Stright thru NH
- Thread starter fast rajo
- Start date
criswellnk
Senior Member
Any information in particular, or just general information? Just let us know what you are looking for, folks here should be able to help you out.
I have an early NH carb ('20), and it has a larger air passage than the later models. The venturi area, when opened, is wide open and you could see straight through it. The later versions ('21-'26) had a dip in the center where the needle valve was located and you could not look through the opening as well. The universal joint needle valve was used in late '25/'26 I believe. Just my opinion. Good luck.
criswellnk
Senior Member
The intial/early Holley NH with the "straight-thru" venturi was used (roughly) from the introduction of the NH through mid to late 1920. The reason for the change from the early straight venturi design to the more common "swayback" style was one of fuel economy and improved low speed and idle characteristics. The idle problem is why on the aftermarket straight-thru carburetors (Wizard, Simmons, Duplex, etc.) you will see the addition of the flapper valve in the bore to improve the low speed and idle issues.
The NH carburetor was built by both Holley and Ford (under license from Holley), with the only difference being that the Ford carburetor carried a Ford nameplate. Ford also built the Ford model F carburetor which is just the NH with a different nameplate, the model F was the earliest of the Ford built NH carburetors.
The straight-thru design will give you a little more top end speed but a reduced fuel economy. Depending on how "highly modified" your engine is, there are other carburetors that would give better performance results (the Stromberg OF being one of the most common). Combing the straight-thru carburetor with an earlier aluminum intake manifold (or reproduction one) with a higher volume and a dual exhaust set-up will give you a noticable increase in your engines performance. What types of modifications have been done to your "highly modified" engine? More (and better) performance would be garnered through a combination of good coils, a good magneto and the use of a new camshaft.
As far as the performance of the straight-thru carburetor is concerned, I have run the Holley and a few of the other aftermarket straight-thru models, and between them I would use the aftermarket ones to avoid the low speed and idle lope (currently running a Wizard straight-thru). Hopefully this was somewhat helpful and had some of what you were looking for.
The NH carburetor was built by both Holley and Ford (under license from Holley), with the only difference being that the Ford carburetor carried a Ford nameplate. Ford also built the Ford model F carburetor which is just the NH with a different nameplate, the model F was the earliest of the Ford built NH carburetors.
The straight-thru design will give you a little more top end speed but a reduced fuel economy. Depending on how "highly modified" your engine is, there are other carburetors that would give better performance results (the Stromberg OF being one of the most common). Combing the straight-thru carburetor with an earlier aluminum intake manifold (or reproduction one) with a higher volume and a dual exhaust set-up will give you a noticable increase in your engines performance. What types of modifications have been done to your "highly modified" engine? More (and better) performance would be garnered through a combination of good coils, a good magneto and the use of a new camshaft.
As far as the performance of the straight-thru carburetor is concerned, I have run the Holley and a few of the other aftermarket straight-thru models, and between them I would use the aftermarket ones to avoid the low speed and idle lope (currently running a Wizard straight-thru). Hopefully this was somewhat helpful and had some of what you were looking for.
Running a balanced T crank, Milled elongated ports, both intake & exhaust, 4" exhaust, Milled Z head. Makes a nice combo for a Ames speedster, Whippit radiator, Winfield carb/ Pump. Not really satisfied with the Winfield. Just Traded for a 1915 power unit with a straight thru, hence the inquiry.