Printable View
Hey guys i'm starting to work on my chevelle again, and i'm going to take off the carb. thats on it. When i purchased the car the owner gave me a holly carb., and now i'm thinking about rebuilding it and putting it on the car. I was judt wondering if anyone could help me figure out some more information about the carb. Like what cfm and so on.
Here's one more pic.
On the choke horn there should be a couple numbers stamped. Like a 4 digit with a dash and another number, then another 4 digit number under that.
4776=600cfm
4777=650cfm
4778=700cfm
4779=750cfm and so on.
Sorry if this sounds dumb, but what is the choke horn?
The area the choke plate is in.
Hey guys i think i found it. The number reads 4779-6 and underneath that another number reads 0324.
Does this carb have vacuum secondaries?
No, mechanical.
How do u know what the difference is? Just wondering.
For one, since you were good enough to put up a pic, there's no vacuum "motor" on the side. Second, if you go to the Holley site it will be listed as a mechanical secondary, along with a bunch of other good info.
Hey Bob thanks for all the good information. Are these carbs hard to rebuild?
The carb is pretty easy to rebuild. That appears to be an older version so it will need upgraded to blow out protection for the power valve. If your engine is fairly stock you will not be happy with the carb. It is just too big and if you have an automatic mech secondaries shouldn't be in the same sentence.
I'm planning on rebuilding a stock 454 soon, and i was going to use this carb. Will this carb be ok for it? Also how hard is it to upgrade the power valve for blowout protection? And which is better mechanical or vacuum secondary?
I would think a 750 would be fine for a 454, they just don't work real well with an automatic on the street. The secondaries being mechanical come in too soon causing a very rich condition and bog. Summit, for one, sells the blow out protection kit and everything else you would need to rebuild the carb.
So in other words, this carb wouldn't do good on a automatic 454?
Not on the street. I don't think you would be happy with the performance. Depending on cam, heads, etc, you'd probably be better off with a Street Avenger.
This carb is the right size for a 454. It's a double pumper (accellertor pump on both primaries and secondaries) and will work fine, if: (and there's the rube), if your running an automatic trans with a tight (stock) torque converter, it's going to bog if you open it up all the way under 2500 rpm or so. If your running a stick and launch higher it's going to work fine. The power valve protection is a kit from Holley that's inexpensive and consists of a ball bearing type projectile and a spring. You have to take off the base plate, then drill a hole with the supplied drill bilt in the carb body, put in the ball and the spring and then reinstall the base plate. It's simple to do. As far which is better, well as I stated earlier, it depends on your torque converter or trannie and your rearend ratiio. I hope this helps.Quote:
Originally Posted by chevymotorhead
I'll be using a TH 350, and so should i upgrade the torque convertor to one with a stall? And if so how much stall?
They all have a stall speed of some rpm. It would help to know what rearend ratio you are running. More (ie 4.10 instead of 3.23) would require less stall speed. Most stock 350 Turbo's have a stall speed of between 1100 and 1500. A stall speed of say 2500 or more would make that carb on a 454 work great. And if you have a steep rearend (higher number) it will work fantastic.
As far as i know the rear end is stock, and i know this might sound dumb but how exactly does a stall speed work?
Stall speed in a torque converter is when the internal impellors finally quite slipping in the trannie fluid and the converter starts to draw the trannie to the motor rpm. There is built slippage in an automatic to make them work. When the converter "stalls" it means it is finally taking the torque and rpm from the motor and applying that to the gear ratios in the transmission. Remember "power braking" (one foot on the gas and the other on the gas pedal and the motor will only rev so high?) that is the stall speed. Sorry, I am old cuss and that's the easiest way I can explain it.:)
So in other words, as long as i keep the rpms below 2500 for example the car shouldn't start rolling.
Well, yes, if you have your foot off the brake. It'll roll any way, even with a high stall speed converter if there is no resistance. ;)Quote:
Originally Posted by chevymotorhead
Well everybody i guess this thread is officially closed, and i want to thank all you guys for ansewring my questions.
With any converter, the car, from a standing start, will launch or get under way when you hit the gas pedal. The higher the stall speed built into the converter, the more the motor will rev before it really locks up. It would really be in you best interest to find out what you rearend ratio is. If the car is stock there should be a tag on the door or glove compartment that tells you what rearend is in it. Also, most cars have a metal tag on the rearend that gives you the correct info on the gears. You would just have to read it and then find a web site or manual that tells you how to break it down. Depending on the brand of the car. I take it since you are putting in a 454 that it is a Chevy. I don't know the web sites for them but some one here should.
Hey Duane thanks for all the suggestions.