Phssthpok

..to eliminating that hot-water-bath on the underside of the intake manifold on my 20r?

I was thinking about fabbing an intake manifold from scratch (I have access to the needed tools and supplies), but I want to make sure that water passage heating the intake charge isn't a critical part of Toyota's engineering of the 20r's functioning parameters.

I understand the cold run benefits, and how the water passage feeds the choke assembly, but I can work arond the choke problem, and everything I've ever been taught was to keep the air/fuel mixture as cool as possible for better perfomance/efficiency once the engine warms up. (I blocked the exhaust crossovers on my 383 RoadRunner, and insulated the fuel rails on my Sebring) I also want to eliminate as many superflous ports, and openings on the manifold as I can. Since the truck is a '77 I no longer need worry about emissions inspections, and the less stuf to go wrong.. well.. you get the idea.

kyle_22r

i think that the benefits wouldn't be too great, as the manifold gets pretty hot on its own just from the head! i think that it would be time and effort better spent on other things such as a better carburetor(the 20R unit is a piece of junk) or port work

the only way i can see to practically delete it would be to go to sidedraft carburetors

Phssthpok

Suggestions for a replacement carb? I've seen the webber 32/36, and 38/38's mentioned quite a bit, but I fear they may be a tad too much for the 20r. Idealy I'd find something in the boneyard that I could rebuild fairly cheep.

I was thinking if I isolated the plenum from the head, then heat transfer could be minimized with airflow past the runners. Something like this:

only desigened for use with a carb, not as a F.I. set up.

jimbo74

the 32/36 should be good.. and about too much carb, you can detune it for precise performance to fit your needs...

kyle_22r

a 32/36 is actually smaller than a 22R carb! the 22R only has 200CC more displacement than a 20R...i dislike the adapters that webers use on toyota engines, they're a leaky 2 piece design that never seems to seal right.

a good junkyard carb would be a 22R carb. you can buy an adapter plate from LC engineering to use it on your manifold. 22Rs are electric choke instead of water choke like a 20R. really easy to rig up, only 3 wires, 2 are switched to your ignition(hot coil wire does the trick) and 1 is a ground

Phssthpok

Back to the original question... is there a drawback to eliminating the water passage under the manifold?