The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1969 - 1972 Blazers and Jimmys Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 06-12-2012, 05:55 PM   #1
Jake's 72' blazer
Registered User
 
Join Date: Jun 2012
Location: New Hartford N.Y
Posts: 11
2wd blazer 6cyl, gas in oil!

ok im a new member here any help would be appreciated. i have a 72 2wd blazer with the 250 inline 6. it has been bored .30 over and has a cam and headers. It has a 4 barrel offenhauser intake on it. along with this was a 2 barrel holley carb w adapter plate. this was all done 15 years ago by my fathers friend. i could never get it to run right with this setup. It allways backfired and sputtered like crap, even trying all possible timing settings. (because someone said it could be the timing)?? so then i went through the carb and now it is basically just dumping gas into the oil. must be something i did to the carb?? and also what carb and intake settup should i run? get a 4 barrel or get a 2 barrel? get a stock intake or leave the offy? i just want to be able to drive it. thanks in advance, i figured i came to the right place.
Attached Images
    
Jake's 72' blazer is offline   Reply With Quote
Old 06-12-2012, 11:26 PM   #2
old man jimmy
Registered User
 
Join Date: May 2007
Location: texas
Posts: 329
Re: 2wd blazer 6cyl, gas in oil!

sounds like you need to set your float, and replace your power valve. not up on the 2 barrels, but looks like half a 4 barrel. that brass screw on top of the bowl is how you set the float. just take the brass plug out of the side of the bowl, and adjust the top screw so gas just starts to drip out the hole (with engine running) the drop the float just a little. put the plug back in. the power valve is in the metering block (behind the bowl.) you have to take the 4 screws holding the bowl on to get it off. If it's like a 4 barrel their will be a power valve in the middle of it. the old holleys were really simple to work on, and you can do just about anyting they ever need without even pulling the carb. the power valve was kinda their weak link. all they had to do was sneeze once, and it was usually toast. You have an old school set up their for sure. Only built one like it, an old 65 dodge half ton slant six. the 4 barrel was just too much juice for it, and endend up adapting to 2 barrel. good luck.
old man jimmy is offline   Reply With Quote
Old 06-12-2012, 11:28 PM   #3
old man jimmy
Registered User
 
Join Date: May 2007
Location: texas
Posts: 329
Re: 2wd blazer 6cyl, gas in oil!

forgot to mention. if you get it running right. be sure to change your oil and filter right away. gas in the oil is a bad combination.
old man jimmy is offline   Reply With Quote
Old 06-13-2012, 04:28 PM   #4
Jake's 72' blazer
Registered User
 
Join Date: Jun 2012
Location: New Hartford N.Y
Posts: 11
Re: 2wd blazer 6cyl, gas in oil!

well last winter i took the whole carb apart and put in the replacement kit w/ new power valve. i set the float level with a pencil (some book said that). it must have been something i did as it was my first time in a carb(for a vehicle). would there be any problem running that 2 brl on a 4 brl intake?
Jake's 72' blazer is offline   Reply With Quote
Old 06-13-2012, 04:31 PM   #5
Jake's 72' blazer
Registered User
 
Join Date: Jun 2012
Location: New Hartford N.Y
Posts: 11
Re: 2wd blazer 6cyl, gas in oil!

also i checked the oil after trying to set the timing for about 10, 15 mins and it was probably 2 quarts over full with gas. when i drained it it was a lot of thin fluid.
Jake's 72' blazer is offline   Reply With Quote
Old 06-13-2012, 07:34 PM   #6
cleszkie
Registered User
 
cleszkie's Avatar
 
Join Date: Feb 2003
Location: Santa Ana, CA
Posts: 2,191
Re: 2wd blazer 6cyl, gas in oil!

If you had 2 quarts of gas in your oil after 10 to 15 minutes of running, that sounds like more than a float bowl out of whack. I suggest you take a look at your mechanical fuel pump. The fuel pump can dump gas directly into the oil pan if the diaphragm is toast. A bad fuel pump may also explain the performance troubles you are having as well.
cleszkie is offline   Reply With Quote
Old 06-13-2012, 07:36 PM   #7
old man jimmy
Registered User
 
Join Date: May 2007
Location: texas
Posts: 329
Re: 2wd blazer 6cyl, gas in oil!

pull that brass plug on the side of your fuel bowl, start it and if you have gas running out the hole. your float is set too high. Also if you are setting your timing at factory specs, and it's cammed, you can throw away your specs. Just set it up by ear. Start it advance your dist. until the rpms are about the highest, then back it off a little. With a cam, it's kinda a trial and error thing. Glad you changed your oil, gas makes a real poor lub. Another thing that can make it spit and sputter is the condenser in your dist. Sounds like an easy fix for your problem as long as your motor is sound. you just have to find it first. Let me guess. I'd say the po is in his late 60's early 70's. just guessing from the way he put it together. luck to ya.
old man jimmy is offline   Reply With Quote
Old 06-14-2012, 05:00 PM   #8
Jake's 72' blazer
Registered User
 
Join Date: Jun 2012
Location: New Hartford N.Y
Posts: 11
Re: 2wd blazer 6cyl, gas in oil!

I had changed the fuel pump because i thought the same thing. it was fine. yes i agree i hope it is the float! i'll just have to do it again. also i hope if i get the fuel comming in right then i can get the timing set finally. thanks alot guys!
really appreciated.
Jake's 72' blazer is offline   Reply With Quote
Old 06-16-2012, 11:47 AM   #9
Jake's 72' blazer
Registered User
 
Join Date: Jun 2012
Location: New Hartford N.Y
Posts: 11
Re: 2wd blazer 6cyl, gas in oil!

ive got the carb all back apart. the float is about a quarter inch from the top of the housing before it seats the needle valve. is this too high? the carb it a holley 4412 2brl.
also when i blow in the fuel line and shut off the flow by lifting the float. when i let the float down again the needle sticks up for a sec.?
Jake's 72' blazer is offline   Reply With Quote
Old 06-16-2012, 04:50 PM   #10
old man jimmy
Registered User
 
Join Date: May 2007
Location: texas
Posts: 329
Re: 2wd blazer 6cyl, gas in oil!

you're going about it the hard way. you didn't have to take the carb back apart. all you had to do was take out that brass plug on the side of the fuel bowl. if gas runs out the hole, your float is set too high. that would tell me a lot more. the screw on top of the bowl is how you set the float. it's been a lot of years since i ran a holley so don't remember the specs on the float with the carb off. you should have got that info. with the kit. if you can't adjust the screw enough to stop the gas from coming out the overflow hole, then it could be your needle and seat, or your float is bent too much for the screw to adj. or too much fuel pressure. start with the easy checks first, and go from their. don't get frustrated, old cars take a lot of patience.
old man jimmy is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 03:52 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com