? for small block to big block swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

centsless · 02-24-2009, 05:47 PM

I pulled the 283 out of the "72, and installed a 454. It is in and bolted up using the small block mounts. Everything fits fine...except the headers. The right header clears everything fine, the left header is hitting the engine perch...BAD. I am not against denting the tube a little to introduce some clearance, but I would have to cut the front tube in half to get around this one. I have a '71 Suburban with the correct big block perches, but I don't want floor clearance issues with the TH400 trans, and also need the hood clearance for the blower. Anyone have any ideas or solutions for this dilemma?
Thanks!
Bob

70rs/ss · 02-24-2009, 06:29 PM

You can cut the SBC mount and use a piece of pipe to get the curve of the 69-71 BBC mount and then the header will clear. I don't think the BBC mounts raise the engine that much?? I have seen the above mod done to a SBC mount in order to allow the BBC header tube to clear, I wouldn't beeat on the header, just make the mount fit around the tube??

centsless · 02-24-2009, 08:18 PM

I was thinking about that. I have a plasma cutter and a mig, so it would not be too big a deal, but was wondering if there were any other avenues first. That may be the way I go.

*67/72junkie* · 02-24-2009, 08:29 PM

I think you can use 73 up 350 mounts that are almost the same as 72 bb mounts and only have to drill one hole for each side.I bought a 71 gmc with a 454 and thought it had correct 72 only mounts until closer look it had 2 humps spaced instead of 1 in the center like 72 only.

mrh33916 · 02-24-2009, 08:37 PM

I'm using frame and engine mounts from a '86 s/b suburban, the upper holes line up and you must drill a lower hole. i'm using Flowtech headers with no clearance issues

mrh33916 · 02-24-2009, 08:46 PM

Here are some pictures, Name: left motor mount.jpg
Views: 606
Size: 57.7 KB

Name: right motor mount.jpg
Views: 596
Size: 53.4 KB

*67/72junkie* · 02-24-2009, 08:49 PM

looking good thats exactly what I was talking about.

Twisted78SS · 02-24-2009, 08:58 PM

That's good news, i was just going to go find my 77 350 towers/mounts to put the 454 in my 70 Blazer project. I had heard that this combination worked.

Thanks

Drew

green724x4 · 02-24-2009, 09:06 PM

hey centless, do you have a build thread.
I did a blown big block swap last year in my 72.
love to see some pics and specs.

primered_junk · 02-25-2009, 04:30 PM

I jumped on this late, I did one and swapped the mounts side to side, had to drill two holes, but it fixed the issue.

redneckgirl · 02-26-2009, 03:09 AM

Quote:

Originally Posted by green724x4

hey centless, do you have a build thread.
I did a blown big block swap last year in my 72.
love to see some pics and specs.

I did a build thread...if you click the link in my sig, it takes you there....aren't any updated engine swap pics, since someone is taking his time with the clearance issue....

petey-pablo · 02-26-2009, 07:46 AM

I used 72only big block mounts with flowtech hedders with No clearence problems On my 72 truck

HuggerCST · 02-26-2009, 11:25 AM

Quote:

Originally Posted by centsless

I have a '71 Suburban with the correct big block perches, but I don't want floor clearance issues with the TH400 trans, and also need the hood clearance for the blower. Bob

I don't think you'll have any floor clearance issues. This link has pics that show the floor clearance on GSFmech's 72 with a 454/th-400, 72 BB engine mounts and a low hump floor. (post #122) http://67-72chevytrucks.com/vboard/s...=271489&page=5

**Ron 586** · 03-02-2009, 10:35 AM

What happened. Any progress on resolving the problem.

02-24-2009, 06:29 PM	#2
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,270	Re: ? for small block to big block swap You can cut the SBC mount and use a piece of pipe to get the curve of the 69-71 BBC mount and then the header will clear. I don't think the BBC mounts raise the engine that much?? I have seen the above mod done to a SBC mount in order to allow the BBC header tube to clear, I wouldn't beeat on the header, just make the mount fit around the tube??

