inlet valve galling/picking up on modified guide!

twinpipes · Post by **twinpipes** » Wed Oct 09, 2013 2:28 pm

Has anyone else had a problem with any valves galling/picking-up on the stem diameter in a new modified bullet guide with the full hooded type stem seals fitted? I recently rebuilt the heads on my 3.9 range rover,with new modified/bullet guides and hooded stem seals,it had been running better than ever,until a few days ago it developed a miss-fire and went in to limp mode.I got some new plugs and did a compression test/no compression on number 5.Removed heads and the inlet valve as picked-up with the valve guide and hit the piston.My thoughts are lack of lubricant after fitting the hooded seals.Now thinking maybe I should remove the stem seals from all the other valves and run it without them and allow a bit of lubricant to pass through.Originally the exhaust did not have any seals and the useless washer on the inlets did not achieve much.What does anybody else think,or does anyone run a engine with no stem seals? Many thanks twinpipes!!!

kiwicar · Post by **kiwicar** » Wed Oct 09, 2013 2:49 pm

Hi
have a look at the injector on number 5, is it leaking continually? I think it very unlikley that stem seals would starve your guides suficiently of oil to cause gauling. I think it far more likley that the oil that is getting past the seal is being washed away by a very rich mixture on that cylinder. I run very rich methanol mixtures and as a result use top end lube in with the fuel, if I ran closer to chemically correct ratios I would not bother. what does the plug on number 5 look like?
How modified are the guides? are they just tapered of have they been shortened aswell?
Best regards
Mike

ChrisJC · Post by **ChrisJC** » Wed Oct 09, 2013 9:18 pm

Guides are supposed to be reamed to size after fitting as the fitting process may distort them slightly.

Chris.

twinpipes · Post by **twinpipes** » Wed Oct 09, 2013 10:42 pm

Hiya,the new guides had been reamed,because you can not fit the valve in the newly fitted guide without reaming them.I will check with regard to the injector on that cylinder being at fault,this sounds plausible,but as it went into limp mode because of the miss-fire all the plugs are well black.The new ones will be fitted on rebuilding.I have purchased a set of new guides stem seal and the valve,the 14 cux system is controlled with the two narrow band lambdas,but I have fitted a sensor bung for a wide band sensor and would like to fit one and a AFR gauge but do not know what would be best,or if I need a controller or not.I would also like to use megasquirt and loose the dizzy.Again this I have no idea of the best route to take.All help appreciated on this.P.S. back to testing the injector/injectors whats the best method to test them,on the vehicle system, or take them two have them sonically cleaned and tested.How much do injectors come in at new any way.I have a lot of electronics test equipment,including oscilloscopes,power supplies and calibrated containers to test them on the bench if required.All help appreciated.and once again thanks to all on these forums.Twinpipes!!!

stevieturbo · Post by **stevieturbo** » Wed Oct 09, 2013 10:52 pm

maybe not reamed with suitable clearance.

twinpipes · Post by **twinpipes** » Wed Oct 09, 2013 11:57 pm

The engine build and work and all guides were reamed by my self.I am a toolmaker by trade. Can any of you give the correct working tolerance/limits for the valve to guide clearance,so has I can double check the others whilst the motor is down. Thanks again twinpipes!! Just looked in haynes manual and it is stating .0015" to .0035"/not sure if this is correct,but got landover manual in workshop so I will a look their tomorrow. thanks,twinpipes!!

ChrisJC · Post by **ChrisJC** » Thu Oct 10, 2013 7:25 am

DIY injector testing is a new one on me - but it does sound interesting.

I suppose you could measure it's flow rate.
Also spray pattern
And leakage when off
Not sure what differentiates a good vs bad signal when looking with a 'scope.

Chris.

DaveEFI · Post by **DaveEFI** » Thu Oct 10, 2013 7:42 am

A dwell meter will also show the pulse length to the injectors, as that's what it does with points etc - shows the mark /space ratio. But unless there is a wiring fault they will all be the same on each bank.

stevieturbo · Post by **stevieturbo** » Thu Oct 10, 2013 8:25 am

twinpipes wrote:The engine build and work and all guides were reamed by my self.I am a toolmaker by trade. Can any of you give the correct working tolerance/limits for the valve to guide clearance,so has I can double check the others whilst the motor is down. Thanks again twinpipes!! Just looked in haynes manual and it is stating .0015" to .0035"/not sure if this is correct,but got landover manual in workshop so I will a look their tomorrow. thanks,twinpipes!!

