Leaking Valve Covers on 305 Motor

[paklein]

HELP!

I have a 78' C-10 work truck that I did a motor swap in awhile back and have perpetually leaking valve covers.

The original 305 motor dropped a valve and I got a long block 305 from NAPA and did the swap. Used the valve covers from the original motor, and they leaked. Tried replcing with a couple of different gasket sets with no luck. Went as far as replacing valve covers, but still no luck in stopping the leaks.

I was told by somebody that this is a common problem due to the fact that these valve covers only use 4 bolts to hold them down.

What can I do to solve this problem? Kind of embarrassing pulling up to customers' houses and have smoke pouring out from under the hood......

Any help would be appreciated

Paul

[Lt.Del]

dang, if it is that bad as to have smoke rolling out, you must have warped valve covers.

Get yet another set.  Put two sets of valve cover gaskets on her at one time.  Doubling the gaskets will improve seal--especially if they are warped.

A couple of hundred miles after installing them, ensure you retighten the cover bolts once more. Don't overtighten though, they will snap. YOu can get some of those chrome type of brackets that tighten down under the valve cover bolts....they are like two inches long and presses down on the valve cover in two places after you tighten each bolt down.

SgtDel
aka "Andy"

www.delbridge.net

1979 Big 10 383 stroker
1991 Blu 'Burb 3/4 ton 4x4

[autonuerotic]

>>>>>What you can do is go to Autozone and buy a set of thick valve cover gaskets, they are about 1/4" thick and made by Mr. Gasket and dont forget some black high temp silicone. Pull your valve covers off, cover your heads with some rags and close your hood.  Scrape all the silicone off with a gasket scraper and clean the remaining residue off with some brake cleaner or gasoline.  Next find some weights and a scrap piece ply wood big and wide enough to cover both valve covers (length isnt as important as width.) You can also use some heavy spare books.  
>>>>>Smear some silicone on the face of the gasket, dont just gob it, do it liberally and place it on one of the valve covers (do the same for the other side.) Let the silicone set up for about 2-3 mins, next find somewhere flat and out of the way like a workbench.  Set the valve covers onto the flat (clean) surface gasket side down, while making sure that the gaskets are not disturbed and the holes still line up. If the gasket moved a little use one of the bolts or t-bolts to line back up the holes.  Place the plywood over the tops of the valve covers and set the wieghts on top, or books and let it dry over night, then install them when you have time.  There is no need to put silicone on bottom of the gasket when you install the valve covers (some people do that.)
>>>>>I had a similar problem years ago and did what I have just described, its been two engines and seven years and I still have the same valve cover gaskets with no leaks. A heads up...Some people put too much silicone on something and dont let it set up a little, so when they install it especially valve covers the silicone will act like a lubricant and the gasket may slide out of place. If you are using bolts or studs, just snug them you do not have to crank on them.  Double gaskets is not a bad option either, but be careful that may cause a leak too. Hope that helps and good luck!

[Blazin]

I would ckeck the covers to see if they are warped. Find a garanteed flat surface after cleaning all gasket material off set them on it and see if they touch all the way around. If not I would'nt waste my time, get some new ones. If they are good spend the extra $ and get rubber gaskets ( not cork ) like the thick ones previously mentioned. You should only have to use oil to get them to seal good. General rule of thumb is use what ever you are trying to seal as a gasket sealer. Oil for oil, Water for water, etc.  

Edited by: Blazin at: 6/30/06 9:45 pm

[VileZambonie]

You can get a cheap set of valve covers with load spreaders and gaskets at autozone for $40 bucks. Done deal. By the way RTV shouldn't be used with the gasket.

[paklein]

Thanks guys, gives me a place to start.

Paul

[1976Scottsdale]

The spreaders that you want are the ones that are about 3-4" long.  They will work perfectly for you.  Also, if you are not planning to either double the gasket or use a thick one, buy a set of felpro valve cover gaskets that are rubber.  They cost about $10.00 and work wonderfully, however, they will slide if over-tightened.