Small block to big block conversion questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mahanian · 10-11-2011, 09:44 PM

I did a search on this before posting but didn't find what I was looking for. I found a really good deal on a 454 big block crate motor so I'm thinking about swapping my 327 small block for the 454. My question is what will I need to complete this conversion? I know I will need the big block engine stands. Will I have any clearance issues with the firewall? My truck currently has the 327 with a turbo 400 transmission, 4 core radiator, factory air and the 454 has a serpentine belt system with air conditioning and a HEI distributor. Will I have any clearance issues with this set up?
Posted via Mobile Device
Posted via Mobile Device

mahanian · 10-11-2011, 09:55 PM

I forgot to mention that it has the gm exhaust manifolds as well
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fastwillie 696969 · 10-12-2011, 01:05 AM

hei might have a clearance issue ,i got msd pro billet in my502 . the motor mounts some people cut them to fit the headers ,im sure other on here nows whats different

petey-pablo · 10-12-2011, 04:26 AM

You shouldn't have any clearance issues at all remember some of these trucks came with a BigBlock. As long as you position the motor mounts in the correct position. Other than the transmission cross member might have to be moved.

VA72C10 · 10-12-2011, 04:41 AM

different linkage for the th400 and different power steering setup if you want it to look factory....

dos0711 · 10-12-2011, 07:52 AM

This made it easier for me...

http://www.performanceonline.com/196...RACKETS-16820/

denny5625 · 10-12-2011, 09:53 AM

I swapped a small block out of my 71 to a 454 with no problems. It also has HEI and factory ac on it. For the exhaust I used the sanderson shorties and they worked great. Good luck and enjoy that torque!

**Classic Heartbeat** · 10-12-2011, 10:58 AM

Looking at your signature you are talking about installing it in one of your 67s I gather. If so the frame rails will need to be trimmed to make room for the exhaust manifolds. If you go to my website, and click on "67 Panel Project", go through the pages untill you find where I prepaired the chassis for a big block. There you will see what I did, to do just what you want to do plus more. WES

mahanian · 10-12-2011, 11:45 AM

Thanks for all of the great information! I didn't realize I would have to modify the frame in my 67 to get it to fit. My CST is all original including the 327, which I plan to re-install down the road so maybe I shouldn't convert to a big block

decisions...decisions...

hugger6933 · 10-12-2011, 12:02 PM

The trimming would [ithink] only be needed if you are running manifolds. If the trimming needed was slight, you could have the manifolds trimed down on the mounting flanges or run headers. I don't think you should abandon the thoughts of rat motor in you ride for that reason. I have put one in an s-10 before you can do it in a c-10.

71tahoe · 10-12-2011, 05:46 PM

I think the frame has to be trimmed to use 72+ motor towers. Not sure about others.

**Classic Heartbeat** · 10-13-2011, 02:16 AM

Not just for brackets. Exhaust manifolds too. WES

fastwillie 696969 · 10-13-2011, 02:42 AM

the old motor mounts that was on this was cut and trimmed with a plasma cutter ,to clear the headers and it wasnt safe for driving ,so i had replaced them with the tubular mounts /
heres a picture of the old mounts and headers

mahanian · 10-17-2011, 11:27 AM

Will the tubular engine stands like the ones sold by performance online eliminate the need to cut the 67 frame for manifold clearance?
Does anyone know if these tubular mounts shift the engine in any direction over the stock stands?
Did the big block have a different fan shroud?
Has anyone used the big block serpentine belt setup? If so, are there any clearance issues, especially since it doesn't have a remote PS reservior?

Thanks again for all the help!

*Fitz* · 10-17-2011, 12:58 PM

Quote:

Originally Posted by mahanian

I know I will need the big block engine stands. Will I have any clearance issues with the firewall? My truck currently has the 327 with a turbo 400 transmission, 4 core radiator, factory air and the 454 has a serpentine belt system with air conditioning and a HEI distributor. Will I have any clearance issues with this set up?
Posted via Mobile Device
Posted via Mobile Device

If this fits on the stock big block stands without requiring a smaller distributor, your 454 will fit.

10-11-2011, 09:44 PM	#1
mahanian C10 addict Join Date: Apr 2006 Location: Arizona Posts: 2,432	Small block to big block conversion questions I did a search on this before posting but didn't find what I was looking for. I found a really good deal on a 454 big block crate motor so I'm thinking about swapping my 327 small block for the 454. My question is what will I need to complete this conversion? I know I will need the big block engine stands. Will I have any clearance issues with the firewall? My truck currently has the 327 with a turbo 400 transmission, 4 core radiator, factory air and the 454 has a serpentine belt system with air conditioning and a HEI distributor. Will I have any clearance issues with this set up? Posted via Mobile Device Posted via Mobile Device __________________ Jared 67 C10 CST Short Fleet Big Window 65 C10 Custom Short Fleet Big Window 67 Camaro RS

10-11-2011, 09:55 PM	#2
mahanian C10 addict Join Date: Apr 2006 Location: Arizona Posts: 2,432	Re: Small block to big block conversion questions I forgot to mention that it has the gm exhaust manifolds as well Posted via Mobile Device __________________ Jared 67 C10 CST Short Fleet Big Window 65 C10 Custom Short Fleet Big Window 67 Camaro RS

10-12-2011, 01:05 AM	#3
fastwillie 696969 ~Rest In Peace~ Join Date: May 2005 Location: CALIFORNIA NOR CAL Posts: 9,707	Re: Small block to big block conversion questions hei might have a clearance issue ,i got msd pro billet in my502 . the motor mounts some people cut them to fit the headers ,im sure other on here nows whats different __________________ is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex

10-12-2011, 04:26 AM	#4
petey-pablo "THE GREEN GOBLIN" Join Date: Mar 2008 Location: Fremont Ca. Posts: 1,025	Re: Small block to big block conversion questions You shouldn't have any clearance issues at all remember some of these trucks came with a BigBlock. As long as you position the motor mounts in the correct position. Other than the transmission cross member might have to be moved. __________________ 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

10-12-2011, 04:41 AM	#5
VA72C10 VA72C10 Join Date: Mar 2008 Location: Midlothian, VA Posts: 25,269	Re: Small block to big block conversion questions different linkage for the th400 and different power steering setup if you want it to look factory.... __________________ Looking for a 67-72 swb or blazer project in or around VA.

