#21  
Old 02-22-2023, 05:16 PM
Sirrotica's Avatar
Sirrotica Sirrotica is online now
Ultimate Warrior
 
Join Date: Jan 2005
Location: Catawba Ohio
Posts: 7,193
Default

The only time I've blocked the heat crossovers, is in a dedicated race car that saw zero street duty. The convenience of having it operational, far outweighs the reasons to block it. I guess if you want to keep feathering the gas until the intake warms from the rest of the heat transfer from the cylinder heads, that's your prerogative, to me it's an annoyance. Yes I have done it years ago on my own vehicles, the juice, wasn't worth the squeeze, IMO.

I set my carb and choke adjustments so that the car runs the same as if it was fuel injected. No stumble, or flat spots during warmup. I however takes a bit of work, and attention to detail for a carb to run like this, everything has to be 100% correct, no guessing. You must adhere to all the choke adjustments, or you'll never achieve the smooth running engine during warmup.

Even GM used heat from either the exhaust, or from the coolant, to work in conjunction with TBI, or tuned port injection.

The talk about a water laden air fuel charge causing ice inside of a intake is not idle talk. When I attended my high school auto mechanics class our instructor told us about a friend of his that hand built a intake manifold from tubing for an inline GMC 6 cylinder to adapt 3 carbs to it. He said that when the humidity was high, and the air temp was low, the car wouldn't run right. like it was starving for fuel, or air. One night it got to the point that it would barely run, and they unbolted the carb from the manifold. Imagine the owners surprise when he looked into the manifold, and saw the tubing had ice formed in the inside of the manifold.....

They found some 12 volt heat tape to use to heat the manifold for when the temps and humidity got to the crucial point to cause ice to form in the intake, problem solved.

Having to keep feathering the gas during warmup also makes the accelerator pump dump a lot of excess fuel into the manifold to cover for lack of heat. That excess fuel is washing the oil from the cylinder walls and causing the oil to be diluted, as well as increasing ring, and cylinder wall wear. For a race engine this isn't going to be a huge problem, for a street car it's going to show up with fuel dilution, and premature wear.

To me, not worth the tradeoff for some slight possible performance gain.

Your car, and your choice.

__________________
Brad Yost
1973 T/A (SOLD)
2005 GTO
1984 Grand Prix

100% Pontiacs in my driveway!!! What's in your driveway?

If you don't take some of the RACETRACK home with you, Ya got cheated

  #22  
Old 02-22-2023, 05:42 PM
nas t eh nas t eh is offline
Senior Chief
 
Join Date: Jun 2015
Location: Edmonton Alberta
Posts: 272
Default

Quote:
Originally Posted by wbnapier View Post

Do any of the after-market aluminum heads use these hot air crossovers?
Yes, Edlebrock D-port heads have the crossover holes In them. I have an old Torker intake and my 1973 Rochester in place with the factory heat pipe style choke assembly. All works like it should, but the big roller cam does cause some cold start up stumbling/ stalling if I kick it off fast idle too soon.

I know I’m giving away some power with the Torker but there are only so many options that work in Canada’s climate with a stock hood TA.

__________________
73 T/A 455, 4speed
  #23  
Old 02-22-2023, 05:58 PM
dataway's Avatar
dataway dataway is offline
Ultimate Warrior
 
Join Date: Jan 2012
Location: Saratoga NY
Posts: 8,921
Default

Was always amazed running VP C12 in an air cooled four stroke, head temps ran around 300 degrees, at the end of a race the carb was ice cold .. that pressure drop through the venturi can create some pretty dramatic cooling ... but then it was running wide open at 10,000 rpm for 20 minutes.

__________________
I'm World's Best Hyperbolist !!
  #24  
Old 02-22-2023, 07:21 PM
JSchmitz's Avatar
JSchmitz JSchmitz is offline
Ultimate Warrior
 
Join Date: Jan 2000
Location: Union, MO
Posts: 2,131
Default

Quote:
Originally Posted by Goatracer1 View Post
JS the valley cover is not to keep oil from heating the intake. It is to keep the hot intake from heating the oil.
Ok. Never heard that explanation. Interesting. Have to ponder that one. Thanks for thought food! lol

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 10:21 PM.

 

About Us

The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.

 




Copyright © 2017