Fuel starvation??? 5.0 RV8, Stage 3, eddy carb in a Landy 90

DaviesDJ · Post by **DaviesDJ** » Mon Aug 27, 2012 9:50 pm

Thought of that, checked and changed them, fine it seemed.

DaviesDJ · Post by **DaviesDJ** » Fri Aug 31, 2012 8:20 pm

Didn't work!! Facet gold flo fuel pump installed and working, engine running, revs to 4000 then farts and sputters still!! Crap!! Time to look at ignition, am a bit worried that it may be valves hitting pistons when the high rev lifters 'pump up'??? Runs sweetly at lower than 4000 though. Haven't had it on the road since new fuel pump installed though. Any thoughts?? Could it be a weak spark being "blown out" when gas velocity rises at higher revs???

Ian Anderson · Post by **Ian Anderson** » Fri Aug 31, 2012 8:31 pm

What is a facet gold flow fuel pump?

If it is one of those little square things they do not normally flow enough for high hp engines.

Ian

DaviesDJ · Post by **DaviesDJ** » Sat Sep 01, 2012 7:28 am

Aftermarket fuel pump, tubular quite large, rated to over 40 gallons and hour, have a regulator off it set to 4.4 psi (max of 5). Should flow enough for revving at idle (at least!!!)

sidecar · Post by **sidecar** » Sat Sep 01, 2012 7:39 am

Do the flow test at the carb end of the fuel system, i.e after the regulator!

You can not even go on what the pump manufacturer states, my old silver top according to Facet was only good for 150 BHP or something like that but it worked fine on my 300 BHP engine.

Your system will need to flow 1 litre every 30 seconds if your engine is making 300+ BHP.

Having said all that if it won't rev in neutral then the problem is something else.

I did have a coil go funny once, the car was fine below 3k RPM but higher than that it would be fine for about 10 seconds then it would misfire. If I held the revs high for say 20 seconds the ignition would totally shut down for about 30 seconds. The engine would just die but would light up again half a minute later.

As to valves hitting the pistons do you have a high lift cam? have the heads been skimmed and are there any cut outs in the pistons?

I don't think that lifters pump up in the way that some people think they do, they pump up when a valve floats because there is then no pressure on the lifter. The pump up then cause that valve to stay open even when the lifter is back on the base circle of the camshaft. This causes the engine to loose power and misfire which is exactly what is supposed to happen. So really the revs that this happens at is 'mainly' determined by the valve springs. I presume that you have decent springs?

sidecar · Post by **sidecar** » Sat Sep 01, 2012 7:48 am

OK this is all very rough but 40 US gallons an hour is 160 litres an hour.

(4 litres = 1 US Gallon)

So 160 litres an hour is 2.6 litres per minute or 1.3 litres every 30 seconds.

So your pump should be OK but your regulator might not be. Like I said either in a post or a PM a bloke on the Cobra Forum had a regulator that staved the engine.

If the pump is not higher than 6.5-7 PSI I'd ditch the regulator as its not needed.

sidecar · Post by **sidecar** » Sat Sep 01, 2012 7:57 am

According to youtube its around 4 PSI so you don't need the regulator

DaviesDJ · Post by **DaviesDJ** » Sat Sep 01, 2012 10:45 pm

A breakthrough!!! The timing marks on my crank pulley are obviously shite!! I retarded a few degrees and it seems much better!! Must have been detonating under load and when the final "all in advance kicked in" - the fuel pump has made a difference because it's not leaning out now (11.5 AFR) - think some road testing might help more. Think I was just running too much advance, and my timing marks are not correct. Never checked them win a lift gauge through the spark hole etc!! Seems a different car but a way to go yet! Thanks for all your support topcat - legend! Megajolt???? Tempting!!

DaviesDJ · Post by **DaviesDJ** » Sun Sep 02, 2012 2:40 pm

Spoke too soon! Although better and creamy up to 3-4000 depending on load and duration of throttle- its "fluffy" when revved at rest above 4000.- even at a blip. Think I could either change ignition components 1 by 1 or trade the lot in for mega jolt?? What would you guys do??

sidecar · Post by **sidecar** » Sun Sep 02, 2012 3:33 pm

DaviesDJ wrote:Spoke too soon! Although better and creamy up to 3-4000 depending on load and duration of throttle- its "fluffy" when revved at rest above 4000.- even at a blip. Think I could either change ignition components 1 by 1 or trade the lot in for mega jolt?? What would you guys do??

