12 replies to this topic

[kavesh]

Hi guys

 

I have a 308 motor which is from around 1969.

 

History on the motor was it was running well but was taking oil although not smoking at all. Previous owner removed motor to install a big Chev motor.

 

The 308 stood for about 5 years before I got it. Motor had to be freshened up, so I stripped and installed new rings, bearings. Engineer confirmed bore had less than 10thou wear so I decided to go the cheap route and just reringed the piston.

 

I installed new valve stem seals being the little O ring. And yes the O rings are installed correctly for the Holden motor. Sadly though its not sealing well as on cold start i get lots of smoke until its warm and then no smoke.

 

I am not ready to pull the heads to redo the valves so looking for a cheaper option. I have head of the umbrella seals from a ford that can be used. Question is which ford motor is that, Ford 302 or 351 or some other?

 

If anyone has some experience or knowledge in this area would appreciate it.

 

Thanks

 

[Dr Terry]

Leaking valve stem seals usually smoke a lot more on a hot start.

 

Your problem maybe elsewhere. Is your PCV set up properly ?

 

10 thou is a lot of bore wear.

 

Dr Terry

[caterham2]

10 thou IS about half the first rebore oversize. Sounds like the cheap job is going to cost more to rectify than doing it properly first time.

[kavesh]

Hang on guys, maybe my measurement terms may be wrong. The bore wear was so minimal which was confirmed by the engineer when it was measured.

 

My PCV is not connected to vacuum source. I have 2 breathers on the valve covers one on each side as well as the one on the timing cover riser.

[Redslur]

I am guessing the guides are worn. To fit decent valve stem seals you need to machine the heads to suit anyway. 

[kavesh]

I am guessing the guides are worn. To fit decent valve stem seals you need to machine the heads to suit anyway. 

I agree, however, I don't want to pull the heads just yet. I have heard of people using the Ford seals and was hoping to maybe try it out, Maybe I would get lucky. I do realize that it won't be a long term fix, but considering that I only cover about 3 000km a year I should be fine.

If only I know which seal fits nicely and works.

[76lxhatch]

Measured a couple of different sets of HQ heads and the guides have OD of around 0.575", so you'll want something that fits tightly around that, and hope you get lucky that everything is machined on centre. The secondary problems will be clearance, both in the OD of the seal to the damper spring (will be tight) and the height to allow full lift (if you have an aftermarket cam this could be tricky too).

[mick_in_oz]

Isn't he asking about the umbrella type seals used on Fords, maybe Windsors etc, are a neat fit on the valve stem and travel up and down with the valve but come down far enough to prevent splashing or oil onto the stem and then into the guide?

 

 

Personally, a worn guide would normally only give a puff of smoke at start up and be gone a few seconds later, and if very badly worn, again if the throttle is shut after the engine being at cruse or speed and the engine makes a sudden lot of vacuum and it pulls oil through the guide. They would have to be very tired to smoke all the time, or more likely its another problem.

Edited by mick_in_oz, 21 June 2019 - 07:02 PM.

[dron]

It sounds like something ealse may be the problem to me. Was there a ridge at the top of the bore when it was rebuilt ? If so was it removed or the top ring chamfered to clear the ridge? (old bush trick) Was the bore deglased well with a hone and then cleaned well ?. I have had heads with valve guides that worn that the valve started to not seat well and did not use a lot of oil or blow any somke other than when de accelorating.

 

 Just a side note, When you install a set of lifters that most have had a slot left unground internaley and they do not feed oil to the rockers you get about 60 000 out of the engine. The guides then have about 3 to 4 mm clearance, Rockers and posts are not good and the freshley reboared 60TH over 253 needs new block and pistons. It ran verry well up to that point with no noise or other problems. (bugger)

[kavesh]

Isn't he asking about the umbrella type seals used on Fords, maybe Windsors etc, are a neat fit on the valve stem and travel up and down with the valve but come down far enough to prevent splashing or oil onto the stem and then into the guide?

 

 

Personally, a worn guide would normally only give a puff of smoke at start up and be gone a few seconds later, and if very badly worn, again if the throttle is shut after the engine being at cruse or speed and the engine makes a sudden lot of vacuum and it pulls oil through the guide. They would have to be very tired to smoke all the time, or more likely its another problem.

 

I seal in picture is the type that I am referring to.

 

My smoking is only taking place when the motor is cold. Drive for 5 minutes and no smoke at all. So its only smoking when cold.

All my research has pointed to the valve guide seals being the culprit.

[kavesh]

It sounds like something ealse may be the problem to me. Was there a ridge at the top of the bore when it was rebuilt ? If so was it removed or the top ring chamfered to clear the ridge? (old bush trick) Was the bore deglased well with a hone and then cleaned well ?. I have had heads with valve guides that worn that the valve started to not seat well and did not use a lot of oil or blow any somke other than when de accelorating.

 

 Just a side note, When you install a set of lifters that most have had a slot left unground internaley and they do not feed oil to the rockers you get about 60 000 out of the engine. The guides then have about 3 to 4 mm clearance, Rockers and posts are not good and the freshley reboared 60TH over 253 needs new block and pistons. It ran verry well up to that point with no noise or other problems. (bugger)

So there was a very tiny ridge at the top. I took the block to an engineer and they advised that it was very minor and standard rings would work, although they did suggest reboring. BUt I was not in a position to go that route due to budget issues.

I did deglaze the bore in a cross hatch shape and removed what little ridge there was. The bores was washed with dishwashing soap as advised by a mechanic buddy, before doing a proper clean and oiling.

 

Incidentally I can confirm that the valves are all getting oil as I removed the valve covers to inspect and all was draped in oil

[kavesh]

Measured a couple of different sets of HQ heads and the guides have OD of around 0.575", so you'll want something that fits tightly around that, and hope you get lucky that everything is machined on centre. The secondary problems will be clearance, both in the OD of the seal to the damper spring (will be tight) and the height to allow full lift (if you have an aftermarket cam this could be tricky too).

Will those measurement be the same as the original cast iron heads?

You are correct the umbrella seal needs to fit inside the spring and not bind up to work successfully.

[76lxhatch]

The ones I measured are original cast iron heads, two different sets from different sources. However while they seem original any 45 year old part has a high chance of having been modified and I can't remember for certain so no guarantees.

 

Those umbrella seals could be more of a problem on the ID of the spring since they need to be larger to clear the guide. The ID of an original spring with damper is about 0.800", the Z28 or LT5 drop-in replacements are a little smaller again.