Questions on Previously Swapped Engine?

[Fortrex]

I am the new owner of a 1985 Monte Carlo SS, here are the specs on the car:

350 4 bolt main
Dart S/R Heads
Bored .30 Over
Flat top pistons
300hp cam
Holley 650 carb

700r4 trans
Stage 2 shift kit
4.10 spooled rear end

Now, I have a couple questions. Firstly, I've come to notice that if I stomp on the brakes at fairly fast speeds or if I take a turn fast, the car will stall. It has no stalling issues under normal operation or anything, pretty much just on emergency stops (standing on the brakes at 60KM/H) or taking turns very fast. Is this normal operation for a carbed 350? The last 350 I had was TBI, and the last carbed vehicle I had was a 1990 YJ years ago.

Second question, because of the flat top pistons should I use 89 or 91 octane gas? Or is the regular cheap stuff good enough?

Thirdly, can I hook up the stock speedo to the 700r4? Will a stock speedo cable for an '85 monte carlo hook up to the trans?

And lastly, I'm looking at un-spooling the rear end. I may go open or posi, not sure yet. This rear end is 7.5" 10 bolt, right? What is the spline count for the axles? I was told the P.O. put stronger axle shafts in it, would that have changed the spline count or would it still be the same as stock?

Any help would be greatly appreciated!

 

[t01blaze]

I am the new owner of a 1985 Monte Carlo SS, here are the specs on the car:

350 4 bolt main
Dart S/R Heads
Bored .30 Over
Flat top pistons
300hp cam
Holley 650 carb

700r4 trans
Stage 2 shift kit
4.10 spooled rear end

Now, I have a couple questions. Firstly, I've come to notice that if I stomp on the brakes at fairly fast speeds or if I take a turn fast, the car will stall. It has no stalling issues under normal operation or anything, pretty much just on emergency stops (standing on the brakes at 60KM/H) or taking turns very fast. Is this normal operation for a carbed 350? The last 350 I had was TBI, and the last carbed vehicle I had was a 1990 YJ years ago.

Second question, because of the flat top pistons should I use 89 or 91 octane gas? Or is the regular cheap stuff good enough?

Thirdly, can I hook up the stock speedo to the 700r4? Will a stock speedo cable for an '85 monte carlo hook up to the trans?

And lastly, I'm looking at un-spooling the rear end. I may go open or posi, not sure yet. This rear end is 7.5" 10 bolt, right? What is the spline count for the axles? I was told the P.O. put stronger axle shafts in it, would that have changed the spline count or would it still be the same as stock?

Any help would be greatly appreciated!

First of all I don't understand the 300hp cam. I would look into degreeing the cam or finding the cam card to get the specs. If you want to pull the cam there might be some sort of part number or grind number on it but I really can't guarantee it.

The compression ratio plays a big part of determining the octane level. What cc are the heads? Is the block decked? Head gasket thickness? Does the engine ping? Etc..? We need some more info. You want to run the lowest octane fuel without detonation or pre-ignition.

On the rear end, you can post a picture of the pumpkin and we can tell you what rear it is. To determine the spline count I would pull a shaft and count the spines.

The stalling condition might be float height from your description. It's hard to diagnose a car over the internet.

 

[Fortrex]

I'm not too sure on it either, the motor was built a couple owners ago but the guy I got it from said the cam was out of a stock 300hp 350.

I'm not sure on the motor details. It was built by a reputable shop and runs great, doesn't ping.

I'll grab a picture of that rear end.

 

[Fortrex]

 

[axisg]

regarding the cam - well you wont know until you get the cam card or you pull it.

seems very strange that someone would over bore it + dart heads then put in a "stock" camshaft.

Carb sounds like the floats are set too high ( letting the fuel slosh over and flood the motor under hard deceleration ). I fought that for 2 years with my holley and eventually switched back to qjet.

Fuel, I would set the timing and run Mid-grade to see if it pings with still making power. If down power or pinging then move up to 91 or better.

Yes the 700r trans cable should hook up

Lastly you will have to tear into the rear and see what has been done.

Like I stated earlier, the mods seem a little strange to me and the fact that the PO doesn't know the upgrades would steer me away from a car in that condition.

 

[Fortrex]

The modifications were done previously and the car passed through 2 owners before it came to me, so I'm sure some of the mods were left out/mixed up in translation.

I have been running 87 and haven't had any pinging or power loss yet.

Is the float adjustment a simple turn a screw kind of adjustment or does the carb have to be taken off?