70 4x4 suburban- wanting to go big block - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**STP67-72** · 03-14-2017, 11:04 PM

I have a local guy wanting to put a bigblock in his 4x4 suburban. I was told to move engine forward for firewall clearance ?? Gives room for valve covers and HEI clearance ?? Will stock small block mounts work. It's a 350- granny 4 speed. Going 454 , t-400 etc. thanks for any and all help.

**kwmech** · 03-15-2017, 01:25 AM

Much easier to pull the engine forward to the next set of bolt holes in the frame (You only have to drill one side) than pounding the firewall for the valve cover and the distributor if you've got an HEI. I have not put a big block in, but I know there will be an issue with the big block oil pan hitting the factory x-member with the small block cushions. You may want to try or measure the 2wd big block cushions. I know they are thicker.

B. W. · 03-15-2017, 10:20 AM

kwmech is spot on, when you move the engine forward you also need to check clearance between the engine cross member & the front axle. If springs are stock (and worn out) you may not have enough clearance. Also, with 350 mounts you will probably have clearance issues on the passenger frame rail with the exhaust manifold. Headers may solve this (or may make it worse.) I have have not done one but a friend of mine has a 71 K20 that he put a BB in. He did not change the mounts & had to notch the pass frame rail.

ajviper · 03-15-2017, 05:14 PM

Replied in your original thread up in the Suburban section.

03-14-2017, 11:04 PM	#1
STP67-72 Senior Member Join Date: Jan 2002 Location: PORT NECHES, TEXAS / USA Posts: 1,668	70 4x4 suburban- wanting to go big block I have a local guy wanting to put a bigblock in his 4x4 suburban. I was told to move engine forward for firewall clearance ?? Gives room for valve covers and HEI clearance ?? Will stock small block mounts work. It's a 350- granny 4 speed. Going 454 , t-400 etc. thanks for any and all help. __________________ 55 Chevy original swb (big back window) 61 Chevy bubble top (427-5 speed) 67 Chevy stepside (Krusty) 68 Chevy swb fleet (Lola) 68 Chevy swb fleet 71 Chevy swb fleet ( future PB project) 97 crew cab power stroke 07 SS Trail blazer

03-15-2017, 01:25 AM	#2
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,659	Re: 70 4x4 suburban- wanting to go big block Much easier to pull the engine forward to the next set of bolt holes in the frame (You only have to drill one side) than pounding the firewall for the valve cover and the distributor if you've got an HEI. I have not put a big block in, but I know there will be an issue with the big block oil pan hitting the factory x-member with the small block cushions. You may want to try or measure the 2wd big block cushions. I know they are thicker.

03-15-2017, 10:20 AM	#3
B. W. Registered User Join Date: Nov 2014 Location: Bigfork, Montana Posts: 1,137	Re: 70 4x4 suburban- wanting to go big block kwmech is spot on, when you move the engine forward you also need to check clearance between the engine cross member & the front axle. If springs are stock (and worn out) you may not have enough clearance. Also, with 350 mounts you will probably have clearance issues on the passenger frame rail with the exhaust manifold. Headers may solve this (or may make it worse.) I have have not done one but a friend of mine has a 71 K20 that he put a BB in. He did not change the mounts & had to notch the pass frame rail.

03-15-2017, 05:14 PM	#4
ajviper Registered User Join Date: Jul 2014 Location: Lakewood, Colorado Posts: 90	Re: 70 4x4 suburban- wanting to go big block Replied in your original thread up in the Suburban section. __________________ Chevy Runs Deep. 1956 210 LS1 TH350 3.31 Posi 12 Bolt 1969 Z/28 5.3 T56 3.73 Posi 12 Bolt 1973 Nova SS 355 TH350 2.73 Posi 12 Bolt 2000 K2500 Suburban LS 6.0 4L80 3.73 G80 2005 K2500HD CCSB LS 6.0 4L80 4.10 G80 2010 2SS/RS Camaro LS3 T56 Aqua Blue Metallic



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