Time to rebuild DRLA's? Options

[era vulgaris]

This is a continuation from another thread, but to summarize my car very suddenly started driving like crap yesterday. In the middle of a drive it started popping and sputtering, and became pretty much undriveable. AFR was suddenly in the high teens.

At first I thought it was to do with fuel delivery. That turned out not to be the case. What I noticed today after I managed to get it to actually idle is that during warm up, cylinders 1 and 2 seem to be acting normal. But 3 and 4 heat up extremely quickly, and heat up past their normal idle temps and would probably continue to heat up well into the danger zone if I let them.

I'm running DRLA 40's, and I'm still getting to know these carbs. The idle jets are clean. All I can think is that there's possibly a vacuum leak, maybe a seal or gasket failed suddenly while I was driving. They were rebuilt about 5 years ago though. Time for a rebuild? Anyone who knows Dells well know of anything I should check before I start tearing them apart?
And does the rebuild kit from CB include everything I'll need?

[ljubodraz]

This is a continuation from another thread, but to summarize my car very suddenly started driving like crap yesterday. In the middle of a drive it started popping and sputtering, and became pretty much undriveable. AFR was suddenly in the high teens.

At first I thought it was to do with fuel delivery. That turned out not to be the case. What I noticed today after I managed to get it to actually idle is that during warm up, cylinders 1 and 2 seem to be acting normal. But 3 and 4 heat up extremely quickly, and heat up past their normal idle temps and would probably continue to heat up well into the danger zone if I let them.

I'm running DRLA 40's, and I'm still getting to know these carbs. The idle jets are clean. All I can think is that there's possibly a vacuum leak, maybe a seal or gasket failed suddenly while I was driving. They were rebuilt about 5 years ago though. Time for a rebuild? Anyone who knows Dells well know of anything I should check before I start tearing them apart?
And does the rebuild kit from CB include everything I'll need?

Can't speak much to the higher temps on 3/4 but my thoughts are lean condition. Lean from vacuum leak or needle valve/float. Currently rebuilding my DRLA's and have the following advice from my experience and what I've learned here:
Order rebuild kit from Eurocarb/Dellorto UK because CB kit's needle valves are rumored to be poor quality. From UK, I ordered the more expensive kit with Viton tipped needle valve. The kit included wrong filters for inlet, too long intended for small bolt version. Do not remove all o-rings at once. Clean parts with o-rings intact. When ready, remove o-ring and compare to the many included in kit... sometimes hard to differentiate. You could categorize sizes pre-cleaning too.

Beyond that, I regret dipping crabs in pine sol. Chose pine sol because I wanted to avoid removing the bearings per advice. My carb's aluminum looked like new but now all aluminum has darkened and in some cases corroding. First carb dip of 24 hours, second only 6; same results. It will look OK while submerged but will darken within minutes once removed and rinsing. Don't even let ventures soak in water after rinsing. I thought starved of O2 in water would prevent oxidation/corrosion for one week. Bad mistake. Boiling afterwards in vinegar solution doesn't really help either. Certain parts are more sensitive such as top cover and inlet; they turned pasty as though dissolving surface. I wish I had followed Modok's advice on the samba who once stated there is no reason to dip the carb's if they're not bad. Simply spray with carb cleaner and blow out all ports. The pine sol didn't even clean very well IMHO.

Boiling the brass in vinegar/water only made more work for me too as they would darken significantly after removal. Ended up polishing with minimal amounts of metal polish to return to intended condition. Don't think that after boiling you should dip them in something like olive oil since it's handy in the kitchen to seal from oxidation lol! It's like magnifying the impact of the oils on your skin by 100 and will really darken the brass.

Sorry for the long winded response from a noob... simply hoping to help you so you can avoid my mistakes. I'm a cautious person and researched the subject thoroughly before hand and still have regrets.

[era vulgaris]

I just picked up the rebuild kits from the alfa guy on ebay. Got my jets from him and was pretty happy with em. He also had the best price by far. I'm just gonna rebuild em. They need it anyway. They're getting covered in grime and crud.
Fingers crossed it solves the problem!!!!!

