Need help with my Spit/GT6 conversion.

[Yakooza2]

as a thought have you placed the gasket on the head and block do the coolant ports all align ?

 

did you run a die nut  down the studs to clear any crud form the threads ?

 

it has  definitely not got a fire ring recess around the bore periphery ??

 

there is a water distribution (brass fabricated ) tube  in the cyl head pump outlet cavity ?

 

just some odd ideas     Pete

Spent the day wondering what else I could do before the test kit arrives, so I proceeded to tighten the head bolts down a bit more to 10kg , which is 3.5kg above the standard and found a bottle of head gasket repair in the garage and put that in the rad too. Run the engine and it seemed to show signs of improvements after a while, ie, it did not boil over after 15 minutes of running but the temperature gauge stayed at 3/4 mark and no more bubbles rushing past the radiator cap into the bottle.

 

by torquing the head down a bit more, i had to adjust the valve clearances and checked the ignition all over again to ensure all was as it should be.

 

I noticed while the engine was running hot, from the treads of the top of the bolts at far ends of the head, tiny tiny bubbles coming through. so I tightened them a bit more and it stopped.  Run the engine again after letting it cool down, for about 35 minutes and it seem to hold on to temperature at around the 1/2 to 3/4 mark, which is a massive improvement so far.

 

Now I am wondering about your comments about cleaning the crud from the bolts and what that really  means with regards to the tiny bubbles coming up past the nut visible at the last few tread above the nut.  

Was it the dirt and oil just getting hot and coming through, or was that were the sealing problem was?

 

I am still going to do the gas test in the cooling system, now that I have bought one and waiting for its delivery.

 

I let you know how I got on. In the meantime, what are your thoughts about the above?

 

Nader 

[Yakooza2]

We look fwd to the results, I still think whilst you have back filled and bled that this level of expasion is

generated by air lock somewhere, in the block and stat area

Gt6 are not the easiest to refill as I said some lift the front of the car up high, to allow the low filler to vent

 

pete

Oh I do so hope that you are right about the airlock, I just have this fear of all that work gone to nothing if my engine block has some sort of crack.

I will most definitely try the trick with raising the front to see if that would do the job.

 

Nader

[Yakooza2]

Oh forgot to say that I have bought a service kit for the HS6 carbs too with normal jets and butterflies to get rid off the wax jets and vented butterflies, since the carbs not running right, does not help the situation. hopefully by then, I will eliminate the cars spit back too.

 

Nader

[Pete Lewis]

Just question why has it got HS6 carbs, was the engine ex big saloon ?

 

pete

[KevinR]

Spent the day wondering what else I could do before the test kit arrives, so I proceeded to tighten the head bolts down a bit more to 10kg , which is 3.5kg above the standard and found a bottle of head gasket repair in the garage and put that in the rad too. Run the engine and it seemed to show signs of improvements after a while, ie, it did not boil over after 15 minutes of running but the temperature gauge stayed at 3/4 mark and no more bubbles rushing past the radiator cap into the bottle.

 

by torquing the head down a bit more, i had to adjust the valve clearances and checked the ignition all over again to ensure all was as it should be.

 

 

Have you had the accuracy of your torque wrench checked - if the valve clearances changed by a measureable amount then the gasket was never properly compressed, which would indicate that your torque wrench is reading much higher than the actual torque being applied.

[Yakooza2]

Have you had the accuracy of your torque wrench checked - if the valve clearances changed by a measureable amount then the gasket was never properly compressed, which would indicate that your torque wrench is reading much higher than the actual torque being applied.

It's a new wrench I bought from and used for the first time, so I expect it would be accurate. I was a bit worried when going the extra tightness, that I might sheer off a nut or bolt, so I think I have tighten it as far as I can go. 10kg , book says 6.3kg

The tappet clearances was just tight on majority but not all of them!

Lets wait and see what the gas test will show.

[Yakooza2]

Just question why has it got HS6 carbs, was the engine ex big saloon ?

 

pete

No, the carbs came with it was stromburgs and in poor condition, so I bought this lot with a manifold to fit the engine, can't remember what engine it came from, it was a long time ago.

[Yakooza2]

gremlins, that's what it is.

