Cooler Carbs
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Anonymous
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Dave-R
- Posts: 24752
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- Location: Dave Robson lives in Geordieland
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Hello Don and I should have said welcome too in my last message sorry.cuda66273 wrote:Dave, if you could measure the location and depth of the recess I'll adjust the CnC program to notch it.
Well I could give you a measurement Don but I am not sure what reference point to start from as things like the bolt holes are not accurately placed.
Can I fill you in with my findings seeing as I seem to be some kind of test mule on this?
OK starting with Photo 1.
If this carb gasket is designed to insulate the carbs why cut out those large openings under the fuel bowls? It would work better if it was one piece as it would shield the rear and centre carb fuel bowls and might make fitting an ally plate unnecessary.
Also when placed onto the carbs or manifold, so that the throttle bores line up, the holes for the bolts do not then line up very well. (See photos 2 and 3).
Photo 4.
You can see that the displacement of the bolt holes is the same on the carbs. Making it difficult to find a meaningful reference point to measure my notch from for you. You might want to place a 2bbl carb on your gasket yourself and cut a smaller notch than mine (it does not need to be so wide) because i wouldn't want to be responsible for messing up a run of gaskets for you.
Of course if you did away with the large openings in the gasket under each fuel bowl this notch would be the only opening you would need.
I hope this helps.
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Anonymous
You need to understand the way those manifolds were drilled 40 years ago....we didn't have CnC machines and the accuracy of the machinist who drilled and taped them was not always the same. The New Edelbrock 6 pack manifolds are CnC drilled and are much more consistant.
Some triming on a complex gasket like these may be needed but like ALL Parts the owner need to be prepared to make minor adjustments to ensure a proper and correct fit.
I can see that the clearence issue is easily resolved, we'll make the adjustment.
The heat is not transferred by air to the carbs it's transfered through the manifold into the fuel bowls.
Which brings up another part of this post.....you think you have a heat issue boiling the fuel out of the accelerator pumps....I don't believe that is your issue. The pumps fill by gravity feed from the main well or float bowl. Now you may have an issue with your pump condition but I don't think it's from evaporation.
Further more if your getting that much heat into the manifold you may have an underlying problem. It sounds to me like you've got something going on with the timing, it's possible that your not running enough advance which is forcing unburned fuel into the exhaust runner of the head creating a blow torch effect. This in turn transfers massive heat into the head which then transfers it into the intake manifold.
I can't and won't get into tuning 6 pack cars on line, I'd be doing nothing but typing for the rest of my life.
I would like to get more info on the timing events and the type of ignition your running to see if we can get that part resolved.
Ignition type MSD or ECU?
If your using a ECU, who's is it?
What Coil are you running with your system?
Are you running a vac cannister on the distributor?
How much initial timing?
How much Vac timing?
Where is your vacuum source coming from, ported or constant?
What type of distributor are you using?
How much total timing?
What RPM is it all coming in at?
What's the cam duration at 50?
How much compression in the Motor?
What octane fuel are you running?
What gear?
What Convertor?
How much does this car weigh?
Just one more....how much manifold vacuum do you have at idle in gear?
Some triming on a complex gasket like these may be needed but like ALL Parts the owner need to be prepared to make minor adjustments to ensure a proper and correct fit.
I can see that the clearence issue is easily resolved, we'll make the adjustment.
The heat is not transferred by air to the carbs it's transfered through the manifold into the fuel bowls.
Which brings up another part of this post.....you think you have a heat issue boiling the fuel out of the accelerator pumps....I don't believe that is your issue. The pumps fill by gravity feed from the main well or float bowl. Now you may have an issue with your pump condition but I don't think it's from evaporation.
Further more if your getting that much heat into the manifold you may have an underlying problem. It sounds to me like you've got something going on with the timing, it's possible that your not running enough advance which is forcing unburned fuel into the exhaust runner of the head creating a blow torch effect. This in turn transfers massive heat into the head which then transfers it into the intake manifold.
I can't and won't get into tuning 6 pack cars on line, I'd be doing nothing but typing for the rest of my life.
I would like to get more info on the timing events and the type of ignition your running to see if we can get that part resolved.
Ignition type MSD or ECU?
If your using a ECU, who's is it?
What Coil are you running with your system?
Are you running a vac cannister on the distributor?
How much initial timing?
How much Vac timing?
Where is your vacuum source coming from, ported or constant?
What type of distributor are you using?
How much total timing?
What RPM is it all coming in at?
What's the cam duration at 50?
How much compression in the Motor?
What octane fuel are you running?
What gear?
What Convertor?
How much does this car weigh?
Just one more....how much manifold vacuum do you have at idle in gear?
