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In need of some Healey help!

restorationist

Freshman Member
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A customer approached us about installing a used (1275cc) engine in his '69 sprite. The customer and I drove about 250 miles away to pick up the engine. I took a borescope along to check out the internals of the engine in question. The seller said the the engine was a relatively fresh reman, and gave us a short back story on how he got the vehicle and engine. We loaded her up and off we went. The job went as smooth as one could expect, I painted the engine and cleaned the engine bay up, installed the engine, and installed all of the accesories off of his (well running, but severely knocking) old engine, carbs, dizzy, water pump, the whole 9 yards. The engine fired right up without any issues, no knocking, no overheating. So I turn the throttle a hair and it puffs a cloud of raw fuel out of both carbs. My first instinct was CHECK FLOATS. Float levels were a bit high, so i adjusted them down to about an eighth inch while the bowl cover is held upside down. fire it up, same issue. So I checked timing (set to 10 degrees at 1000 RPM with advance disconnected), fuel pressure (a nice steady 3 PSI), Checked valve lash (and subsequently had to re-adjust the valves to .012in) checked cam timing, firing order, spark strength, thoroughly checked for a vacuum leak, and I have turned every screw on the dang carbs. It has 2 SU carbs, which in my eyes, are beautifully simplistic. I have adjusted the carbs full lean, full rich, and just about everywhere in between. I have tried ATF in the dashpots, tried 10W30, and I have tried 20W50, All yeilded the same results. The engine also seems to bog/miss while increasing the RPMs until you get to about 3500 to 4000, and even then it seems to really lack power. Has anyone ever run into any such issues? Im kinda pulling my hair out over here.

Any advice would be GREATLY appreciated.
Thank You!
 

AH100M

Jedi Trainee
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Any evidence of the carbs having been rebuilt (properly, that)? I'd check for the proper fit between the pistons and suctions chambers and the installation of the proper piston springs.
 

TimK

Jedi Knight
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You might try posting this on the Sprite forum, but SU's are SU's. I've not experienced this problem. You took the carbs off the old engine? Did they run OK on the old one? Are the diaphragms OK. I don't know if HS2 carbs have diaphragms. If they are torn, you'd probably have your problem.

Check this on the Spridget Forum.
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Amount determined by type and condition.

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Here's another source
Speedracer
Hap Waldrop
Greenville, SC, USA
1967 MG MGB "The Biscuit"
Posted: November 16, 2011 03:38AM
Registered: 5 years ago
Top Contributor
Posts: 16,167
All HS2 has plastic flaots, the ealry one had a metal hinges you can bend to correct the float level, the later one came with all plastic flaots which use shims under the needle and seat valves to set the float level, after that it comes down to needle type, biased spring type or solid, the later carbs has biased type, and they wear over time, but are less fussy as for jet alignment, then there are the PCV tubes on the later HS2 as mentioned here, you can use them, plug them, even remove them and tap for 1/8" pip plugs, depending on how you address crankcase venting, I tend to revert all MGs back to atsmophere venting and get rid of PCV system, but other like the PCV, I just don't want to take the chance of sucking oil thru my carbs, nothing good can come from it.

As for parts, I use Joe Curto, www.joecurto.com, he is in your neck of the woods, in NY, Queens to be exact, Joe makes alot of his SU parts, his stuff is top notch, you can choose your own needle with his kits. If you decide you want someone to rebuild them for you, keep me in mind, I do it for a living, and build alot of SUs and take great pride in my work.


Hap Waldrop
MGexperience Supporting Vendor
Member Services:How to advertise on this website
Acme Speed Shop – Greenville, SC USA
MG-Triumph race/street engines, Cylinder head rebuilding and port and polishing, SU carburator rebuilding, Quailty engine rebuilding kits/ with free tech advice thru out the rebuilding process, VTO Classic 8, Retro 4, and Lemans alloy wheels.
 

red57

Jedi Knight
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I agree, the Sprite forum will probably do you more good.

