Rover V8 engine problem.
Discussion
I bought a new Rover 4.0l short engine, new camshaft (Piper 270), stage 1 cylinder heads and new Edelbrock/Webber 500 carb.
I have never been able to get it to run right, lumpy idle and running rich with an erratic vacuum reading at idle and black oily plugs.
I have tried everything i can think of to find the problem. Have rechecked the camshaft timing, changed the ignition system, removed the heads hoping for gasket failure even down to checking that i had the correct dipstick/tube and not been overfilling with oil. Thought the carb may have been too big for the engine size so fitted a Holley 390, but still the same.
Compressions are all equal at 175/180 psi.
Other than the initial startup whereby the engine was kept at 2500 rpm for 20 minutes to bed in the camshaft the engine has mainly been idling whilst i tried to find the problem. I am now wondering whether the oil control rings have not bedded in? (Is there any way to check these?)
So down to my question, should i just run it to, hopefully, bed the oil control rings in? My concern here is bore wash and damaging the engine.
Any suggestions would be welcome as i have been at this for a long time (years)!
Although the car is not a TVR i thought this the best section of the forum to get help.
Originally posted in the Land Rover section it was suggested that i also post in the TVR section.
Thanks.
jenand40.
I have never been able to get it to run right, lumpy idle and running rich with an erratic vacuum reading at idle and black oily plugs.
I have tried everything i can think of to find the problem. Have rechecked the camshaft timing, changed the ignition system, removed the heads hoping for gasket failure even down to checking that i had the correct dipstick/tube and not been overfilling with oil. Thought the carb may have been too big for the engine size so fitted a Holley 390, but still the same.
Compressions are all equal at 175/180 psi.
Other than the initial startup whereby the engine was kept at 2500 rpm for 20 minutes to bed in the camshaft the engine has mainly been idling whilst i tried to find the problem. I am now wondering whether the oil control rings have not bedded in? (Is there any way to check these?)
So down to my question, should i just run it to, hopefully, bed the oil control rings in? My concern here is bore wash and damaging the engine.
Any suggestions would be welcome as i have been at this for a long time (years)!
Although the car is not a TVR i thought this the best section of the forum to get help.
Originally posted in the Land Rover section it was suggested that i also post in the TVR section.
Thanks.
jenand40.
What is the idle vacuam reading? This is a good base line to establish. You may need ignition advance. It needs a good suck, lol. Also have you sorted the idle settings on the carb? Are the accell pump squirters delivering fuel at idle when they shouldn't? What power valve is installed in the carb, it may be open?
Edited by Boosted LS1 on Friday 19th February 22:46
Have been tinkering with car yet again today, car sounds as if the choke is out, it is not, chugging away with the vacuum gauge readings changing between 14 - 16 in time with the chugging!
Played around with the idle settings but if i weaken it off any more the engine dies.
Accelerator pump is not squirting fuel into the engine. Not sure of anything with the Holley as i bought it secondhand, and was told it was set up for the Rover engine, BUT regarding the power valve, the engine is behaving exactly the same as when it was fitted with the new Webber carb.
I have played around with the timing settings.
I just cannot get my head around this, what is so annoying is that it starts, after 3 pumps on the accelerator peddle, immediately!
Five years of building up the car, with everything mechanical new, and 8 years of trying to get it to run right. All i want to do is drive the bl***y thing!
MOT runs out in June so i need to sort it out by then. If all else fails i will swap the perfect 3.5 Rover engine from the Stag into the TR8 to get it on the road for the summer (i have a new 4.2 Rover engine for the Stag that was to go in when i got around to it).
Please, any thoughts.
Played around with the idle settings but if i weaken it off any more the engine dies.
Accelerator pump is not squirting fuel into the engine. Not sure of anything with the Holley as i bought it secondhand, and was told it was set up for the Rover engine, BUT regarding the power valve, the engine is behaving exactly the same as when it was fitted with the new Webber carb.