 

Got the gas testing kit and set about carrying out the test and after two attempts, it was negative, no gases yepee.

Got the carbs reconditioning kit and set them up, all run OK for a few minutes, then developed a misfire.

Checked all the leads and plugs for spark, all OK

Did a compression test just to compare the pressure between all cylinders, and all read between 2.1 to 2.5 on my gauge, after two sets of tests, but still a misfire and engine run at 3/4 temperature gauge.

 

It's got to be gremlins or jinxed.

 

Any idea's? 

 

Nader

[Pete Lewis]

Its probably got the rubber sliver syndrome, every time you mess with the fuel pipes there is a high risk the metal pipes will cut a small sliver of rubber off the inside of the fuel hoses these then float about to

confuse you and when your happy and smiling jump into the back of the float needle blocking supply

and low fuel bowl level

You need to take the tops off and check also pump a little fuel into a jar before refitting.

 

if its not that I'llget me coat

 

Pete

[Yakooza2]

Thanks Pete, I think you better get your coat and lend a helping hand, otherwise the car is going to the back of the garage until at some point in the future, when I have some inspiration to start all over again.

 

The misfire was identified from cylinder no4 by pulling the lead off, there was no change to the tone or change in the way the engine was struggling, where as each other lead pulled off, made a big difference. 

So I checked the plug, was a bit black but OK, so cleaned up and tested it with the same lead  to see spark, and yes there was a strong spark. So back in, and started again, still missing.

Then did a compression test and all cylinders were at equal pressure give or take a tiny bit.

so if there is spark, fuel, compression, why the misfire?

 

Nader

[Pete Lewis]

Has the dizzy cam spindle got any wear , side play in it , this upset the spark as the point gap keeps changing

 

As compressions are all equal its now becoming something out the box

 

are the rockers on 4 both giving a gap at tdc compression stroke

 

mainfold leak on 4 inlet

 

Something very odd with the valve guide ,, is it moving up and down

 

change the spark plug

 

Does the cam lobe open the no4 inlet

[Yakooza2]

Has the dizzy cam spindle got any wear , side play in it , this upset the spark as the point gap keeps changing

 

As compressions are all equal its now becoming something out the box

 

are the rockers on 4 both giving a gap at tdc compression stroke

 

mainfold leak on 4 inlet

 

Something very odd with the valve guide ,, is it moving up and down

 

change the spark plug

 

Does the cam lobe open the no4 inlet

Thank you, as usual, some good tips.

 

I checked the valve gaps for the 5th time and a couple of the gaps very very tight, and some were a bit too loose!, so I reset them all again.

Took the carbs off the manifold and checked the seals and gaskets to make sure they were OK put back with added gasket seal.

Checked all the plugs for gaps and spark, they seem ok, but in testing them all at the same time, some spark brighter that others!

 

On ruining the engine and listening to it whilst still misfiring, for a brief moment or two the tone changes to a full cylinder firing, then back to missing.

 

So I guess there is an electrical issue here now, you might be right there about the disy plate or possibly a spark plug at fault, although it's hard to fault the leads, cap, plugs, points and condenser, since they are all new and 0 mileage.

 

I was suspecting the rockers after the 3rd resetting, but not sure where to start looking for problems.

 

I sprayed some fine water mist on the manifold to see if the water gets blown out or dragged in, but there was no reaction either way.

 

Of all the things I have checked, I have not checked the valves or the guides. I know, I should have, when the head was off, but was to concerned about it being cracked or warped.

are the rockers on 4 both giving a gap at tdc compression stroke?             Can you enlarge on this point please, not sure what you mean and what the significant of this, is.

 

Is there a device for checking for gremlins

[Pete Lewis]

Apply some thumb load to the side of the dizzy pints cam spindle , is should not move , any sideways slop gives right funny points gaps when its whizzing round.

The top bushes wear badly as they are not exactly engine lubricated and rely on muppet with a squirty oil can down inside .

 

dont have plugs with an R (resistive) in the sufix these can take more HT than our old coils like.

