Holley Help

General Chat About Exhaust, Cylinder Heads, Fuel Systems And Intake

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RoverP6B
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Post by RoverP6B »

Hello Simon,

Here is some information which you might find useful.

This info applies to the Holley 390.

Setting up...Basic jet setting for standard specification Rover V8....
Primary main jets : 52
Secondary main jet (when secondary metering block is fitted) : 55
Accelerator pump discharge nozzle : 25
Accelerator pump cam (check in positions 1 & 2) : Red
Power valve : 6.5
Secondary diaphragm spring (medium) : standard, plain coloured

Float levels : Both must be set to factory specification...ie when the externally adjustable fuel bowls having fuel dribble out the sight plug holes when the car is rocked side to side and parked on level ground. Float levels MUST be set before tuning is carried out. If no fuel dribbles out, the float level needs to be raised. If fuel runs out, then the float level is too high and needs to be lowered. In both cases undo the adjustment screw on the top and at the front of each fuel bowl and turn the adjustment nut clockwise to raise the fuel level and anti-clockwise to lower it. It is critical that the float levels are exactly right!!

Idle adjustment screw : Turn the primary idle adjustment screw so that the primary barrels are open no more than 1/2 a turn from the fully closed position. If the engine runs too slow like this, remove the carburettor and adjust the secondary butterflies so that they are admitting more air. This might have to be done a few times to get it right, but with the engine idling at the requred rpm and the primary barrels closed as much as they reasonably can be, the primary butterflies will sweep past the progression slots to the maximum extent possible, resulting in optimum acceleration without hesitation.

Once the idle adjustment has been finalised, the accelerator pump needs to be adjusted.

Accelerator Pump….Once the idle speed adjustment has been finalised, the accelerator pump needs to be adjusted so that it works in unison with the primary throttle spindle. Any throttle movement must be matched by accelerator pump arm actuation, with the accelerator pump arm just in contact with the actuation lever. This requires some fine adjustment. The accelerator pump arm MUST be set without any slackness in the mechanism, but not so tightly that the pump arm has moved from its rest position.

Idle Adjustment Screws…Next turn the idle adjustment screws approximately 1 ¼ to 1 ½ turns out.

The correct fuel pressure is very important, 3.5psi is the minimum, 4.5psi is the usual and up to 6psi is acceptable.

Hope this helps,

Ron.


4.6 Rover 3500 P6B

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Post by Darkspeed »

I would also carry out a very simple and crude exaust gas temperature test - you can do a better test with an infra red thermometer if you have one but this is pretty good.

Get a water sprayer - kitched cleaner type thing - set to a single jet outlet and spray each exhaust manifold at the area where it exists each cylinder with a jet of water of similar volume and compare the hiss and evaporation time of the wtare at each cylinder. Note cylinders that are hotter and cooler than the average.

Cooler - misfire - If the electrics are breaking down cylinders 7 and 8 - longest leads - will tend to run slightly cooler

Hotter - leaking valves/timing issues / mixture distribution

Andrew
4.5L V8 Ginetta G27

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simontwithers
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Post by simontwithers »

thanks agin

andrew - im not using any alumium block, wire straight to coil

perry - i did the paper clip test, some springs opened others didn't, no improvement

Ian - i checked the TDC mark whilst the engine was in bits, all was ok.

Ron - i've just ordered some 55 primary jets and a kit to up the secondaries to 57. Real steel suggested with my cam i will need to richen up. I will also check fuel pressure asap, although i had a chat with a carb guy today who said it didn't sound like a fueling problem. Still worth a try though, but £130 for a holley pump and reg...ouch.

Andrew - i did this test with an infra red gun, all very close from cold start to warm up.

going to take it to a carb guy this weekend, after that i see V8 developments in lincoln (used to be rovertec) offer an in car analysis.
There's no turning back now, I've finished being nice with this engine.

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Darkspeed
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Post by Darkspeed »

Throwing away the Opless would be my first action to be honest

Andrew
4.5L V8 Ginetta G27

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simontwithers
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Post by simontwithers »

Spent today going through various things,

I checked the fuel pressure which never dropped below 4 psi whilst on the move.

I fitted an additional silencer which has now brought the exhaust note down to a less painful volume. In turn this has enabled me to 'listen' to the engine a little more. What at first sounded like 'missing' turned out to be a quite heavy leak at the joint between the exhaust manifold and down pipe.

I've got to change my exhaust interface a little to seal this fully, but i managed to get it down to a whisper.

I fitted the secondary conversion kit to allow the jetting to be changed on the secondaries.

They are the equivalent of 53 standard, which i upped to 57. I also upped the primary jets to 55 (from 51).

This has improved things greatly, although i feel there is still room for improvement. Im going to order more jets to go up again (just to see what happens). And i larger accelerator pump nozzle (im currently up at 31 from 25 standard).

i also changed the dizzy for another.

