Frans, does the lack stem seal make for a smokey motor, and does it lead to oil contamination on the back of the valve?
807 Competition motor.
- Thread starter Frans
- Start date
Hi,
I wouldn't say smokey, but using a bit oil yes. Specially from the intake valves because when you lift your foot there is a huge suction between the pistons and the butterflies and it will suck some oil through the valve guide/valve stem clearance. That will not contaminate the valve because as soon as you accelerate the fuel will wash it off. Maybe it will contaminate at the exhaust side but then again there is pressure on that side and would rather blow through the clearance of the guides.
It has never bothered me because it gives a little top lubrication. "Top lubrication" was common terminology on old school cars. This is a racing car and power might be increased by up to 50%. So the engine works very hard because all it does is full throttle at all times.
Remember all this is my opinion and what I do. If you don't like it you can fit valve stem seals and have it as per factory and the engine and guides might last long enough.
Regards
Frans.
I wouldn't say smokey, but using a bit oil yes. Specially from the intake valves because when you lift your foot there is a huge suction between the pistons and the butterflies and it will suck some oil through the valve guide/valve stem clearance. That will not contaminate the valve because as soon as you accelerate the fuel will wash it off. Maybe it will contaminate at the exhaust side but then again there is pressure on that side and would rather blow through the clearance of the guides.
It has never bothered me because it gives a little top lubrication. "Top lubrication" was common terminology on old school cars. This is a racing car and power might be increased by up to 50%. So the engine works very hard because all it does is full throttle at all times.
Remember all this is my opinion and what I do. If you don't like it you can fit valve stem seals and have it as per factory and the engine and guides might last long enough.
Regards
Frans.
as it happens, i have never actually removed valves from a head before, and so i dont actually know what a valve stem seal looks like. i have just had a look at images of them on google, and that makes me think they would have some sort of flexible sealing material. having a look at the head, it doesnt seem to have any seal anyway. there is nothing that looks like a seal, it is all metal, and when i look down the guide, it seems to be smooth all the way down ie no join lines. as per the attached photo, it looks like the top of the guide already has the shape you have achieved with your special tool.
this is just a plain 807 head.
this is just a plain 807 head.
Attachments
It's quite common to leave the seals off the exhaust valves. When I use to build ski boat engines I always left the exhaust seals off. They work very hard and as exhaust gas is always pressurizing the guide, oil is always being forced up. Oil only runs down the guide when the engine is off. So you might see a puff on start up. This was quite beneficial as ski boats often don't get used during winter months.
It's less of an issue on the intake, especially when bronze guides are used with quality stainless steel valves.
It's less of an issue on the intake, especially when bronze guides are used with quality stainless steel valves.
Valve Stem Seals
Hi All
The 807 series of engines does not have valve stem seals.
Hi All
The 807 series of engines does not have valve stem seals.
And it isn't a problem. My guess is in later years when Renault were still using these engines that fuel emmissions were becoming harder to comply to, and so that is why the valve stem seals were fitted.
The guides that have seals fitted to them have a groove around the top for the seal to seat into. If the guides are in good order (without seals) it will not be blowing smoke through the minimal amount of oil sucking down the inlet guides on overrun.
I have heard it so many times over the years that all the engine needs is a set of stem seals to stop the smoke on overrun, when in reality the motor is tired and needs a full overhaul. New stem seals may help these engines somewhat, but it is a short term and unsuccessful fix IMO.
Hi All,
It is time to start doing something because all the bits have now been balanced and in my workshop. There are a few changes to this motor in so much as Fuego Turbo conrods and oil pump.
The crank is cut to bare minimum as can be seen in the pictures. This was done by Ross himself and you will see that the webs is shaped like a boat's hull. It should help a lot to reduce friction in the crankcase and I like the idea. I don't think that it is weakened at all and it balanced quite well.
The pistons is forged pistons by Vinolia and rods from a turbo. Much stronger than the standard 807 rods.
