Need help - Stock Balancer and Fastforward overlay pulleys
 

Hi guys,

I have a kindof strange situation, and am looking for some help. I have a 1990 miata with a 1991 Escort GT swap in it. I have been running a Jackson racing M45 kit on it for about 2 years, and it has been working great.

I am now in the process of putting together a homebrew GM 3800 M62 kit to replace the Jackson racing kit.

Step one is to upgrade to a 6 rib belt. It appeared that the easiest way to do this was to buy an overlay crank pulley from: fastforwardsuperchargers.

So, I bought the one listed for 92-05:

https://www.miataturbo.net/attachmen...ine=1443357272

Well - it doesn't fit. Why not, you say? Well, it appears that my Escort GT has the long nose crank (or small nose, whatever you want to call it), and appears to have a unique (not found on any Miata) balancer pulley. So, the 4 bolt pattern is much smaller than the overlay pulley, and the overlay pulley is not deep enough to fit inside the balancer.


https://www.miataturbo.net/attachmen...ine=1443357272


https://www.miataturbo.net/attachmen...ine=1443357272


So, I bought the other crank pulley that Fastforward has for sale - listed as fitting 90-92:

https://www.miataturbo.net/attachmen...ine=1443357272

At first glance, this looks like it will work just fine. But it doesn't.


https://www.miataturbo.net/attachmen...ine=1443357272


https://www.miataturbo.net/attachmen...ine=1443357272

Why not, you say? Well, it looks like the unique Escort balancer pulley may have the step in a different location than the miata pulley? The OD of the crank overlay interferes with the step on the balancer, so it doesn't sit flush.

See the gap here:


https://www.miataturbo.net/attachmen...ine=1443357272


So WTF???

I'm thinking this may be fixable by using a 1.6L short nose balancer pulley???? - the kind from early 1990-1991 Miatas.

Specifically, this one here, most easily identified by the 4 oval slots and the keyway in the middle:

https://www.miataturbo.net/attachmen...ine=1443357272

Here is a comparison of the late "Long nose" 1.6 crank pulley on the left which I don't need, and the "Short nose" one on the right which I think might work.

https://www.miataturbo.net/attachmen...ine=1443357272

Any thoughts on this???


I can buy a brand new short nose balancer pulley and associated parts from Mazdaspeed for ~$150. But, I could also buy an entire Escort GT engine with the big nose crank for $200.

But, I'm not sure that the big nose crank works with the Fastforward pulley anyways.

Here is a comparison of Big nose vs Small Nose Escort GT balancer pulleys:


https://www.miataturbo.net/attachmen...ine=1443357272


https://www.miataturbo.net/attachmen...ine=1443357272


https://www.miataturbo.net/attachmen...ine=1443357272

And, here is a photo of the big nose escort balancer pulley with the "correct" fastforward 6 rib pulley:


https://www.miataturbo.net/attachmen...ine=1443357272


https://www.miataturbo.net/attachmen...ine=1443357272

And, here is the giant gap between the pulleys - meaning the late fastforward pulley doesn't work with this either:

https://www.miataturbo.net/attachmen...ine=1443357272


Help!

Is this last photo in your post the preferred combo? If so, I'd say have a spacer machined that will fit between the two and step up to some high strength fasteners. Perhaps a piece that works like a wheel spacer, where the bolts run through the spacer and original balancer into the crank, and then your pulley bolts to that spacer. Like the ones below are set up.


https://cimg8.ibsrv.net/gimg/www.mia...94cbe6be5b.jpg

Well, I found this photo in the archives here: MiataTurbo



https://www.miataturbo.net/attachmen...ine=1443369381

I'm not sure if this FFS should be able to provide this spacer, or is it custom???

Have you tried asking Tom at FFS (over on miata.net) if he's run into this before. He is usually very responsive to any inquiries even when they aren't for one of his coldsides.


Also, it sounds similar to the issue pointed out in TDR's (4-rib) overlay fitment info: http://trackdogracing.com/crankoverlaypulley.aspx

Damn, and I had not even had any coffee yet! Hopefully it is an off-the-shelf item.

Just sent Tom an email.

Putting a spacer between an overlay pulley and the stock damper, held on with four 6mm bolts, seems like the worst possible solution to this problem. Those OEM high-grade bolts break even without a spacer installed, and the spacer will make that problem much worse. Get the right damper for the car.

I wasn't aware there were two different "noses" on EGT BPs....

What's the issue with just using a BP unit, since you're working with a BP?

Slight update. Tom from FFS was not aware of the existence of a smallnose BP, or the unique EGT crank pulley, so no help there. He suggested using washers on the 4 bolts as spacers between the pulleys, but I don't think that is a good idea.

I ordered a 1.6 shortnose crank pulley from Mazdaspeed. Waiting for that to arrive.

I measured the gap between the smallnose BP pulley and the smaller 110mm FFS pulley. It is around 0.115". There is a steel spacer ring that goes between the 4 bolts and the front face of the OEM pulley, and it is 0.085" thick, which still leaves 0.030" gap. So, it might be possible to use the EGT pulley and FFS pulley together if you use two of the OEM steel spacer pieces stacked up. I ordered another OEM spacer at the same time as the pulley, so I will be able to at least verify that as well.

Should I be concerned with using a 1.6L balancer on a 1.8L engine? Is the damped mass and elasticity tuned specifically for the crankshaft torsionals? I'm sure there isn't a big difference, but it does make me wonder why Mazda/Ford went to the expense of creating a unique part for the Escort when they already had a part designed and in production from the Miata.

Are you asking why I can't use a pulley from a '94 and up Miata? Well, it's because my Escort crank has the small nose. It may be possible to use a Miata longnose ('91-93 1.6L) pulley on my crank, I'm not sure. I have a set of those parts lying around, but it would require me to pull the timing belt on my engine to check, and I don't want to do that at this point in time.

I actually have two Miatas - both with Escort GT blocks/cranks. One has the bignose crank, and the other has the smallnose. I forgot that my supercharged car had the smallnose, which is why I ordered the late FFS pulley first. Oops.

I'm not sure what model year Mazda/Ford made the switch to the cranks - Maybe '92 or '93? I believe I have '91 and '95 blocks/cranks.

Ah ok... i had/have a 93 EGT, i didn't realize that there was a change at one point.

https://www.miataturbo.net/attachmen...ine=1443847025

Cam sensor craps out. Uh, G, can I come over? Aidan wants you to come out here and bring beer and roast marshmallows, but I'm staying in Salinas anyway and can just come to you.

Fucking retarded related thread fuckery needs to go away I'm so sick of this.

I don't even like that word. FUCK. annoying.

Dyno run