i went back and read youre post lt1s10. i forgot to turn the mixture screws in and back out 2 and half after doing that the motor revs when i spray disconnected hoses one by one still doing it not leaking around carb or intake , were else
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i went back and read youre post lt1s10. i forgot to turn the mixture screws in and back out 2 and half after doing that the motor revs when i spray disconnected hoses one by one still doing it not leaking around carb or intake , were else
im getting a little rev around the secondary throttle shaft
around the shaft,that dont mean nothing, most any carb will pick up a little if you spray the shaft. put the new intake gasket on, see what happens. when you cant find the vac. leak no where else then most of the time it will be worn valve guides, and thats hard to prove. most of the time though its just one guide thats bad and it will show up as a miss on that cylinder. with the motor running you can spreay carb. cleaner into the valve cover and if they are worn enough it will suck the cleaner into the cylinders and the motor will idle up. but thats another story.Quote:
Originally posted by S19243H
im getting a little rev around the secondary throttle shaft
you said you had tried a diff. carb. right?
yea its weird i put the holly back on and when i close the choke the idle stays the same until completely closed then shuts off still 12 inches no more
i dont know what to tell you. with 12 " of vac its not gonna idle right, if its a leak you need to fix it , and if its the cam you need a conv. if its a leak it shuld or will increase rpm if you choke it or spray it. ifs its not a leak it want. if its late timing causing the low vac. it want increase the rpm's when sprayed, but i hope you have the timing right.
how can i tell if its late timing? piston tdc on comp stroke both valves one 1 closed three intake open rotor pointing at one on cap ballancer mark on zero on the tab cam dot at 1200 crank dot at 1200 oclock motor starts on one turn at 20 btdc total 34 a converter isnt going to give it more vac at idle id rather give it a cam change than yank the trans with all the info i gave you what cam would you run in this motor just asking
what do you use the truck for? daily driver or what.
if the HB mark is true TDC then what ever the timing light shows is what the timing is. if your mark is right and the light says 10 drgeers then its ok. the only time the timing could be late and you not know it would be for the marks to be off. you still should be able to jack the timing up and smooth the motor out anyhow, if thats your problem.
if it runs, your marks are right and the light says 20 degrees then the timing is not the problem.
its not a truck lt1s10 the motor is out off a 74 blazer stuffed in a 83 camaro if i set the timing at 8 btdc THE IDLE AT 1000 THE GAUGE READS 10 INCHES i have a light with a dial i set it at 8 and look at zero on the tab or look at 8 on the tab and set the light at zero
that sounds right, but set the light where you want it 8 to 12 degrees is a good start. with the light on 10 when you look at your tab that should be on 0. if you have your light on 0 then the tab would be on 10, after that if you jack a little more timing into it the vac. should go up a little. if it dont then thats all the vac. you have. the higher the timing the more vac. but you cant go but so high. you say the motor runs good, other than it cuts off when you put it in gear. i still belive you have a leak. is the vac. hand study or jumping all over the place while its idling at 900 rpm.Quote:
Originally posted by S19243H
its not a truck lt1s10 the motor is out off a 74 blazer stuffed in a 83 camaro if i set the timing at 8 btdc THE IDLE AT 1000 THE GAUGE READS 10 INCHES i have a light with a dial i set it at 8 and look at zero on the tab or look at 8 on the tab and set the light at zero
The hand is steady the carb might idle up and down 1 or 2 hundred rs the gauge might move from 11 to 12 and back you say start at 10 and move up from there i can go to 28 but it will idle at 1500 with 17 inches one thing strange i dont know if its from moving the dist but when i first started it after puting the gaskets in the tach would drop as fast as it would go up thats the way it use to be after moving the dist it wouldnt drop as fast so today ill set timing at 10 an try again maybe to much timing
Quote:
Originally posted by S19243H
The hand is steady the carb might idle up and down 1 or 2 hundred rs the gauge might move from 11 to 12 and back you say start at 10 and move up from there i can go to 28 but it will idle at 1500 with 17 inches one thing strange i dont know if its from moving the dist but when i first started it after puting the gaskets in the tach would drop as fast as it would go up thats the way it use to be after moving the dist it wouldnt drop as fast so today ill set timing at 10 an try again maybe to much timing
something is not right here, forget the timing light, pull your dist up untill you get 17" back down to 15" and idle the carb. to 900 and adj. the air screws will it run then. i thought you said 12" was all you had. if the timing was so far off you only had 12" it wouldnt have power enough to pull off.