I have played around with the timing settings.
I just cannot get my head around this, what is so annoying is that it starts, after 3 pumps on the accelerator peddle, immediately!
Five years of building up the car, with everything mechanical new, and 8 years of trying to get it to run right. All i want to do is drive the bl***y thing!
MOT runs out in June so i need to sort it out by then. If all else fails i will swap the perfect 3.5 Rover engine from the Stag into the TR8 to get it on the road for the summer (i have a new 4.2 Rover engine for the Stag that was to go in when i got around to it).
Please, any thoughts.
OP, have got the cam timing correct? I've reread your posts. So, both carbs have failed to sort out the issue? The 390 holley can be weak on a 4.0l. It starts when you give the pumps a squirt so it clearly needs fuel to get it started. Will it rev and hold a fast idle once warm? Are 8 cylinders actually running?
The sooty, oily plugs could be like that if they're not being fired. Do they smell of petrol? If soaked they'll never fire properly until you've dried them out. I've used a gas hob for this when I had similar problems. Out of interest, did you replace the valve stem oil seals? Oil can be dragged down the guides. If the engines not smoking I doubt it's an oiling issue.
The sooty, oily plugs could be like that if they're not being fired. Do they smell of petrol? If soaked they'll never fire properly until you've dried them out. I've used a gas hob for this when I had similar problems. Out of interest, did you replace the valve stem oil seals? Oil can be dragged down the guides. If the engines not smoking I doubt it's an oiling issue.
Edited by Boosted LS1 on Monday 22 February 12:05
When you build a V8 Rover the oil pump is not self-priming.
You are supposed to insert a special tool (easily made) into the distributor hole in the block.
This tool is a shaft that engages the oil pump drive and can be driven by a power drill.
This is also how you prime the oil pump in Chevy engines after assembly.
Perhaps your motor ran for some time without oil pressure?
You are supposed to insert a special tool (easily made) into the distributor hole in the block.
This tool is a shaft that engages the oil pump drive and can be driven by a power drill.
This is also how you prime the oil pump in Chevy engines after assembly.
Perhaps your motor ran for some time without oil pressure?
Right chaps, thank you for your replies.
Just been out to the car again, spark plugs are black but now do not seem so oily.
Cam timing is correct, after i reset it over winter, 14/15.
Regarding starting the car, i do not use the choke, i read that if you pump the accelerator pedal 3 times it should start okay. Have just tried with 1 pump from cold and it started instantly.
Removed each plug lead in turn and it is running on all 8 cylinders. On a previous occasion i replaced all 8 plugs but still had the same result.
Reconditioned stage 1 cylinder heads were purchased from "V8 Tuner" so i can only assume the inlet valve stem seals were replaced, they certainly look new.
Oil pump was primed before initial start up.
The distributor is a Mallory Unilite with Mallory Promaster coil, Promaster 8mm HT leads and Mallory Hyfire digital ignition system.
Have just come into the house and my clothes smell of petrol/oil fumes, it is that bad!
Unfortunately i do not have access to an exhaust gas analyser.
Please keep the ideas coming.
Thanks.
Just been out to the car again, spark plugs are black but now do not seem so oily.
Cam timing is correct, after i reset it over winter, 14/15.
Regarding starting the car, i do not use the choke, i read that if you pump the accelerator pedal 3 times it should start okay. Have just tried with 1 pump from cold and it started instantly.
Removed each plug lead in turn and it is running on all 8 cylinders. On a previous occasion i replaced all 8 plugs but still had the same result.
Reconditioned stage 1 cylinder heads were purchased from "V8 Tuner" so i can only assume the inlet valve stem seals were replaced, they certainly look new.
Oil pump was primed before initial start up.
The distributor is a Mallory Unilite with Mallory Promaster coil, Promaster 8mm HT leads and Mallory Hyfire digital ignition system.
