Valve Springs

[NobleRogue]

I'm doing a head rebuild. The head is currently at the shop getting inspected for tolerances on the valve guides and checking the valve condition. They will be re-seating the valves and shaving the head by 15. I need new cams and have decided to go with the Toda intake cams. https://www.horsepowerfreaks.com/tod...150735375.html. But now I'm faced with the dilemma of spring rates. What do yall think would be a good spring rate for 288/ 10mm intake cam? The supplier does not know. For the exhaust cam I'm going to have to find a good used one. Here are some pics of the work so far. Head4.jpgHead3.jpgHead2.jpgHead 1.jpgHead5.jpgHead6.jpgHead7.jpgHead8.jpg .This is a sourced head that I got lucky to find at the local bone yard.

[NobleRogue]

So this is OEM or the closest thing I can find to it. http://www.rockauto.com/en/moreinfo....190955&jsn=370 And thees are what I am considering from Auto Zone. http://www.autozone.com/external-eng...?checkfit=true http://www.autozone.com/external-eng...?checkfit=true Any thoughts?

[— kung fu jesus —]

I would look up the maximum lift of the stock valve springs. I cannot confirm at the moment, but 10mm of lift is too much for stock springs. Supertech would be my go to in this instance. Single spring if you are running stock rev limiter, doubles if you plan to exceed it or stay at the top for long periods of time. The kits I saw included the spring seats, springs and spring retainers. I cannot recall if the valve retainers were included. I looked at new OEM springs for my rebuild and the Supertechs were better and cheaper. I had two sets tested and had more than enough OE springs with my stock cams to do the job.

I'm also going to throw this out there, but a '99-00 head is going to flow better and would be cheaper than buying Toda cams, adjustable gears, and dialing them in. The cams are nice, but if you aren't porting the head, running a standalone ECU, you won't get much out of them.

I also have to ask, why only .015" deck on the head?

[NobleRogue]

I spent a good portion of the day yesterday looking for info on cams but couldnt find much. Then after ordering the cam I started looking up springs and that's when I came across Solomiata's html through Flying Miata. I found that my duration was to long for stock ECU and the lift was to high unless I wanted to do more cutting in to the head. So I have re-ordered the cam to be 256/9.0mm. I know about the 99 Head but I was not able to find one out here that wasn't food for the crusher. It would seem that its popularity has made it hard to get. Although I cant get the ECU yet it is on the list of to do's along with porting and adjustable cam gears. I only did the 0.15 for fear of piston slap and I'm not sure how it will effect Carb standards. I need it to be street able. Can I go with more off the deck and still be street-able? I go down to the shop in a couple hours. if I can get more off I'll ask them to do it.

[NobleRogue]

After taking in the cam numbers and the OEM numbers for the springs to the machine shop we were able to find springs that will work with the original seats and retainers while providing adequate rebound for the cam lobe angles. https://www.summitracing.com/parts/slp-vs855/overview/ Ty KFJ for the advice. I looked in to Supertech but wow those were expensive and didn't look to provide adequate information about the spring. ie. open pressure, closed pressure, outer diameter, open height and closed height. I'm sure that they would have worked but I did not want to risk getting them to find out that the seats would need to be bored out to accommodate them. It looks like the ones from Summit are the right size, better than OEM and cheaper than both OEM and Supertech.

[— kung fu jesus —]

If you are worried about CARB, cams aren't going to help you. Still, the 256 cams are pretty mild, should still pass though. The 949racing site has good information on the Supertech springs. They sell a few Miata-specific kits.

I knew NV has testing, but I am not familIar with their procedures.

For the head shave, factory recommends no more than .010", but that would likely be for warpage. I never had issues passing in CA with the modified head on my 1.6. I now have it decked .025", so compression is about a hair over 10:1.

I might still suggest you look into a clean '99/00 head. The price of one of those would likely be more beneficial, cheaper, and reliable, but I know they can be difficult to find. The reason being if you modify your current head, then it becomes damaged, repairing it or replicating it will still expensive.

To get the power from your head, you need porting, polishing, gasket matching, adjustable gears, valvetrain, tuning, header, intake, coatings, etc. With the 99-00, you have a better flowing design, as stock, with the ability to bolt it all on. Add a square top intake, an '01+ stock exhaust manifold, and you have something that looks stock and would likely not have reason to raise suspicion during inspection. I think it bears some research. In the end, the lower compression pistons in your block are also hurting you, too.

Head work, cams, and associated pieces, people don't share their info readily because the of the time and money invested to dial it in. They don't like sharing their formula and work for replication.

[RustRat]

Slightly offtopic, sorry. Now that you mentioned stock ex-manifold, I have a VVT engine that I will try to add itbs in a budget. Do you think the stock exhaust manifold will restrict it too much?

If I raised the budget, would the bp6d benefit from a change in the valvetrain too, or shouldn't I mess with it because of the VVT?


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[NobleRogue]

Ty for telling me about 949racing. I have added that site to my growing list of places to look for parts. They actually have things I have been looking for but can't find elsewhere. The list of things to do to get the power out of this head are on my list of things to do. But it is a list that I must complete over time as the opportunity and money become available. As for "inspection" it's just OBD2 smog test and a quick peek under the hood, unless I have classic plates which it does not qualify for yet. The Smog test is about as strict as CA's test requirements. The Bottom end is also on my list with a balancer, crank, rods and pistons. I wouldn't mind going with a stroker kit I saw that would give it 2.0L of displacement. The problem is finding the right ppl with the right info and as you said, ppl are stingy with that info. lol Thanks again KFJ. As usual you are a reliable fountain of information and a huge asset to MazdaRoadster.net

[NobleRogue]

Rust Rat check out this site, it's supported by Flyinmiata. http://www.solomiata.com/CheapHP.html. I'm not sure if it will answer your question but it may give you an idea. This is where I found some of the info i was looking for about cams.