I fitted the holley quick change kit for the secondary spring and currently have the best (purple) spring for the time being.

I will update this post after i try the jetting, but i feel i am getting there.

When im done with it i'll get it on a gas analyser for fine tuning. im also on the look out for a wide band lamba with gauge. Will keep my eye on ebay for one this side of £100.
There's no turning back now, I've finished being nice with this engine.

mgbv8
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Post by mgbv8 »

Simon!
If you jets and squirter nozzles are the same style as the 600dp carb. I have a very large selection of each mate. You are more than welcome to try them out until you find the right size to buy :)
I have jets from low 60's to about 20 sizes bigger and squirters from about 25 to at least 20 sizes bigger as well.
PM me and I can give you all the numbers I have. You are more than welcome to come down to MK and try all the settings you need until you get the right combo!
Then you know what to order eh??
I'm pretty sure I'm home all next weekend as I'm working on my car to get it ready for the Pod on Friday 6th August for test runs :)

Regards
Perry

Perry Stephenson

MGB GT + Rover V8

9.62 @ 137.37mph

Now looking for 8 seconds with a SBC engine

http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw



https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw

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simontwithers
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Post by simontwithers »

Thank you perry, that is very much appreciated.

My V8 is in a 1967 series land rover, which makes it not the best cruiser out there. So MK is a little far.

Jet wise, i think i am nearly there now and a £3.50 a pair its not too bad.

I hope testing goes well, just seen that you MG is running in the 10's , wow - well done, i see your aiming for that 9.99 run.

Good luck, it would be great to see your street car run in the 9's. Now thats what i call bragging rights.

thanks for your help

Simon
There's no turning back now, I've finished being nice with this engine.

mgbv8
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Post by mgbv8 »

No probs dude!
I'm only an hour away if you want to come and tinker !!

Pel

Perry Stephenson

MGB GT + Rover V8

9.62 @ 137.37mph

Now looking for 8 seconds with a SBC engine

http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw



https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw

nosman
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Post by nosman »

dont know if anyone has said this, but it sounds awfully like insufficent fuel to me, i know you said the fuel pressure is constant, but what about volume?

my experience was like hitting a wall at 3000 rpm in top and around 4000 in third, but fine in 1st and second, after changing my coil, dizzy, plugs, leads, adjusting float levels, allsorts and nothing seemed to improve it, i tried a second fuel pump, and voila, she pulled like a train!

the demands in higher gears are obviously significantly higher, as for the dizzy, try shutting the plug gaps a few thou, if the spark is weak this will improve it and help mask the problem, but at least show the problem up!

I ended up using 2 jaguar xj6 fuel pumps in parallel! only took them off because they arent usable with nitrous

mgbv8
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Post by mgbv8 »

A rough idea of fuel volume required would be 100ml per 100hp in 10 seconds from the open end of the fuel pipe where it connects to the carb. You can do the maths based on your engines needs / output and flow test to see if you have the minimum flow required where it goes into the carb.
All you need is a decent measuring jug and a second hand on your watch :)

And keep a straight face when the wife asks why her measuring jug smells funny :lol:

Perry Stephenson

MGB GT + Rover V8

9.62 @ 137.37mph

Now looking for 8 seconds with a SBC engine

http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw



https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw

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simontwithers
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Post by simontwithers »

Thanks Nosman,

I had the very same fueling issue you mention on another car i had. Would go like stink from a standing start until 3rd gear when is would mysteriously run into a wall.

i couldn't figure why 3rd gear every time ???

I felt daft when someone pointed out it was running on the fuel in the float bowls (twin carbs) before running out and slowing.

UPDATE:

I've redone the exhaust (finger crossed it now seals) so will get round to jetting again this weekend.

richening up helped, so am going up in jet size again.

thanks for the basic figures on fuel reqiuirements Perry.

Just out of interest.... I figure if i know the ideal a/f ratio of an engine (14.5 ish) and i know which jet size my engine likes. I can get the flow rate from holley site of the jet size and work out the CFM my engine is breathing.

would be interesting to see how close to the 390 CFM of the holley carb i am.


will update as i go.

cheers all
There's no turning back now, I've finished being nice with this engine.

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Ian Anderson
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Post by Ian Anderson »

What fuel pump are you running

Is it sufficient flow for the V8?

And have you checked it actually flows fuel at the rate?

Ian
Owner of an "On the Road" GT40 Replica by DAX powered by 3.9Hotwre Efi, worked over by DJ Motors. EFi Working but still does some kangaroo at low revs (Damn the speed limits) In to paint shop 18/03/08.

