This is the first time I have seen Mallory Park for a very long time and the only changes that are noticeable are the trees at the hairpin are gone! Back in 1965/6 I took part in the then annual Apprentices Soapbox Derby around Mallory. This was a challenge open to all the motor manufacturers in the country & being the closest circuit to the main manufacturers it was fully supported by all those from Birmingham, Coventry and further a field. Each companies apprentices had to design, build and then race their soapbox against all the others in a (if I remember) a 3 or 5 lap race with a team of relay runners who did approximately 200 yards at a time. I was in the team from Rootes Group in Coventry (I was a body design apprentice at the time. With The IMP as one of the main vehicles I work on!)
hi John, yes the good old days he sounds like fun with the soapbox racing. I haven’t been to Mallory since 2002 and have to say it’s one of my all-time favourite circuits great for the Imp and other small cars cheers Andy
Andy, You were right about the thickness of the piston where it blew. My first thought for the fuel starvation was a collapsed line due to either a blockage or a vacuum surge, but after seeing the setup I dismissed that idea! One idea to overcome this problem would be to introduce both a swirl pot below the fuel tank with its own vent pipe that ran up the side of the "A" pillar so it was well above the max height of the fuel line & carbs! Another trick I herd of was to have the fuel line as it ran through the car to increase in diameter to one inch which gives the fuel time to settle and has the added benefit of adding to capacity!
not too sure I like the idea of a 1 inch fuel pipe running through the car he he however I am going to change the fuel pump for a larger one as everyone I’ve told about my little solid state facet says they are rubbish
Really enjoyed your autopsy of what happened Andy. Shame you couldn't enjoy the full race weekend. Watching you guys makes me just want to come and play, one day
I feed my twin DHLAs centrally for that reason. Plus there's a big bowl FilterKing pressure regulator just before the carbs in the engine bay which probably acts as a mini swirl too. I adjust fuel pressure on the FilterKing between 2 to 4 psi for DHLAs. Great video.
I like your reasoning for the failure. Seems spot on to me. Perhaps alter the fuel to feed the carbs centrally, and if possible create a return feed to the tank so it will bleed off in the event of a similar occurrence. Less weight in fuel has got to be an advantage. Great video once again.
Great channel Andy, like the way you're ready to try different ideas, then build them, test on the dyno and race, really entertaining watch, well done.
Hi Andy, had a few instances on Webber’s where the banjo gauze filter scrunches up and stops flow of fuel, especially on race cars. Spent hours trying to find that one
Back in the 70's we used to have problems with some cylinders on Lotus's on Webbers, running weak, and it was often the rubber mounting flanges between the carbs and the inlet manifold getting brittle and cracking. They were meant to stop the vibration frothing the fuel in the float chambers.
Great to see you over the weekend and really sad the car broke - you were flying before that! Can’t offer any more on the fuel thing - other than did you fill up with fuel from the same source as Mike? Remember the paint/plastic crud we found in the jet… could it have been something similar but when you gave it some beans to yank the car out of the kitty litter it dislodged it? I couldn’t hear any misfire trackside (til it gave up) and in fact it sounded really crisp.
hi Tim, yes me too. Wasn’t the best of days on the fuel side. I’m pretty convinced it’s an airlock caused by the fuel surge. Thanks for your comments. Speak to you soon andy.
Great video Andy love the driver interview and track action footage. Really glad that you took the time to strip your engine so we could all see what exactly happened and why you exited the race. Such a shame you went out would have been awesome to watch 5 imps fight it out on that hairpin !!! It's odd that just the one carb was lean or lacking fuel, the margin of fuel loss would have to be very close for only one carb to go dry whilst the other didn't. Could the float level play a part in this? Any time I have had problems with lack of fuel from hard or long cornering, it's been linked to having a low float or low tank.
thanks, graham. It’s a new problem so I’m assuming it’s all down to the long right hand at Mallory Park. Hopefully we can sort it out and the problem will go away and never come back.
A return feed and a swirl pot are both good ideas. Might be stating the obvious here but are the float levels set the same on both carbs? And could the float on the carb be catching so as to not allow full flow through the needle valve?
