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May 24, 2016 10:52:37 GMT
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Peak flow is not the be all and end all for a head. The important thing is the area under a flow graph - but as the biggest area is under the biggest number peak flow it is important but so is the flow throughout the valve lift, you modify and test to get the best flows at every mm of lift. thanks for the reply again  i guess my next question is, how do you get it right (or rather how do you not mess it up) when you've got 1 head on the flow tester and can only remove metal ? |
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May 24, 2016 12:23:29 GMT
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Buy another 10 identical heads and then use trial and error.
Research and development is never free!
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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May 24, 2016 17:48:36 GMT
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flyingphil
Posted a lot
Posts: 2,485
Member is Online
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May 24, 2016 20:00:43 GMT
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The picture of the two RV8 valves was very interesting, would the modified one be similar to those valves said to be "3 angle cut" and allow more flow in that crucial region when the valve is close to the seat? This is when the "curtain"? area round the valve, is less than the throat area of the valve seat, to provide the flow restriction?
I remember spending hours in a cold garage with an upside down RV8 head, letting paraffin flow past a valve at various lifts in an attempt to measure increased flow rates as I ground out the seat/throat/port area. I did get a better flow for sure (and the heads did get my Comp Altered into the 11.6's with a pre SD1 3.5 on petrol).
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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May 24, 2016 23:27:30 GMT
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The picture of the two RV8 valves was very interesting, would the modified one be similar to those valves said to be "3 angle cut" and allow more flow in that crucial region when the valve is close to the seat? This is when the "curtain"? area round the valve, is less than the throat area of the valve seat, to provide the flow restriction? I remember spending hours in a cold garage with an upside down RV8 head, letting paraffin flow past a valve at various lifts in an attempt to measure increased flow rates as I ground out the seat/throat/port area. I did get a better flow for sure (and the heads did get my Comp Altered into the 11.6's with a pre SD1 3.5 on petrol). These valves run on a radiused insert - special ground cutter to form them - with just a 45 topped onto them to provide the seat of the valve. The valve is a stock medium valve but the seat width forms a tiny little lip onto the back of the valve just enough to be felt with a finger nail - maybe 10thou. That little lip effects flow from .050" to .300" Curtain area shrouding tests - there is quite a bit of shrouding in the small bore deep chamber heads - the 3.9 engines flow a bit more due to less shrouding from cylinder walls and the 4.6 heads flow a bit more still due to the shallower chamber but work in the chamber pays off with flow.    Rover heads are great for getting quick gains out of as they have quite a few big restrictions, an extra 50BHP is quite easy to get with not a great deal of work but getting really good numbers takes a lot of work which is why good RV8 heads are so expensive. Then again those new TRS heads are just in another league. |
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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May 28, 2016 18:30:32 GMT
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Everyday is a school day. A short while ago I decided to have a look for a car for my son to learn to drive in and I saw this on this forum - VW Polo Genesis not to far from me small enough to fit on the Clubman trailer that I have and quite a cool little car. Picked it up from Barry - VW enthusiast and thoroughly nice guy and the specification of these Genesis versions really impressed me. We got it back gave the starter a wallop with a big stick and it started right up. We wanted to give it a service and check it over as it had been standing for a while so we did a compression test and it came up with decent figures on all 4 but was running a little off. Down to CES and got a full set of service parts and a few spares like exhaust hangers etc. Gave it a wash and it flew through the MOT - Cheap tax job done on the road.  So whats the school day? Starter motors I'm from an era of inertia starters and early pre-engange types and after giving the Polo starter motor a thump it performed well until recently when the non starting returned and no amount of thumping got it to turn over so it was out with it to investigate. Stuck it on the bench and tested it and the solenoid coil would not pull in. further investigation required. A while back the starter on our L200 packed up - all sorts of screeching noises and not much engine turning and this is when I found out that at some point in the development of pre-engaged starters they had started to fit sprag clutches to the pinion and on this one the clutch had given up - a few quid for new clutch and its not missed a beat since. The clutch was fine on the Polo starter motor by the way - Anyway after doing a bit of chasing around contacts with the Ohmmeter I saw that the solenoid coil was connected to the positive connection of the starter motor as well as the casing and earth !! How in hell does that work? - Need a solenoid wiring diagram so off to google. What they do is quite clever and logical. The Solenoid has 2 coils a high power pull in coil and a low power hold in coil. Basically it takes a lot of effort to draw the core into the windings but once in - it only takes a small amount of power to hold it.  As you can see in the image above - The pull in coil has a connection to the ignition switch on one side and the earth is made through the field windings of the motor so when the coil is pulled in 12V is put to both sides of that coil which stops the high current draw and therefor prevents ignition switches getting cooked when people just hold the starters on. So what was wrong with ours? - The comm connections on the motor in one place only had got a little burnt and blackened and so not making a good enough connection to earth to pull the solenoid in. a Quick clean up of the comm and back together and it starts much better time will tell if its a good fix. School day for me I did not realise that they had 2 coils - clever. |
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Last Edit: May 28, 2016 18:38:30 GMT by Darkspeed
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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Well that's it for the Polo for a short while. We did a little bit more work on it last weekend to remove and old alarm system which was chopped into this and that. It probably served its purpose many years ago along with the armour door plates but now its just a liability so we saved a bit of weight and reconnected the drivers side heater/air vent ducting at the same time.
