Thread: carb and rear question

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I was told that I have a 1 1/2" spacer between my edelbrock carb and the manifold. I was also told that if i remove it i would gain more horsepower. It was put in place to give it a higher top end speed. Is this true and if so how do i remove it. Also I have a 10 bolt 8.2 rear with a 2.82 gear. I would like to run a 12 bolt 411 gear. I am running a th350 tranny. Will the 12 bolt hook up directly to the th350 or do i have to go to a th400 tranny. All in all i am looking for more out of the hole power as I do not see myself ever taking her to top end. No place to do it anymore around where I live.

You won't be able to feel the difference in the seat of your pants with the spacer in or out. It simply doesn't make that much difference. A spacer can keep the carb - and therefore the fuel mixture cooler, so I'd leave it in place. If you want to remove it, simply unbolt the carb, lift it up, and take out the spacer. You may need some shorter studs to put the carb back on, though, and you'll need a new carb gasket. Like I said, I don't think it's worth the effort.

Concerning the rear end, unless you have a real stump-puller of the motor, you don't need to switch to a 12 bolt. A gear change in your 10-bolt will do fine. I wouldn't recommend a 4.11, though. It will give the car a real kick in the pants, but if you have to go on the highway, your engine will be operating at a lot of RPMs. You'd probably be turning around 3500 at 65. That's hard on the motor, and uses a lot of $3.00 gas. Something in the 3.55 range would provide a lot of kick over a 2.82, and would be more reasonable at speed - around 2800. Changing the ring and pinion is a lot cheaper than replaceing the whole rear axle.

I'll let the engine experts address your carb spacer, but I wanted to comment on the 4:11 gears. IMO you won't like them for long. If you had an overdrive tranny you could get by, but with a three speed you will be driving around as if you are in second gear. Not only will gas milage go down the tubes, but you will be overrevving, especially on the highway.

One of our car club members had 4:10's in his roadster, and everytime we went on a cruise he kept dropping back further and further........just couldn't keep up with the rest of us. IMO, something like 3:50 to maybe 3:70 will give you a lot more seat of the pants feeling of power, and yet be streetable. Even 3:70 are getting down there, my kid ran 3:73 in his Mustang, and when 4th gear overdrive went out he couldn't stand to drive it anywhere.

I know in the old days we ran deep gears, but we've gotten smarter as time went on. BTW, you really don't need a 12 bolt unless you are really getting on it a lot, 10 bolts are fine for the street, and lighter to boot.


Don

I see Jack and I were typing at the same time. Glad to see we think alike on the rear axle and gears.

thank you henry i think that for now i wil leave things as they are.

thanks don. I do not drive it very far but i want the ride comfortable.

Someone is offering me a 12 4.11 rear and all the chrome trim for the car in great shape for $300.00. I was just wondering about the rear. I do not like the 2.82 that I have now. My engine has more horses than i am used too and I would take advantage of them. I think that I will go with the 3.73 gear and keep the rear that i have. Thanks for all the knowledge.

Don wrote:

I know in the old days we ran deep gears, but we've gotten smarter as time went on.

Back in the old days, gas was less than 50 cents a gallon, there were fewer interstates, and we probably didn't travel much more than 25 miles from home. So a 4.56 or a 5.12 gear worked really well for stoplight to stoplight challenges, especially in our big block pony cars with cheap bias tires or glass belted tires.

Damn, sometimes I really miss those days. Especially when I pull up to the pump.

Originally Posted by jyardgirl

Someone is offering me a 12 4.11 rear and all the chrome trim for the car in great shape for $300.00. I was just wondering about the rear. I do not like the 2.82 that I have now. My engine has more horses than i am used too and I would take advantage of them. I think that I will go with the 3.73 gear and keep the rear that i have. Thanks for all the knowledge.

At $ 300, buy the 12 bolt and store it!!! That is a steal if it is in good shape. You might want to go racing some day. !2 bolts seem to go for more than that when I have seen them.

Don

i will keep the rear. though i won't be installing it any time soon.

About the spacer: If it's a 4-hole spacer, it'll help the fuel/air mixture make the turn into the intake runners instead of slamming into the floor of the intake manifold when it leave the carburetor bores and I'd leave it in place. If it's an open spacer, then it has effectively turned your dual-plane (180 degree) manifold into a single-plane (360 degree) manifold. This is assuming you have a dual-plane manifold in the first place. A 360 manifold is normally used where you have a large displacement motor or are revving a small displacement motor to the moon because each cylinder "sees" the entire volume of the manifold. With a 180 manifold, each cylinder only "sees" half the manifold volume, so cyinder filling and throttle response is better with a low-rpm (street) motor.

I agree that a gear in the "4" range will be a bear on the street and you probably won't like it much if you're over the age of 17 . It will provide ear-to-ear grins though, at least until you pull up to the gas pumps. A change to something in the 3.50 to 3.70 range will make you think you've bolted another motor into the car and still provide a modicum of fuel mileage.

How tall are your tires?
A car with a 3.25:1 rear gear and 28" tall tires will run 2603 RPM @ 65 mph.
The same car with 3.73:1 gears and 31" tall tires will run 2698RPM @ 65mph.
It's just one thing that should be considered....