Hi Andy Fuel pickup sounds likely… I had something similar on a Mk.1 Elite (also twin webers), which we finally fixed by fitting a 1 litre swirl pot between tank and carbs.. after that we didn’t have to go out for quali with the tank half full! I stopped racing when COVID came, & still have lots of race bits including a swirl pot: I’ll send it to you if you want to try it out. (FOC - I don’t need it!). Let me know… Peter R
Wouldn’t hurt to put a heat shield between exhaust manifold and carbs: those pipes radiate a lot of heat at full chat & fuel temp in the carbs can affect mixture etc.
hi Peter, thank you for your kind offer. I think we have sorted the problem out now or at least have a plan on how to? Thanks for all the help on the TH-cam channel. Sorry you’ve not been out Racing since Covid maybe one day cheers Andy.
Holley makes a fuel pickup called hydramat that a pretty good fix for fuel tank surge problems. Might avoid the need to reengineer the tank with baffles/ surge tanks etc.
Hi Andy, I can buy that fuel surge in lap 1 could cause the knocking. I would think it should clear quickly though so long as the float bowl venting is good. Perhaps you could try a 500ml pot after the fuel tank as low down as you can fit it. That would be much less likely to surge in corners or braking. Or go a little bigger and foam fill it.
Hi Andy. Hard to see how fuel surge would affect only one carb but I guess it's possible. Silly suggestion maybe, but I worked on a lawnmower that would only cut out under load, otherwise it would drain the tank. Took a while to get it to do what the customer was complaining of and believe it or not it was a dead fly in the fuel hose which had been in there from the factory. Enough flow to keep the engine running at full revs for a complete tank of fuel when on test, but when under load mowing the lawns outside the shop it eventually cut out as he said. Anyway, did you check for a fuel line blockage between the carbs? Unlikely I know, but worth a check. If it is surge then possibly installing a small header tank with a return pipe and gravity feed to the carbs might be a simple answer. Enjoyed the video and the interview with the other Imp drivers. Hopefully you'll quickly get this issue sorted and have better luck at your next event!
Something to think about are the needle and seats able to flow enough fuel (lpm) and pressure at the same time under all driving conditions ? why i say this is it should be using fuel from float bowl ,how long does it take to consume that before running lean are they a restriction in fuel flow under load
hi, yes they are 175. I use them on all the Imp engines. I’m assuming it was the slug of air from the surge in the tank that was causing the float level to drop and the engine to run lean.
How about fitting a second “Swirl Pot” tank, like you need to do to prevent this effect with EFI cars? Now that the notion is in your head that you have a fuel surge problem it will be hard to forget about it without fitting an iron clad solution. It’ll be a little added weight but less than running the tank with access fuel in it, probably.
hi I am confident we can do the job and make it work without having to fit a swirl pot as well. A new pump and improve tank pick up well hopefully fix a job. Thanks for your comment.
I like your theory. So the damage to the spark plug is secondary to the initial starvation incident on the long corner? Have you seen Rob’s tank from radtec? if I ever afford to get a flying imp engine, I will get one of those. Submerged pump with baffling
Fit a weighted flexible pick up pipe in the tank like a chain saw, a college of mine had a problem at gerards and had to fit a second float chamber to his outfit!
Something i was going to try as to regard cooling was to reverse direction of flow .That is to feed cooled(?) coolant to the Thermostat housing end ,hence cooling the hottest area first( cylinder head) ,not the front end of the block. This theory was tried or rather used by a top Fiat Abarth driver in the USA.. Maybe something for you to carry on as in regard to a worry over detonation.
hi DAVID, yes you have a good point running the cold water into the hot hottest part of the head but I think the theory of the heat rising may cause the reverse flow not to work so well it may be worth a trying though thanks andy
This is the first time I have seen Mallory Park for a very long time and the only changes that are noticeable are the trees at the hairpin are gone!
Back in 1965/6 I took part in the then annual Apprentices Soapbox Derby around Mallory. This was a challenge open to all the motor manufacturers in the country & being the closest circuit to the main manufacturers it was fully supported by all those from Birmingham, Coventry and further a field. Each companies apprentices had to design, build and then race their soapbox against all the others in a (if I remember) a 3 or 5 lap race with a team of relay runners who did approximately 200 yards at a time. I was in the team from Rootes Group in Coventry (I was a body design apprentice at the time. With The IMP as one of the main vehicles I work on!)
hi John, yes the good old days he sounds like fun with the soapbox racing. I haven’t been to Mallory since 2002 and have to say it’s one of my all-time favourite circuits great for the Imp and other small cars cheers Andy
Must be the best showing so far as i liked the variety of the content .Good to see what the contingent of CTCRC Imp drivers look like.
thanks, DAVID. Yes, I thought you might like seeing all your old pals out Racing.
