Hardness of engine blocks. Ring seating?

[Loren L.]

Re: Hardness of engine blocks. Ring seating?

If moly rings were used and properly honed, get yourself to another machine shop because there is a problem elsewhere. Do NOT bother with the hardened seats because in a certain percentage of cases, the machine shop will call and say we broke through the seat and the head is now junk. You're doing this on a 50 year old FI block and you wanted to save $$ by just knurling the guides - bad choice. If the heads have to come off, do the guides.

[Al R.]

Re: Hardness of engine blocks. Ring seating?

Loren, the heads are already off so the new guides shouldn't be a problem. It wasn't a matter of trying to save money, that's not a factor. The shop that originally rebuilt it back in the 90s apparently thought it was a better idea to knurl them or didn't want to be responsible for damaging the heads--I'm not sure which as I didn't question his judgement at the time. This was a shop that had been around since the days of pouring babbit for model Ts and tractor bearings. The owner has since died and the shop is no longer in business. I will instruct the shop to install new guides and not do the hardened seats

[Joe L.]

Re: Hardness of engine blocks. Ring seating?

Thanks Joe, I'll go by the shop Wed. on my way back in from Tn. and look them over. Any suggestions on the best way to seal if this is the case? Would this be a case of the heads being milled too much to allow a proper seal to either of the 2 intakes I used?

Al-----


It does not take too much head milling to throw of the geometry.

How to solve it if this is the problem? I have no answer. I once tried to solve this problem on a 350 cid engine and after an absolutely absurd number of attempts using every strategy imaginable NEVER did solve it. It's one of those few problems that "beat me to submission".

I can tell you this, though: if you find heavy, oily encrustation on the back of the inlet valves, then you know the problem is not the rings and you can forget about working at the problem from that end.

[Wayne W.]

Re: Hardness of engine blocks. Ring seating?

I solved the problem with plain cast iron rings. Nothing else would solve it. It had four sets of rings from birth to 60K miles, and is still standard bore.

The block had multiple hardness test marks on the oil pan surface. The factory certainly knew the thing was hard. Why else were they testing it?

[Duke W.]

Re: Hardness of engine blocks. Ring seating?

Loren, the heads are already off so the new guides shouldn't be a problem. It wasn't a matter of trying to save money, that's not a factor. The shop that originally rebuilt it back in the 90s apparently thought it was a better idea to knurl them or didn't want to be responsible for damaging the heads--I'm not sure which as I didn't question his judgement at the time. This was a shop that had been around since the days of pouring babbit for model Ts and tractor bearings. The owner has since died and the shop is no longer in business. I will instruct the shop to install new guides and not do the hardened seats

Knurling is short-lived and usually done as a cheap way to fix an oil burner before you uload it, so they usually become oil burners again after a few thousand miles.

There are a number of decent valve guide rebuilding processes using either cast iron or various bronze processes. Some may require specific stem plating material and specific seal technologies, so ask the shop what process he uses and do some research to make sure he's using an acceptable process and doing it by the book.

Cast iron inserts are relatively foolproof because you can use the OE valves and sealing system without concern for compatiblilty issues.

Duke

[Domenic T.]

Re: Hardness of engine blocks. Ring seating?

Al,
I have seen many shops install the O-ring seals wrong.

They put the O-ring on before compressing the valve spring instead of after the spring is compressed.

This causes the umbrella to leak oil down the valve stem and get sucked down the valve stem and into the cylinder.

The correct way is to compress the valve sprind assembeled, then put the O-ring on the valve stem, then the 2 keepers, then release the valve compressor. This keeps the retainer from pushing the O-ring out of it's groove allowing oil to run down the valve stem.

It's a common mistake on a chevy head as most other heads use a different type seal that go's on first and is attached to the valve guide.

DOM

[Al R.]

Re: Hardness of engine blocks. Ring seating?

Thanks Dom, I'll ask the shop owner how he does it and mention it if it is different from what you said. It does make sense. BTW He will be installing all new valve stem guides. They had been knurled as previously stated. Also the shop owner show me where the previous owner had used the wrong honing pattern for the moly rings that were installed, least ways he thought they were wrong in his opinion. Joe Lucia, I checked the back side of the valves. They had some residue but no ways the amount that was on the combustion side