HLA conversion?

[zossy1]

I have never tried to convert the factory shim-in-bucket to SUB, so I don't know what (if anything beyond the new buckets) extra that might entail.

This is easy. Solid lifter (shim over bucket) heads already have everything you need for a SUB setup (ie. the correct collets and cam profile) for a SUB setup. Simply remove shim over bucket lifters, and replace with SUBs and 6mm shims on the valve stems (or 5.5mm shims on the SUB stem, or suitable shims of an appropriate size in your gutted HLAs).

BTW, I have seen gutted HLAs used with 6mm shims on the valve stems too - that works also and makes adjustments slightly easier, assuming you have access to 6mm shims.

[ndragun]

I know solid lifters are all the rage, but I'd rather replace knackered HLAs on a regular basis than have to stuff about with shims.

I use relatively high lift Kelford cams with HLAs and stiffer valve springs and its fine. Smooth, no lifter noise, no problems to speak of...
But to be honest I AM conscious of it. If anything though - thats a good thing: Forces me to want to change the oil on a more regular basis than I otherwise would.

[Magpie]

Shim under bucket are less weight hence very important when running high revs and large amounts of lift.

[madjak]

Manga, given you have already done some work to your NA8 head, you could source an entire 323 / Protege solid lifter head and replace the entire valve train. I'm not sure what the difference in valves is but they could be swapped out if they are different. It would be the cheapest option to get solid lifters and you could run larger lift / duration cams. You'd need to do some work to get the lifter clearances right by shuffling around the shims and / or sourcing a few new ones.

I picked up a few of them over the past 6 months as spares or to practice porting. I think I have 3 now sitting on the shelf. If you need shims or the entire head shout out.

[ndragun]

Shim under bucket are less weight hence very important when running high revs and large amounts of lift.

Yes but the OP is talking about shimming a HLA body with the valve gubbins removed. Don't think there is much of a weight saving there!

[project.r.racing]

To be honest, unless you're planning on fitting big cams and turning it over 7500-8000rpm on a regular basis you're better off just getting complete replacement HLA's. They'e not expensive and for what you'r intending to do they'll be fine. My last race engine had 280deg .400" lift 240@50 cams and HLA's and worked fine for 2 years at 8000rpm (and still goes!)

regarding that race engine with the HLAs
I've done piles of reading about running solid lifters with high lift (10mm) lift cams but not many mention keeping the HLAs.
Is there much gain going with solids over hla for 260-270 degree 10mm lift cams, changing at 7500rpm?
Does it effect power or drivability?

btw I like mangas idea of gutting the hlas and using 10mm shims under them - cheap alternative to SUBs

for a BP or B6 camshaft to have 10mm of lift. it needs the base circle reduce. not HLA has enough self adjustment to allow for this. which is why solid lifters are chosen.

[project.r.racing]

Manga, given you have already done some work to your NA8 head, you could source an entire 323 / Protege solid lifter head and replace the entire valve train. I'm not sure what the difference in valves is but they could be swapped out if they are different. It would be the cheapest option to get solid lifters and you could run larger lift / duration cams. You'd need to do some work to get the lifter clearances right by shuffling around the shims and / or sourcing a few new ones.

I picked up a few of them over the past 6 months as spares or to practice porting. I think I have 3 now sitting on the shelf. If you need shims or the entire head shout out.

Yes and no.

They are still shim "over" buckets and wont like high rev applications. If it was a motor aimed at mid range torque with high lift and say 220-230d duration w/ 10mm lift. Then yes, as that motor wont go past 6500rpm. But if it is a motor aimed at full power, 270-280d w/10mm lift. It'll hit 7500 with the chance of spitting the shims out the side of the buckets.

[madjak]

Yes and no.

They are still shim "over" buckets and wont like high rev applications. If it was a motor aimed at mid range torque with high lift and say 220-230d duration w/ 10mm lift. Then yes, as that motor wont go past 6500rpm. But if it is a motor aimed at full power, 270-280d w/10mm lift. It'll hit 7500 with the chance of spitting the shims out the side of the buckets.

The SoB does allow for higher lift cams than the stock NA8 head though doesn't it? The Astina cams are higher lift. I would guess you could push the duration up a little over stock as well. I have no idea at which point the shims could pop out though. Can you hit higher revs with HLA over SoBs?

[project.r.racing]

Yes and no.

They are still shim "over" buckets and wont like high rev applications. If it was a motor aimed at mid range torque with high lift and say 220-230d duration w/ 10mm lift. Then yes, as that motor wont go past 6500rpm. But if it is a motor aimed at full power, 270-280d w/10mm lift. It'll hit 7500 with the chance of spitting the shims out the side of the buckets.

The SoB does allow for higher lift cams than the stock NA8 head though doesn't it? The Astina cams are higher lift. I would guess you could push the duration up a little over stock as well. I have no idea at which point the shims could pop out though. Can you hit higher revs with HLA over SoBs?

Again yes and no.

Yes SOBs will work better the HLAs. But they still have a tolerances that they can work well in between. Moving to the extreme outside of the tolerances may cause a big bang.

The stock SOB has been designed for said BP cam specs. If you reduce the original 36mm base circle and make it 33mm like most aftermarket BP camshafts with 10mm. Then adding 1.5mm to the shim is gonna change the angles the lobes hit it and the horizontal forces applied to the piss weak retaining rings that hold in the shim in place over the bucket.