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simontwithers
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Post by simontwithers »

At 100cc in 10 seconds per 100hp

a 200hp engine would need 200cc in 10 seconds

which is 1200cc per min

which is 72000cc per hour

which is 19 us gallons per hour. - Sad or what !!!!

The (new) silver top facet pump i am using gives 30 us gallons per hour

so i figure im safe.

I suspect if my fuel pump could not supply quick enough, the float bowls would be constantly filling resulting in low fuel pressure.
There's no turning back now, I've finished being nice with this engine.

mgbv8
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Post by mgbv8 »

simontwithers wrote:At 100cc in 10 seconds per 100hp

a 200hp engine would need 200cc in 10 seconds

which is 1200cc per min

which is 72000cc per hour

which is 19 us gallons per hour. - Sad or what !!!!

The (new) silver top facet pump i am using gives 30 us gallons per hour

so i figure im safe.

I suspect if my fuel pump could not supply quick enough, the float bowls would be constantly filling resulting in low fuel pressure.

You should not get low fuel pressure when the floats are fully open. If you do then you have a problem. The pump and lines should be able to deliver your 33 gph at whatever PSI you need when the floats are fully open and needing to be fed. If you do get low fuel pressure at full chat then you have a restriction. This is something to look at when you are testing the car.
Perry

Perry Stephenson

MGB GT + Rover V8

9.62 @ 137.37mph

Now looking for 8 seconds with a SBC engine

http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw



https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw

mgbv8
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Post by mgbv8 »

simontwithers wrote:Thanks Nosman,

I had the very same fueling issue you mention on another car i had. Would go like stink from a standing start until 3rd gear when is would mysteriously run into a wall.

i couldn't figure why 3rd gear every time ???

I felt daft when someone pointed out it was running on the fuel in the float bowls (twin carbs) before running out and slowing.

UPDATE:

I've redone the exhaust (finger crossed it now seals) so will get round to jetting again this weekend.

richening up helped, so am going up in jet size again.

thanks for the basic figures on fuel reqiuirements Perry.

Just out of interest.... I figure if i know the ideal a/f ratio of an engine (14.5 ish) and i know which jet size my engine likes. I can get the flow rate from holley site of the jet size and work out the CFM my engine is breathing.

would be interesting to see how close to the 390 CFM of the holley carb i am.


will update as i go.

cheers all

This is where it can turn into a bit of a minefield Simon!
You will see many 3500's running sweet on a 390. But some wont? Yet others will run really well on a weber 500!
The carb may perform well at low rpm where you still have some manifold vacuum. But then can run lean at wide open throttle when you have no vacuum in the manifold. This is why we sometimes need to over jet the mains to they give more fuel. You may be theoretically over jetting on paper, but the VE of the engine has a lot to do with final fuel flow at full pedal.

I cant remeber if we discussed this earlier, but does the 390 have a power valve fitted? Because another cause of hitting a wall at full throttle at a certain rpm could be over fuelling due to the power valve flooding the manifold??
All these problems are easily sorted on the rolling road to be honest. Road testing can be a pain in the bum...
I removed my power valve and went up 6 jet sizes all round. And I use the same size jet in each corner of the carb. I can explain more later about this method of setting up a Holley.

But why dont you do a simple test. Fit a new set of spark plugs with your normal gap. Take the car out and run it at normal temp around the roads for 15-20mins. Find a nice long stretch of road where you wont be disturbed. Find yourself somewhere to pull over at the end of a test run. Now! Give it the beans in 4th gear for about 15 seconds at the revs where you find the engine hesitates. This will give you 15 seconds of the engine being used in anger with whatever fuel / igniton timing condition is being delivered at this point. At the end of this 15 seconds you need to dip the clutch and shut the engine off so you can coast to a parking point with the clutch pedal depressed so the engine does not get driven by the wheels. Then pull the spark plugs and take good quality pictures of each plug noting which cylinder they came from. Then refit the plugs and go home. Then post up the pictures of the spark plugs on here. We need good quality close up pictures of the centre of the spark plugs which show the end of the threads, the earth electrode and the centre procelain of the power electrode. From this we may be able to get some info on the engine condition at the time of the hesitation.

I know it sounds a bit of a faff. But plug readings after a hard blast with a clean shutdown at the end of the test run can tell you more than you can imagine. If this test is successful, I may ask you to fit new plugs after the next test so the used ones can be cut up for further examination.

I do all my tuning by plug readings. At this moment I would think you will find the front 4 plugs show lighter than the rear four?? If the new plugs are nice and clean we may be able to determine the state of the ignition timing by reading the earth strap if the engine temperature is at normal before you make the test run..
Your ignition timing may be set as per book. But it may not actually suit your particular engine in its present state of tune.

Perry

Perry Stephenson

MGB GT + Rover V8

9.62 @ 137.37mph

Now looking for 8 seconds with a SBC engine

http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw



https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw

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