malmech12
May 7th, 05, 10:31 AM
Below is what I have compiled so far as to all the info one should need to do a SB to BB swap, except 454. If there is any other info that any can add, that would be great. Also if there are any mis-nomers, or incorrect info, feel free to add.
Small Block To Big Block Swap
You can reuse your alternator
You can reuse the lower alternator bracket, but you'll need the bb upper bracket.
You can reuse your flywheel
You won't have any driveshaft issues.
Motor Mounts / Use Small Block PST or Energy Suspension Mounts All Exc.307
Oil Pan / Need Chevelle BB Oil Pan
Water Pump / Long Neck
Fan Shroud / BB
Springs / BB
Throttle Cable
70-72 chevelle w/4BC (396,400,402,454) (exc. SP. H/Per.) PN 3972679 -21 31/32" long.
70-72 Chevelle w/Sp.H/Per.(396/454) lists as PN 336969 (21" O.L.)
Hopefully common/easy SB-to-BB swap questions?
AlanGrove components has nearly every bracket imaginable. That is where I got my brackets when I did my swap in my 72 wagon. I also used hooker part # 2455 for my headers. The only prob I had there was; I had to move the proportioner up a little, and ding the pipe in about a quarter inch to clear the lower control arm rear mounting point. So far it has been reasonably straight forward, except for taking the drivers side header out a few times.
________________________________________
Sorry to post here also, but I didn't get much response in the Engine forum. For those that are familiar with a SB-to-BB swap (327 to 396/402 in a 70 SS), please take a moment, if you would, to read this thread:
http://www.chevelles.com/forums/showthread.php?t=86156
Basically, my wife and I (with the help of Chris -- thanks again!) pulled the 327 from her 70 SS (it is a real SS, but the original 396 was gone long before it came to us). We have the 396 (with the help of yet another TC member!) sitting on a stand waiting to go into its new home. But, we're complete newbies at this, so I'm trying to verify some things to see what I need to buy.
And, before anyone suggests it, I really HAVE done a LOT of searching here -- reading all of the threads I could find involving a SB to BB swap and I STILL have questions. In fact, MOST of the search results are just people saying "this is common -- do a search!" Well, I've done said searches -- and while it answered a few things, it actually brought up several OTHER questions that I didn't see answered anywhere.
water pump pulley questions
i'm swapping my 350 for a world 509, and need some advice on water pumps. i'm probably going to go for an edelbrock victor. my sb has a long pump on it with some nice pump and crank pulleys that i'd like to reuse. i know that the center hole in the crank pulley is larger on a bb, i have no problem boring that out. does anyone know if the sb long water pump pulley will line up with the crank pulley on a bb with either a long or short water pump?
• I don't think any of the pullies swap. I did my 71, SB to BB and had to buy all the pullies new, got them off a later truck deal.
• My experience is based on LWP on a BB...
The pulleys look very much the same but are all just a bit different. And it also depends on what you want to do. You may be able to improvise a basic single belt setup using SB pulleys on a BB (a prior owner had done this on my El Camino). But if you get into more advanced stuff like PS and A/C you will definitely need BB specific pulleys.
The BB water pump has a different bolt circle than the SB and the groove offset is just a bit different between them also. The BB also uses a different diameter on front versus rear pulley grooves for water pump and lower radiator hose clearance.
And of course you have already figured out the difference in the inner hole on the crank pulleys.
Pulleys
• March mounting bracket and I also use the moroso pulley on the alt.
• Installed a moroso 5" alt. pulley with a billet alt fan and solved the problem. New problem..... discharge at low rpms.
• Had similar problems on a 69 camaro. I purchased the march v belt pulleys (crank, alt, P/S). They never came off again.
SB to BB Swap Question/Answers
1. I get the impression that the power-steering pump looks similar, but is actually different -- is that correct? Do I need to buy a new power-steering pump for the BB? And, if so, what about brackets to go with it? Or can I reuse the old one with just different brackets? (Note that the brackets that were on it never fit quite right anyhow -- so re-using the SB brackets, even if it were possible, won't work for us).
