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Old 09-19-2010, 07:52 PM
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engine stalls when hammered

Today I got my sons engine intalled and running in his truck and now when you hammer on it from a dead stop to WOT it stalls or loses all power. I have no clue what this would be. I have a 400 small block that I have installed a Weiand action+plus intake(#8004), a Comp cams 280H, Hooker headers, 4 barrel 650 cfm Edelbrock AVS carb sitting ontop of a one inch 4 hole carb spacer. if you hold the brake and get rpms up to 1000 it'll run like a bat out of hell. could it be something wiht ignition?
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Old 09-19-2010, 08:03 PM
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Initial timing too low, or accelerator pump shot not big enough. Accel pump shot too small is a common problem with the Carter/Edelbrock carb design.

Being that you say it is fine from a slightly higher rpm, my bet is pump shot combined with the low rpm maybe causing slightly lower timing. Move the pump link to the larger shot hole and see if it helps. May also require a large pump nozzle/booster cluster to get the shot big enough.

What are your initial and total mechanical timing figures?
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Old 09-19-2010, 08:22 PM
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That 8004 intake is for a spread bore design carb there is it not? I am not sure but you need an adapter for the eddy square carb on these yes/no?, the spacer you are talking about needs to be verified, is there any type of transition adapter needed here? these miss matches (if there is one) can cause throttle response issues as well.

2 more of my cents
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Old 09-19-2010, 08:22 PM
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Quote:
Originally Posted by ericnova72
Initial timing too low, or accelerator pump shot not big enough. Accel pump shot too small is a common problem with the Carter/Edelbrock carb design.

Being that you say it is fine from a slightly higher rpm, my bet is pump shot combined with the low rpm maybe causing slightly lower timing. Move the pump link to the larger shot hole and see if it helps. May also require a large pump nozzle/booster cluster to get the shot big enough.

What are your initial and total mechanical timing figures?
i set initial timing to 12. it's the 12 above the zero on the timing indicator on timing cover. and i have no idea how you even set total timing i have looked every where and i am totally clue less. in gear it idles at 600-650 rpm is that too low you think? thanks.
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Old 09-19-2010, 08:28 PM
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Quote:
Originally Posted by Custom10
That 8004 intake is for a spread bore design carb there is it not? I am not sure but you need an adapter for the eddy square carb on these yes/no?, the spacer you are talking about needs to be verified, is there any type of transition adapter needed here? these miss matches (if there is one) can cause throttle response issues as well.

2 more of my cents
it's just a phenolic carb spacer and square bore design with 4 holes. the intake is a spread bore type. i do not have an adaptor. the square flange on the spacer barely covers the spreadbore on the intake. possible vacumm leak here? nice looking truck
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Old 09-19-2010, 08:37 PM
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Total timing is checked with a timing light by revving the engine and finding out the point the timing stops advancing and noting the degree and rpm reading. You will need a advance adjustable light, or a degreed timing tape on the balancer. Take a look in our Crankshaft Coalition Wiki for tutorials on making a easy degree tape for your balancer. Geting the timing set up right will be the biggest factor in getting the engine to run right and make good power up to its potential, and is the most common thing most young or limited experience rodders don't even know about.

The 280 cam is big enough it really needs to have initial timing in the 16-18 area, but you can't let the total get over 38 without risking getting detonation damage to the motor. Usually requires you to tear the distributor apart and limit its advance amount to get things right. You can search some of the recent timing threads here to get a taste of what is required.

In gear idle seems a bit low, adding 100 rpm may really help you cover some of the problem, but distributor modification is what it really needs to be right..

Try testing 16-18 initial to see how it responds from a stop, but don't run it up the rpm scale far to keep it from getting too much total and going into detonation. Just brief bursts from a stop to see if you are working in the right direction on timing.
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Old 09-19-2010, 08:40 PM
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Quote:
Originally Posted by projectman69
it's just a phenolic carb spacer and square bore design with 4 holes. the intake is a spread bore type. i do not have an adaptor. the square flange on the spacer barely covers the spreadbore on the intake. possible vacumm leak here? nice looking truck
Yes, you will have to make very sure you have a seal around the outside of the spread bore area of the intake. Edelbrock sells a 1/4" thick plate meant for using square bore carbs on a spread bore intake and seal this area, you may have to have one.
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Old 09-19-2010, 08:41 PM
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If you punch it from a dead stop it'll stall or lose all power, but if you hold the break and push on the gas to get the rpms to 1000 and then let off the break while simultaneously smashing the gas it'll smoke the tires for atleast 30 plus feet.
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Old 09-19-2010, 08:43 PM
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yep the transition plate may help then

http://www.edelbrock.com/automotive_..._spacers.shtml

but really I would consider a sqare bore intake and if you don't need it for clearance or something ditch the spacer altogether as it/they can give greif. Another option would be to go with a Qjet with that manifold, or a holley 4010 Qjet replacement carb but they were not so great, mine sits on the shelf.

