73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Got Smoke? on August 01, 2011, 06:45:58 pm
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Ok I've been out of the gasser world for the most part for the last several years. Just recently sold my tow rig Cummins leaving my only truck my 79 Chevy K20, and I want to get it into a more workable status. Let me give you some specs.
350 .030 over, stock style pistons, Edelbrock Performer Intake & 600CFM Carb with one step larger needles & jets, Comp Cams 268 cam, stock HEI distributor, Hedmen Headers, AC delco plugs, & house brand Auto Zone 7mm wires 4spd manual.
The truck runs pretty good when warm, but its a little jerky/sluggish when first starting out on a cold engine. The carb has an electric choke which I do not have hooked up currently, but I am going to look up the directions and set it soon. However its 80 degree's by 7AM here in middle tenn so that's not really an issue this time of year is it?
I'm more concerned with do I have my timing in the right place? Where should it be set up on a truck like this that see's daily driving and will see towing if the need arise's (NOT my pulling truck in my sig)
Thanks for any help
EDIT I forgot another thing that make me think timing is it does NOT like to start up if the motors hot. I got one of those heat shield blankets this weekend at the local parts store and that still hasn't made any improvement in the problem.
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Do you have a standard vacuum advance HEI ignition? Is the vacuum advance hooked up to ported or manifold vacuum?
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Do you have a standard vacuum advance HEI ignition? Is the vacuum advance hooked up to ported or manifold vacuum?
Yes its a vacuum advance, the hose runs directly from the vacuum advance to a port on the front of the carb. Is this correct?
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Which port? Is there vacuum there at idle? Pull the hose off and check.
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Which port? Is there vacuum there at idle? Pull the hose off and check.
This one. I started the truck and pulled the hose to make sure and yes there is vacuum at idle. Had a noticeable idle change when unhooked.
(http://a3.sphotos.ak.fbcdn.net/hphotos-ak-snc6/189383_238263669539068_100000663093294_793830_5371389_n.jpg)
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Hook up the electric choke
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Hook up the electric choke
Next on my to-do list. LoL Thankfully not my daily driver. I need to check my timing, suggestions on where to run it at?
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Without a choke even in hot weather expect a 5 min warm up before it runs right. you'll even need to give it a little gas to keep it running if you idle is set low.
You'll need a 12v key on power source to plug into your choke.
Once you have that; to start the engine, turn the key to "on" (warm or cold), press down the gas pedal and let it back up.
this activates the choke and fast idle cam.
the choke is adjusted by loosening the screws around the black disc rotate the disc forward for more choke and backward for less.
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I thought distributor should not have vacuum at idle?
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I thought distributor should not have vacuum at idle?
Ditto
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I thought distributor should not have vacuum at idle?
From the factory, no the advance didn't kick in until you open the throttle a little (ported vacuum). Some like to change it to regular vacuum ports for performance reasons.
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Heres the edelbrock carb install videos :) Video IV shows an easy way of grounding the choke to the carb itself. Take a look.
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What about the hard starting when hot, even with the protective blanket on the starter?
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describe more about this hard starting. does it crank slowly, or does it crank ok, just takes awhile to actually start?
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describe more about this hard starting. does it crank slowly, or does it crank ok, just takes awhile to actually start?
When trying to restart when its in the 190-210 temp range it spins fast like it wants to start but is hesitant to do so.
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Sounds just like you have an Edelbrock carb. LOL. Mine has the same exact symptoms. I just live with it. Sometimes after restarting, it runs pig rich for awhile until I get it all blown out. Whatever Edelbrock.
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Sounds just like you have an Edelbrock carb. LOL. Mine has the same exact symptoms. I just live with it. Sometimes after restarting, it runs pig rich for awhile until I get it all blown out. Whatever Edelbrock.
Well I'm currently working on that part....I won a Holley Street Avenger at a buddies open house for his Truck Accesory shop, he's trying to get it swapped out for a Truck Avenger for me.
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You might try the heat insulating gasket between the carb and the intake. Those aluminum intakes throw off a lot of heat. Your module may be getting hot in your distributor too. I had a problem with hot starts until I changed my coil to an external and put a good module in there. I still get a slight stumble (but heck it's 100 plus degrees in Houston) but it's nothing like it was when it was winter.
The other thing is to slowly open the throttle halfway so the accelerator pump doesn't activate and then start it and let your foot of the gas once the engine catches so to speak. If it's somewhat flooded with gas, the extra air will help blow it out.
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Yeah I just put on an Edelbrock and noticed if I shut my truck off and went in the store when I came back to fire it up Id have to crank for maybe 5 secs then it would start up. I talked to the guy at O'reilies and he told me to check the choke to see if its open fully after the trucks up to temp. Also told me to make sure my fuel line wasnt by anything that would get it really hot. Both of those checked out fine so Im guessing vapor lock is the problem. Im going to head down and buy a heat insulator gasket before I put new gaskets under my manifold. Ill tell you how the hot starts are after I have the insulator installed :)
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You might try the heat insulating gasket between the carb and the intake. Those aluminum intakes throw off a lot of heat. Your module may be getting hot in your distributor too. I had a problem with hot starts until I changed my coil to an external and put a good module in there. I still get a slight stumble (but heck it's 100 plus degrees in Houston) but it's nothing like it was when it was winter.
