differentials between square bore and spread bore
Thread Starter
Intermediate
Joined: Jun 2010
Posts: 40
Likes: 0
differentials between square bore and spread bore
Good friends tell me that someone would know the difference between these two systems, carburetor, I have seen some intake manifolds accept each other or both, but ... You can install such a spread bore in an intake manifold that will accept?
Thanks for the info
Thanks for the info
Le Mans Master
Joined: Jan 2007
Posts: 5,485
Likes: 7
From: Peekskill NY
Square bore means all 4 openings, primary and secondary, on the carb to let fuel & air are the same diameter. Spread bore is the two primary bore diameter is smaller then the secondary bore diameter.
Regarding manifolds, some except both type of carbs, others are specific to the type of carb.
Regarding manifolds, some except both type of carbs, others are specific to the type of carb.
Race Director
Joined: Jun 2000
Posts: 10,051
Likes: 677
From: FL
Not really.
That manifold has two sets of bolt holes because Holley and Carter carbs (which are both square bore) have different bolt patterns. If you bolt a spreadbore carb (Q-Jet) to that manifold, the secondary thottle plates will hit the sides of the opening. You would need an adapter plate to make it work.
Here is a spreadbore manifold. Note where the opening is in relation to the bolt holes.
That manifold has two sets of bolt holes because Holley and Carter carbs (which are both square bore) have different bolt patterns. If you bolt a spreadbore carb (Q-Jet) to that manifold, the secondary thottle plates will hit the sides of the opening. You would need an adapter plate to make it work.
Here is a spreadbore manifold. Note where the opening is in relation to the bolt holes.
Drifting
Joined: Oct 2004
Posts: 1,255
Likes: 7
From: Coralville Iowa
Not really.
That manifold has two sets of bolt holes because Holley and Carter carbs (which are both square bore) have different bolt patterns. If you bolt a spreadbore carb (Q-Jet) to that manifold, the secondary thottle plates will hit the sides of the opening. You would need an adapter plate to make it work.
Here is a spreadbore manifold. Note where the opening is in relation to the bolt holes.
That manifold has two sets of bolt holes because Holley and Carter carbs (which are both square bore) have different bolt patterns. If you bolt a spreadbore carb (Q-Jet) to that manifold, the secondary thottle plates will hit the sides of the opening. You would need an adapter plate to make it work.
Here is a spreadbore manifold. Note where the opening is in relation to the bolt holes.
The manifold you show is square bore only. The extra bolts holes are for the different configuration of square bores you can put on. ie: Holley and Edelbrock. The Edelbrock square bore Carter copy uses the other bolt holes as does a carburetor adapter.