Have just come into the house and my clothes smell of petrol/oil fumes, it is that bad!
Unfortunately i do not have access to an exhaust gas analyser.
Please keep the ideas coming.
Thanks.
STOP - THINK - GO BACK TO BASICS - USE LOGIC
If the engine is massively over fuelling as you describe it's either getting way too much fuel, or its getting the right amount of fuel and for some reason the engine is failing to burn it completely.
Three potential reasons for this:
MECHANICAL
Assuming the valves are going up & down fully, the cam timing is correct and you've got good/even compression on all cylinders you can more or less rule out a mechanical issue.
IGNITION
Its unlikely to be ignition timing as you say the engine started very easily but you do need to establish the coil & distributor are functioning correctly and you have a strong spark.
THE CARBURETTOR
From everything you've described this seems by far the most likely culprit to me.
I'm a big fan of SU carbs, simple, reliable and elegant in their function its also very hard to get their mixtures horribly wrong. You'd probably pay £100 for a functioning set of SUs (or Strombergs) complete and on the SU inlet manifold, so they're cheap enough too.
http://www.ebay.co.uk/itm/Rover-V8-sd1-3500-inlet-...
http://www.ebay.co.uk/itm/Rover-V8-Twin-Su-Carbs-S...
Try a set and see how the engine runs, I bet it purrs like a kitten
SUMMARY
Its impossible to diagnose such problems effectively over the internet but if pushed I'd put my money on a fuelling issue caused by an issue with your current carb. You are also well advised to avoid running your newly built engine while its significantly over fuelling as the last thing you want to do is wash the oil off the bores.
Good luck with it
If the engine is massively over fuelling as you describe it's either getting way too much fuel, or its getting the right amount of fuel and for some reason the engine is failing to burn it completely.
Three potential reasons for this:
MECHANICAL
Assuming the valves are going up & down fully, the cam timing is correct and you've got good/even compression on all cylinders you can more or less rule out a mechanical issue.
IGNITION
Its unlikely to be ignition timing as you say the engine started very easily but you do need to establish the coil & distributor are functioning correctly and you have a strong spark.
THE CARBURETTOR
From everything you've described this seems by far the most likely culprit to me.
I'm a big fan of SU carbs, simple, reliable and elegant in their function its also very hard to get their mixtures horribly wrong. You'd probably pay £100 for a functioning set of SUs (or Strombergs) complete and on the SU inlet manifold, so they're cheap enough too.
http://www.ebay.co.uk/itm/Rover-V8-sd1-3500-inlet-...
http://www.ebay.co.uk/itm/Rover-V8-Twin-Su-Carbs-S...
Try a set and see how the engine runs, I bet it purrs like a kitten
SUMMARY
Its impossible to diagnose such problems effectively over the internet but if pushed I'd put my money on a fuelling issue caused by an issue with your current carb. You are also well advised to avoid running your newly built engine while its significantly over fuelling as the last thing you want to do is wash the oil off the bores.
Good luck with it
Once again thank you for your replies/comments and logical assessment of this problem.
I think what I will do next is to replace all the fancy ignition system with just a basic dist/coil set up and see how it performs then. As I have tried two different carbs, the idea of not burning the fuel mixture correctly does seem to make sense, and to get away from the problem being the carb is refreshing as I felt I was just going around it circles with it. ( I have tried a different ignition system before when the original Webber carb was fitted, but made no difference).
Also the thought of the inlet valves not sealing is a new idea, but would'nt the valve stem seals prevent this occuring? Recently sold an old 3.9 engine with 10 bolt heads for a song just because it was in the way, that I could have tried the heads off of.
Just another thought I got whilst typing about the heads, I am using a 4 litre cross bolted short motor with the old 14 bolt heads, 35 cc combustion chamber as opposed to 28 cc, with tin head gaskets. I guess this must be okay as I have 175/180 psi compression in all cylinders.
