Maruha 10mm lift cams + Supertech SUB; lifter edge wear?
 

Hey guys, I have the supertech SUB setup from 949, my valves area ll shimmed in and ready to go.

One issue: The machinist believes the camshaft ramps are hitting the exhaust lifters on the edge and will cause engine failure and/or premature wear. He's not 100% sure and I wanted to check with you guys to see if anyone else with aftermarket cams have experienced.

Intake cam and lifter during opening event looks like this;
https://www.miataturbo.net/attachmen...ine=1441153871
Intake camshaft lobe + lifter - opening event

https://www.miataturbo.net/attachmen...ine=1441153871
Exhaust camshaft lobe + Lifter - opening event

Thoughts?

Hard to tell from pics. Easy way to tell would be pull cam, clean the bucket top, apply machinist layout fluid (or use a sharpie) and then reinstall the cam and spin it several times. The lob will wear away the ink and you'll see where the cam is making contact. If it really is applying a load on the edge, I'd agree that's not going to last very long.

Interested to see the results of that one.

I'll talk to the machinist and try that tomorrow before I go to work.. I'm surprised that it's giving this much issue considering the fact that many folks just bolt in, set lash and go..

I see what you mean in the pics. Looks like the lobe rides on the edge of the lifter initially instead of on the face of the lifter for the full rotation.

^ Precisely! My concern is the pressure it puts against the inner-edge of the lifter boss/lifter edge, my machinist thinks it could cause the lifter to seize and hold the valve open. Or it could be completely fine ¯\_(ツ)_/¯

I've tried getting info from Maruha directly but they can take a LONG time to get back to me (2 weeks with my last email)...

Ocean at Chikara might be able to help you out. There is still a slight language barrier, but he is usually pretty quick to respond.
They distribute Maruha stuff for North America.

I'm curious, are these the 264* 264* "race" cams, or the 252* 256* F-cam?

They're the 264/264 race cams, here's the part numbers:

mar06051200 (Intake)
mar06051201 (Exhaust)
Maruha Racing Camshaft Mazda MX-5 Miata

Now, I'm wondering if the buckets Maruha is using is different than the ones I picked up from 949racing a few years back, he had one variety that cost significantly more than the (newer and cheaper) 200-ish variety he has now. The outside diameter can't be any higher but maybe the roof is tapered or something? We were wondering if the buckets and cams are designed to rotate or not, I'll try reaching out to Chikara, thanks a lot Brian.

-Tim

I got a response back form Chikara, they commented that the exhaust side looks normal the way it's laid out so I am going to go forward with the reinstall as-is. We'll keep the VC loose and let the engine break in and pull the VC after break in to check for any wear while also listening for any weird mechanical sounds. Going to get some ZDDP rich break-in oil and some additive to run for the first thousand or so. My biggest concern is getting timing correct w/ the CAS and Crank sensor to get it to start without continual cranking...

"You don't need to worry the cam lobe touching the lifter edge of the exhaust side. As long as you valve spring seat pressure is not over 80lb. It is normal on exhaust side."

Lucky day! My seat pressure is 63 pounds with the light double springs!

Picked up some Rotella T6 as there wasn't any ZDDP oil to break the engine in. I plan to mix a full bottle of the Lucus break-in oil additive and a jug of T6 until breakin finishes then change the oil and run a regular bottle of T6.

Just for kicks, anyone have their valve cover off and can turn over the crank to take a picture of the exhaust cam opening event? I'd like to see how a stock cam appears compared to my image.

Does your motor builder know you plan to break in your brand new engine on synthetic oil? If a customer did that to one of my engines, they would be 100% on the hook for the rebuild bill when the rings failed to properly seat.

Woo response from Maruha is everything looks correct, in their reply it read;

"On your question, it is very good point !!
Mazda B6/BP lifter is 30mm OD size, it is smaller than others.
therefore very difficult to develop high-performance cams.
However our camshafts are leading Mx5 market with high-quality

It looks that Cam side interference with Lifter edge.
but it is not like that in fact.
Cam lobe must be touching with Lifter top always (not edge).
and lifter turns when cam-top push, so there is no-wear out."

Gonna go ahead with the install. Mega relief! :party: Guess I'll spend my lunch buying some modeling clay and a micrometer.

Sav: Good point, the engine was already broken in on dino oil. I only pulled the head to do cams. After some thinking I opted to pickup some oil to breakin the cams, research shows it should be one of the best options (I guess the high calcium in most other breakin oils washes some of the phosphorus off the parts) figured the grease and lucus would be enough but I didn't even stop to think about the synthetic affecting the cams. I'll break the cams in, change over to rotella and toss in the lucus oil and go through a tank of gas out of boost (if I can lol) and change oil/filter again.