SU vs Stromberg carbs

[Bombay Racing Green]

Hi all,

After many years of procrastination I've finally taken the plunge and got myself an Elan. It's a 1969 +2 that was in storage for a few years here in Ireland. At some point in the past the Strombergs were replaced by a pair of SU carbs (from an MGC by the looks of the type numbers). My question is this, should I ditch them and try to replace them with the original Stombergs? I must point out that the engine seems to run fine on them and that a head conversion to Webers is out of the question (at the moment!). The next question is, does anybody have a pair of strombergs that they would be willing to part with?!

Thanks in advance for any advice.

Pete

[Harvey]

Pete,

I run a '71 +2S in California and have a Stromberg head with the Euro high crossover tube between carbs to balance them. There is a Canadian +2 owned by Stu Gilmor who posts under the name"stugilmor" who runs SU's on his car and maybe he will weigh in on your question after he returns from the Orlando, FL Lotus Owner's Gathering (LOG). I had a couple MGBs with SUs and prefer them to the Stombergs for ease of tuning but I'm not going to swap out the Stroms because they seem to make good power, especially at the bottom end.

Lee

[Bombay Racing Green]

Thanks Lee,

I must also point out I would be an advocate of "if it ain't broke...etc".

Pete

[cal44]

I have Webers on the Plus 2 and Strombergs on the Europa...............frankly I can't tell the difference.

Mike

[elansprint71]

I have Webers on the Plus 2 and Strombergs on the Europa...............frankly I can't tell the difference.

Mike

The Europa is the one with the engine in the rear.

[cal44]

Dang it.......I deserved that............

Mike

[stugilmour]

Hi Pete.

As Lee says, my Stromberg head Federal car has twin SU's, I believe they are called H4's and are similar to '71 to '74 MGB's. I am a bit vague on the details as they were on the car when I bought it. Several folks have mentioned they are easier to tune, keep working and to get spares for than Strombergs, but I am no expert.

A week ago I would have mentioned detonation and mid range stumbling. However I found a shop in Orlando that tuned them to perfection in an hour. The front one was way lean and the rear way rich. The car is finally working as it should, and I'm a happy camper. I am not sure of the exact needles in them as we didn't need to remove them to get a good tune.

Long story short, if yours are working leave them in service. When they need attention, make note of the needles and we can compare.

Cheers! Track day tomorrow at Sebring!

[Bombay Racing Green]

Thanks for the advice Stu,

H4 does seem to ring a bell. I'll keep them so. As you can imagine, there are quite a few other jobs to get through first before I get to the tuning phase!

Good luck at Sebring.

Pete

[RogerFrench]

HS4 is more likely - the H4 would be a bit too old.

[YellowS4DHC]

Pete,
I'm going through the same thought process with a TC Europa that I recently acquired. My '72 Europa Big Valve engine has a pair of 1.75 SUs, not the Strombergs it left the factory with. I've had SUs before on other British cars so they don't bother me except here they seem to look out of place - at least to me.

Overall, the conversion looks reasonably decent. It makes use of the original Stromberg intake manifold with a homemade balance pipe (not sure if that was added with the SUs or simply a leftover from when Strombergs were on the car).

Like you, I've decided to keep the SUs at least for the short term. I need to see how the car runs but haven't had much opportunity yet (brakes take priority). If it runs ok, or can be made to run ok I'll keep them.


regards
Rick

'72 Europa TC
'69 Elan S4 DHC
'67 S800 Coupe
'57 T1 Speedster

[Bombay Racing Green]

Hi Rick,

That's some collection you've got there! The person who did mine seemed to do a neat job in the engine bay. However, the choke was slapped to the bottom of the dash to the right of the steering wheel. As the cable is quite stiff in operation it pulls at the veneer and it has cracked. Oh well, I'll survive!

Thanks for getting back to me.

Regards,

Pete

[CBUEB1771]

As Lee says, my Stromberg head Federal car has twin SU's, I believe they are called H4's and are similar to '71 to '74 MGB's.

SU HS4s would be an odd choice. SU HS6s with 1.75" choke bore would be a closer match to the Stromberg 175 CDs that were replaced. The HS4s have a two-bolt flange for mounting to the inlet manifold whereas the HS6s have a four bolt flange which adapts directly to the Twin Cam inlet manifold adapters for the Strombergs. I had an MGB-GT in the dark ages and replaced the HS4s with HS6s and a suitable inlet manifold and a mild cam from the BMC Competitions Department catalog. That made the MG much more fun to drive.

[stugilmour]

Thx for clarification Russ. Mine are the four bolt type, with the bowls integral to the carb assembly.

My choke cable runs to stock location near steering wheel.

Track day was fantastic, although I need a bit of welding on the exhaust can and it will take a bit to remove the racing tape from the hood/bonnet as it popped up a couple of times. Only ~2,800 miles to home now!

Cheers!

[RogerFrench]

Thx for clarification Russ. Mine are the four bolt type, with the bowls integral to the carb assembly.

My choke cable runs to stock location near steering wheel.

Track day was fantastic, although I need a bit of welding on the exhaust can and it will take a bit to remove the racing tape from the hood/bonnet as it popped up a couple of times. Only ~2,800 miles to home now!

Cheers!

The type with integral float chamber is the HIF6 (Horizontal Integral Float). I guess we got it identified in the end!

[YellowS4DHC]

Pete,
I had a very similar experience. Both the choke and throttle cable "fixings" on my SU conversion were very stiff and had to be reworked.

I suggest you disconnect your choke cable at the carb and verify that neither the cable nor the choke mechanism itself is the problem. If cable and carb are ok, you can focus on the choke cable attachment at the carbs. In my case, someone attached the inner choke cable (wire) at an odd angle relative to the outer cable (sheath) resulting in lots of friction. The wire should feed straight into the sheath.

I thought of using my old throttle return spring on my suspension, but it might have been too stiff!

regards
Rick

'72 Europa TC
'69 Elan S4 DHC
'67 S800 Coupe
'57 T1 Speedster