I will modify the camshaft by under cutting the lobes. Info lost last year was very important regarding lobes and followers that destroy themself as soon as you increase valve spring pressures and fit a hot cam. This is a common fault amongst the 807 motors and I am sure other members will agree about this because they expierienced similar problems. Alan Moore comes to mind.
I think I have solved this problem and proof lies within the 1800 motor. That engine has done 2 Targas unopened that equates to 1500km racing plus about 4000km touring. The only issue with that was the cracked crank when I prepared it for last year's Targa.
What has evolved out of that lost thread is that the lobes has to be ground parallel and the cam followers has to be perfectly flat.
I will elaborate on that next time with more detail.
Regards
Frans
It is time to start doing something because all the bits have now been balanced and in my workshop. There are a few changes to this motor in so much as Fuego Turbo conrods and oil pump.
The crank is cut to bare minimum as can be seen in the pictures. This was done by Ross himself and you will see that the webs is shaped like a boat's hull. It should help a lot to reduce friction in the crankcase and I like the idea. I don't think that it is weakened at all and it balanced quite well.
The pistons is forged pistons by Vinolia and rods from a turbo. Much stronger than the standard 807 rods.
I will modify the camshaft by under cutting the lobes. Info lost last year was very important regarding lobes and followers that destroy themself as soon as you increase valve spring pressures and fit a hot cam. This is a common fault amongst the 807 motors and I am sure other members will agree about this because they expierienced similar problems. Alan Moore comes to mind.
I think I have solved this problem and proof lies within the 1800 motor. That engine has done 2 Targas unopened that equates to 1500km racing plus about 4000km touring. The only issue with that was the cracked crank when I prepared it for last year's Targa.
What has evolved out of that lost thread is that the lobes has to be ground parallel and the cam followers has to be perfectly flat.
I will elaborate on that next time with more detail.
Regards
Frans
Attachments
as it happens, i saved that thread on my pc as Web Page, so i have all (maybe only up to some point in the discussion) the posts and attached photos. perhaps if a moderator is looking at this, they will know if that thread can be restored if i send the files to someone.
Just to clarify a couple of points.
The pistons, large valves, springs, retainers and guides were all purchased from Salv Sacco in the UK. The pistons Frans has already described, the valves I cant remember there exact size but I do remember they were smaller diameter stem size (7mm I think) hence the need for new guides. The springs and retainers are also reduced in size from original to reduce reciprocating weight.
The pistons, large valves, springs, retainers and guides were all purchased from Salv Sacco in the UK. The pistons Frans has already described, the valves I cant remember there exact size but I do remember they were smaller diameter stem size (7mm I think) hence the need for new guides. The springs and retainers are also reduced in size from original to reduce reciprocating weight.
"Frans" can you possibly tell me the conrod length c-c & width at BE?
Cant find this info anywhere and no engine atm in my reach.
Also need the Height of the block from crank centre to deck top?
Im trying to work out the rod stroke ratio of the 807 engines.
Engine height (crank centre to deck) = ?
Conrod length= 135.5 136.3 or 136.4mm?
Piston comp height= 40.5 or 42mm?
Conrod BE width= 27mm?
Im really enjoying this thread with detailed pics. The turbo rods are beautifully strong!
My only confusion is the first page has head pics of a wedge motor not hemi crossflow.
Is that just to illustrate your techniques and tools?
here are some specs dug up from wayback machine as site is no longer hosted
http://web.archive.org/web/20050320012204/http://www.laffey.co.uk/renault/renault1517.php
regards, Dave
Cant find this info anywhere and no engine atm in my reach.
Also need the Height of the block from crank centre to deck top?
Im trying to work out the rod stroke ratio of the 807 engines.
Engine height (crank centre to deck) = ?
Conrod length= 135.5 136.3 or 136.4mm?
Piston comp height= 40.5 or 42mm?
Conrod BE width= 27mm?
Im really enjoying this thread with detailed pics. The turbo rods are beautifully strong!
My only confusion is the first page has head pics of a wedge motor not hemi crossflow.
