve.

here here....thats what i did and thats what i would be doing....

  • 2 months later...

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

    • Rezz
      In B4 "Not a Skyline"...

      By Rezz · Posted

      You're not the first person that's said that about this car lol. A Touring wagon GT in Spark yellow mica would be the dog's danglies 😆 I will keep an eye out for a future purchase for sure. The seats are almost like the OEM Recaros... electric adjustment for fore/aft and tilt movements except reclining.   
    • PranK
      In B4 "Not a Skyline"...

      By PranK · Posted

      Yes!! I love these! It's a shame its not the wagon though!   Thank everything that's holy that it doesn't have the interior of the Aussie delivered ones. Those seats are so much nicer.  
    • PranK
      Duncan's V37.......race car?

      By PranK · Posted

      I'm both sorry and thankful that you do that. 
    • Rezz
      In B4 "Not a Skyline"...

      By Rezz · Posted

      2001 BE5D Subaru Legacy B4 RSK (3rd gen) EJ208 (pink injector) Twin Turbo 280PS 5-speed manual Full time 4WD "RSK" grade which means all of the above LQC option which means stock rear spoiler  I got it primarily to export to someone outside Japan who was interested. These BE5 Legacy B4 RSKs are going through a bit of a resurgence right know in Japan as they are one of the few cars from the "turbo, manual, RWD/4WD, 280hp gentleman's agreement era" cars that don't require stupid money to purchase. Which for some people might be a good opportunity to get as a base for restoration. If I can't find anyone to purchase it I will certainly be doing that myself over the long term. Why? Because it's properly fast in stock form, handles well enough for a GT sedan, there's still enough aftermarket and (if you can wait a while) genuine part support to make it a restoration candidate (<-- that will only get worse over time so it's a case of do it now or choose get a BL5 4th Gen). Mechanically it's fine, has only 89,200kms on the odometer. The problem with this car is that the body and exterior trims are weathered from at least the last 10 years being parked outdoors. I'm the 3rd owner, the first owner was the one that had it for 14 years and barely drove it, had a low-speed front impact (which didn't damage anything behind the radiator support) and got it fixed and sold it. The 2nd owner put most of the kms on it and parked it outside for the last 10 years, hence the door rubbers have seen better days but if you overlook those cosmetic details, it presents pretty nicely. There is some minor rust on the LH rear wheel arch which I'll have looked at too at some stage.  Also as you'd expect from a car this age, the clear top coat is gone, leaving a satin finish on the roof.  Mechanically it's fine (as you would expect from a car with less than 100K kms) but the steering does feel slightly vague around the centre position at higher speeds. So first on the list is to get the steering rack bushes looked at. There's also the Lock button on the remote which doesn't work, but the Open button does.... it means that the anti-theft system thinks it's always open? It seems like if you open the car and don't start the engine within 3 mins or so the anti-theft kicks in again without any beeps or signals. So if you got to start it after that, it won't. You have to push the open button again. That's how I understand it anyway. Just a small irritation but not a big problem to sort out. There's only one mod, the Wangan SPL muffler. Just a tad louder than stock. It's a really good mod for those who don't want to wake the neighbours but still want to hear a more prominent unequal length header EJ20 sound. Anyway I hope to get all those things done eventually, that is unless someone wanted to import it to their country from Japan (where I live). I'm open for negotiations as I really would like a Skyline... but this will definitely suffice in the meantime 🙂 *Disclaimer: This is how I picked it up from the dealer, minus the stuff on the back seat. I haven't cleaned the engine bay or done a thorough exterior clean, aside from spray painting the wipers. 
    • PranK
      R34 Gtt Wheel Offset Advice

      By PranK · Posted

      Wow, even with the Audi logo centre caps. I love OEM wheel mismatches. 
×
×
  • Create New...