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Tri carb: order of installation question.

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dcarlg

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Hello.
It's time to install my rebuilt carbs; triple HS4s.
I haven't been able to find a proper diagram or description.
What is the correct order and where are the gaskets placed?
Manifold, gasket, heat shield, insulator block, gasket, carb, gasket & air filter?
Any gasket sealer needed?
Thanks.
Douglas
 
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the order looks fine but i put a gasket both sides of the heat shield and both sides of the insulator block. didn't the first time and i had intake leaks. so i put gaskets all places and also used aviation sealer, except against the carbs and filter. probably overkill on my part but i wanted to make sure i did not have any leaks.
 
As a rule keep the heat away from carbs so seem like the right order. as for sealant I have not seen or used it. One way to check for leaks is at start-up spray carb cleaner or WD 40 RPM will change if there is a leak CUATION WD 40 may fire on hot motor. Remember metals will change with temp so a leak now way go away so surface of man and carb faces must be true but due to bolts may leave edges. better an extra gasket over sealant. I use 600 wet dry sand paper on a flat block it will show bad spots or high spots. Madflyer
 
I noticed that the Scuderia Silva Tri Carb installation video on YouTube also used aviation sealant.
I chose not to use it just in case it needs disassembly.
Also, flat filing/sanding all flanges is a good idea.
I learned that the hard way.
My BT7 motor always leaked water/coolant at the thermostat housing, perhaps since new.
It didn't matter what type of gasket was used or how tight the nuts were.
About 15 years ago I noticed a casting ridge on the housing flange.
After flat filing, new gaskets, studs, washers and nuts that problem was solved.
Thanks for your input.
Douglas Glesmann
 
Drone Dog,
I enjoyed reading your posts regarding installation of a HF air valve and creation of a PCV system.
What is your opinion of placing the HF air valve in the hose between the valve cover "T" and the rear air cleaner?
I plan to try this, but I lack a proper vacuum gauge to properly measure effectiveness.
There is obvious vacuum, since that air filter was loaded with oil.
I installed a rebuilt motor with rebuilt rocker arm assembly last week.
Regards.
Douglas
 
first off i would buy a vac gauge if you plan to install a PCV valve. my car created way too much vac in the crankcase. my only clue at the time was the oil pan popping. i think you want to know how much vacuum you have. too much just sucks dirt and crud in thru the seals. not good! not enough vacuum accomplishes nothing either. gauges are cheap.

the engine does not operate in a vacuum. the blow-by from the pistons creates a positive pressure in the crankcase. this vents out of the valve cover or side of the engine. thus it is supposed to blow in the rear breather and be sucked in by the carb. this system was done to keep it from blowing any oil on the ground. gave the engine a chance to burn it and any gasses from the crankcase. No need for PCV or air valve for that system. And keep in mind this system worked for 60 years. so it is not like it has to change. but it does muck up the rear carb. you can just put a small air breather right on the valve cover T.

so the engine creates positive pressure and if any part of the system can not handle the blow-by, it also blows out the seals. this is also why the dipstick tube and the oil filler cap are not sealed.

Then why did i go PCV? it has been written that bringing fresh air in to the crankcase is good for the engine parts. a low negative pressure not only helps to keep oil in the engine, it also expands the rings and helps improve compression. All good things and why cars today still use a type of this same system.

i have just purchased another rear tappet cover (with vent) for my car. i plan to put it in the middle opening and move my air breather forward in the engine. probably does not make a big difference but i figure the the further the air travels thru the engine the better for removing more gasses. on the older V8's, they had the PCV valve on one valve cover and the breather on the other. So it pulled air across the engine.

the air valve i use is only to control the air coming in the crank case. without some restriction, i get no vacuum. not sure what you are trying to do with your air valve. if you are installing a PCV valve then i guess it would depend on where you are pulling air out of the engine to the PCV. i was advised to do it at the valve cover because the side vent might suck out too much oil.

would need more info on your system to give you an opinion.

And it is just that... an opinion. there are plenty on this forum that think these cars were not designed for a PCV system and it may not be good for the engine.

Hope that helps
 
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