Considering trying out a new Indy. Had engine rebuilt in 2020/21. 2.3L, mild cam, Weber's. For some reason, Indy has been unable to zero in on its tune. Not from a lack of effort. He suggested I needed larger carbs, still rough. Then electronic/tunable ignition, still rough. Lots of popping/backfire and it doesn't sound like the carbs are working in sync, to my ear anyway. Indy initially associated his difficulty with the Tangerine cable throttle set up (I provided) however everything I've read customers are pleased. It does seem to hang up a bit when decelerating, however. Now says it could be related to an exhaust leak but haven't been able to determine there is one...just the latest rationale. We did repair a known leak during build, new gaskets, machined flange, etc. I like the guys and don't want to disparage their work. I just feel I need another set of eyes before I go crazy. It's been almost 2 years since build and I can't drive the car without getting completely annoyed, so it just sits on its lift. Not to mention, he's 10 weeks out before he can fit me in to re-evaluate...don't want to miss Hershey yet again! Feeling like I should have left engine alone. It ran fine. Half a mind to swap in six and be done with this;-) Recommendations in Maryland area?

PS. The Indy in this pic was NOT the engine builder. Great guys BTW...they mounted new rims/rubber and addressed some minor cosmetic work. Quality shop, particularly if you're looking for vintage British car service/work!

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I'll be curious to hear what others say as my 2056 runs well enough to enjoy but still has a lot of carb popping and can be a bit uneven.

I've been told that Ray at AutoSportSystems Group in Merrifield VA is the regional expert for 914s, but in my experience he usually wants to take everything back to stock. DM if you want me to share who built my engine -- I have a high opinion of them -- but they also haven't been able to solve everything.

Are you sure the engine was rebuilt correctly. We got in a car with a “rebuilt” engine. Buyer paid for 3.2 SS. Was a 3.0 with the cis pistons installed upside down. 6 cylinder shims to keep the piston hitting the valves, lots of tomfoolery and sub standard parts. Must have reused a bunch of parts even though he charged for new.
The “rebuilt” trans was just as bad.

The builder is a reputable shop...literally millions of dollars of classic/modern 911's in his shop from all over that he's been entrusted with. Some of the rarest around. I definitely don't believe this is a competency issue but rather a focus/prioritization matter. They've been 'almost' as frustrated with the issue as I have;-) He's a 'one tech' shop. All the right intentions...not enough time. My 2-year-old build with a lingering unresolved issue just isn't a priority.

@flipb

I did not have a good experience with Ray at ASG. Someone here on 914 recommended him (it might have been you, actually). Happy to share my experiences over PM if you'd like.

Not sure where in MD you are located, but the only shop that comes to my mind is Translog up in York, PA. I have not used them at all, as the minor work my 914 has required over the years I did myself, but many years ago when the shop was owned by the original owner, I used them to rebuild my transaxle before putting it back into my restored car.

Yes, familiar with them. Thank you

Love the concept of a piston installed upside down. I think I know what you mean, but the concept of con rods in space is intriguing.

Back to the engine build. I heard of a cam being installed one tooth off and it never would run correctly. They finally tore the engine back down and found the problem. Not sure if you could pull the valve covers and try to see your valves opening and closing.

180 out. So the cis pistons need would contact the valves unless an excessive amount of cylinder base gaskets were used. Compression must have been super low. Engine was a mess. Now it runs awesome. I personally put about 50 miles on the car.

Gennady at GTP? I’m in Parkville’

Maybe bring on it back by to me when it gets a little warmer and I will see if we can dial it in. I know you brought it by maybe a year or 2 ago and I had suggested getting the tangerine linkage.

Remind what carbs and jetting you are running again? Also, if you go too large on jetting it can be a bear to tune.

EDIT: Chris at Eurotech is a good dude been around 914s his whole life, but I wouldn't bring my 914 to him for tuning. He's suggesting throwing parts to fix the problem, some of which better the car i.e. electronic ignition, but not a good approach.

If you are near Summit Point, nobody better than Dave Coleman.
Billy Ring in Middleway is good.

Hmm. Another thread of shops charging customer but learning about 914’s at their customers expense? Hope not, but sure sounds familiar.

OP doesn’t state size of Webers. Highly unlikely they are too small for a 2.3L. More likely to be 44’s and too big.

When a shop starts suggesting throwing parts at problems . . . Time to find a new shop.

OP wise to be seeking a second set of eyes.

No one cares about your car like you do.
I suggest to bring it home and have the people here help you.
Have experienced same thing (previous 914), paid a shop $4,000 to stop the popping to bring it home much worse four months later. The braintrust on 914World will help you each step of the way.

Ps: it’s also very satisfying once you did it yourself.

If I can't get resolved by then I'll be sure to reach out...much appreciated!

BTW, Chris at Eurotech did not perform any work on the motor. They just put on new rubber and performed some minor aesthetic tweaks. The motor was built by a shop in Jessup.

Webers are new 44's...I don't know jetting off the top of my head. The builder sized up to the 44's because they said the 40's that were on the car were too small and the reason for the tuning problem

Thank you!

