Weber 38/38 DGS and various Distributors

[Sickboy49]

I went through the carb again with a thin wire and cleared every passage that I could get to. Reassembled and re-installed, and I still can't get it to idle correctly. So with that I am giving up on this carb and ordering a new one. I have wasted to much time trying to figure this one out. On the plus side I learned alot about Weber's and carburetors in general. If the new 38/38 doesn't do the trick I am just going to throw a Holley 4 barrel on it and be done.

 

[Blairsville Ed]

I went through the carb again with a thin wire and cleared every passage that I could get to. Reassembled and re-installed, and I still can't get it to idle correctly. So with that I am giving up on this carb and ordering a new one. I have wasted to much time trying to figure this one out. On the plus side I learned alot about Weber's and carburetors in general. If the new 38/38 doesn't do the trick I am just going to throw a Holley 4 barrel on it and be done.

The Weber 38/38 can be maddening to figure out. I set up one of these up on a truck 240 motor and the main issue was the synchronization of the 2 barrels. They MUST open exactly at the same time. My final solution for this was to use a dial indicator to measure the throttle blade opening, although feeler gauges would probably work. This is best done with the carb off the motor. Using the idle speed screw, open the throttle blades so that a .010 feeler gauge can be used. Open or close the throttle to the .010 feeler gauge on one throttle bore. Now check the other bore. They should both have the same opening size within .002. If they do not you must adjust the gear backlash on the throttles.

 

[Sickboy49]

The Weber 38/38 can be maddening to figure out. I set up one of these up on a truck 240 motor and the main issue was the synchronization of the 2 barrels. They MUST open exactly at the same time. My final solution for this was to use a dial indicator to measure the throttle blade opening, although feeler gauges would probably work. This is best done with the carb off the motor. Using the idle speed screw, open the throttle blades so that a .010 feeler gauge can be used. Open or close the throttle to the .010 feeler gauge on one throttle bore. Now check the other bore. They should both have the same opening size within .002. If they do not you must adjust the gear backlash on the throttles.

Thank you. I will be sure to check that on the new one.

 

[Sickboy49]

Well I got the new carb yesterday and installed it. I did check the butterflies and I needed to adjust them a little bit. Started car (with choke) let her warm up a little bit, and took the choke off. It died immediately. I am going to search for vacuum leaks for the forth time now. On the upside the engine, when running, is a lot smoother now.

 

[Frank]

man, seriously. . . disappointing for sure. . . I don't know these carbs, but this popped into mind with the essentially non-functioning idle circuit: is the carb base gasket/ manifold gasket matched to the orifices in the carb? Sometimes a wrong or upsidedown gasket will block an important passage, or expose what should be blocked.

 

[Sickboy49]

I purchased a new carb to manifold gasket just to be sure, and the new one is identical to the old. I am hoping to get to the garage tonight to check for vacuum leaks again. Two carbs same issue.... so it is not the carb.

 

[Sickboy49]

Went over the motor again and no vacuum leaks. Here is where I am at currently.

Idle Speed: 1 turn in.
Idle Jets: 100
Mixtures: 1 turn out
Timing: 28 degrees I realize it is high but I am into the vacuum ports by having the speed screw 1 turn in. Also the choke is off.

 

[Sickboy49]

So I finally have some good news to report. I found I was trying to solve a lean condition when in actuality it is a rich condition. After I got the motor warmed up I set the Idle Speed screw to 1/2 turn in and removed the vacuum line to the distributor and plugged it on the carb.. I then put the 70's idle jets back in and and messed with the timing and mixture. I kept on adjusting the mixtures and timing until she almost wanted to idle. I found that the mixtures were less then 1/2 turn out before any noticeable change. I then went down to 60's, then 50's on the idle jets, with the same results, but she idles now. Not well but it is a start. I am going to change the main jets to 135's, and then put the 70 Idle Jets back in and test the results. I would like to see the Idle Mixtures about 1 turn out for the sake of making adjustments. I am still concerned about having to have the timing set so hi (just by looking at the orientation of the distributor) and will get a proper reading once I have it idling consistently.

 

[Sickboy49]

I am going to monkey with the jets tonight, but before I do I am going to do a compression check. I know I need to change the head gasket because it leaks anti-freeze. It is only on the water jacket side because the oil looks fine. The motor builder refuses to return my calls so I am doing it myself. Would low compression cause some of my issues?

 

[Frank]

I am going to monkey with the jets tonight, but before I do I am going to do a compression check. I know I need to change the head gasket because it leaks anti-freeze. It is only on the water jacket side because the oil looks fine. The motor builder refuses to return my calls so I am doing it myself. Would low compression cause some of my issues?

