any suggestions to help me,my 396 411rear-end,4 sp. on hot days,temp. shows 215-220.is this to hot for the engine?,also i beleive the engine tries to shut down,like i am out of gas,been told cars in this era,68-69 chevelles have been knowned to vapor lock,once engine cools off it is ok.runs great.any info would be appreciated.

This may not be the answer but it is a start!!!!!!!!!!!!!!
ALL of the stock parts and pieces MUST be in place, such as all under hood rubber pieces, inner fenders, Splash guards over A-frames, Fan shroud, Correct fan and clutch if so equipped. WHY !!!! ?????
70-72 Velles are designed to have the outside air enter at the Rad. opening and EXIT ONLY at the rear bottom near the left and right exhaust manifolds. The exhaust manifolds are the major heat source under the hood.
With ALL the correct parts and pieces in place the HOT air is forced to exit at the only opening, This will be at the lower cowl by the manifolds. NOTE: With some underhood items missing the HOT air will stay under the hood and not exit. Thus causing boiling of fuel.
If you have a basement, Take the duct work off of you furnace. It will become very hot in the basement and you will be freezing your azz off upstairs.
Also note the location of the power steering pump and the A/C comp. on a 70-72 B.B. Velles. They are behind the open section of the rad. to get direct air flow while driving.
I believe Chevrolet Eng. Dept. spent 20 or 30 dollars to get a design to control the heat flow of a B.B. in confined area. I had this problem and went back to the stock configuration of the engine compartment. No more problems. Automotive engines are a big furnace and you need duct work to direct the heated air. You may want to consider some of the above items. If you Vell is in the stock form now, you may have other problems.

Bob ACES AACA:thumbsup:

Bob is right on,and one more thing to add to that is did you notice the 69 stock q-jet intake for 396/325 & 350hp motors use a thin stainless steel heat shield sandwitched inbetween 2 carb gaskets to shield/protext the crab from the excessive heat?

If your missing that heat shield the carb will overheat and vapor lock all the time and some times the std carb gasket will also burn out and cause an intake leak on top of that.

The exccessive heat i am reffering to is comming from the exhaust crossover that goes directly underneat the front of the carb to warm it up some in cold weather for better driveability & to avoid carb icing but the heat shield keepsit from overheating in summer.

You can see the exhaust crossover chanel,it's right inbetween the 2 front carb mount bolt holes in the intake.

Some people that live in warn climates simply tap those holes for i think 1/4' pipe plugs. Then they simply thread in a couple pipe plugs with high temp sealer and that keeps the carb cooler. Of you can also block the exhaust xover at the heads off by using the block off plates that come in some intake manifold gasket sets.

I left the exhuast crossover unblocked at heads and also in front of the stock q-jet intake on my 69 396 . That's because i live in the north east and on do drive the car in cool weather as long as there is no snow or salt on the roads and the carb needs the heat for that application. I did have the ex xover blocked in the past it it definately had issues when driving i like 40 deg or lower temps so i unbloked them .

But i did install an oil heat shiled to at least keep the hot oil off the bottom of the intake in an attempt to keep it a little cooler in the summer months.

I also warpped the stock fuel line from f/pump (behind the w/pump) up to where it attaches to the lrg stock metal in line GF432 fuel filter with insulation to keep it cooler too.

I have the return line/vent blocked off due to leak issues (leaking fuel onto hot exhuast pipes & smoking /YIKES!!!/almost blew it up that day) i was having with it at the fuel tank in 1978 that i could not get resolved so i drilled a sml hole in fuel cap to vent tank and moved on/forgot about it.

I have run this setup since 1978 (with the return line /vent line blocked) when i bought the car and never once had any kind of vapor lock issue even when running in 95 deg hazy/hot/humit weather. I drilled a small hole in the fuel cap to vent the tank since the return line/vent were blocked off due to a leak issue at the time i could not remidy at the time no matter what i tried to do using stock rep parts ike others have experienced here in t/chevelle.

But again,with the fuel return/tank vent blocked ,sml hole drilled in fuel cap to vent tank,and fuel line insulated from f/pump to the bottom of lrg stock inline GF432 filter i have not had one issue with vapor lock in 95 deg weather with the completely stock gm setup with the sml heat shield under carb & stock ac 40727 f/pump for the 29+ yrs i have owned the car.

I am also running a stock 772 clutch fan & std(not h/d) fan clutch,shroud,hi flo w/pump & hi flow 180 deg stat along with a 25 yr old somewhat tired 4 core radiator and no vapor lock in 95 deg heat in all those yrs .

Even on a 95 deg f HHH day it runs pretty warm esp in traffic when it hits approx 205-210 deg f after 8-10 mins sitting still or stop/go traffic(mostly stopped). Then it runs approx 198-200 on avg (maybe for a very short while at 205 deg f ) when i finally get back to open road cruise speeds of approx 60mph in 95deg heat but ir runs approx 6-10 deg cooler in 80-85 deg f weather. But keep in mind these temps are with the temp sender in the head where it will read approx 6-8+ deg hotter then the rest of the motor is seeing on avg.

So my fuel supply setup is seeing plenty of heat and it never had an issue with vapor lock in 29+ yrs i have been driving it in 90-95 deg HHH heat so something must be wrong with your setup.

Maybe the fuel pump is weak/tired,maybe you also need to insulate the fuel line going from f/pump to motor,maybe you need to install the stock heat shield under the carb to keep it from overheating,maybe the initial timing & fuel calibration need to be dialed in better for get the motor running a little cooler too,maybe you running lower oct fuel and need to step up to 93 oct fuel,better fan ,need a fan shroud if you dont have one,get a 4 core or alumitech radiator if your running a marginal 3 core radiator/esp when running a lot of gear like your 411's on the street with higher cruise rpms,etc.

If your motor is truely seeing 215-220 deg on a regular basis in hot weather,thats no good at all and you need to get the temps down,try checking out some of the items i mentioned above and maybe you can get the temps down a bit.

Scott

Where do you come up with a stock heat shield to go between the intake and the q-jet? I remember seeing one on a '69 SS years ago. My '67 q-jet intake has the pipe plugs installed to block off this passage.

Brad,you ask where did i come up with the carb/q-jet heat shield.

If you mean where can you get one just go to any good Auto Parts Store That Sells Felpro Gaskets And Have Them Look Up The Stock Carb Gasket & Heat Shild Application For A 69 396/325hp & 350hp Motor In A Chevelle Ss 396 And They Should Be Able To Find It.

Opps,sorry About Caps.

Scott