theoUK

Can anyone out there with a decent shop manual (ie not the Haynes book of lies) give me a proper torque figure for the oil pan bolts? Perhaps I'm being too harsh on the good ol' Haynes manual, but it always seems to miss out on the most basic points...... In mine, the torque is listed as something around 160 inch-pounds (if my memory serves), for all 18 bolts..... are the corner bolts not supposed to be tighter?
It's a late 1980 L48, with seven small bolts down each side of the pan (3/8 head size, i think) and four bigger corner bolts, which I reckon are 1/2 inch.
However, those bolt sizes are only from my poor memory...
:cheers:

KenSny

8 lb/ft on the rail bolts and 18 lb/ft on the corners according to the FEL-PRO one piece gasket instructions.

80 lb/in on the rail bolts and 265 lb/in on the corners according to the GM service manual.

I'd say they don't agree. since 8 lb/ft = 96 lb/in and 18 lb/ft = 216 lb/in.

Rail bolts are 1/4-20 and the corners are 5/16-18



[Modified by KenSny, 10:06 AM 9/16/2003]

theoUK

Cool, cheers.
Those two sets of torques are not a million miles from each other, though. The difference is probably due to the different gasket materials - is the felpro one-piece reinforced somehow? Perhaps that's why it takes a tighter torque on the rail bolts.
One more daft question - what do 20 and 18 refer to in the bolt sizes 1/4 -20 and 5/16 -18?? I know the first figure is the thread diameter naturally, are the second numbers threads per inch or something?
(Brought up on the metric system, being British :D )
:cheers:

KenSny

Yep, threads per inch.

The fel-pro has a metal insert at each hole in the gasket so that is probably the reasoning. You're right about them being real close, I just thought I'd put it out there. Had the info on hand since I just did that project 2 weeks ago.

theoUK

Thats great, thanks Ken.
This is where i have to admit to my stupidity... I'd seen torque figs before, and thought the 18 and 20 were referring to the number of bolts used! :rolleyes:

...as if there had been a design change at some point, from 1/4 to 5/16. I guess that's almost excusable, given that there are indeed 18 bolts overall. Doh! Yes, yes, I did realise that they aren't even all the same size, but it's amazing how bloody dim you can be when you set your mind to it!
Still not to worry, I torqued all the bolts up to around 10 ft.lbs, and a little more on the corners. Those rail bolts are a little tight then, but I don't think it will be the end of the world. I'll nip the corner ones up tighter at the next opportunity...
I've not had any leaks yet, (so i haven't warped the pan flange then!) and i clocked up 1500 miles in the last 3 weeks since i did it (standard type of gaskets/rubbers) so hopefully thats a job to forget about.

Thanks again for the info.. How do you rate the one piece? Some people say they still leak.... Some form of leak seems inevitable on these old chevs....
:cheers:

KenSny

I think the one-piece is fine, about twice as expensive, but easier to install and you can reuse it if you have to drop the pan again. I put one on my neighbor's Camaro in the early Spring time and there's no leaks yet. I did use a dab of RTV at the four corners though. If you look at the block you can see where it would be hard for the gasket to fill the void where the rail area starts to roll up to the back and front curves. I think most people don't realize that you need to have a good rear main seal AND a good timing chain cover seal otherwise it looks like the pan gasket is leaking again. Of course changing the timing chain cover is not a easy as the oil pan. I have not run the Corvette yet after the new gasket as I got bitten by an electrical problem (see my thread on Fusible Links).

BTW: what - no conversion to Newton/Meters? just kidding.....

theoUK

Yeah, I did the timing cover and rear main at the same time. Swine of a job, when you only have axle stands, no workspace in the garage and only a few hours each weekday. I had to push it in and out of my garage and work for a few hours at a time on the drive. You're right, its a lot of work to do the timing cover, pulling that bloody balancer off and heaving it back on again - made my own tools to do it. Hopefully, this is going to be an example of how you CAN get the old style sump gasket to seal right - and the balancer shaft seal.... lots of people seem to say they leak again even with a new lip seal. This is probably tempting fate, but i reckon it's 90% preparation - good clean smooth mating surfaces and all that jazz. It's been dry so far. I'm going to go home to find 5 qts of oil on the garage floor now:D

Strangely, I don't really have a good concept of Newtonmeters (I can convert of course, if i must - I'm an engineer after all!) But in the UK, we tend to go by HP and lb.ft for power and torque. But automotive bolts and so on have been metric over here for years, definitely back as far as the era of my 1980 vette. :cheers: