Valve Guide Seals

[Scrrem]

The early motors (1990) did not have valve seals on the exhaust valves, correct? Those who have rebuilt early motors.....should you add exhaust valve seals to the rebuild as long you have the heads apart anyway for porting? Is there anything special that has to be done to the guide or valve seat to accomplish this?
Thanks
Rich

[edram454]

I believe all 1990 LT5's did not have exhaust valve seals. I have a 1990 #3028 and have no exhaust valve seals. If you do a rebuild you should have them installed if you want that initial smoke to go away forever.

[Schrade]

I noticed a clear Blue startup puff first time the other day here - that cause mine's W/O exhaust seals???

32K on mine..................................

[Kevin]

never noticed any smoke on my 90

[Schrade]

never noticed any smoke on my 90

How many miles behind the car there Kevin?

I had my front end up on jackstands 16"; thought that might have had something to do with it there...

[Kevin]

How many miles behind the car there Kevin?

I had my front end up on jackstands 16"; thought that might have had something to do with it there...

64,000 (i think) it's around there.

[edram454]

a little smoke only on start up. Most 1990's seem to have this issue. Lotus did not use exhaust valve seals in there engines at the time so since they engineered this engine it wasnt even an issue. It wasnt until some customers complained that the seals were installed in all 1991 and up zr1's.

[edram454]

mine has 45k miles. fyi..

[Scrrem]

Mine has over 80K and it puff's a little blue on startup, but goes away. From what I am able to find out from Jerry, the exhaust valve guides were not machined down to accept the steals like the intakes, so you would have to take a new guide, machine it down and install it and re-grid the valve seat to ensure it's concentric to the guide. May not be worth the trouble.
Rich

[Paul Workman]

Mine has over 80K and it puff's a little blue on startup, but goes away. From what I am able to find out from Jerry, the exhaust valve guides were not machined down to accept the steals like the intakes, so you would have to take a new guide, machine it down and install it and re-grid the valve seat to ensure it's concentric to the guide. May not be worth the trouble.
Rich

Nothing that extensive is needed, actually, so long as one is only just going to machine the valve guides to accept the seals. However, some might take the opportunity to "freshen up" the heads by doing a more comprehensive overhaul, e.g., guides, valve job, etc "while you're in there anyway". But, just to prep the guides for seals, is no biggie. And, I agree to your point about the expense vs. practical trade-off. Lotus designed the motor w/o the seals with the idea of providing a bit of lubrication to the exhaust valve stem, so it won't hurt anything. So unless that little blue puff drives one to distraction, I wouldn't bear the expense to have the seals installed unless the heads were off for other work, and then "oh, by the way" do the seals then too.

Marc Haibeck prepped my 90 exhaust valve guides to accept the seals when I was doing the rest of the head work, for a very nominal price, as I recall.

I got my seals from Jerry. However, oil from the PVC can drain down the intake runners, resulting in the same puff of blue on start-up. So, although there is little to no blue smoke on start-up after normal driving especially, it will probably require the PVC oil catch can I'm installing to address that source of blue smoke as well.

[Scrrem]

Nothing that extensive is needed, if one is only just going to machine the valve stems to accept the seals. However, some might take the opportunity to "freshen up" the heads by doing a valve job, etc "while you're in there anyway". But, is another matter.

Marc Haibeck prepped my 90 exhaust valves to accept the seals when I was doing the rest of the head work, for a very nominal price, as I recall.

I got my seals from Jerry. No more blue smoke on start-up, unless it has been sitting for some weeks. (I'm thinking some PVC oil could drain down from the plenum. An oil catch can is "in the works" for my car this winter which should address at least some of that too.

Yeah, I'm having the heads ported anyway, so it would be the time to address it, have to see what the cost would be. Yeah, I put a catch can on mine last year, really keeps a good majority of the oil from reaching the plenum.

[Paul Workman]

Yeah, I'm having the heads ported anyway, so it would be the time to address it, have to see what the cost would be. Yeah, I put a catch can on mine last year, really keeps a good majority of the oil from reaching the plenum.

Correction: I meant to say the valve GUIDES are what require machining to accept the seals. Fixed on my post (above). My bad.

[A26B]

If your guides are not worn, then they can be removed, machined for the seal and re-installed. Because it is the same guide in the same hole doesn't necessarily mean it will be concentric with the valve seat. The valve seat may need re-cut to align properly with the valve. Not a big deal. Not unusual for the guide i.d. & o.d. to not be perfectly concentric.

As an aside, all of the new valve guides I have are configured to accept seals. New guides must have the bores reamed to fit the valves. Not a thing wrong with machining/re-using the original guides if not worn.

[Don in VT]

My 90 with 52K does not smoke at all at start up.

[Paul Workman]

If your guides are not worn, then they can be removed, machined for the seal and re-installed. Because it is the same guide in the same hole doesn't necessarily mean it will be concentric with the valve seat. The valve seat may need re-cut to align properly with the valve. Not a big deal. Not unusual for the guide i.d. & o.d. to not be perfectly concentric.

As an aside, all of the new valve guides I have are configured to accept seals. New guides must have the bores reamed to fit the valves. Not a thing wrong with machining/re-using the original guides if not worn.

Maybe Marc will chime in here, but I seem to remember him saying he has a jig that will make the necessary groove w/o removing the guide...least that is what I think I recall (but I've slept since then, and it was almost 4 years ago).:o Hopefully his ears will be burning and prompt him to pop in here and clarify that this item for us.