175/14.7 = 11.90. That cannot be right, can it? 11.90 compression ratio? Anyone care to educate me on that?
Will replace ignition system and report back.
I have been at this problem for so long now I felt I was going around in circles with it. So please keep the ideas coming in.
Many thanks.
jenand40.
I think what I will do next is to replace all the fancy ignition system with just a basic dist/coil set up and see how it performs then. As I have tried two different carbs, the idea of not burning the fuel mixture correctly does seem to make sense, and to get away from the problem being the carb is refreshing as I felt I was just going around it circles with it. ( I have tried a different ignition system before when the original Webber carb was fitted, but made no difference).
Also the thought of the inlet valves not sealing is a new idea, but would'nt the valve stem seals prevent this occuring? Recently sold an old 3.9 engine with 10 bolt heads for a song just because it was in the way, that I could have tried the heads off of.
Just another thought I got whilst typing about the heads, I am using a 4 litre cross bolted short motor with the old 14 bolt heads, 35 cc combustion chamber as opposed to 28 cc, with tin head gaskets. I guess this must be okay as I have 175/180 psi compression in all cylinders.
175/14.7 = 11.90. That cannot be right, can it? 11.90 compression ratio? Anyone care to educate me on that?
Will replace ignition system and report back.
I have been at this problem for so long now I felt I was going around in circles with it. So please keep the ideas coming in.
Many thanks.
jenand40.
One last thing OP. Both carbs will have an outlet pipe on the base plate that sucks air from the brake servo. This pipe must be blanked off if not in use as it'll case a massive air leak into the engine and resulting vacuum drop at idle.
If you have a servo connected it needs a one way valve in the pipework. As an experiment you could disconnect the servo (if fitted) and blank the port on the carb to see if the engine responds any differently.
As for the ignition, I once had very erratic problems with the Rv8 dizzy (hall effect). This dizzy has the white wheel inside with 8 ferrite rods in it. I replaced it with the later item and all worked well. Some rv8 distributors have an 'air gap' inside that needs to be adjusted correctly otherwise you'll get a weak spark or no spark. A mallory unilite is also a nice bit of kit.
I wouldn't worry about the compression.. Your cranking values are good.
If you have a servo connected it needs a one way valve in the pipework. As an experiment you could disconnect the servo (if fitted) and blank the port on the carb to see if the engine responds any differently.
As for the ignition, I once had very erratic problems with the Rv8 dizzy (hall effect). This dizzy has the white wheel inside with 8 ferrite rods in it. I replaced it with the later item and all worked well. Some rv8 distributors have an 'air gap' inside that needs to be adjusted correctly otherwise you'll get a weak spark or no spark. A mallory unilite is also a nice bit of kit.
I wouldn't worry about the compression.. Your cranking values are good.
Edited by Boosted LS1 on Tuesday 23 February 09:05
The ideal thing to diagnose this is a Gunson Colour tune- or even better 2 of them- one for each bank. You can then see the mixture burn that should be a pale blue in colour- over rich goes orange and is quite obvious. I bought 6 of them to get a V6 running on Delortos years ago, so you could tweak the mixture on a per cylinder basis- I may have them laying around somewhere- not used them in years. You can still get them new:
http://www.ebay.co.uk/itm/Gunson-Colortune-14mm-Ki...
http://www.ebay.co.uk/itm/Gunson-Colortune-14mm-Ki...
jenand40 said:
Also the thought of the inlet valves not sealing is a new idea, but would'nt the valve stem seals prevent this occuring? Recently sold an old 3.9 engine with 10 bolt heads for a song just because it was in the way, that I could have tried the heads off of.
jenand40.
The valve stem seals stop oil from the valvetrain getting into the inlet port, they are not exposed to the cylinder when the valve is shut and they sit on top of the valve guides anyway.jenand40.
The tiny amount of compression leakage needed to upset the idle running might not affect your compression readings because the leak happens after the cylinder has fired, not on the compression stroke.
