Hi,
I am building a 383 sbc.

This is what I have right now:
holley 4150 HP series 750 cfm (no choke tower)
Performer RPM Airgap
AFR 195 75cc

I am told that lack of choke will make for rough running cold starts. I also was told that with a newer multispark ignition, which i will be running, and the exhaust crossover hooked up, I will not have a problem. I am in WA, lows in the winter are around 25 degrees. Is it true that with the above two items, and without the choke, I will be okay for winter cold starts?

I am confused a little by the terms here: exhaust crossover, heat riser. Am i correct in assuming that exhaust crossover is the same as heat riser?

I understand that the AFR heads have the heat riser passages. The Airgap doesnt, so I will be returning that and getting a regular Performer RPM that does. I cant find the part number for it though.

http://store.summitracing.com/partd...01&autoview=sku

the picture shows a crossover (i think) but it says that it does not have a crossover in the "notes" section.

how is the exhaust crossover regulated? is there always exhaust gas heating the intake up? is there a way to make it only crossover when the engine is cold?

also, i think it would be good to use the fast idle cam from the holley choke kits to dump more fuel in on cold starts, but since my carb has no choke provisions, is there a way to do this? and how would it work, does it just idle fast until i give it gas, then it idles normal?

Thanks,
Jerome

nobody knows?

Before capacitive discharge ignition and modern combustion chambers I used
a choke, I no longer need one. I live in the south but it does get cold here.

As for heat risers they will cost performance. Warming the engine before
driving is all that's needed.

i've heard its possible to put in a thermal valve that will close the exhaust crossover once engine is warm. is this true? anyone have info on this?

Jerome

Deleted By Death

You will be happier with a choke on a street driven carburated motor regardless of where you live. There should be a thermostatically operated damper at the exit of the passenger side exhaust manifold. When the motor is cold this will direct exaust through the heat riser under the carburator. This will help prevent carburator iceing. Carburator iceing happens when the temperature is just above freezing and the humidity is high. It will kill the motor a minute or two after starting. Idle mixture is pretty lean and the choke enriches it to help a cold motor run. When the motor warms up the thermostatic damper in the exaust opens and exaust flow through the carburator heat riser is mostly gone. If you are running stock cast exaust manifolds these devices will not cost you any horsepower and save you a lot of frustration. If you're running tube headers you just have to learn to cope with the cold motor blues.

http://store.summitracing.com/partd...15&autoview=sku
found it. 3" valve, hedman's site says that it is mechanical/vacuum operation
anyone know how that works?

also, still looking for a way to put more fuel in at idle. anyone know how to retrofit a fast idle cam to a carb without choke provisions?



and will h, i understand that a choke would be better, but i'd rather not have a choke cable to operate, or an electrical one that could cause problems. Since carb iceing is a concern even with the choke, i would be hooking up an exhaust crossover anyways, so i want to get away without a choke if i can.

Thanks for your input,
Jerome

Jerome,
I don't know of any way other way than a throttle cable to get a fast idle without a choke. So you have your choice, Choke cable or throttle cable, or a different carb with electric choke. My first car was a '38 Ford and it had both cables stock from Ford. I liked it. Since you live in WA which is prime carburator iceing territory you are wise to use the exaust heat riser. Carb iceing is one of the most frustrating things that you can experience with a street driven car. I remember blocking traffic at shift change in the parking lot of a 5000 employee factory because the exhaust damper on my '62 T-Bird was frozen open and I had no carb heat.

Forget the fast idle cam with no choke butterfly. Use a throttle cable as suggested.

Operating a street engine with no choke is difficult as resultant driveability problems will increase the amount of fuel used and a lot of that will find it's way into the crankcase and also foul spark plugs (not to mention resultant carbon build-up).