Hi-Hump and Low-Hump - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Striker169 · 05-14-2005, 02:19 AM

Can I use a low hump on a 1/2 with a 454 and a TH350? Will it fit? My current cab has a hi hump but my new cab has a low hump will I have to cut out the low hump to put in a high hump?

garthdader · 05-14-2005, 02:59 AM

Is it a 4wd or 2wd chassis?

thecatseye66 · 05-14-2005, 03:01 AM

I really want to read the replies on this thread. I hope you get it right, too!

My Custom Camper 396/TH400 (my avatar) has a high hump, but my CST/10 4 spd has a low hump.

Originally I thought it had more to do with the toploader/floorshift situation but now I think the front side of the firewall with a big block engine determined that a high-hump was needed even on a two-wheel drive.

The tranny in my C-10 isn't that tall so your TH350 might not be a problem. I think the BB situation crowds the bellhousing into the firewall/hump area but I'm just speculating.

**Yukon Jack** · 05-14-2005, 09:11 AM

It should be fine. The high hump was used on the trucks that had the TH400 or were 4 wheel drive. Being a big block shouldn't matter cause the length difference of a big block and small block is from the engine mounts forward, however a big block is taller than a small block.

I'm sure someone will respond that can give you a definite answer.

1STtimePRo'71 · 05-14-2005, 11:51 AM

High Hump=4x4+sm465 Right?

Purs · 05-14-2005, 01:53 PM

several guys here are successfully running a BB/TH400 with a low hump provided you have GOOD cab mounts. I'm sure the TH350 is the same size or smaller case than the TH400.

stelth2002 · 05-14-2005, 02:05 PM

From the factory mine had a high hump with 292 and sm420 and its 2wd

Swbman · 05-14-2005, 02:38 PM

I have a 72 bbc 402/400 burb high hump, 71 swb sbc 400/400 with high, and 71 4x4 with high hump.All the 4x4 and rigs with turbo 400 all had high hump cabs.

longhorn71 · 05-14-2005, 10:51 PM

all 4x4s were hi humps,all 4speed ,and big block trucks were hi-humps as well.the low humps were any 2wd smallblock auto trucks.

HOTFUN · 05-15-2005, 01:10 AM

I don't think they used the high hump in all turbo 400 installations as in 67 is questionable. My factory original 67 GMC 3/4 with V6 and turbo 400 truck has a low hump floor. I always thought GM went to the high hump for better heat disapation especially when the big block was installed in 68.

05-14-2005, 02:19 AM	#1
Striker169 Car O'Holic Join Date: Jan 2005 Location: Austin, Tx. Posts: 692	Hi-Hump and Low-Hump Can I use a low hump on a 1/2 with a 454 and a TH350? Will it fit? My current cab has a hi hump but my new cab has a low hump will I have to cut out the low hump to put in a high hump?

05-14-2005, 02:59 AM	#2
garthdader Registered User Join Date: Sep 2002 Location: Atoka, Tn Posts: 64	Is it a 4wd or 2wd chassis? __________________ 1971 Chevy 6" superlift 35" xterrains 350 VORTEC crate

05-14-2005, 09:11 AM	#4
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,684	It should be fine. The high hump was used on the trucks that had the TH400 or were 4 wheel drive. Being a big block shouldn't matter cause the length difference of a big block and small block is from the engine mounts forward, however a big block is taller than a small block. I'm sure someone will respond that can give you a definite answer. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

05-14-2005, 11:51 AM	#5
1STtimePRo'71 Registered User Join Date: Feb 2005 Location: Lake Crystal, MN Posts: 656	High Hump=4x4+sm465 Right? __________________ -Cory 1967 2 Wheel Chevy

05-14-2005, 01:53 PM	#6
Purs Got Big Block? Join Date: Apr 2000 Location: West Texas Posts: 1,510	several guys here are successfully running a BB/TH400 with a low hump provided you have GOOD cab mounts. I'm sure the TH350 is the same size or smaller case than the TH400. __________________ "Experience is what you get when you didn't get what you wanted."

05-14-2005, 03:01 AM	#3
thecatseye66 '68 C-20 396 CST CC Join Date: Mar 2005 Location: Spokane, WA Posts: 454	I really want to read the replies on this thread. I hope you get it right, too! My Custom Camper 396/TH400 (my avatar) has a high hump, but my CST/10 4 spd has a low hump. Originally I thought it had more to do with the toploader/floorshift situation but now I think the front side of the firewall with a big block engine determined that a high-hump was needed even on a two-wheel drive. The tranny in my C-10 isn't that tall so your TH350 might not be a problem. I think the BB situation crowds the bellhousing into the firewall/hump area but I'm just speculating.

05-14-2005, 02:05 PM	#7
stelth2002 Young Gun wth Fast Inline Join Date: Jan 2002 Location: Idaho Posts: 1,475	From the factory mine had a high hump with 292 and sm420 and its 2wd __________________ 1967 Chevrolet LWB with built 292! 415 ft. lbs of torque, 4 speed :O with 27% overdrive too, 3.73 Posi. Frame and body done... getting painted!!!

05-14-2005, 02:38 PM	#8
Swbman Senior Member Join Date: Mar 2004 Location: Tulsa,Oklahoma Posts: 606	I have a 72 bbc 402/400 burb high hump, 71 swb sbc 400/400 with high, and 71 4x4 with high hump.All the 4x4 and rigs with turbo 400 all had high hump cabs. __________________ 1961 BUICK LESABRE 1968 CHEVELLE SS 396 1969 BUICK RIVIERA GS 1971 2 WHEEL DRIVE BLAZER 1971 4X4 BLAZER 1971 SHORTBED CHEYENNE FLEETSIDE 1971 SHORTBED 4X4 FLEETSIDE ** ...My Ebay

05-14-2005, 10:51 PM	#9
longhorn71 Senior Member Join Date: Sep 2004 Location: CANADA Posts: 1,681	all 4x4s were hi humps,all 4speed ,and big block trucks were hi-humps as well.the low humps were any 2wd smallblock auto trucks.

05-15-2005, 01:10 AM	#10
HOTFUN Registered User Join Date: Jan 2001 Location: Lincoln, Nebraska Posts: 2,145	I don't think they used the high hump in all turbo 400 installations as in 67 is questionable. My factory original 67 GMC 3/4 with V6 and turbo 400 truck has a low hump floor. I always thought GM went to the high hump for better heat disapation especially when the big block was installed in 68. __________________ '66 CST BBW swb fleet 327 fac ac '67 CST 4x4 swb 327 stepside project '72 Cheyenne K20 50k original '72 Cheyenne Super K20 project '73 Sierra swb 4x4 frame off in paint stage '74 Cheyenne Super swb w/16k actual '71 & 72 Cheyenne K10 4x4 swb's '70 426 HEMICUDA conv SHAKER 4 sp Dana 60 '60 Impala conv 327 PG fac ac loaded 3rd owner '72 GMC K2500 4x4 '59 Apache CST BBW fleetside swb 283 '73 ElCamino SS LS1 T56 true SS bucket tach '76 ElCamino SS 52k survivor '87 Grand National 41k True 2nd to last built in 1987. '86 K30 454 SRW fleetside CA since new '88 Trans Am GTA 39k bought new 2018 DEMON plum crazy @ 840HP! "Need for speed"



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