Andy, You were right about the thickness of the piston where it blew. My first thought for the fuel starvation was a collapsed line due to either a blockage or a vacuum surge, but after seeing the setup I dismissed that idea! One idea to overcome this problem would be to introduce both a swirl pot below the fuel tank with its own vent pipe that ran up the side of the "A" pillar so it was well above the max height of the fuel line & carbs! Another trick I herd of was to have the fuel line as it ran through the car to increase in diameter to one inch which gives the fuel time to settle and has the added benefit of adding to capacity!
not too sure I like the idea of a 1 inch fuel pipe running through the car he he however I am going to change the fuel pump for a larger one as everyone I’ve told about my little solid state facet says they are rubbish
Really enjoyed your autopsy of what happened Andy. Shame you couldn't enjoy the full race weekend. Watching you guys makes me just want to come and play, one day
hi Noel thanks yes glad you enjoyed the video and I will be on with your 1040 that engine soon so you can come out and race us cheers andy
I feed my twin DHLAs centrally for that reason. Plus there's a big bowl FilterKing pressure regulator just before the carbs in the engine bay which probably acts as a mini swirl too. I adjust fuel pressure on the FilterKing between 2 to 4 psi for DHLAs. Great video.
thanks yes I run three psi fuel pressure when I’ve got fuel that is ha ha
I like your reasoning for the failure. Seems spot on to me. Perhaps alter the fuel to feed the carbs centrally, and if possible create a return feed to the tank so it will bleed off in the event of a similar occurrence. Less weight in fuel has got to be an advantage.
Great video once again.
thanks for kind comments Steve. Yes, central carb tee piece could be the answer
Great channel Andy, like the way you're ready to try different ideas, then build them, test on the dyno and race, really entertaining watch, well done.
hi, thanks for kind comments. Yes, it’s a bit like Andy‘s toy shop rather than Workshop.
Hi Andy, had a few instances on Webber’s where the banjo gauze filter scrunches up and stops flow of fuel, especially on race cars. Spent hours trying to find that one
Back in the 70's we used to have problems with some cylinders on Lotus's on Webbers, running weak, and it was often the rubber mounting flanges between the carbs and the inlet manifold getting brittle and cracking. They were meant to stop the vibration frothing the fuel in the float chambers.
hi, yes all the my o rings were new and couldn’t see any evidence of air leaks. Thanks for your comment.
I like the way you've thought this through, and to me it sounds totally plausible. I guess time will tell. Better luck next race!
thanks, Ralph. Yes, hopefully we will finish up brands with the trophy.
Is it possible the rear carb boiled? Maybe put some temperature labels and heat shields on them. :)
hi, I would hope not the evaporation norm causes the carb is to run very cold
Great to see you over the weekend and really sad the car broke - you were flying before that! Can’t offer any more on the fuel thing - other than did you fill up with fuel from the same source as Mike? Remember the paint/plastic crud we found in the jet… could it have been something similar but when you gave it some beans to yank the car out of the kitty litter it dislodged it? I couldn’t hear any misfire trackside (til it gave up) and in fact it sounded really crisp.
hi Tim, yes me too. Wasn’t the best of days on the fuel side. I’m pretty convinced it’s an airlock caused by the fuel surge. Thanks for your comments. Speak to you soon andy.
Great video Andy love the driver interview and track action footage. Really glad that you took the time to strip your engine so we could all see what exactly happened and why you exited the race. Such a shame you went out would have been awesome to watch 5 imps fight it out on that hairpin !!! It's odd that just the one carb was lean or lacking fuel, the margin of fuel loss would have to be very close for only one carb to go dry whilst the other didn't. Could the float level play a part in this? Any time I have had problems with lack of fuel from hard or long cornering, it's been linked to having a low float or low tank.
thanks, graham. It’s a new problem so I’m assuming it’s all down to the long right hand at Mallory Park. Hopefully we can sort it out and the problem will go away and never come back.
A return feed and a swirl pot are both good ideas. Might be stating the obvious here but are the float levels set the same on both carbs? And could the float on the carb be catching so as to not allow full flow through the needle valve?
hi, yes, both float levels looked identical and nothing catching that. I can see.
Hi Andy
Fuel pickup sounds likely… I had something similar on a Mk.1 Elite (also twin webers), which we finally fixed by fitting a 1 litre swirl pot between tank and carbs.. after that we didn’t have to go out for quali with the tank half full!
