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]

Originally Posted by Kevin

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]

Originally Posted by Schrade

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]

Originally Posted by 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

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.