MomsDuster
Well-Known Member
Was just curious as to what’s involved in converting say a 750dp to work on a 671? I realize it requires more fuel, but what physical changes are required? I’m not considering doing anything of the sort, just curious.
What’s required to make an N/A carb work on say a 671 blower?
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MomsDuster
Well-Known Member
Well a quick google search and bingo!
https://www.motortrend.com/how-to/1511-how-to-modify-a-carburetor-for-boost/
Next time I’ll do a search first.
https://www.motortrend.com/how-to/1511-how-to-modify-a-carburetor-for-boost/
Next time I’ll do a search first.
oh no! whatcha up to there Mark? I thought carbs ON a blower were pretty straight forwards - blow through needs to be sealed and solid floats.
MomsDuster
Well-Known Member
LOL I’m just curious.
a large amount of blower surge would sure add to the overall look, sound, and vibe you got there
MomsDuster
Well-Known Member
That it would!
I've built a few roots blown engines for others in the past and we did nothing but slap the carburetor on. I think that boost reference article may be for blow through. With draw through, I've never known of anything that needed to be done.
MomsDuster
Well-Known Member
Here is a quote from the article:
“Check out the captions below to see how simple it is to boost reference any 4150/4160-style carb. Note: this modification does not work for blow-through carburetors, only draw-through setups, in which the carburetor sits on top of a roots-style blower.”
I suppose the amount of boost would directly affect the need for the modification.
“Check out the captions below to see how simple it is to boost reference any 4150/4160-style carb. Note: this modification does not work for blow-through carburetors, only draw-through setups, in which the carburetor sits on top of a roots-style blower.”
I suppose the amount of boost would directly affect the need for the modification.
That's interesting, because the carburetor sees no boost whatsoever in a roots application.
MomsDuster
Well-Known Member
No, but the carb can see an abundance of vacuum while under boost keeping the power valve closed, inducing a lean condition.
well that's easy. we don't need no stinking power valves! I don't miss mine. lol.
MomsDuster
Well-Known Member
Now that I can see!
TT5.9mag
Two atmospheres are better than one
If the car is street driven and any semblance of fuel economy is desired then boost referencing the power valve circuit is really the only right way to do it. Plugging the PV can work but to make the engine happy at wot the mains are so rich that cruise economy suffers badly. Boost referencing the PV gives you a whole new circuit to tune the fuel delivery. It keeps the mains in check when you’re not in positive pressure.
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