Is that just to illustrate your techniques and tools?
here are some specs dug up from wayback machine as site is no longer hosted
http://web.archive.org/web/20050320012204/http://www.laffey.co.uk/renault/renault1517.php
regards, Dave
Last edited:
Dave,
Engine height = 219.5mm
conrod length = 136.2mm
Piston comp height = 40.5mm
BE width = 27mm
The head on the 1st page is a 1400 Sierra non crossflow head and it is the only pictures I had available to demo the tools.
Conrod length differs from yours and I measured twice and came up with the same length.
Regards
Frans.
Hi All,
I have done the work on the cam and I want to re-cap on that issue others and myself had when installing a hot cam in a 807 motor. I am not sure what a mild cam would do but my "hot" is around 295 degrees and higher (advertised duration) This is the info that was lost last year.
So what happens is that the cam and follower destroys themselves with stronger valve springs which is obvious in a racing motor. The 807 motors are designed to have flat surfaced followers and flat or parallel ground lobes on the cam. If you do a dry assembly and you fit the head and cam you will notice that the cam lobes sits off center with the follower guides. That is there to induce the rotation required on the follower so that it can wear evenly. What I have noticed on the 1800 motor was that 5 lobes were off set to the one end and 3 were off set to the other end. That means that 5 will turn one way and the other 3 the other way.
When you have a "hot" cut cam the base off the lobe drops very low and into the actual shaft of the cam.
After doing everything right in running in the cam it was destroyed on the 4th day of Targa. About 600kms of racing conditions. (first time around)
My theory....When the follower starts turning as it should because of the off set, it is stopped or slowed down after one complete rotation of the cam when the base of the cam which is now as wide as the follower's head comes in contact with the head. See in the pics how wide the base becomes. I know that there is no pressure on the follower at the time but I am sure that if we could look inside we would have noticed something like that. My method of under cutting the lobes after the "hot" cut worked and after 2 Targas that added up to 1500kms flat out and about 3500kms of touring and a few track days the cam and followers showed normal wear and tear.
In the first few pictures you will see the damage done to the cam and followers of the 1800 engine. I have no pics after the mod but it is the same as done to the new 1600 motor on the last few pictures. The cam Ross had cut according to the Cylinderhead guy is milder than the 1800 cam and it shows because I know that the flat base area is not as bad on Ross's cam although it is there. I have not yet dialed Ross's cam out so I don't know the duration. You will see what it looks like before and after.
Another mod that I do is to assist oil into the follower guides for added lubrication. I take my small angle grinder and fit one of those new thin cutting blades in it. Then I grind a spiral groove into the shaft so that it can draw oil in. Remember to grind 5 the one way and 3 the other way so that the direction of rotation causes the oil to get screwed into the guide.
Running a new cam in on these engines is very important and do it as follows. With a new engine make sure that you assemble it with that special high pressure assembly paste, especially on the lobes. Get oil press before starting. Make sure it will fire up and when it kicks into life rev it to 4000rpm immediately and keep it there for 20 minutes or more. I know it sounds very cruel but you have to do it. Make sure you have a fan ready for additional cooling if needed. The cam will become work hardened.
Regards
Frans.
I have done the work on the cam and I want to re-cap on that issue others and myself had when installing a hot cam in a 807 motor. I am not sure what a mild cam would do but my "hot" is around 295 degrees and higher (advertised duration) This is the info that was lost last year.
So what happens is that the cam and follower destroys themselves with stronger valve springs which is obvious in a racing motor. The 807 motors are designed to have flat surfaced followers and flat or parallel ground lobes on the cam. If you do a dry assembly and you fit the head and cam you will notice that the cam lobes sits off center with the follower guides. That is there to induce the rotation required on the follower so that it can wear evenly. What I have noticed on the 1800 motor was that 5 lobes were off set to the one end and 3 were off set to the other end. That means that 5 will turn one way and the other 3 the other way.
When you have a "hot" cut cam the base off the lobe drops very low and into the actual shaft of the cam.
