Carbs, Specs, Jets, and Suppliers

[2002#3]

Which Weber carb suppliers will pre-jet a carb according to engine build specs?  Of course, such "custom" jets might need tweaking for a particular engine/build.

Thanks.

[visionaut]

Suggest dividing the problem into two parts:

- experts in M10 builds who can suggest jettings specs

- shops that’ll build a carb to spec where you supply the spec

 

Otherwise you’re trying to intersect two pretty small groups with little overlap.

[2002#3]

visionaut, Yes, that would be two productive routes, indeed.  Good idea.  Thanks much, for the prompt.

 

I have already done your first suggestion:  ask what others have tried with their builds.  I did it for a 32/36.  I gathered 17 jetting prescriptions from 17 different (mostly) FAQers who have experience with stock, small mods, big mods, different builds, etc. (see image below; NO guarantee I recorded all data correctly).  I expect to go with a 38/38 so, as my build progresses over the next 3 months, I plan to gather prescriptions for a 38/38, thus, another table .

 

Now, for your second suggestion, I have to see what suppliers can provide/suggest via my specs.

 

 

['76mintgrün'02]

Pierce Manifolds is where I'd shop for jets.  Installing them is easy and fun to do yourself and if you install an AFR gauge, you can make adjustments as needed.

[billy g]

I think Ireland Engineering will do this.  They ask customers to provide compression ratio and engine mods when ordering.

 

Pierce will definitely supply whatever you need, but they won't figure it out for you.

[2002#3]

Tom, I have experience jetting 100-year-old dual Solex 40PHHs and have grown to love those suckers.  Already have an AFR gauge.

 

billy, yeah, I saw that on their site and it sggests they can provide pre-jetting of some sort.  

['76mintgrün'02]

Don't you already have the 32-36, Larry?

[2002iii]

Redlineweber.com might be another option.

[2002#3]

Tom,

 

Yep, I rebuilt a 32/36 and certainly can use it, if I so desire.  However, a 38/38 likely will better feed the demands of my M10 rebuild-in-progress (10:1, 292, and 91-mm bore).  In truth, all of this carb education, build, design, jetting, selection, etc. is being done pretty much way ahead of time while a machinist sloooooowly does his magic.

 

Any other suppliers to consider other than Redline, Carbs Unlimited, Ireland Engineering, Pierce Manifolds, and Pegasus?

 

Larry

[Markster]

I have a 38/38 out of box from Ireland.  I have a 292 cam from same.  91 mm bore and an e12 head and Maxsill pistons. Idle is my challenging issue. It is a bit rough until I get to 1000 rpm. Otherwise the engine seems to me (newbie) to perform really well. Happy to give any assertions if needed.  @2002#3-Great work here! 

Edited February 9, 2023 by Markster

[2002#3]

Thanks, Markster.  Ireland info is good to know.  Your build likely similar to mine.  Might be in contact.  Stay tuned.

Larry

[jimk]

I'd begin that new engine build with a carb that you know worked good in previous use.  Starting a fresh engine with poor fueling will cause you to concentrate on fueling issues when you should be running in the engine.

 

That goes for EFI guys too, if the EFI is not set right, use a carb first.

[2002#3]

jim,

I never thought about approaching a new build in that way.  Yep, the guts/block/head/all new stuff will be the most important to examine and watch closely with a new build - not the carb.  The carb should work well and allow the new items to shine/not shine and work/not work.  Instead of starting with a new carb and hoping and assuming it will work well, perhaps I should find a perfectly functioning used carb...

Thanks for the tip.

Larry

[jimk]

What carb was on there before?  Use it if it worked ok.

[2002#3]

Jim,

Another good suggestion.  Thanks.

I rebuilt the 32/36 which came with the engine I am rebuilding (photos below).  I don't know the carb's history; however, I'd trust if for the reasons we are discussing, i.e., getting the engine up-to-snuff.  Now, it looks good, seems to move mechanically well, and now has several new components which are not included in a standard rebuild kit, e.g., new power valve and new water choke assembly.  I can only assume it worked OK when the engine was pulled.  Maybe start with this carb, as you suggested.  Easy to move to more carb after satisfaction with the engine rebuild is achieved.