I'm guessing you used his old carbs, dizzy, etc. because the new motor came without them. If it came with these items then I might try swapping them out for the ones that were on the motor.

I wonder if the new motor has some long duration "demon" cam in it. I have had problems with a vapor cloud forming outside the carb mouths at full throttle with a long duration cam with big int/ex overlaps.

Is the dizzy advancing properly? I don't know about Sprite motors, but I know in the case of the big Healeys you want 35-36 deg full advance and you should see full advenace before 3000rpm (don't know what my timing is at 1000rpms because I set mine for 36 at full advance & my dizzy is set to give full advance at 2800). Anyway, if the dizzy isn't advancing properly the timing may be retarded for anything above idle.

I'm outta guesses, good luck

Dave
 

Healey_Z

Jedi Warrior
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My base setting for the SUs is to screw the all the way in, the back off 2 1/2 turns. That has always got me really close. Have you synced them to make sure they are each pulling in the sae amount of air?
 

EV2239

Jedi Warrior
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The manufacturers always set the shoulder of the needles flush with the dashpot face and the main jets 35-38 thousandths of an inch down from the bridge, so provided they are correct for the car, no further adjustment is likely to help.

If the float needles are leaking, fix them, don't adjust jets. If fuel level in jets is too low, you'll get symptoms you describe, so remove dashpots and see if fuel is visible in jet but not spilling over.

Make sure the throttle butterflies are exactly synchronised or you'll get symptoms described.

Most cars are adjusted by people with no understanding who just keep tweaking. Eventually someone has to sort out the mess and, even with a simple BMC engine, it can be a nightmare.

I've got so fed up with trying to adjust SUs on old cars, I take them off, rebuild them, reset to manufacturers original settings and they are superb immediately with no need for more fiddling.

Best of luck

Ash
 

Legal Bill

Jedi Knight
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Dear restorationist,

I have owned 5 bugeyes and four of them were converted to either 1100 or 1275 cc engines. Any type of backfire out of the carbs is usually caused by the ignition. There is either a misfire due to bad plugs or wires, crossed ignition wires, bad advance or, the wrong distributor and timing.

As to the fuel system, if the ignition is all correct, I'd be looking for some type of vacuum leak. You could also check the needles and make sure they are right for the engine you installed.
 

Legal Bill

Jedi Knight
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Also, I never used a timing light to set the timing on a Sprite. Set it using the static method to the specs for this engine (somewhere between 5 and 7 degrees before TDC). If all else is right, it will run smoothly using this method and you can then fine tune using the adjuster knob on the distributor to deal with any run-on problems the car has when you switch it off when hot.
 
OP
R

restorationist

Freshman Member
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I'm a dummy. I didn't scroll down far enough to even see that there was a spridget forum. As for the ignition, the plugs are fresh and the wires are in the correct order according to the haynes I have here at the shop. I have adjusted the jets to dead on flat with the bottom of the venturi, then screwed them out 2 turns to start, although this engine seems to like it a bit leaner (1.5 to 1.75 turns each). These carbs and dizzy came off of his old, drivable engine. When I swapped them, I made absolutely no adjustment right off the bat. I figured that if they ran alright on the old engine, they should do fine here. Guess I was wrong. The only difference on the engines is that the original engine was a higher compression Healey engine and the new one is a lower compression Midget motor. I will copy my original post to the spridget forum and maybe fish for some answers there too. Thanks guys.
 
OP
R

restorationist

Freshman Member
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Alright, here's a little update. I removed the radiator and double checked cam timing (pictured below), looks pretty close to me. I have since swapped in a brand new set of plugs, to no avail. I inspected the points and condenser, both in like new condition. So I checked the distributors, the one off of his original engine ('69 sprite), has both vacuum and mechanical advances, but the one off of the replacement engine ('72 midget) has only vacuum advance. So I figured, what the heck, swapped them, reset timing to 10 degrees. Same gig. I'm honestly not all that concerned about the fuel cloud. I just want the dang thing to run right, and I thought the fuel cloud might have been some sort of red flag to one of you guys. It still has a very lumpy idle, and breaks up until about 3500 RPM. its undrivable without revving the living heck out of it and slipping the clutch.