• Will advise
2. I believe I can re-use my alternator, but will need a new bracket for it -- is that correct? I believe that my existing one already has a "deep-groove" pulley.
• Yes, the Pulley may have to be swapped
3. We have a Muncie M-21 4-speed that we used with the SB that we are going to continue to use. I'm not sure how to tell if I need anything as far as connecting the engine to the tranny!
• ALL the same except, 11” clutch, and 621 bell housing
4. I put a clutch-fan on the SB a year or so ago. I'm not sure if I need to replace this or not... Unfortunately, I don't remember any specs from it -- so I don't know if it is "good enough" for the BB... Any thoughts on how to tell/know? Or should I just replace it to be sure? Any recommendations on a good clutch fan for the BB?
• Yes, you need a clutch-fan, check the fan/blade diameters in the books
5. Can I re-use the fuel pump from the SB? Or do I need one specific to the 396? I believe that I need a replacement, yes?
• Yes, you need a BB fuel pump
6. What about belts in general (to the alternator, P/S pump, and such)? Can I just get these at any local place like AutoZone, CarQuest, and so on? Or should I be ordering these now from Summit or something?
• As for #6, the 396 that I bought came with a three-grove pulley on it plus the water pump already attached -- so I should be fine there as far as pulleys go, I believe, if my P/S pump pulley works fine as you suggest. I think just the belts will do me there.
7. Do I need to get new front springs? The car was originally a 396 a long time ago -- but I have no idea if the previous owner changed springs when they went to a 327 or not. Nor do I know how "good" the springs still are. Anything I can check really? Should I just try it with the old springs and see how it goes -- swapping in new springs later if I need them?
• Springs aren't that hard to replace, but you must observe serious safety requirements when removing and installing them. It deserves a dedicated thread for discussion if you have never done coils before. There are a few tricks that can make it much easier and safer.
I would suggest leaving them alone until you have observed and driven the vehicle post-swap. You will then be in a better position to make an educated choice and get it right. Doing it before is doing it merely on speculation without evidence to support your conclusion.
8. I shouldn't have to deal with any driveshaft length problems or anything, right? Sticking with the M-21 and going from the 327 to a 396 should mean that I can leave the driveshaft as is, correct?
• Your transmission will remain in the same position. The parting line between block and bellhousing does not relocate in position. The additional length of a rat is taken up from the mounts forward in the BBC installation. Therefore the only consideration for driveshaft issues will be the additional torque you will be requiring it to transfer. I'd be thinking of a balance job and new u-joints, perhaps even a good look at the yokes to determine if they've been "helped" during a previous u-joint replacement attempt. Most of the time amateurs screw this up.
9. What about flywheel issues? The new 396 came with a flywheel on it -- although I don't see any numbers. What do I need to check/know to make sure that this is going to bolt right up to the M-21 that was used with the 327? Will I need anything new as far as interfacing those together?
• The flywheel does not contact the transmission input shaft or any other part of the trans. It is an engine/crankshaft issue. The trans will not care what flywheel you are using. The trans input shaft connects only to the clutch disc, and the tip of it rides in a bearing (or bushing) that is inserted into the rear of the crankshaft. You must be sure that this bearing or bushing is present and in good condition. If not, or if it is worn, your input shaft on the trans will be unsupported and the front bearing will fail, you may break your bearing retainer (the part the throwout bearing rides/slides on), and your shifting will be imprecise. The trans pilots on this, and it is very important.
10. Should I order new bushings/rubber/whatever-it-is for the motor mounts? The existing ones LOOK ok to me -- but I probably wouldn't know anyhow. heh. Any recommendations here?
• My advice is to always replace parts that can deteriorate, parts that are safety issues, and parts that are very difficult to replace later. The mounts fall in all three of these categories.
As with electronics, do not go with "looks" here.
11. As far as radiator hoses and such I assume that is like the belt question above? Maybe get those from AutoZone or some place local that has an SS396 listed in their parts database?
