Outta_OC Posted February 20, 2016 Report Share Posted February 20, 2016 What to do? Have replaced fuel filter and have run Lucas fuel system cleaner through two tanks of (always) premium. Rebuild carb? Clean jets? Idk... Quote Link to comment
Draker Posted February 20, 2016 Report Share Posted February 20, 2016 What carb... what engine? 1 Quote Link to comment
Outta_OC Posted February 20, 2016 Author Report Share Posted February 20, 2016 74 l18 with a Weber ... I can't seem to remember the exact model of carb atm... Quote Link to comment
datzenmike Posted February 20, 2016 Report Share Posted February 20, 2016 The 32/36 is a progressive carb with the secondaries on demand. The linkage is set to tip the secondary in somewhere after half throttle on the primaries. The point is that you can open them any time by simply stepping down on the gas pedal. The point of the secondary is to provide more gas and air when needed. When Needed. If you tip the secondary in too soon the volume of air flowing through the carb is not enough to form a proper vacuum at the venturies. Without this the gas can't be sucked in. To test this allow the engine to rev higher before stepping the gas pedal fully to the floor. The 32/36 is a carb that has to be 'driven' with this in mind. Never floor the gas immediately, but step near to the tip in point of the secondary and allow the engine to rev higher. Then step more towards the floor. Some practice and paying attention to intake and exhaust sound and this problem should resolve itself. A vacuum secondary such as used on the original Hitachi, allows full throttle of the primary immediately, and when a preset vacuum is reached the secondary is actuated. If the engine is not ready for more carb it doesn't get more. Otherwise... Bogging is an indication of going lean. Clean the secondary jet and also find out what the correct size is. 2 Quote Link to comment
Outta_OC Posted February 20, 2016 Author Report Share Posted February 20, 2016 Thanks for the in-depth analysis Mike. It happens at half throttle, it's a certain rpm range. I was a bit toasty last night when I posted the OP. It doesn't really happen in first, second it bogs and kinda blubbers high into the rpm range, and third it bogs maybe 3/4 of the way through the rpm range. 4th and 5th do the same - it sounds like it's not getting enough fuel when at freeway speeds; I can feel it chugging and I want to call it "missing a beat" - at full throttle. 3rd gear is easiest to test your theory - and yes the problem occurs regardless of throttle position in the upper rpm range Quote Link to comment
Outta_OC Posted February 20, 2016 Author Report Share Posted February 20, 2016 I love hitting the secondaries at just the right time in 2nd and 3rd. It makes me think she's beefier than she really is... Quote Link to comment
Doctor510 Posted February 20, 2016 Report Share Posted February 20, 2016 Remove the secondary idle jet and clean it and squirt the carb where you took it from. If that doesn't cure it, try a larger jet. 1 Quote Link to comment
datzenmike Posted February 20, 2016 Report Share Posted February 20, 2016 Thanks for the in-depth analysis Mike. It happens at half throttle, it's a certain rpm range. I was a bit toasty last night when I posted the OP. It doesn't really happen in first, second it bogs and kinda blubbers high into the rpm range, and third it bogs maybe 3/4 of the way through the rpm range. 4th and 5th do the same - it sounds like it's not getting enough fuel when at freeway speeds; I can feel it chugging and I want to call it "missing a beat" - at full throttle. 3rd gear is easiest to test your theory - and yes the problem occurs regardless of throttle position in the upper rpm range Change the fuel filter. If restrictive you are using fuel faster than it can be replaced. Then check the fuel level in the carb and adjust the float if needed. Again if set too low you may be emptying the carb faster than the gas can get in. 1 Quote Link to comment
Stoffregen Motorsports Posted February 20, 2016 Report Share Posted February 20, 2016 Weber re-designed the DGV about 18 years ago. The early DGV's had a unitized fuel circuit where primary and secondary both shared the fuel circuit. The redesigned carb (DGV 5A) had separate fuel circuits, one for the primary and one for the secondary. The reason for the redesign was the typical bogging between primary and secondary transition. When the secondary opened, it essentially robbed fuel from the primary until the fuel circuit could be brought up to speed. This problem creates the lean condition at primary/secondary transition. The bogging is a typical problem with the early carbs, but you can tune around it to an extent. If it continues and really bothers you, the only fix is to buy a newer carb. A lot of the older carbs still exist so the only way to be sure is to check the number stamped on the carb. Note - I don't know if there are stampings NEWER than "5A" so maybe a bit of research would be a good idea before you decide to buy a carb, but I do know that if it's stamped "5A" then it's the newer design. 1 Quote Link to comment
banzai510(hainz) Posted February 20, 2016 Report Share Posted February 20, 2016 you positive on the 2nd barrel when this happens. For me It was m distributor vaccum/mechanical advance was stuck.. My carb is only about 1 year old since I put it on so I figured it WASNT it. it possible to manipulate the carb get the reves up then open the 2nd side with enough vaccum it should stay running. one can put a hand on the main barrel side to get the flow on the 2ndary side if runs then you might assume the dist is out of wack. reck the timming also. if point distributor regap them also 2 Quote Link to comment
