Carbs for a Rover V8
Discussion
Dear people of PH,
Recently, my MGB GT V8 received a fresh(er) engine to replace the original engine that had, to my knowledge, never been rebuilt.
The 'new' engine is a rebuilt Land Rover Disco engine, a 3.5.
It has increased compression, flowed heads, EFI cam, Edelbrock 1403 on JWR manifold, new distributor with RPI ARP Amplifier, ARP mains studs and a Cloyes roller timing chain set. The engine has about 10.000 miles on it, so should be nicely run in.
Rolling road results: 186hp at 4800 rpm (flywheel, 143 at the wheels) when the carb and timing were tweaked at Airey Tuning.
I noticed during my first drive that, below 3.5k rpm, some torque seems to have been lost. The fact that the difference in torque in such a relatively light car is so noticeable, makes me somewhat unhappy to be honest.
Above 3.5k rpm however, there is quite a bit more power than before. (but it's not a track car)
Generally, the engine runs very very smoothly except when I floor the throttle, at which point the car seems to develop a 'hickup'.
Now, there are several ways to fix this, and I'd like to have some of your input on what the wisest approach would be:
Recently, my MGB GT V8 received a fresh(er) engine to replace the original engine that had, to my knowledge, never been rebuilt.
The 'new' engine is a rebuilt Land Rover Disco engine, a 3.5.
It has increased compression, flowed heads, EFI cam, Edelbrock 1403 on JWR manifold, new distributor with RPI ARP Amplifier, ARP mains studs and a Cloyes roller timing chain set. The engine has about 10.000 miles on it, so should be nicely run in.
Rolling road results: 186hp at 4800 rpm (flywheel, 143 at the wheels) when the carb and timing were tweaked at Airey Tuning.
I noticed during my first drive that, below 3.5k rpm, some torque seems to have been lost. The fact that the difference in torque in such a relatively light car is so noticeable, makes me somewhat unhappy to be honest.
Above 3.5k rpm however, there is quite a bit more power than before. (but it's not a track car)
Generally, the engine runs very very smoothly except when I floor the throttle, at which point the car seems to develop a 'hickup'.
Now, there are several ways to fix this, and I'd like to have some of your input on what the wisest approach would be:
- Replace Edelbrock carb, intake etc and refit factory twin SU HS6 setup - with the appropriate needle
- Fiddle with Edelbrock jets etc (to be honest, I'm not quite sure this is going to improve as the car was set up at Airey Tuning, which has quite a good reputation)
- Increase acceleration pump action (either by replacing it or by increasing its duration)
- Some other bright solution I haven't thought of
Have an edelbrock on my Camaro. Used to suffer with from a flat spot when giving it some from light throttle. Certainly a 1st try would be to change which hole on the lever the rod that operates the accelerator pump is in(think I had to bend the rod on mine).
Did a lot of playing with different jets, rods and springs on mine (also fitted a wideband 02 meter). Still have a graph from Edelbrock somewhere with lots of symptons on and which way to adjust things, will try and find it and post it up.
Did a lot of playing with different jets, rods and springs on mine (also fitted a wideband 02 meter). Still have a graph from Edelbrock somewhere with lots of symptons on and which way to adjust things, will try and find it and post it up.
Alex, great news...you have the engine in the car! PH is the wrong forum for this Q? Place the same Q? here
www.v8forum.co.uk/forum/viewforum.php?f=12&sid...
From my side this engine sounds great...though, you know, it is highly probable to lose a little torque with an EFi cam. Do you know the cam's duration? Some loss in torque can be refound with carb' and ignition set up...to drop it down by 500rpm, but with the 3.5 litre torque should be plentiful between 1500-4500. As above, pose the Q?'s to the V8forum guys, then once a plan's in place, get the car set up on a rolling road. The multiple sessions should square up torque/bhp et al.
www.v8forum.co.uk/forum/viewforum.php?f=12&sid...
From my side this engine sounds great...though, you know, it is highly probable to lose a little torque with an EFi cam. Do you know the cam's duration? Some loss in torque can be refound with carb' and ignition set up...to drop it down by 500rpm, but with the 3.5 litre torque should be plentiful between 1500-4500. As above, pose the Q?'s to the V8forum guys, then once a plan's in place, get the car set up on a rolling road. The multiple sessions should square up torque/bhp et al.