• The only thing I can help you with is the belts. I know Kragen(Checker/Schucks) has the SS396 model in their system so the belts and hoses and such should still be available. Don't recall if AutoZone lists the SS396 but I believe they do.
Small Block To Big Block Swap
You can reuse your alternator
You can reuse the lower alternator bracket, but you'll need the bb upper bracket.
You can reuse your flywheel
You won't have any driveshaft issues.
Motor Mounts / Use Small Block PST or Energy Suspension Mounts All Exc.307
Oil Pan / Need Chevelle BB Oil Pan
Water Pump / Long Neck
Fan Shroud / BB
Springs / BB
Throttle Cable
70-72 chevelle w/4BC (396,400,402,454) (exc. SP. H/Per.) PN 3972679 -21 31/32" long.
70-72 Chevelle w/Sp.H/Per.(396/454) lists as PN 336969 (21" O.L.)
Hopefully common/easy SB-to-BB swap questions?
AlanGrove components has nearly every bracket imaginable. That is where I got my brackets when I did my swap in my 72 wagon. I also used hooker part # 2455 for my headers. The only prob I had there was; I had to move the proportioner up a little, and ding the pipe in about a quarter inch to clear the lower control arm rear mounting point. So far it has been reasonably straight forward, except for taking the drivers side header out a few times.
________________________________________
Sorry to post here also, but I didn't get much response in the Engine forum. For those that are familiar with a SB-to-BB swap (327 to 396/402 in a 70 SS), please take a moment, if you would, to read this thread:
http://www.chevelles.com/forums/showthread.php?t=86156
Basically, my wife and I (with the help of Chris -- thanks again!) pulled the 327 from her 70 SS (it is a real SS, but the original 396 was gone long before it came to us). We have the 396 (with the help of yet another TC member!) sitting on a stand waiting to go into its new home. But, we're complete newbies at this, so I'm trying to verify some things to see what I need to buy.
And, before anyone suggests it, I really HAVE done a LOT of searching here -- reading all of the threads I could find involving a SB to BB swap and I STILL have questions. In fact, MOST of the search results are just people saying "this is common -- do a search!" Well, I've done said searches -- and while it answered a few things, it actually brought up several OTHER questions that I didn't see answered anywhere.
water pump pulley questions
i'm swapping my 350 for a world 509, and need some advice on water pumps. i'm probably going to go for an edelbrock victor. my sb has a long pump on it with some nice pump and crank pulleys that i'd like to reuse. i know that the center hole in the crank pulley is larger on a bb, i have no problem boring that out. does anyone know if the sb long water pump pulley will line up with the crank pulley on a bb with either a long or short water pump?
• I don't think any of the pullies swap. I did my 71, SB to BB and had to buy all the pullies new, got them off a later truck deal.
• My experience is based on LWP on a BB...
The pulleys look very much the same but are all just a bit different. And it also depends on what you want to do. You may be able to improvise a basic single belt setup using SB pulleys on a BB (a prior owner had done this on my El Camino). But if you get into more advanced stuff like PS and A/C you will definitely need BB specific pulleys.
The BB water pump has a different bolt circle than the SB and the groove offset is just a bit different between them also. The BB also uses a different diameter on front versus rear pulley grooves for water pump and lower radiator hose clearance.
And of course you have already figured out the difference in the inner hole on the crank pulleys.
Pulleys
• March mounting bracket and I also use the moroso pulley on the alt.
• Installed a moroso 5" alt. pulley with a billet alt fan and solved the problem. New problem..... discharge at low rpms.
• Had similar problems on a 69 camaro. I purchased the march v belt pulleys (crank, alt, P/S). They never came off again.
SB to BB Swap Question/Answers
1. I get the impression that the power-steering pump looks similar, but is actually different -- is that correct? Do I need to buy a new power-steering pump for the BB? And, if so, what about brackets to go with it? Or can I reuse the old one with just different brackets? (Note that the brackets that were on it never fit quite right anyhow -- so re-using the SB brackets, even if it were possible, won't work for us).
• Will advise
2. I believe I can re-use my alternator, but will need a new bracket for it -- is that correct? I believe that my existing one already has a "deep-groove" pulley.