 

As for rockers its just making sure that on a compression stroke that both rockers are giving a 0.010 gap

on both rockers,

Thats set 1 and 2 when 11 and 12 are rocking thats inlet is closing and exhaust is just opening

likewise for each cylinder, if unsure look at where the rotor is pointing at which ht lead

 

Firing order .....often get gets mixed up 15 36 24 anticlockwise at the dizzy

 

keep at it gremlins and classics are well known factor

 

simple rules are when you find the culprit the replacement doesnt cure the fault

 

pete

[Yakooza2]

Apply some thumb load to the side of the dizzy pints cam spindle , is should not move , any sideways slop gives right funny points gaps when its whizzing round.

The top bushes wear badly as they are not exactly engine lubricated and rely on muppet with a squirty oil can down inside .

 

dont have plugs with an R (resistive) in the sufix these can take more HT than our old coils like.

 

As for rockers its just making sure that on a compression stroke that both rockers are giving a 0.010 gap

on both rockers,

Thats set 1 and 2 when 11 and 12 are rocking thats inlet is closing and exhaust is just opening

likewise for each cylinder, if unsure look at where the rotor is pointing at which ht lead

 

Firing order .....often get gets mixed up 15 36 24 anticlockwise at the dizzy

 

keep at it gremlins and classics are well known factor

 

simple rules are when you find the culprit the replacement doesnt cure the fault

 

pete

I checked the points gap at each lobe to ensure no funny business and the plate is secure.

All the HT leads tested OK

The rockers are probably at fault to some extent, since the gaps checked again and again, they seems to have slight variations.

 

A ray of hope came, when I pulled the leads off while engine running, and one plug was at fault. so a prompt replacement got the engine singing the right tunes again.

The carbs received the service kit and set up again to run smoothly for now, but need a good tune once I overcome the current over heating issue.

 

Remember when I said I was getting spit back from carbs? well the spit back is almost gone, but the rear carb at high revs and at high engine temperature gives a spit back, which might enforce my theory of the rocker shaft being worn and keep altering the gaps for the valves.  What do you think?

 

I am not giving up yet, I will get the gremlins out one way or another.

 

The overheating seems to have mellowed down a bit, by that I mean it does not boil over and shoot water out, but it is still at 3/4 mark on the gauge. this is without road test.

 

I also contacted Searls for a cost of a total engine rebuilt, which was over £2200 +VAT, so I will give that a miss and persevere with what I have for now.

 

In case I forgot to mention earlier, I do appreciate all the help you are offering. Many thanks.

 

Nader 

[Pete Lewis]

There are two senders early for non stabilised gauges 121997 and stabilised sender GTR108

 

if mixed you get high gauge readings is early type is fitted to a stabilised system

 

they used to be different colours but not these days they look the same .

 

spit backs can be weak mixture, over advanced , thin dashpot oil, running without air filters

or having pancakes and std needles

 

pete

[Yakooza2]

The sender was purchased on Ebay, as an OM direct replacement unit for a GT6, so not sure what that is.

And since my stabilizer unit was playing up, I replaced it with an electronic unit.

 

Carbs, you are right on all points, but why only one carb spitting back? Since the fuel mixture is set the same.

 

I have set the timing to 6 BTDC with distributor vacuum hose off.  the engine starts on the button.

 

You have not commented on the rocker assembly wear or gaps varying from time to time

 

I will re check the carbs oil again to be sure. 

 

Nader

[Steve P]

I know you`ve probably eliminated it but i had the same symptoms of boiling on a Mini which turned out to be the pump not doing its job properly,dont assume new ones can`t be faulty if it is new?.

 

Where in London are you?

Steve

[Pete Lewis]

rocker wear after all these years is common, , some can seize on the shaft and makes gaping a bit difficult , 

tip wear on the valve stem can restrict feeler 'feel'  ,  

 

if in doubt i would remove the shaft assy and see that all are free to rotate,  as for wear on the valve face that can be dressed off with care to keep the base profile , dont attack with a angle grinder,  but some careful work with a softish wheel  to remove the step and they will work for years .

 

they dont need a lot of oil . when aged the small oilways can get crudded up and need a clean , sometimes a new shaft

the rockers are generally reclaimable 

 

the oil supply is a interupted feed from the back cam journal it has a flat on it which allows a squirt once for each rvolution of the cam its not a continuous supply from the oil gallery,    do not fit the external oil feed this reduces pressure to the mains and over oils the top end so excess oil down the guides and makes smoke ...dont go there.