thanks for the note on the chevy.
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Old 09-19-2010, 08:45 PM
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Quote:
Originally Posted by ericnova72
Total timing is checked with a timing light by revving the engine and finding out the point the timing stops advancing and noting the degree and rpm reading. You will need a advance adjustable light, or a degreed timing tape on the balancer. Take a look in our Crankshaft Coalition Wiki for tutorials on making a easy degree tape for your balancer. Geting the timing set up right will be the biggest factor in getting the engine to run right and make good power up to its potential, and is the most common thing most young or limited experience rodders don't even know about.

The 280 cam is big enough it really needs to have initial timing in the 16-18 area, but you can't let the total get over 38 without risking getting detonation damage to the motor. Usually requires you to tear the distributor apart and limit its advance amount to get things right. You can search some of the recent timing threads here to get a taste of what is required.

In gear idle seems a bit low, adding 100 rpm may really help you cover some of the problem, but distributor modification is what it really needs to be right..

Try testing 16-18 initial to see how it responds from a stop, but don't run it up the rpm scale far to keep it from getting too much total and going into detonation. Just brief bursts from a stop to see if you are working in the right direction on timing.
okay thanks i'll check out the timing a little better. i havent even brought the engine over 3000 rpm makes good low end power. there's really no need to rev high when the power is there.
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Old 09-19-2010, 08:51 PM
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Quote:
Originally Posted by Custom10
yep the transition plate may help then

http://www.edelbrock.com/automotive_..._spacers.shtml

but really I would consider a sqare bore intake and if you don't need it for clearance or something ditch the spacer altogether as it/they can give greif. Another option would be to go with a Qjet with that manifold, or a holley 4010 Qjet replacement carb but they were not so great, mine sits on the shelf.

thanks for the note on the chevy.
I will take the spacer off tom. and see what happens and i know the carb does seal better to the intake with out the spacer. the spacer is a little more narrow than the carb itself.
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Old 09-19-2010, 09:05 PM
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Quote:
Originally Posted by ericnova72
Total timing is checked with a timing light by revving the engine and finding out the point the timing stops advancing and noting the degree and rpm reading. You will need a advance adjustable light, or a degreed timing tape on the balancer. Take a look in our Crankshaft Coalition Wiki for tutorials on making a easy degree tape for your balancer. Geting the timing set up right will be the biggest factor in getting the engine to run right and make good power up to its potential, and is the most common thing most young or limited experience rodders don't even know about.

The 280 cam is big enough it really needs to have initial timing in the 16-18 area, but you can't let the total get over 38 without risking getting detonation damage to the motor. Usually requires you to tear the distributor apart and limit its advance amount to get things right. You can search some of the recent timing threads here to get a taste of what is required.

In gear idle seems a bit low, adding 100 rpm may really help you cover some of the problem, but distributor modification is what it really needs to be right..

Try testing 16-18 initial to see how it responds from a stop, but don't run it up the rpm scale far to keep it from getting too much total and going into detonation. Just brief bursts from a stop to see if you are working in the right direction on timing.
oh by the way the timing light i have is really old all it does is flash will this for for total timing?and for intial to be set at like 16-18* do you just kinda guess some where above the timing indicator where it looks right? i looked at Crankshaft Coalition and it wouldn't show anything up.
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Old 09-20-2010, 05:18 PM
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Here:

http://www.crankshaftcoalition.com/w..._a_timing_tape

this topic/link gets more hits than a buck decoy at the rifle range,

good luck and let us know how she goes

2 more of my cents
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Old 09-20-2010, 05:53 PM
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Quote:
Originally Posted by Custom10
Here:

http://www.crankshaftcoalition.com/w..._a_timing_tape

this topic/link gets more hits than a buck decoy at the rifle range,

good luck and let us know how she goes

2 more of my cents
Thanks i took the spacer off and got a lot more power out of it. the initial timing is set just above 16* and that really woke it up. and im getting a spring kit for it tom. to fine tune it.
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Old 09-20-2010, 06:11 PM
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Looks like you are getting close, I was just going to say i had one that done the same thing and it was a combination of timing and carb adjustment. Ok there's my 2 cents also.


Cole
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