My rebuild - It's amazing how well it ran

My two pistons with oil-fouled plugs - it's amazing how well the car ran like this. Makes one really appreciate how robust the Healey engine is:



Some of the rings were in 1/2" chunks. The bores were fine - no ridge and no vertical scoring.
Am installing .060" overbore Venolia forged pistons with a DWR8 278 degree cam.

PS - Venolia in Long Beach turned the order around in 2 days!

That's down right ugly.

The Healey's like a B-17 - returns home with half the tail shot away on 2 engines.

Did you have a ticking sound, valves hitting broken piston rings on top of the pistons?

Should run much better after the rebuild. Really surprised there was no cylinder wall scoring, looks like you lost a big chunk off the crown. Good luck with the rebuild.

Slight smoking on startup or going downhill, smooth general running; no particular odd sounds.

Which two pistons are they? 6? & ?

Danny

That's scary. To think that one could buy a Healey thinking that it ran well, when it really needed a rebuild that badly.

Dandare said:

Which two pistons are they? 6? & ?

Danny

Click to expand...

2 & 3

blueskies said:

That's scary. To think that one could buy a Healey thinking that it ran well, when it really needed a rebuild that badly.

Click to expand...

My mechanic, Russ Thompson, says pistons in a shape like mine are common in LBCs, especially MGs.
I bought the car in 1999 so who knows if the pistons were like that then?

Wonder what caused one to melt around the periphery--heavy detonation? Maybe a DPO tried to get away with running low-octane gas?

Bob_Spidell said:

Wonder what caused one to melt around the periphery--heavy detonation? Maybe a DPO tried to get away with running low-octane gas?

Click to expand...

Healeys were originally designed for regular gas.

John Turney said:

Healeys were originally designed for regular gas.

Click to expand...

What was the octane rating of 'regular' gas in 1967? Not being snarky; I suspect it was higher than contemporary 87-octane 'regular,' but it's hard to find data and the older fuel was likely reported in Research Method only, not (R+M)/2. I've seen regular gas rated at 85-octane in the Plains States; I wouldn't put it in a Healey unless my life depended on it.

Hi Steve,

Although I am very happy to hear how well your engine rebuild turned out, what were the signs that convinced you to do the rebuild?

Ray(64BJ8P1)

RAC68 said:

Hi Steve,

Although I am very happy to hear how well your engine rebuild turned out, what were the signs that convinced you to do the rebuild?

Ray(64BJ8P1)

Click to expand...

Ray - it hasn't turned out yet. The engine has been dismantled and hasn't yet gone to the machine shop.

It smoked a bit and the bad cylinders had 120 psi when I checked last summer. I had done a dyno run a couple of years ago at 93 bhp - which was the same as a friend's stock 29D having been rebuilt in the '90s.

Before I traded up I had a Frogeye. I rebuilt the engine on that after going through eight pints of oil on a 150 mile motorway blast (the clue was the oil pressure going to nothing as I pulled off the motorway and slowed down - dipstick wasn't long enough to reach the oil). Anyway I filled her up (with oil) and drove another 500 miles or so before the rebuild - after all it was only smoking a little and running quite smoothly! When I rebuilt the engine only two piston rings across the four cylinders remained completely intact.

Hi Steve,

Although I am not incline to rebuild my engine, having owned and driven my Healey for so long, I always wonder what triggers enough concern to rip into an engine rebuild. I think it was in 2015 when you brought a discussed on blackened plugs and corresponding compression readings and that stimulated me to evaluate my plugs and do the compression test. The funny thing was that, although most of my plugs looked reasonably good (darker brown due to running rich), cylinders 2 and 3 appeared blacker. Following your lead, I then did a Compression Test and, although all cylinders appeared good, readings from Cylinders 2 and 3 were showing lower readings.

Keep in mind I had shaved the head in around 1969 or so by 0.060 (a mistake as I had intended to have it shaved 0.006) as part of replacing a blown head gasket which is still in place. Additionally, although I run a little rich on purpose, after a carburetor adjustment my Cylinder 2 and 3 plugs cleared to a dark brown.

2015 Compression Test

Cylinder 1 2 3 4 5 6
Dry 170 162 165 171 171 172
Wet 210 200 210 183 183 183

As you will note, reading are within 10% of a selected Base reading. However, Cylinders 1,2,3 jump substantially to a high pressure where Cylinders 4,5,6 move moderately higher. I am not sure what this means or if any concerning signs are even present per the test, but, I have been driving my Healey without issue since although not as frequently as when it an I were younger.

Ray(64BJ8P1)

Ray,
IIRC my plug posting was summer of 2015 after I'd fouled the #4 plug.

Steve,

I couldn't remember when it was an mixed 2 different issues. I stand corrected.
Ray(64BJ8)

My first Healey got 25 miles to the quart when I bought it. The pistons looked like that when I pulled them out, but the bores were fine.

I assume the iron block can withstand much more abuse than the aluminum pistons.