To save me grubbing around in the garage and getting shot for putting any greasy finger printed paper in SWMBO's scanner, found the link
http://www.edelbrock.com/automotive/misc/tech-cent...
P35 has a list of symptons
P34 possible solutions
P18 graph for your carb
P19 bits you may need to change
Rest of the manual's good read too, p13 and 14 may be of interest to you.
Edelbrocks are supposedly good 'from the box' IMHO, they all need tweaking.
These guys sell calibration kits and spares
http://www.roadcraftuk.co.uk/#
Anyway ask on other website (as this is the 'wrong place to ask'
) before you start down the road of stripping your carb down after every drive and changing bits, adjusting needles, dropping jets on the floor, swearing and generally smelling of petrol all the time 
.
http://www.edelbrock.com/automotive/misc/tech-cent...
P35 has a list of symptons
P34 possible solutions
P18 graph for your carb
P19 bits you may need to change
Rest of the manual's good read too, p13 and 14 may be of interest to you.
Edelbrocks are supposedly good 'from the box' IMHO, they all need tweaking.
These guys sell calibration kits and spares
http://www.roadcraftuk.co.uk/#
Anyway ask on other website (as this is the 'wrong place to ask'
) before you start down the road of stripping your carb down after every drive and changing bits, adjusting needles, dropping jets on the floor, swearing and generally smelling of petrol all the time .Church of Noise said:
Dear people of PH,
Recently, my MGB GT V8 received a fresh(er) engine to replace the original engine that had, to my knowledge, never been rebuilt.
The 'new' engine is a rebuilt Land Rover Disco engine, a 3.5.
It has increased compression, flowed heads, EFI cam, Edelbrock 1403 on JWR manifold, new distributor with RPI ARP Amplifier, ARP mains studs and a Cloyes roller timing chain set. The engine has about 10.000 miles on it, so should be nicely run in.
Rolling road results: 186hp at 4800 rpm (flywheel, 143 at the wheels) when the carb and timing were tweaked at Airey Tuning.
I noticed during my first drive that, below 3.5k rpm, some torque seems to have been lost. The fact that the difference in torque in such a relatively light car is so noticeable, makes me somewhat unhappy to be honest.
Above 3.5k rpm however, there is quite a bit more power than before. (but it's not a track car)
Generally, the engine runs very very smoothly except when I floor the throttle, at which point the car seems to develop a 'hickup'.
Now, there are several ways to fix this, and I'd like to have some of your input on what the wisest approach would be:
You have two immediate problems. The first is the cam, which is profiled to run an injection engine with a suitably matched distributor. The second is you have compounded this by also changing the distributor. Depending on the type you may be able to alter the vacuum/centrifigal advance to suit the cam and compression. You will almost certainly need to change the jets in the carb.Recently, my MGB GT V8 received a fresh(er) engine to replace the original engine that had, to my knowledge, never been rebuilt.
The 'new' engine is a rebuilt Land Rover Disco engine, a 3.5.
It has increased compression, flowed heads, EFI cam, Edelbrock 1403 on JWR manifold, new distributor with RPI ARP Amplifier, ARP mains studs and a Cloyes roller timing chain set. The engine has about 10.000 miles on it, so should be nicely run in.
Rolling road results: 186hp at 4800 rpm (flywheel, 143 at the wheels) when the carb and timing were tweaked at Airey Tuning.
I noticed during my first drive that, below 3.5k rpm, some torque seems to have been lost. The fact that the difference in torque in such a relatively light car is so noticeable, makes me somewhat unhappy to be honest.
Above 3.5k rpm however, there is quite a bit more power than before. (but it's not a track car)
Generally, the engine runs very very smoothly except when I floor the throttle, at which point the car seems to develop a 'hickup'.
Now, there are several ways to fix this, and I'd like to have some of your input on what the wisest approach would be:
- Replace Edelbrock carb, intake etc and refit factory twin SU HS6 setup - with the appropriate needle
- Fiddle with Edelbrock jets etc (to be honest, I'm not quite sure this is going to improve as the car was set up at Airey Tuning, which has quite a good reputation)
- Increase acceleration pump action (either by replacing it or by increasing its duration)
- Some other bright solution I haven't thought of
If Airey tuning are that good why is your car noit running properly?