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Dave-R
- Posts: 24752
- Joined: Sun Apr 18, 04 11:23 pm
- Location: Dave Robson lives in Geordieland
- Contact:
Then I would advise you not to use an original intake as a template.cuda66273 wrote:You need to understand the way those manifolds were drilled 40 years ago....we didn't have CnC machines and the accuracy of the machinist who drilled and taped them was not always the same.
My manifold is what? 5 years old?
I'm sorry Don but the machinist at Holley and the machinist at Edelbrock both got the bolt hole spacing the same. Are you trying to say the intake and the carbs are wrong and the gasket is right?
Are you also saying the intake does not radiate heat? Or that the front fuel bowl is not getting a good blast of hot air from the radiator fan?
I think you missunderstand my post. I don't have any major issues with heat. I just think keeping the carbs (or rather the fuel) cooler would not be a bad thing.
The problem with the "pumps going dry" is an issue only when the engine has been switched off when hot and I get heat soak. When the engine is running normally it is fine. It may even be that it is more an issue with the way the fuel is transported from the pumps on my outer carbs. Remember these outer carbs are modified. They are mechanical and have pumps but DON'T have metering blocks. The fuel has to go through a narrow groove cut into the edge of the fuel bowl under the gasket. A hot fuel bowl is going to create a bit of a vapour lock in there I would imagine. There is probably nothing wrong with the fuel in the pumps themselves.
Otherwise I am quite happy with the tune of my engine thank you. Just low buck and stock parts you understand but it does exactly what I want it to do and that's the main thing.
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Dave-R
- Posts: 24752
- Joined: Sun Apr 18, 04 11:23 pm
- Location: Dave Robson lives in Geordieland
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Ok I had 5mins spare while getting ready to go away for a weeks holiday so I took a measuring stick to the intake and carbs.
The side-to-side spacing on your bolt holes in the gasket is spot on. The first error is that the holes for the throttles is not exactly centered between them.
The second error is in the fore-aft spacing of the carb bolt holes.
Now granted that the spacing BETWEEN each carb is not critical because the linkage is adjustable. However the spacing for the four bolts ON each carb should be 88mm fore-aft.
The gasket holes are spaced 87.19mm, 89mm and 87.22mm. Not a major problem when fitting the gasket but using them as a reference to measure from I could have been almost 2mm out in that direction alone.
The side-to-side spacing on your bolt holes in the gasket is spot on. The first error is that the holes for the throttles is not exactly centered between them.
The second error is in the fore-aft spacing of the carb bolt holes.
Now granted that the spacing BETWEEN each carb is not critical because the linkage is adjustable. However the spacing for the four bolts ON each carb should be 88mm fore-aft.
The gasket holes are spaced 87.19mm, 89mm and 87.22mm. Not a major problem when fitting the gasket but using them as a reference to measure from I could have been almost 2mm out in that direction alone.
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Anonymous
We used a new 6 pack Eddy manifold to make the pattern I'll double check to be sure the program is to our original spec and adjust as needed. We've sold dozens of these gaskets and most gyuy's have told us they fit perfect and a few like yourself have had to make slight minor adjustments, we just haven't any chronic issues to this point that would deam a change. It's just a gasket and minor fitting isn't that uncommon.
The Original question:
"I have noticed over the last couple of years that the heat of the engine tends to evaporate the fuel from the pump shots so sometimes we get a bog if the secondaries have not been opened for a little while. If they boil dry it is the third stab on the throttle that produces the good "squirt" and the first two blips are poor. "
Sorry if I wasn't clear....yes the intake does radiat heat but the heat source is from the combustion chamber and exhaust runners. If the timing events aren't correct then you'll build excessive heat in both transferring to the intake and carburetors.
Of course cooler fuel is better, but I doubt your problem with the pump shot is being caused by that, you can't boil the accelerator pumps dry while you have fuel in the bowl, the pumps are fed from the bowl and bowls are fed by the fuel pump. If they're drying out then something is wrong.
The A-pumps draw fuel on the down stroke through the small mushroom valves in the float bowl. These valves seal on the pressure stroke and force fuel into the main body, lift the check valve and force a nice shot of fuel into the engine.
When the throttle is release the mushroom valve open and draws fuel from the float bowl into the A-Pump housing.
From your video I saw a dry A-Pump and yet the float bowl was full as it should be. Even a dry A-Pump housing will fill slowly through seapage through the mushroom valve. So the real issue is why is the float bowl going dry after a couple of days?
2 possibilties.....
1. As you suspect the carbs are too hot and they're boiling dry....this is usually caused, again by excessive heat from somewhere.
2. You have an internal leak in the carb allowing it to drain the bowl dry. This is most likely your problem anyhow, next time it sits for a couple of days pull the float level screws out and shake the car, you should still see fuel slosh in all 3, if the front one is dry then you've found your problem. You have a leak, whatever mods you have made need to looked at.
The next thing you need to consider is where the fuel is going?....Does you oil smell like gas?