[type2man]

Maybe the linkage went out of sync. Hard to diagnose, but I dont think a problem that showed up from one day to the next requires rebuilding carbs, much less dells. I would check the pump jets and the mains before anything else...

[era vulgaris]

I tried re-synching the linkage. I was able to get a rough idle around 1200rpm, but nothing I did cured the high head temps or AFR. And any attempt at revving over 2K rpm caused massive popping and snapping.
I had the car tuned so well, and it's like the whole tune went to shit in a matter of seconds while I was driving.

[ThePaintedMan]

That's a weird one. I too agree with the notion that nothing that a carb rebuild would fix would let go fast enough to cause an entire bank to run erratically.

I can, however vouch for the rebuild kits from Alfa1750 (can't remember his name, it's Giuseppe or something similar). Full disclosure, when I do rebuilds for people, that's where I order my parts. Everything is high quality and the kits are 100% complete every time. It's worth shipping them from Italy.

I would suspect linkage as well, then accelerator pump function second. That would be the only thing in the carb which would affect both cylinders on the same bank, short of a massive air leak in or around the intake gasket(s). However, before you go tearing things apart, have you done a compression test? Let's rule out the internals first. Pull the plugs, hold the throttle wide open with ignition disabled and check all readings.

[JOEPROPER]

That's a weird one. I too agree with the notion that nothing that a carb rebuild would fix would let go fast enough to cause an entire bank to run erratically.

I can, however vouch for the rebuild kits from Alfa1750 (can't remember his name, it's Giuseppe or something similar). Full disclosure, when I do rebuilds for people, that's where I order my parts. Everything is high quality and the kits are 100% complete every time. It's worth shipping them from Italy.

I would suspect linkage as well, then accelerator pump function second. That would be the only thing in the carb which would affect both cylinders on the same bank, short of a massive air leak in or around the intake gasket(s). However, before you go tearing things apart, have you done a compression test? Let's rule out the internals first. Pull the plugs, hold the throttle wide open with ignition disabled and check all readings.

(IMG:style_emoticons/default/agree.gif) I would do a compression test to rule out a mechanical problem (valve train) first. If this problem occurred all of a sudden, check your basics first before you get too involved.

[era vulgaris]

Oh man, I hadn't even considered that possibility. Now im a little worried. I haven't done a compression test since I owned a TR6 years ago. Remind me again....engine hot or cold? All plugs pulled, or just the cylinder being tested?

[JOEPROPER]

Oh man, I hadn't even considered that possibility. Now im a little worried. I haven't done a compression test since I owned a TR6 years ago. Remind me again....engine hot or cold? All plugs pulled, or just the cylinder being tested?

Remove all plugs, disconnect ignition and fuel source. throttle wide open, connect compression tester and crank engine. You want 4 good puffs at each cylinder. If you have equal compression around 90psi, then you are good. First puff should be around half of final. Slightly low, add a drop or 2 of oil and retest. Very low or 0 suspect mechanical damage ie valve train, piston/ring catastrophic failure. remember, exhaust and/or intake restriction could and would have an effect.

You can also do a running compression test, but with the description given, you probably won't have to. Remember to record all findings. Compression test is easy! Do the easy stuff first!

Good luck!

Joe

[JOEPROPER]

Remind me again....engine hot or cold?**********

Do it cold. No sense in running it the way it is. Suspect rocker shaft or valve spring fault.

[era vulgaris]

Awesome, thanks for the info. I was going to do it tonight, but thought it might be beneficial to do a valve adjustment first. All my valves were tight, especially the 3/4 side. But I was able to adjust them all and it didn't feel like anything was odd. I dunno, would I have noticed something if there was valve train damage? I was surprised they were all so tight with still 1,000 miles til my next scheduled adjustment. They didn't move that much between the first two adjustment I did.

What was odd, is that while turning the wheels to move the valves, I would occasionally hear a whistling noise like air was being squeezed out from somewhere. (I always leave my plugs in btw, when I do a valve adjustment). That leads me to believe that air is getting in somewhere if it's whistling like that.

Test fired it after I was done. It still runs like crap but the AFR is down to the 15's from 17's at least.

I'll see what happens tomorrow with the compression test.