J
http://www.advancedautomotives.com/rover-v8-4-x-we...
that may help, a mate had a very similar setup on an old escort with a RV8 in it
changed the car from good to 'kinhell
that may help, a mate had a very similar setup on an old escort with a RV8 in it
changed the car from good to 'kinhell
Fleckers said:
http://www.advancedautomotives.com/rover-v8-4-x-we...
that may help, a mate had a very similar setup on an old escort with a RV8 in it
changed the car from good to 'kinhell
Nice set of carbs, but that's not the answer.that may help, a mate had a very similar setup on an old escort with a RV8 in it
changed the car from good to 'kinhell
Alex, I'll PM you
jith said:
You have two immediate problems. The first is the cam, which is profiled to run an injection engine with a suitably matched distributor. The second is you have compounded this by also changing the distributor. Depending on the type you may be able to alter the vacuum/centrifigal advance to suit the cam and compression. You will almost certainly need to change the jets in the carb.
If Airey tuning are that good why is your car noit running properly?
J
More or less, this. Not certain the issue is with Airey, though understand your thoughts on this.If Airey tuning are that good why is your car noit running properly?
J
The issue with a lot of Rover/RV8/TVR V8 based conversions is that many an engine loses its low-mid range torque because the modifiers fail to understand the Rover/Buick V8 engine. They instinctively throw in a livelier cam, new ignition, carbs et al...and whoosh...peak power goes up and torque takes a nose drive where it's need most, at low-mid power range. A lot of guys experience this when changing the traditional 3.5 unit with a good old pair of trusty SU's with engine putting out 130-160bhp.
What's the opinion of the Quad SU Boxer intake manifolds?
Here's one for £250:
http://www.rodsnsods.co.uk/forum/stuff-sale/rover-...
Here's one for £250:
http://www.rodsnsods.co.uk/forum/stuff-sale/rover-...
Church of Noise said:
Generally, the engine runs very very smoothly except when I floor the throttle, at which point the car seems to develop a 'hickup'.
Now, there are several ways to fix this, and I'd like to have some of your input on what the wisest approach would be:
Hiccuping could be either too rich or too lean, or it might be the distributor advance, or goodness knows what else. All I do know is that you send a car for rolling road tuning to ensure that this sort of thing is sorted out. Now, there are several ways to fix this, and I'd like to have some of your input on what the wisest approach would be:
- Replace Edelbrock carb, intake etc and refit factory twin SU HS6 setup - with the appropriate needle
- Fiddle with Edelbrock jets etc (to be honest, I'm not quite sure this is going to improve as the car was set up at Airey Tuning, which has quite a good reputation)
- Increase acceleration pump action (either by replacing it or by increasing its duration)
- Some other bright solution I haven't thought of
It's odd that they've not managed to get the car to run properly at WOT - that's normally the one to aim for to make the dyno chart look good. You should go back to Airey and tell them they've not finished the job, IMO.
Thanks for all the replies!
The cam should not be the issue IMHO, it is viewed as the replacement for the standard cam and is identical to it (yet there is a difference of 2° in phase).
Do any of you have power&torque curves for 3.5 engines with similar/other carbs, distributors, cams etc?
Last weekend, a mate and me took off the air filter (while the car was standing) and it seems that when you open the throttle wide (ie: when the second stage of the carb opens), air speed drops quite a lot (we based this assumption on the sound of the air being sucked into the engine, not very scientific I know).
First line of thought is to revert to the SUs and see if it makes a lot of difference.
I'll probably be putting it on a rolling road to see what it is putting out now (with the Edelbrock).
Sadly, I'm in Belgium, so going to see Tom Airey is not likely to happen in the very near future. Might give him a call though.
Cheers!
The cam should not be the issue IMHO, it is viewed as the replacement for the standard cam and is identical to it (yet there is a difference of 2° in phase).
Do any of you have power&torque curves for 3.5 engines with similar/other carbs, distributors, cams etc?
Last weekend, a mate and me took off the air filter (while the car was standing) and it seems that when you open the throttle wide (ie: when the second stage of the carb opens), air speed drops quite a lot (we based this assumption on the sound of the air being sucked into the engine, not very scientific I know).