Outta_OC Posted February 27, 2016 Author Report Share Posted February 27, 2016 You guys are all amazing, thank you for the insight. I fear my descriptions have not been accurate. The truck has been running "fine" for the last year. 2 months ago i noticed an increase in small backfires from my carb if i were to throttle down too hard out of a turn. 3 weeks ago i started bogging/sputtering/chugging in 2nd/3rd/4th/5th gear anywhere over half throttle HEAVILY NOTICABLE ON THE FREEWAY above 50/ 60mph in 4th or 5th gear. I can hardly go along at 75 or 80 as it feels like its hardly getting enough fuel. Where as before my top speed was somewhere around 115 the truck cant get enough in her to get above 80. I went to carburetor land today and it sounded like he was going to rebuild my carb "a new carb for 180" and then tune for 40 until its right. - the whole reason i got a datsun was to do the work myself, so i think ill bum him out by just buying a rebuild kit and learning myself tomorrow. - however i may replace the mr gasket fuel pump for 46 bucks and see if maaaybe that is going out? Quote Link to comment
Outta_OC Posted February 27, 2016 Author Report Share Posted February 27, 2016 I started a new job this week and my commute is a bit further and its been struggling to start the last few days.. maybe timing is the issue I had actually just changed the fuel filter the day or two before posting. Quote Link to comment
Outta_OC Posted February 27, 2016 Author Report Share Posted February 27, 2016 you positive on the 2nd barrel when this happens. For me It was m distributor vaccum/mechanical advance was stuck.. My carb is only about 1 year old since I put it on so I figured it WASNT it. it possible to manipulate the carb get the reves up then open the 2nd side with enough vaccum it should stay running. one can put a hand on the main barrel side to get the flow on the 2ndary side if runs then you might assume the dist is out of wack. reck the timming also. if point distributor regap them also I was talking to my boss today and he mentioned a timing issue. Ive been having issues the last few days when starting the truck, and perhaps the dizzy is loose and has been rotating slowly into dismay Quote Link to comment
Outta_OC Posted February 27, 2016 Author Report Share Posted February 27, 2016 To clean the secondary jet, i just remove the air horn to gain access in the _______ (bubble, float, dish, lol idk the term but i know the location) Quote Link to comment
datzenmike Posted February 27, 2016 Report Share Posted February 27, 2016 Carb won't need re-building if new and only a year old. Bogging in the secondary is likely a jet part plugged or blocked. Clean it and it should be back to normal. '74 will have a points distributor. Replace the points and gap. 0.022" should be close enough. Check timing but with points set it should be close to correct. Another thing to check is the valve lash. 1 Quote Link to comment
Outta_OC Posted February 27, 2016 Author Report Share Posted February 27, 2016 I've been reading a but valve lash for sometime... This lil datsun clicks like my 63 390 ford did lol... I'm a bit intimidated messing with those alone... I'll snap a pic of the dizzy, I'm fairly certain it's not points anymore tho (the guy I got it from changed it) Quote Link to comment
datzenmike Posted February 27, 2016 Report Share Posted February 27, 2016 Excessive lash and the lash pads can pop out. Here this is easy to do... http://community.ratsun.net/topic/16539-l-series-valve-adjustment/ Quote Link to comment
Outta_OC Posted February 27, 2016 Author Report Share Posted February 27, 2016 Dizzy seems tight... Doesn't feel like it's moving around... Quote Link to comment
Outta_OC Posted February 27, 2016 Author Report Share Posted February 27, 2016 Thanks Mike. I've been reading/watching videos on adjusting the valves... Should I buy a new gasket for the vlve cover? I would think yes.... Lol Should I get some new gaskets today before taking the carb apart? Quote Link to comment
datzenmike Posted February 27, 2016 Report Share Posted February 27, 2016 Just take apart carefully and you won't need gaskets. I'm expecting the secondary jet to be gummed up. Have a can of carb cleaner handy, the one with the straw so you can blow it though small openings. 1 Quote Link to comment
Outta_OC Posted February 27, 2016 Author Report Share Posted February 27, 2016 Bitchin. Just got back, put 40 down for a rebuild kit that won't be here till Monday - but I'll have it... I will be extremely careful, I'm a journeyman carpenter/cabinet builder so believe it or not I do comrehend the word finesse haha Thanks again Mike. I'll take some pics and post em up in. Couple hours. Sidenote - neither autozone or o'riley had anything in their computers for a Weber... Quote Link to comment
Outta_OC Posted February 27, 2016 Author Report Share Posted February 27, 2016 It's not the greatest, but I think you should be able to hear the problem. The video is 2nd to 3rd to 4th gear Quote Link to comment
banzai510(hainz) Posted February 27, 2016 Report Share Posted February 27, 2016 OK I see you have a pertronix. Make sure the red wire of Pertronix is on the plus side of the ballast resisitor. Take photos. Make sure no side to side movement on distributor shaft. this is a worn bushing if so. But if tight its OK. if worn it may be a proplem. also make sure the the advance moves on the dist. turn the dist plate that the pertronix sits on... sometimes they can lock up. now I would shoot a lot of carb cleaner in there. I never heard a a weber 33dgav. I know 32/36 dgav carbs. by the sound I think the carb is fine. rev up the motor and manpolate the 2nd barrel opening and put your hand on the main barrel to block the air so you use the 2nd barrel side. retime the motor again using a light 1 Quote Link to comment
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