10-12-2011, 07:52 AM	#6
dos0711 Registered User Join Date: Feb 2011 Location: Jacksonville,Fl Posts: 131	Re: Small block to big block conversion questions This made it easier for me... http://www.performanceonline.com/196...RACKETS-16820/ __________________ 1972 C-10 Cheyenne Super \| Short Stepside\| 454 ci \| TH400 \| 4:11 rear

10-12-2011, 09:53 AM	#7
denny5625 Registered User Join Date: Jul 2007 Location: Kennewick, WA Posts: 152	Re: Small block to big block conversion questions I swapped a small block out of my 71 to a 454 with no problems. It also has HEI and factory ac on it. For the exhaust I used the sanderson shorties and they worked great. Good luck and enjoy that torque! __________________ 66 el Camino 70 1/2 RS Z-28 71 C10 2wd 72 2 wd Blazer (2) 72 4 x 4 Blazers 88 24' Mirage 70 mph+ 08 Harley Night Train 08 Silverado 4d 4 x 4

10-12-2011, 10:58 AM	#8
Classic Heartbeat Project Junkie! Fishing Poor!! Join Date: Dec 1999 Location: Olympia,Wa. 98512 Posts: 10,768	Re: Small block to big block conversion questions Looking at your signature you are talking about installing it in one of your 67s I gather. If so the frame rails will need to be trimmed to make room for the exhaust manifolds. If you go to my website, and click on "67 Panel Project", go through the pages untill you find where I prepaired the chassis for a big block. There you will see what I did, to do just what you want to do plus more. WES __________________ On-line catolog Classic Heartbeat Pickup Parts WEHEPP@comcast.net Call us Toll Free (888) 338-2502 Like Us on Facebook No appointment necessary. 72 BB Chevy Custom Deluxe / Custom Camper 67 I-6 (Soon to be 5.7 LS1) Panel 68 BB Chevy Short Bed 72 6.0 LQ9 Short Bed Chevy 4X4 Olympia's fastest growing truck parts supplier. Olympia's home for Wayward Chevys

10-12-2011, 11:45 AM	#9
mahanian C10 addict Join Date: Apr 2006 Location: Arizona Posts: 2,432	Re: Small block to big block conversion questions Thanks for all of the great information! I didn't realize I would have to modify the frame in my 67 to get it to fit. My CST is all original including the 327, which I plan to re-install down the road so maybe I shouldn't convert to a big block decisions...decisions... __________________ Jared 67 C10 CST Short Fleet Big Window 65 C10 Custom Short Fleet Big Window 67 Camaro RS

10-12-2011, 12:02 PM	#10
hugger6933 Registered User Join Date: Oct 2008 Location: Marianna Arkansas Posts: 7,279	Re: Small block to big block conversion questions The trimming would [ithink] only be needed if you are running manifolds. If the trimming needed was slight, you could have the manifolds trimed down on the mounting flanges or run headers. I don't think you should abandon the thoughts of rat motor in you ride for that reason. I have put one in an s-10 before you can do it in a c-10.

10-12-2011, 05:46 PM	#11
71tahoe Registered User Join Date: May 2006 Location: Jonesboro, AR Posts: 916	Re: Small block to big block conversion questions I think the frame has to be trimmed to use 72+ motor towers. Not sure about others.

10-13-2011, 02:16 AM	#12
Classic Heartbeat Project Junkie! Fishing Poor!! Join Date: Dec 1999 Location: Olympia,Wa. 98512 Posts: 10,768	Re: Small block to big block conversion questions Not just for brackets. Exhaust manifolds too. WES __________________ On-line catolog Classic Heartbeat Pickup Parts WEHEPP@comcast.net Call us Toll Free (888) 338-2502 Like Us on Facebook No appointment necessary. 72 BB Chevy Custom Deluxe / Custom Camper 67 I-6 (Soon to be 5.7 LS1) Panel 68 BB Chevy Short Bed 72 6.0 LQ9 Short Bed Chevy 4X4 Olympia's fastest growing truck parts supplier. Olympia's home for Wayward Chevys

10-13-2011, 02:42 AM	#13
fastwillie 696969 ~Rest In Peace~ Join Date: May 2005 Location: CALIFORNIA NOR CAL Posts: 9,707	Re: Small block to big block conversion questions the old motor mounts that was on this was cut and trimmed with a plasma cutter ,to clear the headers and it wasnt safe for driving ,so i had replaced them with the tubular mounts / heres a picture of the old mounts and headers Attached Images __________________ is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex

10-17-2011, 11:27 AM	#14
mahanian C10 addict Join Date: Apr 2006 Location: Arizona Posts: 2,432	Re: Small block to big block conversion questions Will the tubular engine stands like the ones sold by performance online eliminate the need to cut the 67 frame for manifold clearance? Does anyone know if these tubular mounts shift the engine in any direction over the stock stands? Did the big block have a different fan shroud? Has anyone used the big block serpentine belt setup? If so, are there any clearance issues, especially since it doesn't have a remote PS reservior? Thanks again for all the help! __________________ Jared 67 C10 CST Short Fleet Big Window 65 C10 Custom Short Fleet Big Window 67 Camaro RS

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