Any clearances in a Haynes manual will refer to factory valves and materials. Differ from this, and clearances may differ.

But most likely cause is clearances too tight. The only other thing that could cause valve heating to the point where it sticks is incorrect seat clearance.

Almost all valve/guide combos are self lubricating metals, so do not need any oil.

ChrisJC · Post by **ChrisJC** » Thu Oct 10, 2013 7:01 pm

I have always liberally lubricated a valve stem before inserting into the guide (with seal already attached). Never had an issue of a valve picking up on the guide.

Chris.

bigaldart · Post by **bigaldart** » Sat Oct 12, 2013 10:50 am

I have never had to ream a valve guide after fitting. New guides new valves, lots of pressurised methanol mix and no seals. Never an issue. We use only AE guides and valves, guides are shortened to leave just a small radius in the port. I really think the issue is elsewhere. Is there evidence of that valve getting hotter than the others? Is the seat width too narrow? Anything causing a high spot on the seat? Was this an exhaust or inlet that failed.

Alan

twinpipes · Post by **twinpipes** » Sun Oct 13, 2013 7:51 am

hiya,it was the inlet guide,they are the realsteel modified ones/bulleted & take the full hooded stem seal.I know they are self supposedly self lubricating.I have not got any further as yet,but what do you think could cause the problem.It is only the one inlet valve on cylinder number five.I would like to use a wide band lambda and air fuel meter on rebuilding as I have fitted a bung in the X pipe already,but I am not sure on what is best.I would also like to use mega-squirt,and now very little on this aswell.What is the best route to achieve the afr meter and megasquirt engine control,if doing the work yourself?Any advice and help much appreciated.Many thanks twinpipes!

DaveEFI · Post by **DaveEFI** » Sun Oct 13, 2013 8:56 am

Perhaps the biggest snag with MS is the choices it gives you. At the most simple, ExtraEFI do a plug and play conversion for the hotwire where you simply plug in an MS which has been built into a Lucas ECU case. So is a straight swap. But you do pay quite a bit extra for this convenience. And, of course, it stops you changing to things like sequential injection.

What you need to do it write down a wish list of what you want an aftermarket system to do, and choose the appropriate MS. An MS2 V3 would be the minimum since you have a stepper motor idle valve.

MS normally dispenses with the AFM and uses a combination of throttle position and manifold air pressure instead. All the original sensors are kept.

The simplest way to get mapped ignition is to change to wasted spark and fit a crank trigger wheel and sensor - kits for this are available. You can use EDIS (easy) or have MS drive the coils directly ( more difficult)

twinpipes · Post by **twinpipes** » Sun Oct 13, 2013 2:31 pm

Hiya,Dave thanks for the reply.I have looked on your website a few times,but am still unsure of the best option,I would like to get rid of the dizzy and the airflow meter.The engineering side of modifications necessary to swap to mega-squirt is no problem.Perhaps you can advice me better if I give you as much info as possible.The vehicle is a 91 range rover with an auto box,its a 3.9 with a single point LPG system,with lambda feedback,I have ported the heads a bit and it as wasted stem valves standard diameter,real steal modified guides bulleted with the full hooded stem seals,tin head gaskets with a 15 thou head skim to up the compression a bit,it was originally a low compression engine/8.13-1.I have headman headers with the narrow band lambdas in the collectors,I fabricated two stainless pipes that come together with an X piece with a bung to take a wide-band lambda then back to two with one box in each pipe,these are run over the axle side by side in a siamese fashion then twist to clear the chassis and exit just under the bumper,the pipes are two and a quarter inch diameter.The fuel system is std 14 cux,apart from the AEB 175 leonardo lpg system and a K & N type air filter,std ignition with a bit more advance.Was running very well until the problem with the inlet valve of number 5 picking-up on the guide,the rest seem fine.While it is stripped down at the moment seems like a perfect time to improve things by going mega-squirt and loosing the dizzy and perhaps a better cam.Let me know what you think or if it would be better to give you a phone call and speak to you,many thanks twinpipes/Mark!!!

DaveEFI · Post by **DaveEFI** » Sun Oct 13, 2013 2:52 pm

I doubt you've looked on my website as I don't have one.

I'm afraid I've no experience of LPG - but I'm sure others will help.