Carb Conversion "Kits" ETA March-April 2016

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... automatics usually don't shift high in the RPM range anyways.

One of the interesting nuances of the Renault automatic is external control of how many RPM's before the transmission shifts. That's what the second cable on the throttle spool does. Tightening or loosening it raises or lowers the shift points (can't remember which direction raises or lowers the shift points -- perhaps Farrar can confirm).

My automatic conversions include a second clevis to pull on the shift point cable, which passes through the clevis and gets locked into place with a cable stop after the user picks shift points he or she likes.

Bill Robertson
#5939

[dmruschell]

One of the interesting nuances of the Renault automatic is external control of how many RPM's before the transmission shifts. That's what the second cable on the throttle spool does. Tightening or loosening it raises or lowers the shift points (can't remember which direction raises or lowers the shift points -- perhaps Farrar can confirm).

My automatic conversions include a second clevis to pull on the shift point cable, which passes through the clevis and gets locked into place with a cable stop after the user picks shift points he or she likes.

Bill Robertson
#5939

I've adjusted the cable on her DeLorean. It shifts at 5,000 rpms at WOT. I think there's enough adjustment left to get it to 5,500, but I'm not sure if there will be any way (without modifying the electronics) to adjust beyond that. It does have performance camshafts, so it makes power in the high rpm range. I'm just wondering if it will be worth the potential sacrifice in bottom end power when it's not driven aggressively and probably won't shift much above 5500. A dual plane seems to make more sense, unless I'm mistaken or not a lot of bottom end power is sacrificed by using a single plane.

[content22207_2]

The engine will spin at lower RPM's. It's not as though you need to drive through a parking lot at 5,000 RPM.

But the power band definitely shifts upward. If you drive the car where it feel natural, then look at the tachometer, you will discover that you are turning at least 1,000 RPM more than usual, if not more. I'm talking about shifting-- I cruise on the highway at 2,500-2,800 RPM all the time. But on the on ramp I'm 5,000 plus RPM.

If you ever buy a single plane manifold easiest thing to do would be to put it on Ellon's car and test drive it. Carbed manifolds can be popped on & off in a matter of minutes. I orient Peugeot 604 manifolds with the carb towards the rear, so you'd need to swap throttle cables too (throttle plates are about a foot away from K-Jet's location). There's really no way to put a big kink in the throttle cable sheath and still have the cable slide smoothly.

Bill Robertson
#5939

[dmruschell]

The engine will spin at lower RPM's. It's not as though you need to drive through a parking lot at 5,000 RPM.

But the power band definitely shifts upward. If you drive the car where it feel natural, then look at the tachometer, you will discover that you are turning at least 1,000 RPM more than usual, if not more. I'm talking about shifting-- I cruise on the highway at 2,500-2,800 RPM all the time. But on the on ramp I'm 5,000 plus RPM.

If you ever buy a single plane manifold easiest thing to do would be to put it on Ellon's car and test drive it. Carbed manifolds can be popped on & off in a matter of minutes. I orient Peugeot 604 manifolds with the carb towards the rear, so you'd need to swap throttle cables too (throttle plates are about a foot away from K-Jet's location). There's really no way to put a big kink in the throttle cable sheath and still have the cable slide smoothly.

Bill Robertson
#5939

Ok, then it sounds like single plane is the right way to go for both cars. Thanks! I look forward to when you have them for sale.

Another question: What CFM carburetor would you recommend, keeping in mind that both cars have performance camshafts? Holley has their 2 barrels (I've confirmed that they will bolt on in place of the 2100 carburetor) in 350 or 500 CFM.

[Farrar]

The Ford 1.08 venturi on my automatic flows 287 CFM, so I imagine that or ever so slightly more would be good.

[content22207_2]

When I said the sky's the limit for carburetors, I meant for other owners on their own recognizance. For me, 2100's are the limit. All my OEM cores are 2100's. All my spare parts are 2100's. All my rebuild kits are 2100's. All my templates for manifolds and adapter plates are 2100's. Just as Rob Grady only stocks 2.8 parts, not parts for 3.0's, LS1's, Chevy small blocks, Acura and Nissan engines, or any of the other power plants that have been dropped into DeLoreans.