The other thing is to slowly open the throttle halfway so the accelerator pump doesn't activate and then start it and let your foot of the gas once the engine catches so to speak. If it's somewhat flooded with gas, the extra air will help blow it out.
Wasn't quite sure what gasket you were talking about so I did a Bing Search...my carb is a square bore and my manifold is a spread bore so there is an adapter in between...would this serve the same purpose, or amplify the problem since its made out of metal/aluminum?
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Sounds just like you have an Edelbrock carb. LOL. Mine has the same exact symptoms. I just live with it. Sometimes after restarting, it runs pig rich for awhile until I get it all blown out. Whatever Edelbrock.
Well I'm currently working on that part....I won a Holley Street Avenger at a buddies open house for his Truck Accesory shop, he's trying to get it swapped out for a Truck Avenger for me.
My street avenger never lets me down.
There is an adapter for your application, You could find a phenolic version to insulate from heat if thats a concern. I would find an open version to help balance out your a/f mixture between the right and left bank as well.
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Sounds just like you have an Edelbrock carb. LOL. Mine has the same exact symptoms. I just live with it. Sometimes after restarting, it runs pig rich for awhile until I get it all blown out. Whatever Edelbrock.
My street avenger never lets me down.
There is an adapter for your application, You could find a phenolic version to insulate from heat if thats a concern. I would find an open version to help balance out your a/f mixture between the right and left bank as well.
If my truck was already restored I would have just slapped the street avenger on there...its the nice all aluminum version. However, my truck is far from pretty and still gets taken off road frequently so I opted to swap it out for a Truck Avenger(hopefully)
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Yeah I just put on an Edelbrock and noticed if I shut my truck off and went in the store when I came back to fire it up Id have to crank for maybe 5 secs then it would start up. I talked to the guy at O'reilies and he told me to check the choke to see if its open fully after the trucks up to temp. Also told me to make sure my fuel line wasnt by anything that would get it really hot. Both of those checked out fine so Im guessing vapor lock is the problem. Im going to head down and buy a heat insulator gasket before I put new gaskets under my manifold. Ill tell you how the hot starts are after I have the insulator installed :)
If you have an electric choke, the choke operates off of 12v power not engine heat. So if your key is turned off the choke closes (when activated). when you turn on your key the choke slowly opens becuase the 12v power is heating the choke thermostat. your choke would most likely be closed somewhat. (btw you can check this by leaving the key on next time you stop for a few minutes). If this is your issue and you have plenty of choke for a cold start; dial back the choke a little and try it.
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vapor lock. aka fuel in carb turning into vapor, or something like that. mine does it too, but I have a electric pump so i just let it prime.
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You might try the heat insulating gasket between the carb and the intake. Those aluminum intakes throw off a lot of heat. Your module may be getting hot in your distributor too. I had a problem with hot starts until I changed my coil to an external and put a good module in there. I still get a slight stumble (but heck it's 100 plus degrees in Houston) but it's nothing like it was when it was winter.
The other thing is to slowly open the throttle halfway so the accelerator pump doesn't activate and then start it and let your foot of the gas once the engine catches so to speak. If it's somewhat flooded with gas, the extra air will help blow it out.
Wasn't quite sure what gasket you were talking about so I did a Bing Search...my carb is a square bore and my manifold is a spread bore so there is an adapter in between...would this serve the same purpose, or amplify the problem since its made out of metal/aluminum?
I thought you had a performer intake which should be both square and spreadbore flanged?
http://www.summitracing.com/parts/EDL-9265/
Something like that might work. Or you could try the whole plate setup. http://www.summitracing.com/parts/MRG-3710/
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A lot of performer's can use square or spread bore carb.'s, but there's plenty that are one or the other.
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I thought you had a performer intake which should be both square and spreadbore flanged?
http://www.summitracing.com/parts/EDL-9265/
Something like that might work. Or you could try the whole plate setup. http://www.summitracing.com/parts/MRG-3710/
It is a performer intake I bought it new from my local auto zone several years ago while a buddy & his dad were helping me rebuild the 350. You can get them in either form, at the time I was reusing my Qjet carb so I needed spread bore.
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I thought distributor should not have vacuum at idle?
If you have a bone stock application and wish to keep it that way, yes it was timed and ported from the factory. If you have done any modifications and or just want to benefit from a stronger idle and better throttle response connect it to the full vacuum port on the front of the carb.
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You should wire the elcetric choke off of an oil pressure switch. If you have it hooked to key on B+ as soon as you turn the key on it will start to heat the choke coil.
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You should wire the elcetric choke off of an oil pressure switch. If you have it hooked to key on B+ as soon as you turn the key on it will start to heat the choke coil.
Is there another oil pressure port besides the one the OEM sender using next to the distributor. Sorry I know that's a newb question... :-[
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I think just above the oil filter if I remember right.