Carb selection help

[72Daphne]

I was looking to upgrade my stock Hitachi carb and was hoping for some suggestions. My Hitachi needs to be rebuilt and I have read Weber 32/36 DGV is a good upgrade. Trying to budget under $300.

[bertvorgon]

The Weber 32/36 is a very good upgrade! Easy to tune and there is lots of support for suggestions, etc, both on this site and others, with base settings.

[okayfine]

However, don't assume you'll just be able to bolt on that 32/36 and go. It'll likely need to be tuned to your engine, even if it came off an L-series.

DQ Volume 1 Issue 3 - Downdraft Tuning Guide - A guide to understanding downdraft carburetors, what the parts are for and how they fit together and work.

DQ Volume 2 Issue 1 - Carburetor Tuning Guide:Part Two - Tuning tips and guidelines for Hitachi and Weber carburetors for the L-series four-cylinder engine.

and

DQ Volume 2 Issue 1 - Tuning the Weber DGV for the L-Series 510 motor. - Weber DGV carburetors were original applications for various European vehicles with displacements ranging from 1300cc to 2000cc. Dennis Hale discusses tuning the Weber DGV for the stock 510 engine.

[datzenmike]

Let me be the devil's advocate here. For 1/10 the cost you can simply rebuild your Hitachi carb. It's already the correct fit and jetted properly, better yet, everything connects to it already like the fuel line, and it takes the stock air cleaner with the ATC warmed air from the exhaust (to prevent carb icing) and the valve cover vent hose without having to modify it. It has the superior vacuum operated secondary rather than the weber's mechanical that has to be tipped in by the driver. (usually too soon resulting in a slight bog or too late) If you have a mechanical choke you will have to rig something up on the weber, if you need electric choke and idle cut solenoid (after '71?) you have to order it on the weber.

[72Daphne]

Let me be the devil's advocate here. For 1/10 the cost you can simply rebuild your Hitachi carb. It's already the correct fit and jetted properly, better yet, everything connects to it already like the fuel line, and it takes the stock air cleaner with the ATC warmed air from the exhaust (to prevent carb icing) and the valve cover vent hose without having to modify it. It has the superior vacuum operated secondary rather than the weber's mechanical that has to be tipped in by the driver. (usually too soon resulting in a slight bog or too late) If you have a mechanical choke you will have to rig something up on the weber, if you need electric choke and idle cut solenoid (after '71?) you have to order it on the weber.

I took your advice and bought a rebuild kit for my Hitachi. Figured I could at least try it and if I wasn't happy upgrade at a later date. Unfortunately rebuilding the carb didn't help my car run any better yet. I am having a problem getting the engine to idle. Only way she runs now is if I give her a little gas to keep the engine going. Doesn't take much but when I let off the gas the engine will sputter for a few seconds and then die.

To me the problems seems like it isn't getting enough gas. I was hoping rebuilding the carb would fix that but so far it hasn't. I have adjusted the idle speed and air/fuel but not much has helped. The float level is right around the line on the carb window so I don't believe the float is the problem either.

My problems are complicated by the fact my tachometer is not working (one of many problems to fix) so I cannot tell what RPMs the engine is around before it dies.

[James]

The carb is probably not the culprit. First did you adjust the idle speed screw or the mixture screw on your carb? Increasing the idle speed may help you get it to the point where you can tune it.

Carbs get blamed for a lot of ignition tuning problems. The first thing I would check is your timing. Then I could go through and make sur you don't have any vacuum leaks at the manifold or hoses.

Give us a bit more with what you have done and what the symptoms are and we can better assist you.

[72Daphne]

The carb is probably not the culprit. First did you adjust the idle speed screw or the mixture screw on your carb? Increasing the idle speed may help you get it to the point where you can tune it.

Carbs get blamed for a lot of ignition tuning problems. The first thing I would check is your timing. Then I could go through and make sur you don't have any vacuum leaks at the manifold or hoses.

Give us a bit more with what you have done and what the symptoms are and we can better assist you.

I got the idle speed and mixture set to where I think they are good. I changed the timing slightly today to see if a small adjustment would help. Ended up getting her to idle for about a minute which was the first time I was able to get her to idle at all. Unfortunately I ended up draining the battery with my method of adjusting, start, adjust, start so I will have to try again later. I'm hoping a slight adjustment to the timing will help her idle.

[James]

If everything is stock, you should be at 10 deg BTDC (using a light) with the vac advance disconnected at idle.

Get the dwell, timing all set THEN mess with the carb. If it won't idle - go ahead with a few more turns of the idle screw - if its too much, it can always be backed down.

[James]

Also - if you are basing the screw settings on something from a book - that is only a starting point, and until the timing is squared away, they don't mean much.

[datzenmike]

Check/set the valve lash. If one is tight the valve may not be closing all the way. This can play havoc with intake vacuum and idle. Set the valves hot and get the timing squared away. Check any manifold hoses for cracks which will leak vacuum. Are carb and intake bolts snug? Do you have a brake booster?

[72Daphne]

I have been pretty busy the last few months relocated for my job and had an electrical issue on the 510 which is now fixed. So I am now just starting to get back into working on getting the car running again. I'll be using the suggestions in this thread when I can get a chance to start working on the car again and update if I still have issues.

In the meantime, anyone know where I could get the banjo fitting filter for the stock Hitachi carb?

[Doctor510]

I think I have one or more of the filters. I'm in Arizona

[72Daphne]

Finally got to working on this again. Since last time I had rebuilt the carb and installed a matchbox distributor. Not having luck getting her started still. The problem I am having now is when I try to start her she will kind of run as long as I have the starter going but will not try and run at all by herself. I'm confident that the timing is correct (or at least enough to get here started) and I checked the valves and they seemed ok. Didn't see any cracks in the manifold or in any of the vacuum lines. No brake booster or anything so not much to check there.

Can someone check to make sure my carb linkage was installed properly? I may have messed something up when I was rebuilding it.

[zKars]

The point about running with key in start position but not when you release it makes me think you have an ignition switch problem. Put the key at the run position and see if you have +12 at the coil + terminal, or if it will come and go as you wiggle the key.

[James]

Agree with above.