• Yes, the Pulley may have to be swapped
3. We have a Muncie M-21 4-speed that we used with the SB that we are going to continue to use. I'm not sure how to tell if I need anything as far as connecting the engine to the tranny!
• ALL the same except, 11” clutch, and 621 bell housing
4. I put a clutch-fan on the SB a year or so ago. I'm not sure if I need to replace this or not... Unfortunately, I don't remember any specs from it -- so I don't know if it is "good enough" for the BB... Any thoughts on how to tell/know? Or should I just replace it to be sure? Any recommendations on a good clutch fan for the BB?
• Yes, you need a clutch-fan, check the fan/blade diameters in the books
5. Can I re-use the fuel pump from the SB? Or do I need one specific to the 396? I believe that I need a replacement, yes?
• Yes, you need a BB fuel pump
6. What about belts in general (to the alternator, P/S pump, and such)? Can I just get these at any local place like AutoZone, CarQuest, and so on? Or should I be ordering these now from Summit or something?
• As for #6, the 396 that I bought came with a three-grove pulley on it plus the water pump already attached -- so I should be fine there as far as pulleys go, I believe, if my P/S pump pulley works fine as you suggest. I think just the belts will do me there.
7. Do I need to get new front springs? The car was originally a 396 a long time ago -- but I have no idea if the previous owner changed springs when they went to a 327 or not. Nor do I know how "good" the springs still are. Anything I can check really? Should I just try it with the old springs and see how it goes -- swapping in new springs later if I need them?
• Springs aren't that hard to replace, but you must observe serious safety requirements when removing and installing them. It deserves a dedicated thread for discussion if you have never done coils before. There are a few tricks that can make it much easier and safer.
I would suggest leaving them alone until you have observed and driven the vehicle post-swap. You will then be in a better position to make an educated choice and get it right. Doing it before is doing it merely on speculation without evidence to support your conclusion.
8. I shouldn't have to deal with any driveshaft length problems or anything, right? Sticking with the M-21 and going from the 327 to a 396 should mean that I can leave the driveshaft as is, correct?
• Your transmission will remain in the same position. The parting line between block and bellhousing does not relocate in position. The additional length of a rat is taken up from the mounts forward in the BBC installation. Therefore the only consideration for driveshaft issues will be the additional torque you will be requiring it to transfer. I'd be thinking of a balance job and new u-joints, perhaps even a good look at the yokes to determine if they've been "helped" during a previous u-joint replacement attempt. Most of the time amateurs screw this up.
9. What about flywheel issues? The new 396 came with a flywheel on it -- although I don't see any numbers. What do I need to check/know to make sure that this is going to bolt right up to the M-21 that was used with the 327? Will I need anything new as far as interfacing those together?
• The flywheel does not contact the transmission input shaft or any other part of the trans. It is an engine/crankshaft issue. The trans will not care what flywheel you are using. The trans input shaft connects only to the clutch disc, and the tip of it rides in a bearing (or bushing) that is inserted into the rear of the crankshaft. You must be sure that this bearing or bushing is present and in good condition. If not, or if it is worn, your input shaft on the trans will be unsupported and the front bearing will fail, you may break your bearing retainer (the part the throwout bearing rides/slides on), and your shifting will be imprecise. The trans pilots on this, and it is very important.
10. Should I order new bushings/rubber/whatever-it-is for the motor mounts? The existing ones LOOK ok to me -- but I probably wouldn't know anyhow. heh. Any recommendations here?
• My advice is to always replace parts that can deteriorate, parts that are safety issues, and parts that are very difficult to replace later. The mounts fall in all three of these categories.
As with electronics, do not go with "looks" here.
11. As far as radiator hoses and such I assume that is like the belt question above? Maybe get those from AutoZone or some place local that has an SS396 listed in their parts database?
• The only thing I can help you with is the belts. I know Kragen(Checker/Schucks) has the SS396 model in their system so the belts and hoses and such should still be available. Don't recall if AutoZone lists the SS396 but I believe they do.