M20 SETA-I Stroker Tear Down.

[vWBIRDWv]

Ok guys, been waiting for a while before posting this one, I tore into my Seta today to see why I had low compression, I re did the rings, the rod and main bearings new bolts fresh deck on the block and head, the head was completely rebuilt before use as well. Got about 30,000 miles of hard abuse out of this motor, it never smoked ran strong just started to vibrate horribly ended up replacing tranny driveline flywheele and clutch trying to find out the source of the vibration before performing a compression test..Any input is greatly appreciated,

[vWBIRDWv]

every cylinder was scrubbed the same as the pitting and skirt wear, these pistons were sourced used and this block is a completely different block than the SETA Pistons, the block the pistons came in had main journal tolerance issues so i had to use a ETA block and Respective crankshaft..The SETA Rods and Wrispins were never dissassembled Brand new Goetze rings and Glyco bearings, None of the Rod or main bearings show any wear what so ever.

[vWBIRDWv]

Crickets '_' chirping ... bunp?

[ADEN]

Did you check piston ring groove gaps?

[vWBIRDWv]

ADEN I did not, you are referring to the tolerences in the piston ring grooves correct , for just the compression ring or all three ring glands? I did not clock my ring gaps properly as well, i know for a fact.

[ADEN]

If you are using oem piston and oem rings, Ring ends gaps are ok. My concern is piston grooves if they are too much out of clearance they do this.

[ForcedFirebird]

Cylinder walls are polished. Rings need the cross-hatching to seal. We have a car in the shop right now for the same thing. Wipe the bores out, and note any cross-hatching left.


Were the walls de-glazed before the new rings were put in?

[vWBIRDWv]

Thanks ForcedFirebird , Yea the Machinist said "You hit it with a ball hone good enough" Apparently not... so is that the cause. Thats what i have came to the conclusion as well..I honed the cylinders pretty good. let me see if i have a picture.. keep in mind this is the first engine i have ever built. i NEED to learn why this failed so i do not repeat this mistake in the future ..I can see cross hatchings still at the bottom of the cylinder ,but as you mentioned there polished smooth...weird thing is the car never smoked or burned any oil?

[vWBIRDWv]

[digger]

top land and cylinder walls look partly eroded /sand blasted almost. Cross hatching looks a bit too shallow an angle

[ForcedFirebird]

Yup. Digger is spot on. Hatches need to be more vertical, 60° is preferred. The dingleberry hone was to high of speed and not enough oscillations.

[digger]

Did the engine get really hot ?

[vWBIRDWv]

Oh yea it did,3 times pretty badly where it was boiling over.I can not describe the abuse this motor endured.I got about 35k miles of Hard abuse out of it before it lost compression,and I mean Abuse.. The radiator hose blew off one time and I was on a one way mountain road with no turnouts for 4 or 5 miles..But that was WAY after I found low compression in 3 cylinders it was, starting from the cylinder closest to the fire wall 145-140-110-129-136-145
I was experiencing extreme cabin vibrations that lead me to believe I had destroyed my clutch basket again.I replaced my Clutch,Flywheel,and Bought a brand new driveshaft before my father convinced me to do the compression test rofl

I ended up driving it for 8 months with low compression before it started getting hot ... it slowly got worse and worse getting hotter and hotter each day until the Radiator hose blew off going over the pass,im assuming my clamp was on too tight as it broke off with a piece inside the hose..I was able to put the hose back on with about a quarter inch of radiator left to put the hose on,It lasted 7 months after the radiator hose blew off.... that is when things got really bad, I had to add water every day it was my only transportation..it would get harder and harder to start each morning until it just wouldn't start, ..I ended up purchasing a vehicle to get me to work and back...


This car has changed my life in ways unimaginable .It has taught me everything I know about life from how to take care of myself and who I am as a person..I promised car I would do anything in the world for it after all the work it has done for me..

ANYTHING

[digger]

yeah so improper hone (its like the rings are sliding on a corrugated surface because the cross hatch angle is so shallow) wore the rings and gave lowish compression (without there being any with zero) and overheating toasted the slugs expanded too much and on verge of seizing probably. you're almost certainly gonna need to rigid hone it (not a dangle berry hone) and oversize slugs by the time enough material is removed to get it round, straight etc. You need new slugs anyway but will be some machining costs.

[vWBIRDWv]

Dont worry digger , I cut the bullshit last year after seeing ForcedFirebird Post some High compression slugs on his Instagram and sent him funds. told him to go nuts :) Ive been inspired by his work ever since I fell in love with these cars.

2.8l m20 with m52b28 crank 10:4cr +1mm Supertech valves O-ring block
Aiming for 200HP NA with the stock TB and wasted spark hopefully 220+ with RHD ITB's

A man can dream cant he?!! hahahaha