Who is GTP?

I found them...Essex area. Thank you

You should do some preliminary investigation to see what you currently have. It is super easy to pull the main stacks out from webers and check jetting. The idles are also easily accessible from the side. Let's start with what the Indy shop put in and go from there.

Idle size?
Main size?
Air corrector size?
Venturi size?
emulsion tube?

So the same Indy shop that built the engine is also doing the tuning?

I'll gather that info.

Yes, same guy that built the engine was/has been unable to get properly tuned. Unresolved for since build completion almost 2 years ago. I've dropped off car to have tune straighten out too many times to count. They'd call a couple days later to say it's ready. I'd drive home with the same issue...sputtering carbs/incessant backfiring. As mentioned, since the build, we've changed out carbs (twice) at their direction, changed ignition system at their direction, numerous jetting set-ups, all in an effort to resolve issue. They blamed it on the Tangerine cable set-up that was recommended. The latest is that it must be another exhaust leak (actually something I suggested as a possibility). Nice guys but I have lost confidence. I've been willing to do whatever is recommended. Have basically given up and just look at her sit on the lift. Definitely need another set of eyes. Have been hesitant up to this point as they said if anyone else works on engine he'll void warranty. Warranty is now expired, and they can't fit me in for 10 weeks...now is the time.

I've owned the car for 14 years. It was a solid 2056 that ran very well. Never had any of these issues.

I did not see anyone mention valve adjustment. May be a good idea to check there first. Couldn't hurt.

Excellent suggestion

You are far too nice and accommodating.

So if I understand correctly, the guy that built the engine can’t tune it and eventually ran out the warranty clock ?

Here is the classic Venturi sizing chart that is for max HP, not street driveabiluty. Street use usually is 2-4 mm smaller to develop good vacuum signal and transitions rather than WOT power.

2.3l puts you at 36 or 37mm Venturi to make WOT power. A Weber 40 IDF can accommodate a 36mm Venturi. So much for 40 IDF being too small for street use with a 2.3l motor.

The good news is that you can choke down the IDF 44’s to work.

lol, pretty much sums it up

Get those carb specs. I'm pretty sure I have 34mm, maybe 36s, chokes we can try if you don't already have 36mm installed.

I inquired about carb specs and this was their response…

“We didn’t change any of these items except for 2 idle jets because we replaced your carbs with Weber 44IDF carbs. Those come from Weber with a particular configuration. Rich believes that he played back and forth with your idle jets and settled on a 55 idle jet.”

Sounds like someone that knows little about Weber carbs, but anyway. If you have the stock specs for 44 IDF you should be fine to start with.

-Check the valves
-Check the timing
-Check the linkage

I'm assuming it is sputtering backfiring on acceleration? If its on decel, I wouldn't worry about it. If its on acceleration, it could be a jetting/ could be accel pumps / could be an air leak around the gaskets / could be the linkage out of sync. I think I remember it idling fine. My hunch is on the linkage, especially if the shop was having issues with the sync link.

meter is pegged.

Webers are among the most tunable carbs in the world. Weber has no idea what is best for a given car since they don’t know how it is going to be used, at what altitude, etc. It would be impossible for Weber to know what is best for a custom built t4, 2.3L motor.

Run far and as fast as you can. Shops like this, and how they have treated you, really make me mad

And yet, amazingly, they don’t know what is in them, or refuse to tell you.

If you’re not comfortable with carb disassembly to document a baseline of what tuning parts are in them you’re going to have to find someone like Nditiz1 to help.

Backfires on decel only (badly). However, carbs will sputter/pop an accel...sounds like not sync'd to my ear. Also, throttle will hang up after engine heats up. When decelerating, idle will remain elevated.

They did not care for the Tangerine linkage. They bucked it from the beginning. Feel like because I insisted using it...because it was recommended by other teeners...they were annoyed by that. It does however seem to bind up...maybe installed/adjusted improperly?

1) Will have valves checked/adjusted.
2) Programable ignition was installed at their recommendation (123/Tune+)
3) Will take a deeper look into linkage.
4) Going to check passenger side heat exchanger to see if weld failed (small crack was previously welded). Could be cause for decel backfiring?

Make sense?

Changed carbs twice. Does that mean used or rebuilt/new? What type of fuel pump is installed? Look for a number cast into the top of the Venturi. What is that number? Other than WOT the engine will run like shit if the Venturi are too large. The carbs were tuned for idle only? Screwing around with the idle jetting doesn’t seem to paid much of a dividend. Tuning for max, way up there, RPM is pointless. How do the carbs balance out with the idle turned up a bit?

Sounds like your shop did not know what the hell they were doing.

Cable systems are a little more challenging to set up initially but are probably the most accurate carb syncs out there.

Zach

That's also telling. You may not like everything Chris makes. You may not NEED everything Chris makes. But everything he makes is well engineered, fabricated, and supported.

There's a lot of people relatively local to you that I'd trust way more than that shop. They may be able to help. I'd offer, but I'm zero help with carbs.