V8 Tickover troubles

Hi, If your carb wont adjust down any further i think you must be drawing air in somewhere?
 
hi, I always use a lead replacement additive as I have no way of knowing if the cylinder head has been updated for unleaded. I always thought that for unleaded as it burnt hotter u needed different valves and seats etc and if u didn't it would do damage. Im sure I asked this b4 but about the only response I got was well by the time damage is caused u would of spent more on additive than the cost of 2 new heads. However I have also been told that the additive can gum up the fuel lines and carbs if left sitting.

coop
 
cooper1203 said:
hi, I always use a lead replacement additive as I have no way of knowing if the cylinder head has been updated for unleaded. I always thought that for unleaded as it burnt hotter u needed different valves and seats etc and if u didn't it would do damage. Im sure I asked this b4 but about the only response I got was well by the time damage is caused u would of spent more on additive than the cost of 2 new heads. However I have also been told that the additive can gum up the fuel lines and carbs if left sitting.

coop
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I couldnt have said it better, and the octane boost wont make your engine tick over faster either.

I am going to take the carbs off strip and check them, then replace the gaskets.

Matt.
 
Hi Matt,

Rebuilding the carburettors certainly seems like the way forward. Also be sure to check the seals between both the adapters and the air canister, with the elbows.

As an aside, I used both Castrol valvemaster and an octane booster 104+ in years past with my Rover's original engine, and neither made any difference to the idle speed. Ignition timing and the air fuel mixture however will make a profound difference.

Ron.
 
vonkeyvong said:
As I stated earlir in the thread the idle is set to minimum (basicaly the stop screws arent actualy touching anything). Unless of course there are some other adjusting screws I dont know about. Fast idle is corectly set aswell and not touching anything when the choke is pushed in.

I also checked the setting of the main jets today and found that on one of the carbs there is not full adjustment, this isnt a major problem as I managed to set them both equal with a depth vernier but I will need to strip that particulsr carb to see what is wrong. It looks like the previous owner didnt know about this so both carbs had different settings on the main jets. Resetting them has helped a little.

I also sprayed all around the carb and manifold gaskets with WD40 while the engine was running and found no drop in RPM so dont think there is an air leak.

Must say I am realy scratching my head now.

Matt.
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Have you tried pulling the elbows off and looking into the carb? With the throttle stops backed right off like that, the car shouldn't run at all.

Richard
 
I spoke to a chap called Andrew Turner today who is a carburetor expert. He suspects that there is probably some wear in the throttle spindles and jets caused by being stood with straight unleaded fuel in them.

I am going to strip them down and see what I find but treat them to a referb kit which uses jets which are not made of brass and do not get eroded by the acid which can be found in fuels with have methanol blended into them.

As it is It pulls like a train anyway, so a referb kit should get it running perfectly.

I will report my findings back as I start the work.

Matt.
 
It sounds as if one or both of the butterflies is not closing properly.
If there suspected wear in the spindles/spindle bushes, perhaps the oval nature of the butterfly means it cannot close now?
Jim
 
I've had one other thought, and a pic of the engine and carbs would be helpful to either take it further or discount it.
 
Well that's not what I was hoping, but nevertheless, I'd check to see whether the carbs have emission poppet valves fitted to the butterflies, as some P6B had them.
 
Hi Matt,

To see where the pistons are sitting when the engine is at idle, take the elbows off and look in through the adapters. Each piston should be effectively sitting right down on their respective stops.

Ron.
 
The engines were manufactured by landrover who did say they were fine on unleaded (even if rover never did). Also the heads were fitted to 'nada' cars without change. If they were destined for the usa they had to be ok on unleaded.

If the worst did happen (not that it's a known 'thing' ) a couple of later sd1 type heads are available cheaply and are a big improvement.
 
The choke mechanism on HIF's has a rubber O ring in it,and if this is leaking extra fuel will get in as if the choke is on.
I had this on mine and it only affected 1 carb but caused high tickover,but went like the clappers when the throttle was floored.
 
Pilkie said:
The choke mechanism on HIF's has a rubber O ring in it,and if this is leaking extra fuel will get in as if the choke is on.
I had this on mine and it only affected 1 carb but caused high tickover,but went like the clappers when the throttle was floored.
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Have to say that what you describe is what I am seeing. It doesnt miss a beet at all and goes like a scalded cat when you put your foot down hard from a standing start right through to motorway speeds. The gear changes are smooth, quick and at the right speeds.

I am going to order a carb refurb kit and rebuild both carbs over the next couple of weeks when chance presents itself.

Matt.
 
rockdemon said:
The engines were manufactured by landrover who did say they were fine on unleaded (even if rover never did). Also the heads were fitted to 'nada' cars without change. If they were destined for the usa they had to be ok on unleaded.

If the worst did happen (not that it's a known 'thing' ) a couple of later sd1 type heads are available cheaply and are a big improvement.
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Thats good to know. I think I will do some tests with and without additive but only after I have the engine set up and running as it should be.

Matt.
 
harveyp6 said:
Well that's not what I was hoping, but nevertheless, I'd check to see whether the carbs have emission poppet valves fitted to the butterflies, as some P6B had them.
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Yes, you are correct. After talking to Andrew Turner that was going to be my next check(will probably have a look this evening), but I have decided a rebuild is in order anyway.

Matt.
 
Pilkie wrote,...
The choke mechanism on HIF's has a rubber O ring in it,and if this is leaking extra fuel will get in as if the choke is on.
I had this on mine and it only affected 1 carb but caused high tickover,but went like the clappers when the throttle was floored.
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My Rover suffered from this problem recently, but rather than sending the idle high, it dropped significantly most of the time.

You can check if this might be the cause Matt by removing the spark plugs fed by the R/H carburettor, ie 2, 3, 5 and 8. They will all be extremely sooty, well mine certainly were, whereas the others looked normal. Fitting a new seal kit fixed the problem immediately.

Ron.
 
Hi

I had this exact problem on my 2200TC last year; idle speed too high. btw you can't set the timing accurately as others have suggested if the idle speed is high because the centrifugal advance is active.
It turned out to be the vacuum advance diaphragm was holed. Air was being drawn in through the holed diagphragm in the distributor via the vac pipe to the front carb. You won't find this fault by spraying brake cleaner around either.

I'm not sure of the vac advance arrangement on the V8 but its worth a look.

Pat
 
pat180269 said:
Hi

I had this exact problem on my 2200TC last year; idle speed too high. btw you can't set the timing accurately as others have suggested if the idle speed is high because the centrifugal advance is active.
It turned out to be the vacuum advance diaphragm was holed. Air was being drawn in through the holed diagphragm in the distributor via the vac pipe to the front carb. You won't find this fault by spraying brake cleaner around either.

I'm not sure of the vac advance arrangement on the V8 but its worth a look.

Pat
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Good call Pat,

Another thing I will check later!!

Matt.
 
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