Yes it sure could. Also if minute amounts of coolant are finding their way into the chamber. One of my diesels (Detroit 60 Series) had not been well maintained before I got it well used. Rusty coolant passages. It developed an odd issue which I could not diagnose for a while- pinhole in a cylinder liner. Didn't have obvious coolant loss, oil dilution, etc but the tiny amount of coolant entering the cylinder just above BDC affected the firing intermittently under certain conditions. Thankfully figured it out before it got bad enough to hydraulic-lock.

 

[Sickboy49]

Thank you Frank. Looks like I will be ordering a new head gasket. I am going to try out Best Gasket (part#632g).

 

[Sickboy49]

I got the new gasket in yesterday. So I will be in the garage organizing and getting ready for disassembly. Any advice on putting the new head gasket on? I was going to use the Permatex Copper sealant along with the head gasket. This new one looks a lot stouter then the Fel-pro.

 

[Frank]

Can't address the sealant, only "advice" is, be sure the alignment dowels are in place when installing.

 

[Sickboy49]

One question for you all. Should I replace my cylinder head bolts? This will be the forth time of tightening them. If you guys suggest that I do, where can I find replacements? I have been having a heck of a time trying to find new ones.

 

[manglass]

The original bolts were long before torque-to-yield so, as long as they are in good condition, should be safe to re-use. As long as you torque to specs and in gradual steps they should secure the head properly. Should you need bolts I was going to supply you with the information I have including part numbers and other engines they were used for but your engine is a 61 and my information is for a 58 which has smaller head bolts. The only listing I can find is on headbolts.com but they are not in stock. You might contact them directly about availability. If you need the OEM part number I might be able to pull it out of the parts catalog.

Lou Manglass

 

[Frank]

One question for you all. Should I replace my cylinder head bolts? This will be the forth time of tightening them. If you guys suggest that I do, where can I find replacements? I have been having a heck of a time trying to find new ones.

I agree with Mr. Manglass- use the original bolts. Threads/ stems real clean, and assembly lube would increase torque accuracy.

 

[Sickboy49]

Thank you guys. I installed the new head gasket per the shop manual. I made sure the threads were good and clean, and both mating services were clean as well. The only sealant I used was on threads that are on the water jacket side of the head.
One thing I found that was odd when I pulled the head off.... the sealant the engine builder sprayed on the head gasket never set up. I could literally wipe it off the deck and the head with my finger. I used brake cleaner and a rag to clean everything up before installation of the new gasket. I am putting everything back together this week, and will let you know the results. If it still leaks I am going to have a few choice words with the machine shop that rebuilt the motor.

 

[Frank]

Thank you guys. I installed the new head gasket per the shop manual. I made sure the threads were good and clean, and both mating services were clean as well. The only sealant I used was on threads that are on the water jacket side of the head.
One thing I found that was odd when I pulled the head off.... the sealant the engine builder sprayed on the head gasket never set up. I could literally wipe it off the deck and the head with my finger. I used brake cleaner and a rag to clean everything up before installation of the new gasket. I am putting everything back together this week, and will let you know the results. If it still leaks I am going to have a few choice words with the machine shop that rebuilt the motor.

Sounds good! not a recommendation just FWIW, I've never used any sealant on a head gasket. High quality gasket, both sides real clean and dry, dowel pins in place, a very careful drop-in-place, and proper torque procedure. After a few days I'll recheck torque. Sometimes it yields an extra 1/16-1/8 turn of some bolts, sometimes not.

 

[Sickboy49]

I was lucky enough to be able to use my engine hoist to set the head on top of the block. That way I got all the head bolts started before lowering the head in place.

 

[manglass]

Thank you guys. I installed the new head gasket per the shop manual. I made sure the threads were good and clean, and both mating services were clean as well. The only sealant I used was on threads that are on the water jacket side of the head.
One thing I found that was odd when I pulled the head off.... the sealant the engine builder sprayed on the head gasket never set up. I could literally wipe it off the deck and the head with my finger. I used brake cleaner and a rag to clean everything up before installation of the new gasket. I am putting everything back together this week, and will let you know the results. If it still leaks I am going to have a few choice words with the machine shop that rebuilt the motor.

There are multiple types of sealant, some will stay tacky even when used on something like a head gasket so there's no problem there. Composite style gaskets don't really require sealant as long as the mating surfaces are clean so you should be good to go. I recommend you take Frank's advice and recheck in a few days after you've run and let it cool down a few times.

Lou Manglass