When the throttle is opened and the airflow increases, the vacuum can be sufficient to pull the carb jets properly. It is when on the idle circuit that the little bit of pressure difference makes you run the idle jets too rich because you have the mass airflow without the corresponding vacuum (because it is reduced by the combustion leak) to pull the jets properly.
In this scenario carbs cannot meter the fuel correctly, no matter how much you try.
It is a difficult one to diagnose, but having a pair of known good heads should makes it easier than gauging all the valves.
Edited by 010101 on Tuesday 23 February 22:15
Update.
Removed the Hyfire ignition system, Promaster coil and HT leads and replaced with original parts, but still the same!
Took out each plug, in turn, blanked off the hole in the head with a spare plug, and checked that each plug was firing. All firing but the spark did not seem very strong, especially when compared to videos on Youtube. The only thing not changed on the ignition side was the distributor, but that only distributes the spark and does not generate it, right?
Noticed that the vacuum gauge was reading the same when the engine was running on 7 cylinders as it does when running on 8, thought there may have been a difference.
Plug type is BP6ES.
Managed to get hold of a Colortune and checked cylinders 1 & 2. Indicated yellow (rich), but not very bright, tried to weaken off but no change and the engine dies.
Not sure that the vacuum fluctuation is the cause or a symptom.
Brake servo has been blanked off, but still the same.
So, not sure of my next step, as "Boosted LS1" suggests, not enough spark or too much fuel.
010101 - can't say i fully understand your suggestion of compression leakage, should i remove the heads again and lap in the valves, or fit another set of heads, maybe this time the correct 26cc type?
Just remembered that when it was on the road it was very jerky on a light throttle.
Keep the ideas coming in, please.
Again many thanks.
jenand40.
Removed the Hyfire ignition system, Promaster coil and HT leads and replaced with original parts, but still the same!
Took out each plug, in turn, blanked off the hole in the head with a spare plug, and checked that each plug was firing. All firing but the spark did not seem very strong, especially when compared to videos on Youtube. The only thing not changed on the ignition side was the distributor, but that only distributes the spark and does not generate it, right?
Noticed that the vacuum gauge was reading the same when the engine was running on 7 cylinders as it does when running on 8, thought there may have been a difference.
Plug type is BP6ES.
Managed to get hold of a Colortune and checked cylinders 1 & 2. Indicated yellow (rich), but not very bright, tried to weaken off but no change and the engine dies.
Not sure that the vacuum fluctuation is the cause or a symptom.
Brake servo has been blanked off, but still the same.
So, not sure of my next step, as "Boosted LS1" suggests, not enough spark or too much fuel.
010101 - can't say i fully understand your suggestion of compression leakage, should i remove the heads again and lap in the valves, or fit another set of heads, maybe this time the correct 26cc type?
Just remembered that when it was on the road it was very jerky on a light throttle.
Keep the ideas coming in, please.
Again many thanks.
jenand40.
Have you dried the plugs and set the gaps? Wet, oily, fouled plugs will only generate a weak spark. Is your battery healthy and the starter motor? The engine needs to crank over quickly and in cold weather may struggle. I wonder what the battery voltage is when you're trying to idle the engine? Has the alternator kicked in?
Edited by Boosted LS1 on Wednesday 24th February 18:56
The diagnostic procedure I am suggesting is only realistic if you are happy that you have exhausted your options.
The valves need to be checked with a surface plate, two V blocks, a lever dial and a height gauge. You could manage without the height gauge and a good benchtop is probably good enough to find bent valves. If you know they are straight +or- a few thou and your seats look good, then you can likely rule out combustion leakage into the intake runners.
The valves need to be checked with a surface plate, two V blocks, a lever dial and a height gauge. You could manage without the height gauge and a good benchtop is probably good enough to find bent valves. If you know they are straight +or- a few thou and your seats look good, then you can likely rule out combustion leakage into the intake runners.
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