RB26 cam regrinding

[Rowdyr32]

How much extra lift is it possible to get out of stock rb26 cams by regrinding them and also being able to achive the right durations as well? I was thinking that if I was to change the cams with other ones the valve shimming needs to be changed so why not just get my cams reground. Have any of you had it done and what does it normally cost?

[DAN00H]

I haev heard of this being done to the old V8's etc, I'd suggest you contact Yella Terra or somewhere like that and ask them about regrinds look in the yellow pages? don't really know mate. let us know. (could be cheaper than a set of poncams )

[browny]

Get in touch with lukevl

[Rowdyr32]

Thats why I was asking. It would be a really cheap option if they can do it for a reasonable price. They can do if for most other cars so why not rb's. I'll call around on monday.

[browny]

Personally I really would get in touch with lukevl first. He works at a cam place (Tighe Cams?) that seems to be pretty well up to speed on the Nissan engines.

Yella Terra is a name I more associate with old aussie/english/US stuff. If they even do cams, they probably aren't the best to ask about Nissan stuff.

[Timd]

ive had reground cams in a few different cars with no problems. Not long ago tho i was reading a zoom article which pretty much said your a cod if you stick regrinds in your engine. The particular article was focusing on an rb26 from memory. The idea was stick to stock if you dont have the money or incliation to buy billet. im not so sure, crank regrinds are pretty common, i assume its a similar process.

Im interested to see what someone in the know says.

The other option would be porting, cheaper than cams and can get good power gains.

tim

[bigcarl]

anyone know how much it costs for a basic port job to an rb25 head?is it a waste of time with standard cams? much of gain to be had if your running high boost?

[Rowdyr32]

I just rang wade cams and they said that they can regrind them and they only charge $220 a pair, sounds ok to me. I am trying to find a page on the net that lists all the durations and lifts for all the gtr models. I have seen it before but can't find it now.

I think zoom is a waste of time. Some of there tech artilces are full of **** if you read them properly. They said they couldn't tune a rb20 with 440c injectors but in the next paragragh they talk about how well the car could be tuned with 550cc injectors. Not to mention what they said you have to do to put a rb26 in a gtst was all rubbish.

[Angry]

http://www.tomei-p.co.jp/_2003web-catalogu...haft-specs.html

thats the closes i could find on the cam specs for ya m8 .. hope that helps

interesting wade cams will do em .....is that standard regrind or increase in lift?

Matt

[Rowdyr32]

http://www.tomei-p.co.jp/_2003web-catalogu...0_cam_RB26.html

The poncams type a could be suitable for me. They should be good since I will be putting on n1 turbo's and I would rather a little lost off the top to get some more midrange. I'll send wade an email tonight. They said they cam get a little more lift and duration so we'll see what he says.

[Ronin 09]

Can someone please explain how a regrind works?

If you take off material (ie grind) how can you increase lift / duration?

I must be missing something obvious :confused:

[Trust33]

There must be a process of also adding on to the lobes?? :confused:

Would they then be a bit weak??By the sounds of it there are no problems.

Unless they regrind a new set of cams.Now that would make sence.

[Rowdyr32]

They just grind a new profile into the cams and due to the extra clearance you need to re do the valve clearances. They should only be taking off less than a mm to increase the lift from 8.6 to 9.15 but the added gains should be in the extra duration. Around 20 degrees on both in and ex.

Does anybody sell cheap valve shims?

[SteveL]

It's difficult to explain in words and I suspect a google search will reveal much, but FWIW:

- re-grinding stock cams to increase lift involves reduction of the base-circle diameter while maintaining as much of the original lobe height as possible. The base circle of a cam lobe is basically the diameter of the cam measured at a point 90 degrees to the lobe itself. Reducing the base circle means that, on RB26 engines, increased shim thickness must be used to restore factory clearances. With 24 valves this can get expensive - the shims vary in price between $15 and $25 each. Also, depending on how much is removed from the cam, it's possible that shims of sufficient thickness may be unavailable (max factory shim thickness is 3mm).