First line of thought is to revert to the SUs and see if it makes a lot of difference.
I'll probably be putting it on a rolling road to see what it is putting out now (with the Edelbrock).
Sadly, I'm in Belgium, so going to see Tom Airey is not likely to happen in the very near future. Might give him a call though.
Cheers!
Firstly the Edelbrock 500 (Carter 500 or Webber 500 all the same carb) is a better carb all round for the RV8 especially at 3500cc. It was especially designed for the smaller V8 & is effectively variable venture the same as the SUs.
There are various charts for calibration & I know RPI in Norwich have a lot of experience setting them up.
Did it run OK when it left Tom Airey? If it did then something has changed, if not then it sounds like he didn't do a good job. I'd have gone to someone with experience of the carb as they are quite different.
One thing I had when I fitted mine was that there are two vacuum ports, timed & opened & you A. need to use the right one & B. block the other one off. Also some manifolds have ports for hoses to scavenge the rocker boxes, again if not used these need blocking otherwise you'll have massive air leaks.
As regards the distributor on mine the dyno guy who was one of the best in the UK on RV8s set it to 28 Deg all out, which from memory was at around 3,500RPM onwards. So that is easy enough to sort.
My TR7 V8 with a mildly tuned Rover 3.5 & one of these on a 360 manifold was awesome.
After that give RPI a ring http://www.v8engines.com/ or +44 (0)1603 891209
There are various charts for calibration & I know RPI in Norwich have a lot of experience setting them up.
Did it run OK when it left Tom Airey? If it did then something has changed, if not then it sounds like he didn't do a good job. I'd have gone to someone with experience of the carb as they are quite different.
One thing I had when I fitted mine was that there are two vacuum ports, timed & opened & you A. need to use the right one & B. block the other one off. Also some manifolds have ports for hoses to scavenge the rocker boxes, again if not used these need blocking otherwise you'll have massive air leaks.
As regards the distributor on mine the dyno guy who was one of the best in the UK on RV8s set it to 28 Deg all out, which from memory was at around 3,500RPM onwards. So that is easy enough to sort.
My TR7 V8 with a mildly tuned Rover 3.5 & one of these on a 360 manifold was awesome.
After that give RPI a ring http://www.v8engines.com/ or +44 (0)1603 891209
Church of Noise said:
Thanks for all the replies!
The cam should not be the issue IMHO, it is viewed as the replacement for the standard cam and is identical to it (yet there is a difference of 2° in phase).
Do any of you have power&torque curves for 3.5 engines with similar/other carbs, distributors, cams etc?
Last weekend, a mate and me took off the air filter (while the car was standing) and it seems that when you open the throttle wide (ie: when the second stage of the carb opens), air speed drops quite a lot (we based this assumption on the sound of the air being sucked into the engine, not very scientific I know).
First line of thought is to revert to the SUs and see if it makes a lot of difference.
I'll probably be putting it on a rolling road to see what it is putting out now (with the Edelbrock).
Sadly, I'm in Belgium, so going to see Tom Airey is not likely to happen in the very near future. Might give him a call though.
Cheers!
Are the secondaries vacuum or mechanically operated?The cam should not be the issue IMHO, it is viewed as the replacement for the standard cam and is identical to it (yet there is a difference of 2° in phase).
Do any of you have power&torque curves for 3.5 engines with similar/other carbs, distributors, cams etc?
Last weekend, a mate and me took off the air filter (while the car was standing) and it seems that when you open the throttle wide (ie: when the second stage of the carb opens), air speed drops quite a lot (we based this assumption on the sound of the air being sucked into the engine, not very scientific I know).
First line of thought is to revert to the SUs and see if it makes a lot of difference.
I'll probably be putting it on a rolling road to see what it is putting out now (with the Edelbrock).
Sadly, I'm in Belgium, so going to see Tom Airey is not likely to happen in the very near future. Might give him a call though.
Cheers!
I can recommend the chap who rebuilds my twin carbs he rebuilds them to a very very high standard and often has carbs in stock for the V8's this link is his eBay site.
http://www.ebay.co.uk/itm/Rebuilt-750-cfm-Holley-C...
http://www.ebay.co.uk/itm/Rebuilt-750-cfm-Holley-C...
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