I stopped racing when COVID came, & still have lots of race bits including a swirl pot: I’ll send it to you if you want to try it out. (FOC - I don’t need it!). Let me know… Peter R
Wouldn’t hurt to put a heat shield between exhaust manifold and carbs: those pipes radiate a lot of heat at full chat & fuel temp in the carbs can affect mixture etc.
hi Peter, thank you for your kind offer. I think we have sorted the problem out now or at least have a plan on how to? Thanks for all the help on the TH-cam channel. Sorry you’ve not been out Racing since Covid maybe one day cheers Andy.
yes, very good point that’s on my to do job list
Holley makes a fuel pickup called hydramat that a pretty good fix for fuel tank surge problems. Might avoid the need to reengineer the tank with baffles/ surge tanks etc.
thank you I will check it out
Hi Andy, I can buy that fuel surge in lap 1 could cause the knocking. I would think it should clear quickly though so long as the float bowl venting is good.
Perhaps you could try a 500ml pot after the fuel tank as low down as you can fit it. That would be much less likely to surge in corners or braking. Or go a little bigger and foam fill it.
thanks, yes, we have a plan similar to your suggestion
Hi Andy. Hard to see how fuel surge would affect only one carb but I guess it's possible. Silly suggestion maybe, but I worked on a lawnmower that would only cut out under load, otherwise it would drain the tank. Took a while to get it to do what the customer was complaining of and believe it or not it was a dead fly in the fuel hose which had been in there from the factory. Enough flow to keep the engine running at full revs for a complete tank of fuel when on test, but when under load mowing the lawns outside the shop it eventually cut out as he said. Anyway, did you check for a fuel line blockage between the carbs? Unlikely I know, but worth a check.
If it is surge then possibly installing a small header tank with a return pipe and gravity feed to the carbs might be a simple answer.
Enjoyed the video and the interview with the other Imp drivers. Hopefully you'll quickly get this issue sorted and have better luck at your next event!
hi, thanks for kind words. Yes, checked everything for blockages. Can’t see anything all looks very clean. We will fix it up and try again.
Something to think about are the needle and seats able to flow enough fuel (lpm) and pressure at the same time under all driving conditions ? why i say this is it should be using fuel from float bowl ,how long does it take to consume that before running lean are they a restriction in fuel flow under load
hi, yes they are 175. I use them on all the Imp engines. I’m assuming it was the slug of air from the surge in the tank that was causing the float level to drop and the engine to run lean.
Have you checked the float level between the two carbs?
yes, they are identical thanks andy
How about fitting a second “Swirl Pot” tank, like you need to do to prevent this effect with EFI cars? Now that the notion is in your head that you have a fuel surge problem it will be hard to forget about it without fitting an iron clad solution. It’ll be a little added weight but less than running the tank with access fuel in it, probably.
hi I am confident we can do the job and make it work without having to fit a swirl pot as well. A new pump and improve tank pick up well hopefully fix a job. Thanks for your comment.
Are you not running a wideband O2 sensor to keep track of the mixture?
nope, it’s a Hillman Imp not a Nissan skyline 🤣🤣🤣
How was the updated steering at Mallory?
hi, the new needle roller steering column was absolutely amazing. I loved it. The car felt awesome until it stopped.
I like your theory. So the damage to the spark plug is secondary to the initial starvation incident on the long corner? Have you seen Rob’s tank from radtec? if I ever afford to get a flying imp engine, I will get one of those. Submerged pump with baffling
Fit a weighted flexible pick up pipe in the tank like a chain saw, a college of mine had a problem at gerards and had to fit a second float chamber to his outfit!
thanks,
Grace, hi there I’m going to modify the Pick Up pipe with a heavyweight
Something i was going to try as to regard cooling was to reverse direction of flow .That is to feed cooled(?) coolant to the Thermostat housing end ,hence cooling the hottest area first( cylinder head) ,not the front end of the block.
This theory was tried or rather used by a top Fiat Abarth driver in the USA..
Maybe something for you to carry on as in regard to a worry over detonation.
hi DAVID, yes you have a good point running the cold water into the hot hottest part of the head but I think the theory of the heat rising may cause the reverse flow not to work so well it may be worth a trying though thanks andy
Gerrards was a right hander the last time I raced at Mallory!!!
ha ha, knew someone would pick up on that cheers andy
Great video
🏎🏎🏎🏎🏎