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Rb25 Solid Lifter Head Conversion Problems

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To any body that can help...please....this is the driver talking so forgive me if my explanations are a little layman

Have just spent thousands converting the head to solid. From what I have been told the engineering has been done to accomodate mostly R34 GTR solid components. Included in the build were new cams, valves, springs, lifters, shims, guides etc etc. In other words nothing was meant to be dodgy.

Having completed the job, dynoed the car then out to the track the car immediately felt like it was towing a caravan....ended up finding that it had dropped the shims. Went back and re measured clearances and found a small amount of settling...went back to engineers who promptly tried to get bigger (thicker) shims to close the clearances. Shim supplier told them no way...you cannot install shims any thicker.

From what I am told the lifter and cam combination makes the lifter go too far down past the oil squirters wherever they are and the caps cannot hold the thick shims.

So far the only fix I have been given is to reduce the revs from 8200 down to who knows. As you can imagine...this does not please me as I was able to run the same revs with normal head in the past.

Can anybody assist who has problem solved this before....one other fix suggested was to have custom made caps built to accommodate the thicker shims and hold them more securely....all other people have said it has never been done before...and I find that hard to believe.

Any help greatly appreciated

Thanks

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Thanks so far every one

To the best of my knowledge the shims have ended up around 25 thou but I will have to check.

I had already heard that Tomei did supply something different (We have the Tomei product installed) and were then told another version existed...however after waiting 4 weeks the same product has arrived and now I am told it is the only one available.

Does that give you any more to work with?

If I can I will try and give you part numbers later tomorrow.

Thanks so far

shanef Grand Master

shanef

Posted
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i know john hill of jhh engineering in qld has done quite a heap of solid conversions and he's had no drama's.

i think the tomei springs are no longer made but the lifters are, and u cant use 1 without the other

your in a bit of a pickel, one that your gonna ahve to sort out with whoever did the conversion

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i know john hill of jhh engineering in qld has done quite a heap of solid conversions and he's had no drama's.

i think the tomei springs are no longer made but the lifters are, and u cant use 1 without the other

your in a bit of a pickel, one that your gonna ahve to sort out with whoever did the conversion

You are right ....bit of a pickle is an understatement....all of a sudden the engineers and the workshop are starting to use terms like ....."oh this is R&D work" reading between the lines it is looking like the 12 / 20 warranty (12 seconds or 20 metres).

So far I am trying to keep it civil by trying to find possible solutions that I believe they will act upon...fingers crossed.

I will pass on the contact as a starting point....thankyou

Swiper the Fox Grand Master

Swiper the Fox

Posted
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i think the tomei springs are no longer made but the lifters are, and u cant use 1 without the other

im using the tomei lifter buckets with JUN springs...see's 9500 evertime i drive it...no problem.

we had the same problems running out of shim (thickest shim was not secure at high rpm) and switched to the tomei buckets and no problemo.

stricnynel0s Collaborator

stricnynel0s

Posted
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im using the tomei lifter buckets with JUN springs...see's 9500 evertime i drive it...no problem.

we had the same problems running out of shim (thickest shim was not secure at high rpm) and switched to the tomei buckets and no problemo.

out of curosity with solid lifters can you run rb26 cams that were designed for solid lifter applications ? and if u can what about vct functality, i dont have the need to rev high yet but if i ever get a turbo that works in a high rpm effeciency range, i would like to have an idea where i stand

shanef Grand Master

shanef

Posted
Posted
im using the tomei lifter buckets with JUN springs...see's 9500 evertime i drive it...no problem.

we had the same problems running out of shim (thickest shim was not secure at high rpm) and switched to the tomei buckets and no problemo.

arent you using a 26 head though paul?

what i meant was the tomei solid lifter conversion kit for the rb25

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Sounds like a RB26 head would have been easier however the RB25 motor and head combination was producing most of the goods really really well and in fact better than a similar RB26 motor.

All I was trying to do was to gain some additional reliability (given that the bottom end was very well built and at the time the head was pretty standard with the exception of cams), couple of hundred extra revs and whilst doing the head revision change cams to bring power on just a bit earlier.

Any other ideas that I can pass on greatly appreciated....I am starting to lose my passion for motorsport at the moment

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Further update

From what I have been told now is that the Intake side is perfect running about a 1.7 mm shim but the exhaust side currently has a shim around 4.6 mm.

The head is using the Tomei 270 Pro Cams and Tomei "valve lifter set" (buckets) part number 163005.

From what we have discussed it seems that we need to find an alternative bucket (??Jun??) to suit the low base circle cam.

It was mentioned that Croyden Motorsport? may be able to help but I cannot find the number.

The only other alternative mentioned so far was to pull the head off and re cut the exhaust valve seats to lower the valve.

Any further ideas or sources of supply greatly appreciated

Regards

Swiper the Fox Grand Master

Swiper the Fox

Posted
Posted
Further update

From what I have been told now is that the Intake side is perfect running about a 1.7 mm shim but the exhaust side currently has a shim around 4.6 mm.

The head is using the Tomei 270 Pro Cams and Tomei "valve lifter set" (buckets) part number 163005.

From what we have discussed it seems that we need to find an alternative bucket (??Jun??) to suit the low base circle cam.

It was mentioned that Croyden Motorsport? may be able to help but I cannot find the number.

The only other alternative mentioned so far was to pull the head off and re cut the exhaust valve seats to lower the valve.

Any further ideas or sources of supply greatly appreciated

Regards

Tomei make a bucket...contact Hi Octane Racing and have a chat to Ian. Let him know the base circle cam have and the shims you are currently using that way the correct set of "thicker" buckets can be ordered so that you dont have to "overshim" it.

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Thanks again

I have passed the info on to the workshop and having it all followed up. Certainly looks like there is a reasonably simple fix only problem is when talking with High Octane they swear there is only one bucket available and every body else says there are at least two.

I spoke with someone at Croydon Racing (did not get the name) but he was very helpful.

Fingers crossed the thing will be fixed shortly.

Swiper the Fox Grand Master

Swiper the Fox

Posted
Posted
Thanks again

I have passed the info on to the workshop and having it all followed up. Certainly looks like there is a reasonably simple fix only problem is when talking with High Octane they swear there is only one bucket available and every body else says there are at least two.

I spoke with someone at Croydon Racing (did not get the name) but he was very helpful.

Fingers crossed the thing will be fixed shortly.

Yes well Croydons tried 2 different buckets on mine...so their are definately different types. Im sure the thicker ones we ended up going with were Tomei and im sure we sourced them from Hi Octane. Weird

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