Yep there is the oval port 400hp and the 435hp rectangle they
were both high-rise in 67, open wallet very wide if anyone wants one,
last time I looked about eight ten ys ago they were going for around
$3500.00 for the 67 setups.

 

Expect to pay close to 5k for the 67 oval port as they are scarcer than the square port..factory only produced 18 400 hp versions.

 

In 1974 I bought a 69 rectangle port trypwer for $85.00 spent
$15.00 for three new holley carb kits, ran it for couple yrs on
my 73 sold it for $125.00, every time I look at the prices today
I Get sick.

 

Don't remind me. Still have one rect. port intake, but no more carbs (let them go with a '69 L71 that had crumbling carbs, to seal the deal).

 

Have you seen the prices on the old 68/69 cross ram 302 manifolds
they make the prices on BB trypowers look cheap.

 

yup, 10K -15K

 

Thanks, I will check that.

I played around with it a little more last night. Disconnected linkage to front and rear carb, car will start but not idle at all, not even close. Reconnected the linkage, started car and it idle's, but it's around 1300 again. I disconnected rear linkage while running, forced the rear carb completely closed, car died immediately. Should that happen? Does that provide any further insight?
I appreciate all the help and suggestions, I have been trying to help my father-in-law get this working for several weeks now.

 

Thats your prob. the end carbs shouldnt be open.

 

Sounds like you need to disconnect/remove the linkage between carbs and then set the idle. Leave the vacuum line in place. Make sure the outer carbs are fully closed, set the idle then replace and adjust the linkage acording to the instructions in the AIM. Warm up the motor before adjusting the linkage as it needs to be at operating temp to work properly. If you set it cold it can cause the high revs you describe when it warms up.

 

Turn the outboard carbs over, you will see a set screw. That set screw adjusts how much the blades stay open during idle. I think this is your problem...they are open too wide. The proper adjustment should be that they are barely open. If you can see daylight between the blade and the body, make the adjustment to close the blades.

 

Thanks again guys, I will be working on this more tonight and tomorrow. Should the car idle with front and rear carbs disconnected from the linkage???

 

Yes

 

It doesn't currently, sounds great around 2000 but falls apart around idle.

 

if everything checks ok and outboard carb linkeage is adjusted per service manual instructions, then you either have a warped/cracked body and/or metering block.

If that's the case replacement carb is the fix or you can send the carb to Holley, for an astronomical fee, they will check it out, but the fee they charge, you can buy another carb.

 

Vacuum leak?

Improper jets?

Leaking carb gasket?

Improper idle adjustment?

 

The mechanical linkage does not open the end carbs. It only gives a positive close to them. Vacuum opens the end carbs. Check your vacuum hose routing. The center carb vacuum port on the front of the base plate is for the choke pull-off and the diverter valve (if you have one still there). The vacuum port on the side of the base plate is for the distributor advance. The secondary vacuum comes from the higher port on the carb body.

I may just be something in the carb too. When I first put my tri-power together I got a deal on a center carb that a guy had just rebuilt and it didn't work. He traded it in on a new one and I bought it from the shop. I took it home with a new kit, took it apart and found that body to base gasket was wrong (there are several in the kit). Some gaskets have holes in spots where others don't. That carb has been on my car for 20 years now. I just bought another center carb off Ebay because it looked clean and had good factory plating. I put a kit in it, put it on the car and it ran and idled terrible. This was a few days before a show and drag meet so after tinkering with it a few hours I pulled it off and put the old one back on and it worked fine.

This picture doesn't show it well. I'll see if I can get another uploaded tonight.

 

http://www.corvetteforum.net/c3/gdaina//p0000118.jpg

Here ya go...vacuum line routing

 

That's correct, I think the implication in the thread is if the linkage is out of adjustment, the outboard carbs are not closed fully. At least that's how I interpreted the posts.

 

Thanks for the continued suggestions. The vacuum lines are hooked up the way they show in the pics. I will tinker with it more this afternoon and see what I can find.

I will take the carb off again and take a look at it.

 

Get your end carbs closed up and out of the picture temporarily.Then adjust center carb curb idle and idle mixture screws.Treat it like a 2 barrel until you get that part solved then bring in the other 2.