One benefit that has come from doing the starter is the improvement in the way the car now runs. The car still has all the original warm air ductwork and damper system on the air cleaner but the vacuum connections were what looked like bits of washer pipe and electrical tape. Normally I would just remove the warm air ductwork from the air cleaner and plug off the vacuum connection but as this car is so original and it all works, I just renewed the vacuum line connections with some proper vacuum tube. I am continually amazed at how some cars are so sensitive to silly things like this, some cars have a high tolerance to leaks, others run like a dog unless everything is perfect. This Polo is a bit of a half way in that it ran okay, what do you really expect from a 1.0L, but with the vacuum all sealed and not leaking on this one little item it has what feels like another 10BHP, it was that or the alarm and wiring was heavier than I thought.
On the G31 carb front the 40DFA will only be stop gap as its not the most adaptable carb there is. I had a re-read of the SOHC Vizard book and he had found the same thing. For top end running and flow it's great but for driveability it's pretty darn poor but for the moment until I find a new top of the DGAV it will have to do.
Tatton park show this weekend and manning the Ginetta stand - fingers crossed the old wreck it makes it there.
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VIP
South East
Posts: 8,302
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Perhaps do a separate thread on the Polo, it gets very confusing following folks progress when they have multiple cars in one thread, especially if the reader only has interest in one of those cars.
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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Perhaps do a separate thread on the Polo, it gets very confusing following folks progress when they have multiple cars in one thread, especially if the reader only has interest in one of those cars. I thought about that but it's not my car it's the lads plus, the things that I have posted about it are general in nature and can apply to any old car. It's just a minor diversion and I could see little point in a thread on a Polo with four posts. I find the best threads that I follow do have the occasional twist and turn away from the main theme. @johnnybravo being one of my absolute fave's- Interest in only one car !!!! - all old cars are interesting  I will get back to the Strat - Just lost a bit of motivation recently and picking it up with doing little bits here and there on other things helps. |
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Perhaps do a separate thread on the Polo, it gets very confusing following folks progress when they have multiple cars in one thread, especially if the reader only has interest in one of those cars. Speaking as one of those of us with 3 or 4 cars plus other projects I don't think I would manage to maintain multiple threads so the result would be far less content on here. |
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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Been a busy couple of weeks with one thing and another - mostly car related - This weekend I was lazing around drinking tea and talking carp about cars all weekend on the Ginetta Owners Clubs stand at Tatton park - What a weekend - superb and nice to meet up with Rebuilda who has been good enough to sort out a few tops for my Weber 32/36 DGAS. I also have another good 32/36 from Ade that I will do some mods on, whether on this tread or another we will see. The 40DFA is not a great carb for the Pinto at all and it would take a fair amount of work to get it jetted correctly and even then it would not be anywhere as good as a 38DGAS or a modified 32/36DGAV - done it's job so it can go back to its owner and back onto ebay. Strato's work zero but I should be back on it this weekend with a little luck. |
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Anglia68
Posted a lot
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Your comments on the 40DFA have saved me a few quid as I was very tempted to buy one for my crossflow, I'm a bit of an impulse buyer, which I now know would have been a waste of time and money so I'll be sticking with my 32/36, which is more than good enough.