 

 

Pete

[Yakooza2]

Yet another bit of repair, this time to the tips of the rockers. no problem, will do that in a few days.

I will also take the water pump off as was suggested a few times here, but not sure what sort of fault I should be looking for.

 

Took the car out again today and after a short run in the traffic, it heated up again to between 3/4 and hot mark, but never the less, an improvement on previous boil over, where water used to push out every where. this time just hot and no further boiling activity.

 

I have a push type electronic fan mounted in front of the radiator covering 80% of the rad and the normal pull fan on the crank pulley, but when the engine is switched off and the electronic fan is working, feeling the back of the rad it does not seem to be pushing a lot of air through. So I am wondering if the electronic fan is actually restricting the air flow, rather than helping it.  What are your thoughts about that?

 

Nader

[Pete Lewis]

All down to preference but I have a avide hate of electric fans , many are restrictive, come on too late and dont shift enough air cfm.

some work very well. But carbs need a cool air flow under the bonnet to keep the ambient air at a steady

temperature , with electric there tends to be some very high under bonnet temps before it cuts in

and carbs just wont cope.

 

To prove your thoughts can you remove it easily and do a dun to compare ?

 

get a cheap stick thermometer from the chemist and stick it in the filler , see what temperature you are getting the gauge readings may be misleading with stabilisers and senders comtributing to false reading any engine that has had a 'boil up' realy needs the stat replacing as fhe wax decalibrates

pete

[Yakooza2]

I know you`ve probably eliminated it but i had the same symptoms of boiling on a Mini which turned out to be the pump not doing its job properly,dont assume new ones can`t be faulty if it is new?.

 

Where in London are you?

Steve

Hi Steve, apologies for a late reply.

I am in Northolt, west London.

As I said to Pete, taking a water pump off , I am not sure what sort of fault to look for. But I am going to take it off next week and will report back with my findings.

[Pete Lewis]

The only problem from the past was the impellor coming loose on its spindle when hot

 

its a simple turbine vaned impellor theres little to go wrong its a circulator not a pump, so all you have is a fancy paddle wheel to look at

 

if you look in the filler you should see the flow across the rad when the stat opens ans closes

 

pete

[Yakooza2]

Evening 

 

Took the rocker rail apart and the shaft is scored badly in a few places.

I also noticed, on closer inspection, that some of the trust washers been put in the wrong places, thus the rocker tip was off center to the valve head and causing a side way trust and movements.

I guess there is nothing other than change the shaft ! I wonder if there is anything left that don't need changing?

 

I have also removed the electronic fan, to see if the original mechanical fan would be sufficient, once I reset the valve clearances again.

 

Will let you know if it heats up again.

 

Nader

[Pete Lewis]

At least being a mk3 a replacement shaft will fit , if it was a mk1 engine youre into much fiddle and faf

as everthing is different and mk2 shafts dont fit mk1 engines without modification.

 

so that simplifies any extra head aches

 

clean all the small oil holes in the rockers and look at refacing if possible

 

Or get a new complete assy .

 

wothnthe rockers off spin engine on starter there should be a small interupted flow up the oilway to the rear pedestal , on rebuild make sure the philips screw is tight and give it a dab of loctite

[Yakooza2]

Hi Pete

I have reassembled the shaft as it was and filed off the steps as you suggested.  and have removed the electronic fan from the front of the radiator too.

There is a small improvement on the engine idling and it now takes a bit longer to get to the overheat state, never the less it over heats.

 

I have done all that could be done. I am now wondering if the reconditioned radiator is actually done properly ! 

They may have done bodge job with lots of drain holes blocked in the process of fitting the new core to the header tank .

I paid £199 from someone who has a rad reconditioning business. I guess as it has been mentioned earlier, "just because it's new, doesn't mean its working OK"

 

Do you think my Spitfire 1500 radiator will be a good one to try out? obviously I have to do the expansion tank attachment since it does not have the pump return inlet. Or would the radiator be just too small to cope with a 2000 cc engine?

 

Let me know your thoughts please.

 

Nader