411 S4 Carburettor

[dezelsky]

My 411 S4 (1975) needs a carburettor overhaul. It has a Carter Thermoquad unit fitted with I guess is original. The primary slow running jets are working intermittently, causing hesitation on initial acceleration. Overhaul kits are available but I noticed Summit Racing in the US have "remade" units available at a reasonable price. Has anyone here tried these from Summit? There is no electronic choke, so would have to transfer the current one.

https://www.summitracing.com/dom/par...illocation=dom

I recall some discussion on this forum some time ago about switching to Holley or Edelbrock units, but feel concerned about the linkages and height of these compared to the TQ. Thoughts anyone?

[Geoff Kingston]

A few years back I put an Edlebrock on my 411 series 3, as it has the smaller 383 cu in engine I used the smaller 600 cfm carb, for the larger 400 cu in engine you would need at least the 750 cfm unit and it may be better to go for an 800 cfm carb as you suggest.
The Edlebrock performer series carburettor numbers are:-

600 cfm EB 1405
750 cfm EB 1407
800 cfm EB 1413

You will also need the Edlebrock Throttle Lever Kit for the Chrysler installation, part number is for that is EB 1481, I also bought their fuel line kit part number EB 8135 but from the look of what is still in the box I did not need it.
These Carburettors are available in electric or manual choke form , I opted for the latter and bought a 6ft universal choke cable ref SUN 50525 from my supplier in the UK, Ultimate Spares of America.
I also now buy parts from Summitracing and they also list the Edlebrocks with reference/part numbers EDL 1407 and EDL 1413 for the 750&800 cfm units respectively.
The Edlebrock bolted straight on to the 383 intake manifold and as I understand it the 400 cu in engine uses the same manifold so it fit your engine without any problems. The height of the Edlebrock was about the same as the Carter that came off, the air filter fitted straight on and there were no clearance issues. The installation worked well was easy to set up and hot and cold starting presented no problems.
Summit are very helpful if you have any questions before you buy parts.

[John Keighley]

Originally Posted by dezelsky

My 411 S4 (1975) needs a carburettor overhaul. It has a Carter Thermoquad unit fitted with I guess is original. The primary slow running jets are working intermittently, causing hesitation on initial acceleration. Overhaul kits are available but I noticed Summit Racing in the US have "remade" units available at a reasonable price. Has anyone here tried these from Summit? There is no electronic choke, so would have to transfer the current one.

https://www.summitracing.com/dom/par...illocation=dom

I recall some discussion on this forum some time ago about switching to Holley or Edelbrock units, but feel concerned about the linkages and height of these compared to the TQ. Thoughts anyone?

My service guy is a RR/Bentley specialist and also is familiar with Bristols. He recently installed a Fitech single-point fuel injection system - mounts as per the carb. I looked at a circa 80s Rolls that had it installed and owner assures me that it works extremely well. If my Carter AFB packs it in I will give this some serious consideration.

[irienz]

I asked this group much the same question in 2007. Here is the summary of the answers that I posted then:

"Thanks to all those who replied to my initial post.

"The most frequent recommendation for a replacement carb for a 411 was an Edelbrock usually a 600 cfm model, although others had 650 and 800 cfm models. Almost everyone refers to greatly improved fuel consumption, up from 13 mpg to 20 mpg or so.

"The Edelbrocks are modern copies of the Carter AFB. That brings me to a question: do these carbs experience the fuel boiling problems which lead to the introduction of the Thermoquad (and some 411 owners to convert to fuel injection)? This is usually worse in a Bristol V8 , because of the cramped underbonnet area compared to a US V8. Is a 411 with an Edelbrock hard to start when run to full temperature and then left sitting for a few minutes?This is a specific reservation which my mechanic has about these carbs, both generally and especially in a 411.

"The other recommendation was for a Holley 4 barrel. Clyde recommended a 750 cfm pumper. My mechanic likes the Holley Street Avenger range and thinks the 670 cfm would be best."

I proceeded to replace what had been a bolt-on aftermarket injection system, with the Holley Street Avenger 670 cfm with electric choke. It has worked superbly and I have no regrets. My car has Edelbrock alloy heads and inlet manifold, high comp pistons, a modified camshaft and slightly larger diameter exhaust. I would not use a higher flowing carb and a 600 cfm should suit a standard engine best.

Generally the feedback at the time from those who used the Edelbrock replacement was also very positive as well. I think either woudl be a safe choice.

Chris Browne

[dezelsky]

Thanks Chris.

I went for the Edelbrock 750cfm (part no. ⌗1411, with electronic choke). Maybe based on your comments, it is going to be a little over carb'ed, lets see how it works out once fitted. I also ordered the calibration kit, so there should be a fair amount of adjustment available. It will be into the new year before it gets onto the car so will post back later.