Vertical and Hoeizontal Timing Gears

[Harry]

I decided to start a new thread on this since my prior was getting a bit lengthy.

I want to remove the VTG a d the HTG.  I don’t find something on the forum that goes into detail on how to do this.  The mounting that the distributor fits into looks like it is attached to the block with6socket head cap screws.  I’ve loosens those but the alumni housing seems to still be secure to the block.

I expect this is because the large bolt in the center of this housing is still attached to the HTG?  Can someone say how to remove the VTG and the HTG?

Thanks s always,
Harry

[ja17]

The HTG must be removed through the IP opening in the block, so the IP must be removed also. The VTG  (vertical timing gear) must be removed before the HTG (horizontal timing gear) can be removed.  The front aluminum distributor housing can be removed after the six attachment bolts and the distributor timing gear are removed.  After the distributor housing is removed, you will see a 19mm nut holding a cluster of washers, spacers, a gear and a sprocket on the shaft of the HTG. Pay close attention to and document the sequence of all the parts. Also realize the outward side of the chain sprocket has a different off-set than the inside so it must be installed with the correct side out.  You will need to strip this cluster of parts off the HTG before it can be pushed out the IP opening. Be sure to remove the outer most of two small woodruff keys on the HTG shaft as you remove the parts. Once the cluster of parts are removed from the HTG, the HTG can be driven out through the IP opening.  At this point the chain sprocket will become free and the  second small woodruff key will emerge with the HTG. You will find a 10mm head bolt and special washer holding the bronze HTG bushing in the opening in the front of the block. Check the bushing for excessive wear.

[Harry]

Thanks very much Joe.

So the large bolt in the center of the distributor housing is not necessary to remove?

I'm going to mic the cylinder bores this evening but I expect that this will confirm they are pretty worn.  The car was running fine but the compression was low on some cylinders and it was using a bit of oil.  Squirting oil into the cylinders didn't affect the compression so I decided to pull the head and inspect it, likely having it rebuilt.  That led to just going ahead and pulling the engine (since I also wanted to really freshen up the engine compartment).  I thought that while I had gone this far, I should check to see if I needed to have it bored oversize - which requires oversize pistons/rings.  As you know, this begins to run into some expense, even with me doing the disassembly/reassembly.  There's no end! 

We'll see what the cylinders look like this evening and I'll likely be back on the Forum with even more questions.  I do appreciate people like yourself for your time and interest to answer my questions.

Harry

[ja17]

With most engines (not all) having less than 160,000 miles, a complete head reconditioning solves most of the compression and oil usage issues. Yes the large fitting on the distributor housing does not have to be removed, in order to remove the housing. Alignment pins hold it snuggly in place even with the bolts removed. Gently encourage it to come off!

[Harry]

So there are several local performance machine shops that do very good work in this area.  Is there anything that is particularly special about these heads that a shop would need to be aware of?

Thanks,
Harry

[Harry]

I measured the cylinder diameters this evening with a close friend who does top shelf machining and inspection (but not automotive).  Across all six cylinders we found taper from bottom to top of each cylinder (as you would expect) but the max taper was 0.0020 ins.  The worst oversize cylinder diameter was 0.0023 ins.  No remaining signs of cross hatch.

I was pleasantly surprised that the cylinders were in this good condition and now I am debating whether to leave them as-is or go oversize?

Thoughts?
Harry

[Rick Katucki]

I haven't looked up the tolerances but if it is in spec, leave it alone. Clean it up, hone, new rings and bearings.

[ja17]

I believe that the max. amount of cylinder wear is .005".   Next you will need to check the piston ring grooves for wear. Check the gap with a feeler gauge (ring in place). Photograph the oil ring on your piston if you can. I need to see how bad the rings are worn. As the oil ring wears the valley in the lower oil ring almost disappears.

[Harry]

Thanks everyone.

It'll be a day or two before I can get the remaining work done to take some of these measurements but I will post as soon as I do.

Harry

[ja17]

"With most engines, (not all), having less than 160,000 miles, a complete head reconditioning solves most of the compression and oil usage issues." However, be careful about putting brand new perfectly round piston rings in your worn oval cylinders or you will have an oil usage problem.

[Harry]

I hope to get back on this tonight.  I plan to pull the pan and remove the pistons from the bottom so that I don't have to drag the rings across the lip that forms in the upper cylinder. (Will no doubt take longer than this evening.)  Shouldn't be a problem - correct?

[ja17]

The pistons will not come out of the bottom. Spot check the first cylinder by just removing the small oil pan and push the assembly  out the top.
Scrape the carbon off the top rim first Grease the wear ridge if it has one, and push the rod and piston assembly out. Using a ridge reamer first helps if you have a bad wear ridge. If this is the case, you probably have excessive cylinder wear anyway.

[Harry]

Very good to know.  Thank you.

There is a clear ridge that you can hang your fingernail on.  But as I recall it appears that some of it might actually be deposit.  Maybe not.  I'll look closer this evening.

[Harry]

BTW -  is the reason you're saying they won't come out the bottom is because the crankshaft is in the way?  (I was going to remove it.)

[ja17]

The pistons will run into the main bearing castings of the block before they fully emerge from the cylinders. The crankshaft is not a factor.

[Harry]

OK - I see.  Thanks Joe!

[Harry]

So I was getting ready to do some ridge reaming and my pucker factor was growing exponentially.  Is it necessary to do this to remove the pistons?  There is a lip that you can feel but I don't know that it is enough to warrant taking a chance on damaging a cylinder?

[ja17]

Just scrape the carbon off at the top, with a utility knife blade, grease the ridge, then push the piston out. Ridge reaming is usually not needed unless the ridge is sever.

[450sl]

Harry ,
Seeing  this discussion , and since you have the engine already out , i would recommend you
to do a complete lower end incl oversize pistons.

I think you would regret later not having done that now.

Mark

[Harry]

Number 3 piston out.  (The ridge wasn't that bad - thanks.)  Not pretty (see photos) but probably unreasonable to have expected much more.

I'm headed out of town this morning but when I get back, I'll pull the others.  I'll check the ring grooves with a feeler and report back.  What should the gaps be, and what is acceptable?

(Joe - the oil ring is shown as well.)

Thanks,
Harry

[Shvegel]

Interesting to note that that is a 3 ring piston.  I thought factory was 4 rings with later replacement pistons having 3 rings?  Is there a size stamped on the crown of the piston?