After doing everything right in running in the cam it was destroyed on the 4th day of Targa. About 600kms of racing conditions. (first time around)
My theory....When the follower starts turning as it should because of the off set, it is stopped or slowed down after one complete rotation of the cam when the base of the cam which is now as wide as the follower's head comes in contact with the head. See in the pics how wide the base becomes. I know that there is no pressure on the follower at the time but I am sure that if we could look inside we would have noticed something like that. My method of under cutting the lobes after the "hot" cut worked and after 2 Targas that added up to 1500kms flat out and about 3500kms of touring and a few track days the cam and followers showed normal wear and tear.
In the first few pictures you will see the damage done to the cam and followers of the 1800 engine. I have no pics after the mod but it is the same as done to the new 1600 motor on the last few pictures. The cam Ross had cut according to the Cylinderhead guy is milder than the 1800 cam and it shows because I know that the flat base area is not as bad on Ross's cam although it is there. I have not yet dialed Ross's cam out so I don't know the duration. You will see what it looks like before and after.
Another mod that I do is to assist oil into the follower guides for added lubrication. I take my small angle grinder and fit one of those new thin cutting blades in it. Then I grind a spiral groove into the shaft so that it can draw oil in. Remember to grind 5 the one way and 3 the other way so that the direction of rotation causes the oil to get screwed into the guide.
Running a new cam in on these engines is very important and do it as follows. With a new engine make sure that you assemble it with that special high pressure assembly paste, especially on the lobes. Get oil press before starting. Make sure it will fire up and when it kicks into life rev it to 4000rpm immediately and keep it there for 20 minutes or more. I know it sounds very cruel but you have to do it. Make sure you have a fan ready for additional cooling if needed. The cam will become work hardened.
Regards
Frans.
Attachments
Thank you Frans for the correct info!
Rod stroke ratio is 1.621 when putting those figures in.
Just in case of a future build, I found 150mm Mitsu 4g63 rods
will fit same BE Journal size but more width a 28.4mm so needs
some shaving of each side. but will need 27.5mm custom pistons
Rod stroke ratio is 1.621 when putting those figures in.
Just in case of a future build, I found 150mm Mitsu 4g63 rods
will fit same BE Journal size but more width a 28.4mm so needs
some shaving of each side. but will need 27.5mm custom pistons
I think 150mm is a bit long a rod for an 84mm stroke if limiting to 8000. It will work of course but I think because the speed with which the piston pulls away from TDC is slower not as much suck on the port is produced and so a small reduction in power would result.
A BMW E30 M3 S14 2.3L has an 84 mm stroke but only has 143mm rods and revving and power aren't a problem. The older M10 2L motor which it mostly replicates has a 135mm rod with an 80mm stroke.
My privateer ex Super Tourer BMW 2L has a short 77mm stroke billet crank and very long 152mm rods, but when this series was limited to 8500 rpm I could not see the point. BMWs own competition 2L engines stayed with the 143mm rods.
A BMW E30 M3 S14 2.3L has an 84 mm stroke but only has 143mm rods and revving and power aren't a problem. The older M10 2L motor which it mostly replicates has a 135mm rod with an 80mm stroke.
My privateer ex Super Tourer BMW 2L has a short 77mm stroke billet crank and very long 152mm rods, but when this series was limited to 8500 rpm I could not see the point. BMWs own competition 2L engines stayed with the 143mm rods.
Is there a limit on rpm in this class? There are some methanol 807 going over 10k rpm
Either way I have to say from 1.621 to 1.786 is hardly a loss when the long
considered perfect ratio is 1.75. If you take for example the Alfa Romeo Twin cam 8v
has very poor valve port angles beyond the later twin spark 8v 45 degree head.
Yet the most successful Alfa Romeo tuner/racers of this engine on the track,
use factory 1.774 or higher ratios which also give over 25+ mpg to boot in racing.
The Alfa twin cams are notorious for the sleeves moving around when the
rod angularity is increased hence the factory aimed for less rod angularity for
durability and improve combustion efficiency at higher rpm.
This is the opposite of Honda or later street engines but for the track the longer
rod allows higher rpm with more efficiency. When you look at some of the street
engines used for the track the rod length is also not often factory length.
If the valve gear can hangle it with 1.786 RSR an 807 can live over 8000rpm.