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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Jun 14, 2016 20:02:13 GMT
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Your comments on the 40DFA have saved me a few quid as I was very tempted to buy one for my crossflow, I'm a bit of an impulse buyer, which I now know would have been a waste of time and money so I'll be sticking with my 32/36, which is more than good enough. 32/36 will run a cross flow quite well - It's more likely to be the manifold that will be the thing that holds the engine back as they are quite compact. I have a job on the list to bore out a 32/36 and carry out a few mods and do a before and after on the bench so may be of interest as I will do it without any special tools. Not much has been happening on the Stratos for a bit as I have had a couple of weekends out with the Ginetta crowd and I have been doing a bit of work on my G27 chassis just sanding it back ready for some primer.  Still loads to do especially in the wheel arch area where the years have taken a toll  Something has been happening with the Strato's I fitted the lamp housings to the pods and fitted them into the front clam    The trims need a bit of fettling as they are from the old bodywork - still mulling over whether to get new ones but they look okay at a distance   What I must remember to do it put a drain hole in the lamp boxes as even with a very good cover the recent rain we have had has made its way in and I have small pool developing. Next chapter should really be getting the engine out. |
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ndg
Part of things
Posts: 109
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Jun 14, 2016 20:36:12 GMT
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Happy Stratos: Sad stratos: |
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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Jun 14, 2016 21:05:02 GMT
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A distinct lower lip quiver appears to be going there - LOL
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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Jun 25, 2016 19:34:52 GMT
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Quite a lot of sunshine today so I had a good work window to get a few jobs done - a good ten hours work in fact. Started off - removed the rear clam - took the exhaust system off and popped it up on stands  Drained the gearbox oil out - very nice and clean - and removed the drive shafts  Sighs and shakes head again at this support  Remove the oil cooler, the rear manifold and slacked all the bolts on the engines mounts - Interestingly , well for me anyway there was no load on the the top mount at all - all the load is being taken by the two lower mounts which may explain the lower chassis supports bending.     As the cooling system and wiring were removed a fair old time ago it was time to wrap some old rope arouns the engine and drag the crane up from the bottom of the garden. A few bumps on the handle and up and out she comes.  Cover was back on the car for bit as the summer sunshine started falling from the sky  Space, the place where an engine used to be.  More sighing and shaking of head.  So there we have, it nice clear empty engine bay. |
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Jun 25, 2016 19:47:08 GMT
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That could have been made in Worthing...  |
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1988 DUTTON LEGERRA MK1 - SPARES DONOR
1989 DUTTON LEGERRA MK2 - CURRENT PROJECT
1990 DUTTON LEGERRA ZS MK2
1990 DUTTON LEGERRA ZS MK2
DUTTON PHAETON S2 - Resting
DUTTON PHAETON S4 - Resting
DUTTON PHAETON S4 - PROJECT X
DUTTON SIERRA S2 - Resting
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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Jun 25, 2016 20:16:33 GMT
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With a nice big workspace there was the opportunity to have a close look at the new fuel tank that came with the car - Not a hope of it fitting without cutting out one of the crappy chassis tubes that had been part of the modifications to the original chassis when it cracked. The tank had been drawn up by the previous owner to fit in the space but not enough consideration was given as to how to actually get it in there - It should have been manufactured about 4" shorter and it would have dropped in quite nicely but not an issue with removing the tube as they are all coming out anyway.   I will give some thought as to whether or not I have the tank modified and chopped down, or if I simply chuck it in the bin and have an alloy one made that will take an internal pump.  That ones for another day. |
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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Jun 25, 2016 20:25:39 GMT
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That could have been made in Worthing... - Speaking of Worthing - but nothing to actually do with Worthing I have that second ported 32/36 DGAV in progress that will show up in this thread in a few days - chokes are now out at 30mm and I am just blending the choke in the 32 - Would have completed it this weekend but in-between the works on the Stratos I am grafting a new front end on a G15. |
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Last Edit: Jun 25, 2016 20:27:33 GMT by Darkspeed
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Darkspeed
Club Retro Rides Member
Posts: 4,882
Club RR Member Number: 39
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Jun 25, 2016 20:56:29 GMT
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The Honda engine when dressed for it's work in the Rover 827 looks very uninspiring and dull but under all that safety and emissions curse word is a very good engine - Its a really compact engine with a very strong bottom end. The 90 degree spacing makes it quite low which is good for C of G and as I have two of them I am going to have a play with these for the time being before contemplating anything else. Job one with the engine is to clean it up and make it lighter One thing I must mention again if not make clear previously - I really hate red paint on engines and chassis - especially when that engine is all aluminium. Monstrous intake plenum removed along with all the electrics and quite a few hoses and the like.  Out with the Dyson I think.  Off with all the timing covers timing belt and pulleys and drill a hole here  And another here  All the way through and into the cam cover  So that when you remove the backing casings for the cam belt covers you still have timing marks to set the pulleys against - Now that looks a bit better much more agressive and more importantly lighter.  This monstrosity will also go on a diet over the weekend  Drop one of the throttle bodies on just for the hell of it and operate with a grubber finger - more aggression.   And that's me cream crackered |
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