"What would I do"...Well first of all I'd get the timing markers sorted out, I'd then make sure that the zero mark really is at TDC. Doing that lot can be 3 or 4 hours work on it's own. Once that lots done I'd find out what the timing currently set to. I'd also run the engine up to 4k with the timing light connected, that should help you determine whether the ignition is breaking down. I guess 28 degrees all in at 3k would be good, safe figures to go for with regards to the actual timing.

If your ignition does prove to be duff then you can decide what to do, you could fix what you have or junk it for something else.

I went for an MSD system because I wanted the retard function for use with NOS.

I know you were using an RPI amp but what is the rest of your system?

DaveEFI · Post by **DaveEFI** » Sun Sep 02, 2012 5:42 pm

DaviesDJ wrote:Spoke too soon! Although better and creamy up to 3-4000 depending on load and duration of throttle- its "fluffy" when revved at rest above 4000.- even at a blip. Think I could either change ignition components 1 by 1 or trade the lot in for mega jolt?? What would you guys do??

Even a points dizzy as fitted to the early RV8 is perfectly capable of delivering decent sparks up to the rev limit of a road going engine, when in good condition. Electronic systems basically just require less maintenance.

If yours is calling quits at 4000 rpm, something is wrong and needs fixing.

Throwing it all away and fitting a different system may fix the fault - but it's IMHO not the correct way to go about it. As you may simply just be adding new problems to an unsolved one.

DaviesDJ · Post by **DaviesDJ** » Sun Sep 02, 2012 8:05 pm

I have a land rover series 3 coil which I purchased as an internally ballasted coil, i have no ballast resistor on this, the RPI amplifier, magnacor leads, Lucas blue electronic dizzy. I have a nitrous crossfire plate yet to be plumbed in, and always intended to run NOS therefore I am very tempted by megajolt, have heard/experienced from my mate running a highly tuned a-series that it can really improve the mid range. The cost is 400 quid for the kit, or less if you cobble it together as he did. Obviously proper timing mark allocation etc must be done pre this. I am suspicious of the coil - think a lucas sports coil with a ballast resistor may improve the situation, but then would i just go and change it to a programable system eventually anyway?

sidecar · Post by **sidecar** » Sun Sep 02, 2012 8:22 pm

If you are running an electronic system you should not be running a ballast resistor. (Maybe the OPUS system ran one but none of the later Lucas systems)

Also you can not run a points coil on an electronic system, it needs to be a coil for an electronic system. The reason escapes me at the moment but I read it in a book on dizzy systems.

Out of interest what features does the mega jolt system give you that make is suitable for NOS? (other than a 'fat' spark)

DaviesDJ · Post by **DaviesDJ** » Mon Sep 03, 2012 3:22 pm

The ability to switch between two or more set mappings on the fly was one of the features I thought usefull for NOS - The original coil that cam e with the ingnition kit was a lucas sports coils with no resistor supplied ( i think it required one) - i fitted it without a resistor and it burned out within a month. Are you saying that I would see no real benefit? Sorry to drag the issue out, but am getting confilicting messages

sidecar · Post by **sidecar** » Mon Sep 03, 2012 4:13 pm

DaviesDJ wrote:The ability to switch between two or more set mappings on the fly was one of the features I thought usefull for NOS - The original coil that cam e with the ingnition kit was a lucas sports coils with no resistor supplied ( i think it required one) - i fitted it without a resistor and it burned out within a month. Are you saying that I would see no real benefit? Sorry to drag the issue out, but am getting confilicting messages

No Benefit to what? A ballast registor or a Mega jolt system?

If its the former then you should only use a ballast resistor with low voltage coil (like 9 volts) the coil is then feed 9 volts when the engine is running and 12 volts which over boosts the coil when the starter is cranking the engine.

If you mean the benefit of fitting a different ignition system all together then I guess it depends on how 'bad' your system is now. (how bad it it even when working properly)

I fitted my MSD system because it is fully programmable and has loads of other useful features. I did not think that it would actually improve the performance of my engine which was running a modified 35DML8 Lucas system, I just wanted a NOS retard feature and a 'fat' spark the the NOS would not 'blow' out. Even when I timed up the MSD to the same settings as the old system I noticed a big improvement in both the bottom end and top end performance. I was very pleased! Muscle Manta now runs the same setup as me on his 4.6 stage III lump, he had a big smile on his face on his first test run with the new system.

Mr. 'Love' Muscle and I have now fitted an MSD system to an MGB 4.6 V8 an the chap was very pleased with that too!

I can't comment on the Mega Jolt system as I never seen one!

I think that what some of the other people who are posting up are saying that lobbing on another ignition system when you are not sure that the one that you have got is faulty is a slightly risky way of fixing things, it might not even fix your problem. (it might though!)