[datfreak]

for a BP or B6 camshaft to have 10mm of lift. it needs the base circle reduce. not HLA has enough self adjustment to allow for this. which is why solid lifters are chosen.

why do high lift cams reduce the base circle? Is it a to give enough clearance for the lobe not to hit the head or is it billet expense?

My last race engine had 280deg .400" lift 240@50 cams and HLA's and worked fine for 2 years at 8000rpm (and still goes!)

wozzah - Do you have the cam specs for this engine. Did you have to do anything special for the cams to work with the hlas?

I use relatively high lift Kelford cams with HLAs and stiffer valve springs and its fine. Smooth, no lifter noise, no problems to speak of...

Are these the cams in your profile? I looked them up:
280/272 Duration, 10.25mm/10.00mm Lift. Race cam for well built hydraulic lifter engine.

Thats aggressive cams you have there-- is that a track car? Did you have to do anything extra for the cams and hla to play nicely?


So if building a motor with 10mm (or higher) lift while revving to 7500rpm (or higher) and if the base circle will work with HLAs then:

SUB > GUTTED HLAs > HLAs > SOB

with SOB last because of potential slipped shim engine failure?

[StillIC]

As per wozzah and ndragun I have 280 cams with a touch over 10mm lift. They are on a base circle of -1mm, but with the head work I have done, to increase clearance at the lobes, I can run ~12mm lift on a standard base circle. I am currently running HLAs. Despite what p.r.r said, the HLAs do have enough adjustment to cope with this setup, and in fact any deviation from the base circle can only hurt their performance.

When I first built the engine I was running it to 7500rpm without problems (I don't think my selective memory has kicked in here). Once I was happy everything was working well I started taking it to 8000rpm, which is when I started going through the HLAs. I have done 2 swaps in the last few thousand kms, and it now needs some more swapped.

SUBs are my only answer, as far as I can tell. I am in agreement with some of you on this front. Although I wouldn't mind knowing whether the same cam profile on a standard base circle would solve my issue, as this would align the oil groove in the HLAs with the oil hole in the head, rather than have it out by 0.5mm when the HLA is not on the lobe.

One thing I have noted about MX5 engines is the lack of availability of big duration (>280) big lift, (>10mm) cams. Does anyone know of any other than TODA (whose old local distributor stole my money by failing to deliver)?

[sailaholic]

Wozzah dosent seem to visit here anymore. He is an engine builder some cams are to his specs.

Hydraulic cams and solid lifter cams have different ramp angles.

For memory hydraulic lifter cams have a gentler ramp angle and putting cams designed for solid lifter in an engine with hydraulics does bad things to the valse train.


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[project.r.racing]

Despite what p.r.r said, the HLAs do have enough adjustment to cope with this setup, and in fact any deviation from the base circle can only hurt their performance.

maybe i should have typed "safe" self adjustment levels at those high rpms. the rest of you post doesn't make HLAs sound like a viable option for high rev motors. then go to solids?

I don't really wanna go into a whole epic i-battle with hla vs sub. The issue has been debated long before this thread and has been done to death. If you can swap out the HLAs yourself. Then yes they may be a viable option if you wanna replace them yourself. If you want an install once and forget option, then SUBs might fit the bill. Each option is open to the owner of their vehicle. And as earlier, the subject has been done to death. And it is up to each owner to decide which option is best for them. If you have gone past 7200 regularly and have failing HLAs continuously, so be it. You aren't the first and the info was out there about the subject.

One thing I have noted about MX5 engines is the lack of availability of big duration (>280) big lift, (>10mm) cams. Does anyone know of any other than TODA (whose old local distributor stole my money by failing to deliver)?

http://www.maruhamotors.co.jp/miata/parts/racingcam.html

You can buy directly from them. Pay with paypal. Shipping using EMS. I brought some camshafts from them long ago.

The only Toda cams I've had were 256d w/ 9mm lift in+ex. They didn't require too much work to make right for the engine. They had a base circle of 36mm.

[zossy1]

There are no shortage of big lift, big duration cams available for the MX5. Billets and regrind profiles are a dime a dozen. Speak to your friendly local engine builder for more info, or come and see us at Supersprint Rd.1.

[manga_blue]

Manga, given you have already done some work to your NA8 head, you could source an entire 323 / Protege solid lifter head and replace the entire valve train. I'm not sure what the difference in valves is but they could be swapped out if they are different. It would be the cheapest option to get solid lifters and you could run larger lift / duration cams. You'd need to do some work to get the lifter clearances right by shuffling around the shims and / or sourcing a few new ones.

I picked up a few of them over the past 6 months as spares or to practice porting. I think I have 3 now sitting on the shelf. If you need shims or the entire head shout out.

Thanks for the offer,madjak, but at this stage I think I have everything I need, except time.

I've got an almost unused set of Mazdaspeed SUBs, NB8A stock cams and a spare NB8A head and inlet manifold. The plan is to swap to the NB cams with my SUBs in the existing ported NA8 head. If that doesn't make enough power then I'll port out the NB8A head and swap that in instead. I'm not really chasing outright power - the car runs in the Modified class in NSW which limits it to 90rwkw and I'm sitting around 85rwkw now, just on porting, exhaust, inlet and ECU mods. Bigger overlap cams would take me out of the class. To be honest though there's not much trackwork on the horizon anyway. The car holds most of the NSW lap records and it may be best to retire it while it's still ahead. There is however a whole lot of touring ahead - it's going up Clyde Mountain tomorrow and there will be a couple of big runs across the high country soon. Silent operation, no more clatter, smoothness and good torque then take on higher priority.