Thread: there is definetly a vacuum leak

Tweet

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

Originally posted by S19243H
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.

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

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

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.

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

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.