- using a 'billet' cam can help overcome the reduction in base circle. A billet cam is a 'raw' cam with large, as cast lobes. Using a billet the stock base circle can be acheived (more-or-less) while grinding the lobe for increased lift. Billet cams are expensive and more expensive to grind. I don't know about RB billets, but an L-series billet (L24/26/28) was around $300 about 5 years ago - and that only has 12 lobes (and only 1 per engine !!).

- welding a cam to give more grinding surface is sort of a psuedo-billet arrangement. Personally I'd steer clear - welding cast iron is frought with danger even when done by the skilled. Warping is a major problem in itself.

[Ronin 09]

Thanks steve I just thought about it a bit more... remove material from the circular profile of the lobe, leave as much material in the max height as possible, put in a thicker shim.

Correct?

[SteveL]

Thanks steve I just thought about it a bit more... remove material from the circular profile of the lobe, leave as much material in the max height as possible, put in a thicker shim.

That's pretty much it. There are some other consequences like increased valve opening rates that can cause problems with stock springs.

[Fitzpatrick Speed Works]

RB26 heads are pricks to work on, they are just rubbish because they take so much damn time and every head i have pulled apart the exhaust valve guides are always thrashed out and need replacing... THe shims are also a real pain in the but and bloody expensive... To give you an idea on what you should be able to achieve with a stock cam reground the stock base circle is 33mm, I have a set of jun 272, 10.8mm lift cams and the base circle is 30mm. The overall height from base to pitch is only .8mm difference in favour of the Jun item... So with stock cams I rekon you should be able to get them to around 272 and 9.4-9.6 mm of lift which is nice as you wont need to grind the head down to fit that size cam!! Hope this helps!!!

[Fitzpatrick Speed Works]

With a 9.5mm lift cam the stock springs bind rate should still be okay but anything larger and you will need to replace valve springs with something the will match your cam profile!!!

[SteveL]

With a 9.5mm lift cam the stock springs bind rate should still be okay but anything larger and you will need to replace valve springs with something the will match your cam profile!!!

It's not the amount of lift necessarily but the ramp rate.

[proengines]

Unless you're able to set the tappets yourself, the money you save on regrinding as opposed to new cams is not really worth it. For a start, timewise, you will need to remove the cams and send them away to be ground, say 1 week return and $220+freight, then whatever comes off the base circle radius of the cam will need to be added to the thickness of the shim. This means you will need to refit the cams, measure shims and calculate the thickness of the new shims required, then order new shims. Shims will cost $15 or so each+freight, so 24x$15=$360 and that's if you get it right the first time. This is assuming you already have the tools to do it, including a micrometer and feeler gauges. Thats up to $600 or so without any labour.

This gives you a set of reground cams with questionable hardness, especially on the transition from the base circle to the opening and closing ramps plus a set of shims around 1mm thicker that are slightly heavier plus the buckets will be sitting further out of the bores in the head which may or may not increase wear on the bucket bores. Add to this that you won't be able to have near the range of profiles that are available on new billets. You can have the old cams welded and reground but it really doesn't end up any cheaper than new billet cams and takes quite a while to do. If there was nothing else available it's worth doing but when there is I can't see a benefit.

Compare that to a pair of new billets, from around the $1200 mark from memory for Tomei or $1450 or so for HKS in a range of profiles that run the same base circle as standard so setting tappets is going to be quite an easy job, most will more than likely be within tolerances, you can fit them in 1 day and your car isn't off the road waiting for parts. Add to that you can probably sell your old STD cams for $200 to someone who wants to play with an RB20 or 25 and the cost difference is pretty negligible, especially if you're paying someone to fit them. Also, if you ever plan to sell your car, brand name cams are a good selling point compared to regrinds.

Theres nothing really wrong with regrinding cams for most engines where you have easy valve clearance adjustment and it's quite cheap to have done but in an engine with shim adjustment where new billet cams are available it's false economy in my opinion.