Holley spread bore carb.

jims5600 · 04-03-2013, 06:15 PM

Jeff is spot on,take his advise

Jeff Lee · 04-03-2013, 07:11 PM

I'm not sure the Holley spread bore is a direct bolt-on for a 351C factory Autolite 4bbl intake. I think it needs an adapter. Been a while since I've messed with 351's....

bad440 · 04-04-2013, 03:13 AM

thinking 73s were spreadbore intakes...

Jeff Lee · 04-04-2013, 03:30 AM

I know the 1973 and newer Autolite is a spreadbore but I'm pretty sure the bolt pattern for the four studs is something weird. But there are adaptors available.

Dwight Southerland · 04-04-2013, 06:20 AM

Jeff is correct. The Autolite spread-bore pattern is different than Q-jet, Thermoquad, and Holley layout. There used to be adapters available, so maybe you can find one.

Mike Taylor 3601 · 04-04-2013, 08:33 AM

Spread bores work good,sometimes they take more tuning than regular holley,secondary can be hard to get smooth,vac. secondaries are harder to tune than mechanical secondaries spread bores came both ways
Mike Taylor 3601

Carguy49 · 04-04-2013, 01:34 PM

I have used several of these carbs in the past (20 years ago). They are very tunable and when setup properly can give reasonable fuel mileage on the street. Since they use small primaries and larger secondaries tuning can be somewhat tricky. Shouldn't be a problem for anyone who has spent time tuning a carb for a certain combination. Good luck and should be a very doable project. I have a question, does Holley still build spreadbore carbs??

04-03-2013, 06:15 PM	#1
jims5600 Member Join Date: Oct 2011 Posts: 125 Likes: 47 Liked 21 Times in 9 Posts	Re: Holley spread bore carb. Jeff is spot on,take his advise

04-03-2013, 07:11 PM	#2
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	Re: Holley spread bore carb. I'm not sure the Holley spread bore is a direct bolt-on for a 351C factory Autolite 4bbl intake. I think it needs an adapter. Been a while since I've messed with 351's.... __________________ Jeff Lee 7494 D/S '70 AMX

04-04-2013, 03:13 AM	#3
bad440 Junior Member Join Date: Apr 2010 Location: livermore ca. Posts: 19 Likes: 0 Liked 0 Times in 0 Posts	Re: Holley spread bore carb. thinking 73s were spreadbore intakes...

04-04-2013, 03:30 AM	#4
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	Re: Holley spread bore carb. I know the 1973 and newer Autolite is a spreadbore but I'm pretty sure the bolt pattern for the four studs is something weird. But there are adaptors available. __________________ Jeff Lee 7494 D/S '70 AMX

04-04-2013, 06:20 AM	#5
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 2,001 Likes: 64 Liked 780 Times in 194 Posts	Re: Holley spread bore carb. Jeff is correct. The Autolite spread-bore pattern is different than Q-jet, Thermoquad, and Holley layout. There used to be adapters available, so maybe you can find one.

04-04-2013, 08:33 AM	#6
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,372 Likes: 358 Liked 308 Times in 103 Posts	Re: Holley spread bore carb. Spread bores work good,sometimes they take more tuning than regular holley,secondary can be hard to get smooth,vac. secondaries are harder to tune than mechanical secondaries spread bores came both ways Mike Taylor 3601

04-04-2013, 01:34 PM	#7
Carguy49 VIP Member Join Date: Aug 2011 Location: Fife, Washington Posts: 1,985 Likes: 2,484 Liked 2,966 Times in 713 Posts	Re: Holley spread bore carb. I have used several of these carbs in the past (20 years ago). They are very tunable and when setup properly can give reasonable fuel mileage on the street. Since they use small primaries and larger secondaries tuning can be somewhat tricky. Shouldn't be a problem for anyone who has spent time tuning a carb for a certain combination. Good luck and should be a very doable project. I have a question, does Holley still build spreadbore carbs?? __________________ Ron McDowell - Did Race Every day is a Gift - Enjoy with family and friends.