IMAG0236.jpg
 

TimK

Jedi Knight
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Replace the condensor? make sure connections to points are insulated correctly?
 

Brinkerhoff

Jedi Knight
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Whenever I've been in your situation I find that it helps to start with the basics (you're probably tired of hearing about it). Take the valve cover off again , spark plugs out and turn the engine over either by pushing it or with the starter. Watch the valves open and close then check the compression with a guage . The gear marks lining up on the cam gears look close enough for what you are doing , I think you've got a simple problem you are missing. Are you sure the firing order is: 1,3,4,2 ? double check that . make sure that when the engine is at 10 degrees btdc on its firing stroke that the rotor is directly across the post on the dist. cap that you want the fire to go to. Its possible that the dist. drive gear is not installed properly (Haynes book)You could be off a tooth on the dist drive gear where it engages the camshaft causing the spotty firing. If you have compression at the right time and fire at the right time , all you need is fuel which it sounds like you have. A coil will cause problems but more so when it heats up and breaks down. It sounds to me like something I've listed above should get you on the right track, these aren't that complicated. Kevin
 
5

57_BN4

Guest
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It sounds very much like a lumpy cam. If you haven't checked cam duration before it is really easy despite lots of websites making it sound incredibly difficult.

Set #1 tappets to the camshaft checking lash which should be given in the workshop manual and is quite likely 0.020" plus the normal lash = a a total of 32 thou. Fix a degree wheel to the front pulley- you can find one online and print it out. Once TDC is established and a pointer added to the degree wheel, turn the engine over with the normal lash feeler blade in the inlet tappet until it just grips. Note the reading, and turn till it just becomes free. That is intake open and intake close. Same for exhaust.

You should get figures something like this for a standard cam
in_open 5 BTDC
in_close 45 ABDC
exh_open 51 BBDC
exh_close 21 ATDC

Bigger numbers mean lumpy cam. I'm not sure what your engine should have as standard but those numbers would be close.

Andy.
 
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Having the distributor drive gear out of place will just mean that the distributor will be positioned at a different o'clock. If the drive dog is 180 degrees out then the car would only run on two cylinders (but this would be obvious). I agree that it sounds like an electrical issue. Look for signs of arcing in the distributor. And be sure you points are gapped properly. It sounds as if the coil is not having enough time to fully excite before firing or is firing intermittently due to arcing.
 
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I was referring to the slot drive interface between the distributor shaft and the drive gear shaft. It is offset to one side, but there is enough play to allow it to be installed backwards. Fairly common mistake on an a-series (so I'm told).
 

Brinkerhoff

Jedi Knight
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I think you guys are missing the point. Yes it could be a lumpy cam but it could be a lot of things that I'm not convinced he's checked yet. Either because he assumes they're ok , or he doesn't know how. I never would've started an unknown engine without at least rolling it over and watching the valves open and close and oil flowing to the top. Why ? because then you know if it will even run or not! Did he do that ? I don't know. Does he have compression ? I don't know . Does he have a strong blue spark at each of the plugs ? I don't know. Does the engine smooth out if you cover the carbs with the palms of your hands? I don't know. How can you guys say it must be this or that when you don't know what the basics are ? He is desribing what may be a lot of different things without many specifics.
 
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How can we say for certain? We can't. We are guessing. An internet forum is no place to get a definitive answer for this sort of thing. It is a place to bounce ideas around to help someone think of possibilities that they've missed. He started off listing things that he had "checked" and eliminated. I agree, he needs to consider the possibility that he missed something in the initial diagnosis procedure. That is why I suspect it is electrical in nature based on the description of how it runs. The distributor being 180 degrees out was a side-discussion ...
 
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