Big Block Install Question? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Number98 · 03-25-2003, 09:55 AM

When talking about installing a big block into a 2 wheel drive truck that came with a small block. Among other things people talk about firewall clearance....I understand that the distributor wont clear, or gets real close? Well what is done to solve this, other than beating it with a hammer? Were the trucks that came from the factory with big blocks "adjusted" for clearance?

Jason

JimKshortstep4x4 · 03-25-2003, 11:54 AM

I am not aware of problems with big blocks in 2 wd trucks. 4wd
trucks are tight.

Here is a pick of a 72 bb with HEI and there is plenty of room.

Jim

**1971Stepside** · 03-25-2003, 12:12 PM

As long as you have your BB sitting on BB stands you will have no clearance issues. Some folks have mounted them to 350 stands, but I believe either the engine stand or the frame needs some slight trimming for header clearance.

sakohntr · 03-25-2003, 12:46 PM

I put a BB in my 69 4x4 that originally had a small block. I did use the small block towers, although I moved them forward almost 2 inches so i knew i would have enough room for an hei distributor. The headers did not require trimming but they almost touch the spring shackle.

03-25-2003, 09:55 AM	#1
Number98 Prestige Worldwide Join Date: Feb 2001 Location: Worldwide Posts: 2,553	Big Block Install Question? When talking about installing a big block into a 2 wheel drive truck that came with a small block. Among other things people talk about firewall clearance....I understand that the distributor wont clear, or gets real close? Well what is done to solve this, other than beating it with a hammer? Were the trucks that came from the factory with big blocks "adjusted" for clearance? Jason

03-25-2003, 11:54 AM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	I am not aware of problems with big blocks in 2 wd trucks. 4wd trucks are tight. Here is a pick of a 72 bb with HEI and there is plenty of room. Jim Attached Images

03-25-2003, 12:12 PM	#3
1971Stepside Almost Satisfied Join Date: Mar 2002 Location: Springfield, MO Posts: 2,932	As long as you have your BB sitting on BB stands you will have no clearance issues. Some folks have mounted them to 350 stands, but I believe either the engine stand or the frame needs some slight trimming for header clearance. __________________ 1971 C10 Stepside. LSx 6.0 with BTR Stage IV, Speed Engineering Headers, 4L80e transmission w/3200 Circle-D Stall. 3.73. Posi. Purchased this truck when I was 17. I started the rebuild (or take apart) in 1993. I have drug it around all over the country in pieces. Finally back on the road in 2021. "I can't complain, but sometimes I still do. Life's been good to me so far."

03-25-2003, 12:46 PM	#4
sakohntr Registered User Join Date: Mar 2002 Location: Floodwood Minnesota Posts: 1,057	location I put a BB in my 69 4x4 that originally had a small block. I did use the small block towers, although I moved them forward almost 2 inches so i knew i would have enough room for an hei distributor. The headers did not require trimming but they almost touch the spring shackle. __________________ 1967 K30 Napco 292/SM420 original paint 30k miles 1968 K60 Napco 396/5spd. dbl frame 52" michelins 1969 K10 SWB GMC 454/4spd 6" 35's posi,hooks 1972 C30 longhorn,BB/AT,A/C,Tilt,Toolbox,lokr 1987 K20 Chevrolet Suburban. 6" lift. 5.7L/TH400 1979 K60 GMC Coleman 4x4, 427/Allison.



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