Don Terrill’s Speed-Talk

steve316 wrote:Order a napier second ring & install. time well spent.

Just through it in or is this after a rehone ?

n2xlr8n wrote:As I mentioned in your other post: Vacuum pump.

Before I pulled it down, I'd see if a cheap corvette pump helped your oil control situation.

You're thinking about a windage problem or blowby problem ?

joe 90 wrote:You probably bore washed it through having a real shitty tune.

I would assume in that case the top ring would get damaged as well and my compression test would have shown lower values than those that i got when doing the test after the engine was fire when new. This is not the case however.

Belgian1979 wrote:

n2xlr8n wrote:As I mentioned in your other post: Vacuum pump.

Before I pulled it down, I'd see if a cheap corvette pump helped your oil control situation.

You're thinking about a windage problem or blowby problem ?

I'm not saying a pump that pulls ~7-9 hg will solve windage issues, but I do know from experience it will help ring seal, and in some cases, oil control.

Whether that is from flutter or whatever, I'll leave to the engineers here.

In any case, I use vacuum pumps on every engine I build for my cars.

steve316 wrote:Order a napier second ring & install. time well spent.

that is what GM did on the LS corvette engines that used oil

Don't recall whether in your previous posts about this problem you identified what exact pistons and dimensions you were using, the ring dimensions and tensions, especially on the oil ring set. Compression is pretty much all handled with the top ring and its seal, however you can have issues with the the second ring oil scraping action and the oil control ring and its tensions and you will still have good compression , but you will be using oil in spite of good compression. What were the piston to bore clearances used and what was the exact honing process, ie: stone types and numbers and whether the bore was plateau honed after regular honing.What oil was used for break in and were any additives used during break in?

What type of valve stem seals are you using? You mentioned that there is "a little wiggle" evident at the valves and thus may be your problem. Even with positive type seals, excessive valve stem clearance may be the cause of oil consumption.
If you do install Napier second rings, it is highly recommended that you hone the block and replace all of the rings at the same time. A set of rings is relatively inexpensive.

I'm probably going to take off the heads in winter and turn them in to have the guides and seats redone.
Meanwhile I'm still trying to assess if I do not have a pcv-oil catch can issue. Currently I have a Mishimoto catch can, but it is nothing more than a can with 2 tubes. A Moroso can with baffles is on the way.

As for the oil issue, it doesn't seem to be smoking on accel/WOT. It does smoke on decel at times, although it was less when I did the seal change.
Seals are the Dart seals for .530 stems.

I don't know what grid was used for honing. Shop does nothing else than V8's and have a good rep, so I at least assume(!) they know what they are doing. I used synthetic oil on startup, break in and running 5W30 weight. I know there is a lot of debate but since I use roller lifters, I don't think it matters. After all, new engines from the factory come with synthetics in them as well.

Pistons are Racetecs with metric rings. Don't know tension, but they were regular types and no low tension rings. I should check for piston clearance in my notes but 0.004" comes to mind.

engineguyBill wrote:What type of valve stem seals are you using? You mentioned that there is "a little wiggle" evident at the valves and thus may be your problem. Even with positive type seals, excessive valve stem clearance may be the cause of oil consumption.
If you do install Napier second rings, it is highly recommended that you hone the block and replace all of the rings at the same time. A set of rings is relatively inexpensive.

It's not the cost of the rings I'm worried about, its taking the engine apart for this job to complete and to have it correctly honed.

If this engine is a concern from a standpoint of using oil and not so much from a puff of smoke on decel, how much oil is it actually using in terms of use , miles, hours ,per race, etc.?

Newold1 wrote: ↑Fri Sep 29, 2017 7:14 am If this engine is a concern from a standpoint of using oil and not so much from a puff of smoke on decel, how much oil is it actually using in terms of use , miles, hours ,per race, etc.?

Well I saw my oil level go down 1/4 between high and low on a 100 km drive.

FWIW during these runs I didn't see a puff of smoke on decel anymore. I don't see smoke on accel either. I did reconnect my pcv again. I ordered a Moroso catch can as its design is a lot better than what I have right now.

How much pressure is in the Accusump when you check the level? Some hold up to three quarts. Any difference in pressure will SIGNIFICANTLY change the level in the pan ... which could easily be the difference in oil level after your 100 km trip.

4sfed wrote: ↑Sat Sep 30, 2017 4:37 pm How much pressure is in the Accusump when you check the level? Some hold up to three quarts. Any difference in pressure will SIGNIFICANTLY change the level in the pan ... which could easily be the difference in oil level after your 100 km trip.

I agree the accusump makes it extremely difficult to assess. It usually sits around 60 psi. This is the 3 quart unit.

You could just temporarily shut off the Accusump while running your consumption test.

MadBill wrote: ↑Sat Sep 30, 2017 9:37 pm You could just temporarily shut off the Accusump while running your consumption test.

Well, the valve still allows oil flow in the direction to the accusump, but just not towards the engine. Of course, full is full.