02-24-2009, 08:18 PM	#3
centsless sufficiently talented fool Join Date: Jun 2006 Location: Forest Hill, MD Posts: 2,231	Re: ? for small block to big block swap I was thinking about that. I have a plasma cutter and a mig, so it would not be too big a deal, but was wondering if there were any other avenues first. That may be the way I go. __________________ "it's impossible to be surrounded by idiots when you are part of the circle" 2003 Suburban 2002 Pontiac Montana 1981 Corvette 1966 Impala Convertible Click here to support the board

02-24-2009, 08:29 PM	#4
67/72junkie Account Suspended Join Date: Oct 2002 Location: NC Posts: 1,129	Re: ? for small block to big block swap I think you can use 73 up 350 mounts that are almost the same as 72 bb mounts and only have to drill one hole for each side.I bought a 71 gmc with a 454 and thought it had correct 72 only mounts until closer look it had 2 humps spaced instead of 1 in the center like 72 only.

02-24-2009, 08:37 PM	#5
mrh33916 Project '67 454 Join Date: Jan 2009 Location: Columbia SC Posts: 283	Re: ? for small block to big block swap I'm using frame and engine mounts from a '86 s/b suburban, the upper holes line up and you must drill a lower hole. i'm using Flowtech headers with no clearance issues

02-24-2009, 08:46 PM	#6
mrh33916 Project '67 454 Join Date: Jan 2009 Location: Columbia SC Posts: 283	Re: ? for small block to big block swap Here are some pictures,

02-24-2009, 05:47 PM	#1
centsless sufficiently talented fool Join Date: Jun 2006 Location: Forest Hill, MD Posts: 2,231	? for small block to big block swap I pulled the 283 out of the "72, and installed a 454. It is in and bolted up using the small block mounts. Everything fits fine...except the headers. The right header clears everything fine, the left header is hitting the engine perch...BAD. I am not against denting the tube a little to introduce some clearance, but I would have to cut the front tube in half to get around this one. I have a '71 Suburban with the correct big block perches, but I don't want floor clearance issues with the TH400 trans, and also need the hood clearance for the blower. Anyone have any ideas or solutions for this dilemma? Thanks! Bob __________________ "it's impossible to be surrounded by idiots when you are part of the circle" 2003 Suburban 2002 Pontiac Montana 1981 Corvette 1966 Impala Convertible Click here to support the board

02-24-2009, 08:49 PM	#7
67/72junkie Account Suspended Join Date: Oct 2002 Location: NC Posts: 1,129	Re: ? for small block to big block swap looking good thats exactly what I was talking about.

02-24-2009, 08:58 PM	#8
Twisted78SS Wide n'Low Join Date: Jan 2007 Location: La Center, WA Posts: 1,511	Re: ? for small block to big block swap That's good news, i was just going to go find my 77 350 towers/mounts to put the 454 in my 70 Blazer project. I had heard that this combination worked. Thanks Drew __________________ Trippin Hazard.. 67 swb, Gold Member.. 68 Suburban Air Force Retired

02-24-2009, 09:06 PM	#9
green724x4 Registered User Join Date: Feb 2007 Location: MI Posts: 214	Re: ? for small block to big block swap hey centless, do you have a build thread. I did a blown big block swap last year in my 72. love to see some pics and specs.

02-25-2009, 04:30 PM	#10
primered_junk ASE master tech/machinist Join Date: May 2008 Location: Blue Mound Texas Posts: 303	Re: ? for small block to big block swap I jumped on this late, I did one and swapped the mounts side to side, had to drill two holes, but it fixed the issue. __________________ "I sit here and I pray in my broken down Chevrolet....."

02-26-2009, 07:46 AM	#12
petey-pablo "THE GREEN GOBLIN" Join Date: Mar 2008 Location: Fremont Ca. Posts: 1,025	Re: ? for small block to big block swap I used 72only big block mounts with flowtech hedders with No clearence problems On my 72 truck __________________ Petey-pablo "THE GREEN GOBLIN" 1972 Cheyenne 10 Short Fleet Side Front 2.5inch Spindles with 2inch Springs Rear 4inch drop Springs. 454BBC TH400,Posi 1971 Cheyenne 10 Long Fleet Side 454BBC TH350,Posi Sold Drive it like you stole it! Petey-pablo@sbcglobal.net

03-02-2009, 10:35 AM	#14
Ron 586 RIP Mr Ron Join Date: Dec 2005 Location: Big Sandy, Tn. 38221 Posts: 8,150	Re: ? for small block to big block swap What happened. Any progress on resolving the problem. __________________ Ron (Mr Round Tuit) Be kinder than necessary, for everyone you meet is fighting some kind of battle TN Message Forum TN Facebook Group SETN Truck Show My Photobucket

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