[PotterPorsche]

What is your jetting at ? 15 is super lean . How are you measuring This? An exhaust leak will give in accurate numbers. Popping coughing = lean lean. Do you have the CB jet doctors? With the car off look down the velocity stacks. Do the accelerator pumps work? If there clogged the car is unable to transition from idles to mains.

Let's start with jetting? Air fuel mixture screw 2 turns out at each carb?

60 idles 140 mains 180 airs?

[era vulgaris]

Jetting and tune isn't the problem. Yes, i have CB jet doctors installed. For the last year I've been running low 12 AFR with typical cruising head temps in the 320's on #3 with my setup. It's been nothing short of amazing- excellent performance and driveability. I have an onboard AFR gauge and on board 4 channel digital cht gauge.
This is a problem that appeared suddenly while driving and rendered the car undriveable. Something catastrophic happened somewhere, and I'm trying to figure out where.

[ThePaintedMan]

Stupid question, but have you pulled the valve covers and inspected that bank yet?

Go ahead and do the compression test - we need quantitative data to give you more advice at this point. As said, it doesn't need to be warm. Ideally, to get a fuller picture of the health of an engine, we'd like to do it with the engine warm. In this case, it's a "go/no go" test, so cold will be just fine.

[GregAmy]

This is a problem that appeared suddenly while driving and rendered the car undriveable. Something catastrophic happened somewhere, and I'm trying to figure out where.

Assuming it's not a mechanical with the engine (burned valve, for example) then it sounds like it could be something plugging up a port/jet. How about remove and check both mains and idle jets again, and pull the top of the carb and check for gunk at the bottom of the float bowl? You can do that without removing the carb.

[JOEPROPER]

Stupid question, but have you pulled the valve covers and inspected that bank yet?

Go ahead and do the compression test - we need quantitative data to give you more advice at this point. As said, it doesn't need to be warm. Ideally, to get a fuller picture of the health of an engine, we'd like to do it with the engine warm. In this case, it's a "go/no go" test, so cold will be just fine.

(IMG:style_emoticons/default/agree.gif) Do the compression test first.

[DBCooper]

It's been a long time, but don't DRLA's have a little brass or plastic filter screen behind the inlet banjo? It that's restricted it would explain the overheating on that side and both those barrels spitting.

Also when doing the compression test make sure you squirt in a full squirt of oil in each cylinder before the test, it's essential for the seal, to have the same conditions in all cylinders. And crank the engine with the throttle OPEN, very important.

[era vulgaris]

Thanks for the info guys. Depending on if I have time, I'll do the compression test either today or tomorrow, and then start pulling the carbs apart after.

I mentioned it in my other thread, but I don't think it's fuel related. My tank was cleaned and re-sealed in 2011 with all new SS fuel lines and flex hose. Carbs were rebuilt at that same time. I pulled the evap tank off yesterday to peak in the gas tank and there is not a fleck of anything in there and the sock is clean as can be. The accel pumps on the carbs all work, I can see fuel squirting out of each one when I look down the barrels and open the throttle.

I did get eyes on the valve train as I mentioned a couple posts up when I did the valve adjustment yesterday. While the valves were all pretty tight, nothing seemed odd and I was able to adjust them as normal. The only thing odd was that while turning the engine I would occasionally hear a whistling sound. I couldn't tell where it was coming from (plugs were still in for valve adjustment).

I'll report back with my findings after I do the compression test. Thanks for all the insight guys!

[era vulgaris]

This car has foiled me again! Went to do the compression test today. Turns out the car has 12mm plugs, and the smallest fitting on my compression tester is for 14mm. (IMG:style_emoticons/default/headbang.gif) I thought 914's used 14mm plugs. My old 1.7 did.
So now I have to find some kind of reducer for the compression gauge, or spend another $50 on one that'll fit 12mm plugs.
Btw, I have a brand new set of NGK BP6ES if anyone wants em for the cost of shipping. I obviously have no use for them!

[rhodyguy]

Swap the carbs around 180*. Carbs and linkage intact leaving the intakes in place. Your linkage will now be on the other side. If the problem doesn't follow the carb it's something else. 8 nuts and washers. Is the carb in ? Snapping back thru the carb and exhaust?