My recommendation is to do a complete conversion with a 2100 first, then change to a different carburetor as a separate operation if so desired. If the different carb doesn't share the 2100 footprint you'll need to make an adapter plate anyway.

BTW: That's also my recommendation for any other changes in the engine compartment, such as removing and plugging sensors in the coolant distribution pipe, removing disused K-Jet wiring, painting and detailing, etc. Get the car running on its carb first, then make other changes as separate operations.

I posted this vid on the old .com site:



Somewhat tongue in cheek, but it does show that carbureted intake manifolds can be popped on & off without any fuss. There's no reason not to do a carb conversion one weekend, then do intake valley work, wiring work, detailing and painting, etc on subsequent weekends.

Bill Robertson
#5939

[dmruschell]

The Ford 1.08 venturi on my automatic flows 287 CFM, so I imagine that or ever so slightly more would be good.

Yeah, I was thinking 500 might be a bit much. That, and it's usually better to go slightly smaller than go too big (unless the secondaries are vacuum operated, but 2 barrels don't have secondaries).

[content22207_2]

Our little engines are 174 cubic inches (low compression 174 cubic inches). 2 barrels provide more than enough venturi area.

With a carburetor it's all about airflow. If you don't have enough air passing through the venturis, the carb can't draft fuel. Too large of venturis, or too many venturis (4 barrel), simply won't work right.

I've helped nearly two dozen owners. The carbs we use are sized very well. Byrne Heninger uses the same carbs for his conversions (Chinese replicas).

Bill Robertson
#5939

[dmruschell]

Our little engines are 174 cubic inches (low compression 174 cubic inches). 2 barrels provide more than enough venturi area.

With a carburetor it's all about airflow. If you don't have enough air passing through the venturis, the carb can't draft fuel. Too large of venturis, or too many venturis (4 barrel), simply won't work right.

I've helped nearly two dozen owners. The carbs we use are sized very well. Byrne Heninger uses the same carbs for his conversions (Chinese replicas).

Bill Robertson
#5939

You're preaching to the choir on carburetors. I went through a lot of research, and a few carburetors, before settling on my 750cfm Holleys (vacuum secondary) on my performance cars.

The Holley 2300 bolt pattern is exactly the same as the Motorcraft 2100, and so is a bolt-on replacement. In fact, both were used interchangeably in OEM applications in the 60s. All new 2 barrel Holley carburetors use the 2300 bolt pattern, so they should bolt right up to any of your manifolds I just figure since I'm already familiar with the Holleys, it would make more sense for me to stick with what I know and am happy with. Thanks for all the responses!

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Took a look at a 2300 throttle shaft. It has very large holes where Motorcraft throttle balls would be, most likely 1/4":

Holley2300ThrottleShaft.jpg

1/4" holes may be a Holley thing. My school bus originally had a Holley carb that used a 1/4" clevis pin to attach its carb -- I had to drill out the throttle mechanism and use a 1/4" bolt when converting it to an Autolite:

BusThrottleRod.jpg

If you are going to use a Holley carb, it might be best just to buy a manifold and adapter plate. Everything I have is set up for throttle balls (or #10 clevis pins). Sounds like you would be able to fabricate your own throttle attachment. Don't forget that on Ellon's car you would also need to fabricate a bracket to hold the full throttle kickdown microswitch:

Microswitch1.jpg Microswitch2.jpg

What would be great is if you sourced your own manifold, then I could simply make an adapter plate. I did that for Del Silveira and John Dore (they also got carbs from me). Del's was a fun one because his manifold had already been routed out and a Weber adapter plate welded on -- I made his adapter from a pencil rubbing alone (Del lived in British Columbia). At least for John's I had an unadulterated Peugeot manifold to work with. If you provided your own manifold then I could preserve my inventory for complete conversions. There are a couple of owners on this forum who have spare Peugeot manifolds and might be willing to sell them (Chad Krause on Today also has one). Andrew in Michigan has located several Peugeot 604's using online junkyard searches.

Bill Robertson
#5939