'
12 is all i have if i keep turning the idle back to 900 if i dont turn the idle back then ill get 17''
[QUOTE]Originally posted by S19243H
12 is all i have if i keep turning the idle back to 900 if i dont turn the idle back then ill get 17'' [/QUOTE
ok
ps but the motorwill be idling at 1500
did you put new gaskets on? do one more thing get it running as well as you can and spray carb. cleaner into the valve covers, through the pcv valve hole or breather. see what happens.
Quote:
Originally posted by S19243H
ps but the motorwill be idling at 1500
it want be if you idle it back down. you cant get a vac. reading at 1500 rpm's, i think you might be trying to set the rpm's with the dist. cant do that. move the dist up, idle the carb. down untill you have max. vac at 900 rpm's. the timing will take care of itself if you do that.
Ok, I came in a little late here so let me toss in some stuff learned by experience . . . otherwise known as, "the hard way."
How big a cam do you have?
Using advertised duration, a 284-292 degree cam will idle 600 rpm or so and vacuum will read 10-12"
A cam with advertised duration of 260-266 degrees will idle 550-600 rpm at 18-19" vacuum.
Stock cams idle the same as the mild cam listed above.
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Where are you plugging your vacuum gauge?
If into the ported - or timed as some call it - vacuum source idle at 600 rpm will show zero and 900 rpm will show 12".
Plugged into full time vacuum - or manifold vacuum as it's usually called, you will get 18-19" of vacuum at a 600 rpm idle assuming a stock or very mild cam.
Incidentally, radical cams when spun up to 1200-1500 rpm or so will read 18-19" on a well sealed engine.
Ported vacuum is usually tapped at the carb above the throttle blades.
Usually being the key word, some Holleys have a full-time vacuum source above the throttle blades so you need to be careful here.
Manifold vacuum is anywhere in the intake manifold and below the throttle blades.
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Are you timing the engine with the vacuum advance line disconnected?
If so, that's correct.
If not, you will not have sufficient advance to have a good running engine as well as give away a lot of horsepower.
Pull the vacuum line at the distributor and plug it - golf tees work great for this.
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Do you have an MSD ignition - or similar - module?
And are you using a dial-back timing light?
I ran into a problem using a new dial-back timing light.
It showed 20 degrees off toward the retard side if I remember right.
Re-checking timing with the old non dial-back light - same brands on both by the way - showed the timing to be at 8 degrees initial like it's supposed to be.
You have to be careful here.
Some guys use a dial-back light on MSD equipped engines and get the same reading as a non dial-back and others report the same problem I had.
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Are you running an Edelbrock or Carter carb?
And is the engine running very rough on the bottom end of the rpm scale - and won't hardly idle?
Pull the metering rods and look for a bent one.
I had a bent metering rod in a brand new 500 cfm Carter on a dual quad setup and when it stuck, I thought I had a heck of an ignition problem.
The engine ran strong when revved up and with a bit of throttle applied, but at light throttle settings it wouldn't hardly run.
The bend had locked the metering rod in the up position which made the engine overly rich.
You can check these by rolling them on a known to be flat surface - piece of thick glass works well - with the 90 degree bend hanging over the surface plate and if a bend is found, straighten it by hand.
C9x we found the problem look under the thread faulty vacuum gauge for sale a lot of good info in youre post thank you