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-   -   Alternative bp valve springs. (https://www.miataturbo.net/engine-performance-56/alternative-bp-valve-springs-87604/)

mxnige 02-03-2016 06:48 PM

Alternative bp valve springs.
Hi. I'm looking into some alternative valve springs for the bp engine. Specifically the vvt equipped engines.

I'm aware of supertech and the Volvo valve springs. But would like to find another off the shelf/ oem spring that would work with stock retainers.

I have access to a large selection of stripped down oem engines to measure, spring catalogues, and spring test equipment. I'm sure I can find a spring that can be picked up from a parts store or scrap yard that will fit our engine and be stiffer than stock.

So could someone please provide me the stock retainer and valve spring dimensions so I can begin the search.


Leafy 02-03-2016 10:42 PM

Maybe check the ford zetec motors since the lifters are pretty close to interchanging (just need extended valve stems to use them).

mxnige 02-04-2016 05:04 AM

I actually have the zetec lifters in my engine. The lash was set by grinding the tips of the valve stems down. So no shims are required.

The ID of the zetec lifters are 28mm, so the max spring nominal OD should be 27.5mm.

Can anyone tell me what the minimum spring ID that would work with stock retainer is?

Alternative 02-05-2016 07:19 PM

DSM springs are CLOSE! But I can say with 100% confidence the Manley 4G63 springs don't fit in the buckets.

I believe BogusSVO was using standard BC 4G63 springs.

Alternative 02-05-2016 07:21 PM

1.050" MAX OD
0.710 MIN ID

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