ATTN: HOLLEY Experts...

[GilligansIsland]

Re: ATTN: HOLLEY Experts...

This is where you need to learn to read spark plugs.

I can, but it is a little different than a car - where you can run, pull over and check. Having to travel through no wake zones before getting to a safe place to do work, kind of changes the results on the plugs I think.

I'll check what I can, nonetheless.

 

[Maclin]

Re: ATTN: HOLLEY Experts...

Thanks for the pics, yours definitely has the full metering block, making sense about the jet swapping.

 

[kelleyja]

Re: ATTN: HOLLEY Experts...

May be time to hook up a vac gauge to dial in your idle mix, if you've solved the rest of the problems.

Just curious, does your metering plate have a power valve? It seems like VP fitted some with and some without (like mine), I run it a little rich in the main circuit

 

[GilligansIsland]

Re: ATTN: HOLLEY Experts...

Yes, I have Power Valves and they were replaced. The carb guy said one was leaking but he did a full rebuild anyway. I put 60 in the front and that helped, so I stepped up to 62... then I couldn't get the transfer tube back on right without it leaking. So... I took it back to my guy who said he would put it back right. He said the gaskets on that tube get funny after they've had gas on them and then hit air. As a rule, any time he pulls this carb apart he changes those gaskets.

...fingers crossed that the problem is mostly fixed and then I'll educate myself on throwing a vacuum gauge on it and playing with the mix.

 

[Scott Danforth]

Re: ATTN: HOLLEY Experts...

Have you double checked the accelerator pump.

Are you sure your running rich - what do your plugs tell you.

regarding jetting on a holley

Here is what I have in my 650 CFM Holly 4150 on my warmed over VP 271C (SBC putting out about 330hp)

Primaries are 72, secondaries are 95. the stock set up for my motor from Volvo is 68 primaries and one 80 and one 90 in the secondary (staggered) I am also running a 3.5"hg power valve.

with your stock 7.4 liter (454) you should be very close to these settings. if your running a 56, you are probably either running with a leaking power valve, or your running lean.

If you do not have a power valve (a block off installed) you will need to increase your primary jets by about 6. (this comes directly from the Holley tuning bible)

your secondaries do not open at a particular RPM, they open when the ported vacuum demand on the engine overcomes the spring force in the vacuum secondary actuator. On my boat, the secondaries only open on the hole shot and when I am pushing over 42mph with the B6 props. you can hear them open, and when you start to let off the throttle, you can get the air to whistle past the closing throttle plates.

Setting up the idle circuit is also easy. I use a propane torch. at idle, adjust the screws to maximum RPM, then fine tune so that when I add just a tad bit of propane to the air stream, I see a 20-30 RPM dip. I do this on both primaries. Adding the spark arrestor then richens it up a bit

 

[Tail_Gunner]

Re: ATTN: HOLLEY Experts...

Ok ive been watching this thread with some intrest....vacum was used to open secondary's??? and holley's were used in the mid to late 80"s on 454's.....Id check your vacum close if that is the case..maybe a leak down test is in order.

 

[GilligansIsland]

Re: ATTN: HOLLEY Experts...

Have you double checked the accelerator pump.

Are you sure your running rich - what do your plugs tell you.

regarding jetting on a holley

Here is what I have in my 650 CFM Holly 4150 on my warmed over VP 271C (SBC putting out about 330hp)

Primaries are 72, secondaries are 95. the stock set up for my motor from Volvo is 68 primaries and one 80 and one 90 in the secondary (staggered) I am also running a 3.5"hg power valve.

with your stock 7.4 liter (454) you should be very close to these settings. if your running a 56, you are probably either running with a leaking power valve, or your running lean.

If you do not have a power valve (a block off installed) you will need to increase your primary jets by about 6. (this comes directly from the Holley tuning bible)

your secondaries do not open at a particular RPM, they open when the ported vacuum demand on the engine overcomes the spring force in the vacuum secondary actuator. On my boat, the secondaries only open on the hole shot and when I am pushing over 42mph with the B6 props. you can hear them open, and when you start to let off the throttle, you can get the air to whistle past the closing throttle plates.

Setting up the idle circuit is also easy. I use a propane torch. at idle, adjust the screws to maximum RPM, then fine tune so that when I add just a tad bit of propane to the air stream, I see a 20-30 RPM dip. I do this on both primaries. Adding the spark arrestor then richens it up a bit

Thank for the detailed info, and this is similar to what others have said. I'm a little confuse as to my jetting and how small they are, but like I said, these settings are correct according to the numbers on my carb and the carb is what Volvo called for... very odd if you ask me.

I say I'm running rich because at idle, you can really smell and see the exhaust.

I'm putting the carb back on today set up with 62 prim and 73 sec and will pull the plugs before and after running it and may even have to change them if they are too dirty (which I suspect).

If it goes back to normal, I may play around with larger jetting as you describe just to see how she responds but that will also come with much more fuel burn so I'd really like for it to work the way it's set up now.


....thanks

 

[Scott Danforth]

Re: ATTN: HOLLEY Experts...

Ok ive been watching this thread with some intrest....vacum was used to open secondary's??? and holley's were used in the mid to late 80"s on 454's.....Id check your vacum close if that is the case..maybe a leak down test is in order.