Problem with 150mm rod in this engine is just the pistons have to be superb quality.
Stock 4g63 evo turbo engines see over 300+hp with stock 150mm rods.
Either way I have to say from 1.621 to 1.786 is hardly a loss when the long
considered perfect ratio is 1.75. If you take for example the Alfa Romeo Twin cam 8v
has very poor valve port angles beyond the later twin spark 8v 45 degree head.
Yet the most successful Alfa Romeo tuner/racers of this engine on the track,
use factory 1.774 or higher ratios which also give over 25+ mpg to boot in racing.
The Alfa twin cams are notorious for the sleeves moving around when the
rod angularity is increased hence the factory aimed for less rod angularity for
durability and improve combustion efficiency at higher rpm.
This is the opposite of Honda or later street engines but for the track the longer
rod allows higher rpm with more efficiency. When you look at some of the street
engines used for the track the rod length is also not often factory length.
If the valve gear can hangle it with 1.786 RSR an 807 can live over 8000rpm.
Problem with 150mm rod in this engine is just the pistons have to be superb quality.
Stock 4g63 evo turbo engines see over 300+hp with stock 150mm rods.
I don't think I would like to turn an 807 to 10K too often. It would be nicer if the crank was fully counter weighted, and of course the valvegear is not suited to this rpm. The valve spring life in competition with 11mm+ of lift and aggressive profiles is about 1500Klm at this Rpm. At least this is when the factory Group A racers from various marques in the 80s and 90s replaced theirs, and pistons, rods and cranks every 3000Klm.
I think 8K is much more realistic and then of course the engine is really only good for race conditions if specifically built and tuned for this, and not driving it home after, given the peakiness of the delivery of power.
Don't know about 25Mpg on the track, generally a good 190Hp 2 valve 2Litre will only get 8mpg on track in my experience. I was using just under 1L / 2.4KLm lap.
For us mere commoners it is all a compromise, with the biggest one being how much can you afford to spend.
I think 8K is much more realistic and then of course the engine is really only good for race conditions if specifically built and tuned for this, and not driving it home after, given the peakiness of the delivery of power.
Don't know about 25Mpg on the track, generally a good 190Hp 2 valve 2Litre will only get 8mpg on track in my experience. I was using just under 1L / 2.4KLm lap.
For us mere commoners it is all a compromise, with the biggest one being how much can you afford to spend.
I know zero about Renault engines but I do know you can't start talking about rod ratios without including lobe centre angles and port/runner volume. The three go together. For example, the 1.9L Mi16 has a fairly ordinary 1.625 rod ratio, but when combined with wide LCA's and big port runner/volume it makes a very nice engine.
All very true, I dont expect to spin over 8500rpm however the non full
counterweighed crank will with the right work be able to see over
10,000 rpm just like oin this follwing speedway engine with stock
rocker gear and some complimenting springs, seats, valves and
other modifications made for this rpm with methanol.
http://www.billzilla.org/renault1.jpg
I still feel an extra point of rod stroke ratio is worth chasing if money
can go as far as a custom piston or motorbike sourced one.
This will allow the engine better longevity at 8k rpm, throught less
rod angularity, sleeve movement and a smidgen longer quench time.
The mi16 engine is a diff beast, similar to todays Honda like trend for
the street eg. multivalves, high rod angularity and port control mechanisms.
A modified 807 is a historic masterpiece.
counterweighed crank will with the right work be able to see over
10,000 rpm just like oin this follwing speedway engine with stock
rocker gear and some complimenting springs, seats, valves and
other modifications made for this rpm with methanol.
http://www.billzilla.org/renault1.jpg
I still feel an extra point of rod stroke ratio is worth chasing if money
can go as far as a custom piston or motorbike sourced one.
This will allow the engine better longevity at 8k rpm, throught less
rod angularity, sleeve movement and a smidgen longer quench time.
The mi16 engine is a diff beast, similar to todays Honda like trend for
the street eg. multivalves, high rod angularity and port control mechanisms.
A modified 807 is a historic masterpiece.