214jay

Hello. I am new to the inner workings of the SBC but have the heads off to check/replace the head gaskets.

I know I need to setup the valve lashing but should I be looking to replace the valve seals? I would rather not if it is not needed but someone more familiar with these engines has told me to do it!

Thanks

Jay

UNCLE TOM

iTrader: (1)

an ounce of prevention can be worth MANY , MANY pounds of cure . they are cheap , easy to do , why not ??? a good cleaning of heads and new seals just makes good sense . my personal choice would be new stem seals and new umbrella seals on ALL valves . do it once , do it well , do it right . you will be happy . good luck ..............

TTOP350

iTrader: (8)

^^^^^^^^^^^^^ Good advice.

214jay

Great thanks for the advice, its the first time I will have removed the valves (on any car) but fairly sire I know the process. Only question is I can only find the Stem Seals listed on RockAuto and there seems to be a massive choice, where do I start with knowing which ones suit the vehicle?

rusty vango

you want the kind that fit down over the guide,rather than the ones that merely ride up and down on the valve stem.

214jay

Right, okay thanks. Will do more research as theres loads of different sizes for my car.

tyeo098

What exactly caused you to take the heads off now?
Compression check give you leaky adjacent cylinders?

BASSETT IROC 85

iTrader: (2)

I have seen several 1989 and 1990 chevrolet 350 blow the head gaskets. I always have the heads resurfaced and rebuilt. The last one I did has lasted over 18 years so far.

214jay

Bit of a long story but suspected engine had sucked in a rag so bit of a checkup required! All looks okay, have checked heads and they are not warped or cracked so going to fit some good head gaskets and put them back.

Just not sure which seals are appropriate, I will pull one of the valves and have a look.

torque_is_good

the economy is still stinky so you could probably find a machine shop who would do a valve job on the cheap incl parts, testing springs, checking head, cleaning and if it's not been done, new guides as well.

But, if your wallet is real thin, at least lap the valves and put in new seals

214jay

Would prefer to do myself as I'll learn for the future that way. Based in the UK and not many machine shops I trust around here!

formula_novice

iTrader: (1)

If the heads are off, I would do as much as possible while you have the opportunity. If you want to upgrade springs, valve job, etc.

Once those heads go back on, you don't want to say "I wish I would've ______ when I had those heads off".

Just my 2 cents.

Hope this helps!

tyeo098

^this because once you torque those heads on the gaskets become useless for reuse!

For what its worth I plan on doing the same on my LO5, gonna remove the heads, port 'em upgrade all the moving bits and put new valve seals on (leaking oil somewhere)
Gonna put new headgaskets on as well and see what kind of condition my holes 'n' rods are in.

torque_is_good

kudos for wanting to do things yourself.

Since you yanked the heads, you now NEED new head gaskets and possibly bolts

You also need a new intake manifold gasket and since the distributor is out, give it a good once over.

Now come the options

if it's never been done, at this point, I would inspect the lifters (if roller) and replace if flat tappet. Next is checking the pushrods

OK, now to the heads themselves. Again, if it's aged, then new guides are in order. Are the valves re-usable? At a minimum, lap the valves but a machine shop can clean the heads, (probably cast) magnaflux checking for any cracks and mill them. A machine shop can also check the springs

How are the rockers? Maybe it's time for a poor mans upgrade and go for some 1.6 ratio (if you have 1.5) but your springs will again determine that


or, just check the cylinder ridge and make note as to how bad it is/isn't

slap on a new gasket, lap the valves, slap on some new seals and run it til it breaks

milhouse89

It's been awhile but maybe you can help me. I am interested in what head gaskets and intake manifold gaskets and also valve seals you used and how they worked out for you. Like you said with the valve seals there are a lot of choices. I've got the same engine as you but with Al. heads and I would like to get it right. Thanx for any help , I hope you get this soon.

214jay

Hi Milhouse

I didn't do the valve seals in the end as I ran out of time, I have had no problems at all though and to be honest wasn't that hard to take the heads off and put back on so its on a future list when I do more major engine work.

I used the following gaskets/parts to put the engine back together:

Upper Plenum FEL-PRO MS93160
Cylinder Head Bolts FEL-PRO ES72856
Cylinder Head Gasket FEL-PRO 7733PT2
Rocker Cover Gaskets (these are excellent, great reusable gasket) FEL-PRO VS50088R
Intake Manifold Gasket (think this was the one) MAHLE ORIGINAL/VICTOR REINZ MS15315W

All of the above were from RockAuto and I have had no problems with any of these products, even 2+ years later. Hope this helps in some way!

J