18psi

iTrader: (76)

I had a clutch spring fall out on a different car a very long time ago. Drove fine, but had vibration under accel.

Paulryan

So my two problems are vibration when reving in neutral and a strange noise coming from the front of the engine while running. Not a knock knock noise but something I haven't heard before. Decided to remove alt belt since I only have one belt and to my surprise noise is gone!!.... either my old alternator or brand new gates water pump is responsible. At least I know it's not internal. Still have the vibration but will investigate further once the tranny is out.

BogusSVO

iTrader: (1)

I guess I like to waste time, I balance most all the performance builds I do, to .1g of mean

so pistons are that close, small end of rod and the over all of the rod

Most 4 cylinder cranks are close from the factory as far as balance goes, but they still can be better

I normally take the H-bal n bolt, time belt gear, crank, flywheel with bolts and pressure plate and bolts to be first individually balanced then balanced as a unit

I have seen rotating the pressure plate throw the balance off as much as 52g, and commonly see 20g

So once I get done with the balance job, the pressure plate is indexed to the flywheel

Now IIRC, there is some clearance work done on cyl 1 just behind the water pump on the 1.8l, so with spec stack, your new water pump shaft may be lightly touching Cyl 1

**EDIT**
Thought I did a write up on the Manley rods..
https://www.miataturbo.net/engine-pe...ng-rods-65527/

Paulryan

Thanks for the write up on the rods. I did read your entire post as I was reaserching my build. I guess my lesson learned here is listen to everyone here and not the machinist. The shop that i took my block, crank and head to is a very good shop and the guy who owns the shop is very reputable and does great work. He knew I had aftermarket forged rods but only asked for my pistons once he determimed if my block requried boring. I guess i assumed balancing the rods wasnt needed since he didnt ask for them.

The ATI Damper is quite a bit heavier than stock one would that cause anything??

On a side note I did just take it out for a 15 mile shake down and it seemed to run fine. Maybe im just being over freaked out since ive never built my own motor before and havent really given everything a chance to settle into place.

Going to change the oil for the first time tomorrow so fingers crossed everthing looks ok

Paulryan

Just a little update. I changed the oil and other than a little discoloration from all the assembly lube the oil was as clean as when I put it in with no signs of metal or shimmery bits. I'm pretty confident there's no metal on metal interference taking place. I still have a vibration around 2.5- 3k that I need to figure out but will know more after I drop the tranny and reinstall flywheel and clutch to rule that out.

mx5-kiwi

Are you sure you haven't put the engine mounts in upside down?.....there is a metal tab that is supposed to fit in a locating hole (or something like that).....if you fit them wrong you may have metal to metal contact on each side.

Paulryan

I've checked that already but thanks for the input. When I was out driving it sounds like a heat shield ratteling under the car somewhere so I'm going to get under it again tonight. Hopefully I'll find something obvious. I noticed the down pipe contacting the shelf in the engine bay so I'm sure that is contributing to it but doubt it's solely responsible.