Smoking engine

[Adrian Payne]

Many thanks again for all your comments.
The pistons and rings were both from The Seven Workshop.
The new rings were black and look like cast iron.
If the rings were at fault would the oil and compression test not show more improvement?
I have a set of Tony's valves from Beaulieu and valve guides on their way. I guess this will once and for all determine if it is the bores or guides.
Many thanks.
Adrian.

[GK5268]

Many thanks again for all your comments.
The pistons and rings were both from The Seven Workshop.
The new rings were black and look like cast iron.
If the rings were at fault would the oil and compression test not show more improvement?
I have a set of Tony's valves from Beaulieu and valve guides on their way. I guess this will once and for all determine if it is the bores or guides.
Many thanks.
Adrian.

I had cause a few weeks ago to strip down my re-built engine (done last August) to replace a sheared off crankcase/block stud (don't ask...), took it all to bits and while I was at it (I needed a silver-lining) I fitted the flatter tappet blocks that I had been wanting to fit, so took the opportunity to do that at the same time.

I had been using a straight 30W, put it all back together with a new head gasket, changed the oil to 20/50 (Comma), the clouds of blue exhaust smoke has gone and the exhaust smells quite different, the sickly sweet smell has gone. I have not yet monitored actual oil consumption, but a big difference with what is coming out of the exhaust pipe!

My pistons & rings were supplied by Jamie too.

The replacement tappet blocks have made an improvement to the car's ability to climb hills, much more of a bark and in top gear cruising, the engine is quieter and the revs seem to be down, can really get the engine to idle really slowly, it seems to be much better!

Too soon to know what the fuel consumption is, but imho, it was well-worth it and my silver-lining to a problem that I didn't want!

[Chris KC]

Gary, just out of interest what radius were your cam followers ground to (old vs new)?

[GK5268]

Gary, just out of interest what radius were your cam followers ground to (old vs new)?

I got these off Tony Betts, I think the radius is as described in the William's Austin Seven Specials book, so, would be 3/4" (from standard of 3/8"), the tappet guides were cut down to suit, took about 20 minutes to remove, cut & re-fit each one!

[Chris KC]

Gary, just out of interest what radius were your cam followers ground to (old vs new)?

I got these off Tony Betts, I think the radius is as described in the William's Austin Seven Specials book, so, would be 3/4" (from standard of 3/8"), the tappet guides were cut down to suit, took about 20 minutes to remove, cut & re-fit each one!

I only ask because my 'received wisdom' is that standard cam follower radius generally gives better bottom-end torque. Though it's possible the general improvement in performance through flattening the radii offsets this?

[GK5268]

Gary, just out of interest what radius were your cam followers ground to (old vs new)?

I got these off Tony Betts, I think the radius is as described in the William's Austin Seven Specials book, so, would be 3/4" (from standard of 3/8"), the tappet guides were cut down to suit, took about 20 minutes to remove, cut & re-fit each one!

I only ask because my 'received wisdom' is that standard cam follower radius generally gives better bottom-end torque. Though it's possible the general improvement in performance through flattening the radii offsets this?

My experience on my engine is that it has made an improvement, hill climbing is much easier and the engine seems to rev much freer and it can be made to tick over very slowly. The flatter profile does not change the valve timing, the valves just open & close quicker, so they are open longer allowing a better charge of fuel and better evacuation, I am pleased with the result and has made my car much more enjoyable to drive up hills and in traffic.

[Ian Williams]

I agree, reducing the radius with a std cam makes a worthwhile difference in my experience

[Chris KC]

I agree, reducing the radius with a std cam makes a worthwhile difference in my experience

I think you mean increasing Ian...

Yes, no doubt that it improves performance generally. Specifically though I understood that torque at low rpm is the trade off. Might be wrong.

[fatcatvera]

Could anyone share some pictures of modified tappets vs standard tappets?

Thanks

[Andy Bennett]

   
This is good timing for me.
As part of my top end engine build I have obtained 3 sets of followers, all with different radii (ie each set slightly different).
Hopefully the below picture will show the detail.
The one on the right is I believe original as they came with some corrosion and are taller than the others.
The other 2 sets have a larger radii, with the first almost flat.

it sounds like I should go for the flatter profile (removing an equivalent amount from the guides). But which flatter profile, at what point is flat too flat for normal road use?