I wasn't insinuating that there was something wrong with your combination, only that we should simply look at the timing events to be sure they are correct first. When tuning any engine it's always "Ignition 1st" then carburation. From the info I asked for I may be able to help you with your timing to help you with your issue.
If you don't want help why ask?
In closing I will say that this is not normal and whatever is causing this needs to be addressed.
Enjoy your vacation....isn't it winter there? I hope your heading south
The Original question:
"I have noticed over the last couple of years that the heat of the engine tends to evaporate the fuel from the pump shots so sometimes we get a bog if the secondaries have not been opened for a little while. If they boil dry it is the third stab on the throttle that produces the good "squirt" and the first two blips are poor. "
Sorry if I wasn't clear....yes the intake does radiat heat but the heat source is from the combustion chamber and exhaust runners. If the timing events aren't correct then you'll build excessive heat in both transferring to the intake and carburetors.
Of course cooler fuel is better, but I doubt your problem with the pump shot is being caused by that, you can't boil the accelerator pumps dry while you have fuel in the bowl, the pumps are fed from the bowl and bowls are fed by the fuel pump. If they're drying out then something is wrong.
The A-pumps draw fuel on the down stroke through the small mushroom valves in the float bowl. These valves seal on the pressure stroke and force fuel into the main body, lift the check valve and force a nice shot of fuel into the engine.
When the throttle is release the mushroom valve open and draws fuel from the float bowl into the A-Pump housing.
From your video I saw a dry A-Pump and yet the float bowl was full as it should be. Even a dry A-Pump housing will fill slowly through seapage through the mushroom valve. So the real issue is why is the float bowl going dry after a couple of days?
2 possibilties.....
1. As you suspect the carbs are too hot and they're boiling dry....this is usually caused, again by excessive heat from somewhere.
2. You have an internal leak in the carb allowing it to drain the bowl dry. This is most likely your problem anyhow, next time it sits for a couple of days pull the float level screws out and shake the car, you should still see fuel slosh in all 3, if the front one is dry then you've found your problem. You have a leak, whatever mods you have made need to looked at.
The next thing you need to consider is where the fuel is going?....Does you oil smell like gas?
I wasn't insinuating that there was something wrong with your combination, only that we should simply look at the timing events to be sure they are correct first. When tuning any engine it's always "Ignition 1st" then carburation. From the info I asked for I may be able to help you with your timing to help you with your issue.
If you don't want help why ask?
In closing I will say that this is not normal and whatever is causing this needs to be addressed.
Enjoy your vacation....isn't it winter there? I hope your heading south
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Dave-R
- Posts: 24752
- Joined: Sun Apr 18, 04 11:23 pm
- Location: Dave Robson lives in Geordieland
- Contact:
I don't remember asking for help?cuda66273 wrote:If you don't want help why ask?
I DO remember YOU asking ME for help.The fuel bowls are still full of fuel even when it has been standing. It is not leaking. Something of a minor achivement with the poor Holley design.
You think I don't know how these carbs work? Send me a S.A.E. and I will send you my leaflet entitled "Teaching your mother to suck eggs".
Read my last post again. I probably was not clear. My fault for trying to keep the whole post simple to save me going into all the little details about how THIS particular six pack works.
I think the actual problem is not in the pump itself. It is because of the modification to fit the pumps to these carbs. Are you sure you know how pumps are made to work on my outboard carbs?
The engine is not running any hotter than any other 500+hp 440 I know of. It did need extra cooling capacity to keep the temp down to 180 degrees as you might expect. Overheating problems in the past turned out to be due to low voltages in the poor stock electrical system. Since cured.
Your gasket does indeed fit. I never said it didn't. That is why I ordered a second one. The bolt holes are large enough to absorb the inaccurate spacing.
In fact the ONLY reason this thread exists was because I promised Neil that I would do something to promote YOUR gasket to other six pack owners
Why I don't know. It's not as if I was getting a free one or anything. I was just trying to do the bloke a favour seeing as he imported my new crank for me.
YOU ASKED ME to measure where I put the notch. If I use the carb to get that measurement (the way I originally did it) and then transfer that to the gasket it ends up 1mm or 2mm out. I had to make my notch bigger as a result. So I think it would be better for you to make the holes in the gasket 88mm apart the same as they are on the carbs and on the intakes and then go from there.
!!
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Anonymous
I will be sure not to respond to anything you post in the future, your obviously way smarter than I am.
If you would like to return the gasket, please by all means do so, I will give Neil full credit for it. Your not happy so lets rectify the situation.
I was under the assumption that others may read some of these posts and learn from help offered by others, excuse me for assuming that.
If you would like to return the gasket, please by all means do so, I will give Neil full credit for it. Your not happy so lets rectify the situation.
I was under the assumption that others may read some of these posts and learn from help offered by others, excuse me for assuming that.