Tail Gunner, would you prefer to have "ported air flow operation"? vs vacuum. Technically its a glorified pitot tube principle running off the air flow of the primaries (ported vacuum source) http://www.holley.com/data/TechService/Technical/Carburetor Tech Info.pdf However you already knew that

I go back to an earlier question on plug reading. What color are the plugs? If the engine is leaning out in the mid range, then my guess is a plugged carb circuit, or too small of jets. it this issue has just arisen, then I am leaning toward the plugged carb circuit.

based on your carb number and this chart http://www.v8volvo.se/mekartips/tabeller/holley-specifications.html

you can have either 56 or 59 primary jets. the -1 indicates the 56/73 combination. However note, this is the leanest running 750 CFM on the chart. It is also not listed as Marine. If it is the original carb for the VP motor, my guess is that the engine was leaned out to meet an EPA spec or a just on plane economy spec and not an operational spec. This brings me back to plug color.

If your running rich at idle, that could be a few other things. a leaking power valve comes to mind. your power valve should be a 2.5. while you have the carb apart put a new one in, they are about $6

 

[GilligansIsland]

Re: ATTN: HOLLEY Experts...

Thanks. Right now the plugs are black, so I need to change them before running my carb with 62/73 and see what happens.

I'll let you guys know...

 

[Tail_Gunner]

Re: ATTN: HOLLEY Experts...

Tail Gunner, would you prefer to have "ported air flow operation"? vs vacuum. Technically its a glorified pitot tube principle running off the air flow of the primaries (ported vacuum source) http://www.holley.com/data/TechService/Technical/Carburetor Tech Info.pdf However you already knew that.

Not at all finally after 30+ yrs do i have the pleasure of working with a carb again and a 454. If i have this right It is acutally mechanical in nature with a airdoor that is vacum operated. Im assuming this is for throttle response....good thread.

 

[GilligansIsland]

Re: ATTN: HOLLEY Experts...

Small update:

Changed all plugs. They were black.
With the 63 prim, she idles nice and doesn't smell Rich.

Now when I slowly rev she leans out starting at 3000 and then gets past it.
With the smaller jets she started leaning out about 2200.
With the 72 prim she never leaned out but burned Rich at idle.
I still have to get it under load to test.

Can these symptoms be a function of jet size only? The carb was fully rebuilt by a pro who has taken a look at in again for me.

 

[GilligansIsland]

Re: ATTN: HOLLEY Experts...

Small update:

Changed all plugs. They were black.
With the 63 prim, she idles nice and doesn't smell Rich.

Now when I slowly rev she leans out starting at 3000 and then gets past it.
With the smaller jets she started leaning out about 2200.
With the 72 prim she never leaned out but burned Rich at idle.
I still have to get it under load to test.

Can these symptoms be a function of jet size only? The carb was fully rebuilt by a pro who has taken a look at in again for me.

 

[Bifflefan]

Re: ATTN: HOLLEY Experts...

I can, but it is a little different than a car - where you can run, pull over and check. Having to travel through no wake zones before getting to a safe place to do work, kind of changes the results on the plugs I think.

I'll check what I can, nonetheless.

It really doesn't though. What you are looking for is running at a specific RPM for a sustained time, say a good run across the lake at 3500 rpms. Shut off the motor at that speed, then drop the anchor when you stop. Pop open the engine cover and pull one or two plugs that are easy to get to. They should be clean (new) enough to get a good read. You will be able to tell pretty quickly if you are running to fat of jets.
I mean in my experience, a 56 is to small of a jet for your application.

 

[Bifflefan]

Re: ATTN: HOLLEY Experts...

Small update:

Changed all plugs. They were black.
With the 63 prim, she idles nice and doesn't smell Rich.

Now when I slowly rev she leans out starting at 3000 and then gets past it.
With the smaller jets she started leaning out about 2200.
With the 72 prim she never leaned out but burned Rich at idle.
I still have to get it under load to test.

Can these symptoms be a function of jet size only? The carb was fully rebuilt by a pro who has taken a look at in again for me.

Unfortunately, the jets have no effect on the idle when the carb is preforming properly.
You may have an issue with the primary metering block itself. I would try changing it with a known good one if that is possible.
I really don't want to sound like a jack-hole. Carbs are very sophisticated pieces of machinery. They take years to learn to work on and tune correctly. That being said I found a couple things on you-tube that may help you get set up.

Main circuit (jets)
Idle adjusting

 

[GilligansIsland]

Re: ATTN: HOLLEY Experts...

Unfortunately, the jets have no effect on the idle when the carb is preforming properly.
You may have an issue with the primary metering block itself. I would try changing it with a known good one if that is possible.
I really don't want to sound like a jack-hole. Carbs are very sophisticated pieces of machinery. They take years to learn to work on and tune correctly. That being said I found a couple things on you-tube that may help you get set up.

Main circuit (jets)
Idle adjusting

Thanks, and you don't sound like "jack-hole". I know, that I don't know a lot and have done mostly NONE of the work myself. I've turned this over to a pro, until I changed some jets myself... and after that, I gave it back to him to look at.

I think the carb is as much Art as it is Science.