The 4 Barrel Conversion - My Experience

[RAP260]

Hi All ,

 

Due to fact that I am about to change the carburettor setup on my car ( again ) I thought I would relay my experience with having a 4 Barrel Setup. When I initially set out, to do this conversion, I found that the amount of info out there is limited. This wont be an exhaustive review/analysis, but I hope it can help provide a little additional info to anyone looking to do this. 

 

While many people do frown on this particular conversion , I would like to begin by saying that it has treated me well. A solid performer that makes for a good daily drive. After re-jetting it has produced a solid AFR of around 13.5 ( which seems to be my motors sweet spot ).

 

 

 

The Setup

 

Clifford Water Cooled Intake

 

Edelbrock 500 ( An Edelbrock ?? , will explain shortly )

 

Cable Conversion ( from The Z Store )

 

 

My Engine

 

Recently rebuilt L26 ( About 4 years ago , less than 5000km ). Flat tops , Mild Camtech Cam, Mallory Distributor / Ignition Controller, Electric fuel pump & Radiator Fan. Basically nothing exceptional. 

 

 

Jetting / Tuning

 

Why the Edelbrock 500, when most run 390 Holley's ?, primarily the cost ( that turned out to be a joke..lol ). After a little research I realised the Primary Throttle body sizes are the same ( Venturi is slightly larger on the Edelbrock ). And, as you spend most of your time driving on the Primaries I decided this wasn't going to be an issue. 

 

I can't recall the exact rod/jet combo , so I'll come back and fill in this section with my exact rod/jet sizes ( after I have removed it from the car ) . But every car is going to be different , so my setup isn't necessarily going to be meaningful to others.

 

But , you are going to need to lean the Edelbrock from it's standard setup. It ran very rich out of the box. But, as I stated initially, I now get an AFR reading ( in car gauge ) of around 13.5 at cruise & 12.5 under acceleration. 

 

If I had to do this over again I would go with the Holley 390, as I understand this will work out of the box ??.  

 

 

The Clifford Manifold

 

The water pass-through manifold ?. Honestly I'm not sure how I currently feel about this , as I only have the triples to compare this with , and they would start and run without choke !

 

I feel it has a very slow warm-up period. Now i'll preface this by saying that the oversized carb on a single plane manifold may contribute to this . But I'm looking at around 2 minutes ( with full choke / 15 deg ambient temp ) before I don't have to ride the throttle , and then another 5 minutes before I can fully disengage the choke. Is this comparable to SU's ?? , dry 4 barrel manifolds ??

 

 

Performance

 

Ok , unfortunately I have never had this setup dyno'd. I did have the original triple Webers ( 40's ) dyno'd when the engine was rebuilt and got around the mid 120 rwkw mark. I think it was 123??. Does this setup feel as if it has as much torque ? , definitely not. The triples would pull like crazy from 500rpm. This need to be driven into the 1.5-2k range , but then it goes like crazy. My butt dyno can't tell the difference , lol. Would it have less HP than the triples ? , I suspect so.

 

But, it is far more drive-able in traffic , for me anyway , than the original triple setup. Maybe my triple tuning wasn't optimal ??  

 

 

Cost 

 

A lot more than I expected....Isn't that always the case...lol. Including all the AN fittings, new hoses ect. , I spent over 1.5k on this setup.

 

 

Final Thoughts

 

Fitting the manifold was tough , really tough. Due to the fact that the manifold has to slope downwards , to accommodate the carb height , there isn't enough room ( in some cases ) to get your hand in to fit the nuts/bolts. 

 

I also had to remove the bonnet vent cover/cowling, that normally sits under the bonnet on the left hand side ( to stop water dripping on the carbs ) , as the air filter would rub otherwise.

 

Otherwise I am very glad i decided to try this. It was a fun experience.

 

If anyone want's to know any additional info, has anything to add , or would like additional pictures ( as I'll have the setup for maybe a couple more weeks ) , let me know

 

Cheers,

Rob

 

 

A couple of links to old videos I put up.

 

https://plus.google.com/u/0/photos/photo/104716928338032625573/6215375660745769906

 

https://plus.google.com/u/0/photos/photo/104716928338032625573/6225049601407320498

Edited March 18, 2018 by RAP260

[gav240z]

A comprehensive overview, thanks. I'm not surprised at the cost of set up. It's always more expensive than you anticipate.

 

I find my car on Triples has better driveability than twin SUs.. so I guess it all comes down to how you set it up.

[RAP260]

Cheers

 

Don't say that Gav..... I'm just about to go back to SU's... Lol.

 

HS6's to be exact. That will be a full circle for me.. Looking forward to it

 

I should add though that I never drove it much on the original SU's, as it died not long after getting it. So this will really be a first for me

Edited March 18, 2018 by RAP260

[RAP260]

... so I guess it all comes down to how you set it up.

Absolutely. Which is why I'll never discount the fact, that the setup on my triples possibly wasn't optimal.

 

Maybe I'm just better at setting up 4 barrels than triples ... Lol.

Edited March 18, 2018 by RAP260