car poor Posted July 26, 2011 Share Posted July 26, 2011 I doubt anyone reproduces them, or am I wrong? If possible, would like to see clear pictures of an original. Even better if anyone has comparison pictures of a BBC shroud vs. a SBC shroud - that would be great. Lastly, saw it mentioned a few times... it was said a SBC shroud could be modified. Wish there was a write up of some sort on that modification. Thanks in advance. Link to comment Share on other sites More sharing options...
Andreas Posted July 26, 2011 Share Posted July 26, 2011 Small Block Big Block (a bit shorter) Link to comment Share on other sites More sharing options...
ScottNM Posted July 26, 2011 Share Posted July 26, 2011 I bought a fan shroud from parts place for BB and it is shorter than my sb unit. If I mount the shroud tube from my small block to it, I should pull away from the fan at least 2-3 inches. Hopefully my 454 will work with it. Link to comment Share on other sites More sharing options...
70mcarlo Posted July 26, 2011 Share Posted July 26, 2011 The shroud "tunnel" (or "tube") is the same for both the small and big-block. Just carefully remove the staples (so you can reuse them) and remove the tunnel from your old SBC shroud base, insert into the new BB shroud base, drill new holes in the BB shroud using the holes in the the tunnel as a guide, and insert the staples and bend them back down. Note - be sure to orient the tunnel the same way it was positioned in the old SBC shroud base. Link to comment Share on other sites More sharing options...
car poor Posted July 26, 2011 Author Share Posted July 26, 2011 Where did you buy it from Scott? Link to comment Share on other sites More sharing options...
montefrazer Posted July 27, 2011 Share Posted July 27, 2011 This is the same piece as a big block Chevelle and should be available from any Chevelle parts dealer.Just reuse the tunnel as said. Link to comment Share on other sites More sharing options...
car poor Posted July 27, 2011 Author Share Posted July 27, 2011 Ok, so if I understand this correctly... the "tunnel" is the piece closest to the engine? And it attaches to a standard Chevelle/Malibu fan shroud? I've never really paid much attention to the fan shroud to be honest. Link to comment Share on other sites More sharing options...
70mcarlo Posted July 27, 2011 Share Posted July 27, 2011 Ok, so if I understand this correctly... the "tunnel" is the piece closest to the engine? And it attaches to a standard Chevelle/Malibu fan shroud? I've never really paid much attention to the fan shroud to be honest. Yes - the "tunnel" section is the round cylinder-like section of the shroud that ends at the engine fan. Link to comment Share on other sites More sharing options...
LS5 Posted July 27, 2011 Share Posted July 27, 2011 Ok, so if I understand this correctly... the "tunnel" is the piece closest to the engine? And it attaches to a standard Chevelle/Malibu fan shroud? I've never really paid much attention to the fan shroud to be honest. Ok so now I am scratching my head big time as my Big Block fan shroud in the chevelle that is a factory LS-5 454 looks nothing like a small block or big block Monte fan shroud.. Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted July 27, 2011 Share Posted July 27, 2011 One of our members shortened his Small Block tunnel by cutting a width of it from the fan blade end and worked perfectly for him when he converted to a Big Block. Can't offer you how much of it was removed but knowing where the fan blade should just enter the tunnel should give you an idea of how much needs to be removed should you elect to do so. I can't even say what was used to remove section to keep it even & straight on the cut. If your not concerned about it being exactly factory look, could be a way to go. If I can find the time, I have both a BB & SB shroud that I will get pic's of and post them here for you. Give me a couple three days and think I can supply photo's. Just an idea.... Doug Link to comment Share on other sites More sharing options...
70mcarlo Posted July 27, 2011 Share Posted July 27, 2011 Just to clarify terminology here, the "tunnel" or "tube" is called a shroud "extension" in the factory assembly manual. For the Monte Carlo, the radiator shroud consists of three pieces: the shroud itself (or base) which is the rectangular section attached just behind the radiator, and the upper and lower shroud extensions, which when stapled together form a round cylinder-like extension (eight inches). This extension became necessary in the Monte Carlo because of the engine setback. Link to comment Share on other sites More sharing options...
car poor Posted July 27, 2011 Author Share Posted July 27, 2011 Ok, makes more sense now. See? We do learn something new every day. Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted July 27, 2011 Share Posted July 27, 2011 Took time to supply pic's with some basic dimension differences between BB & SB Fan Shrouds. Essentially the length of each make up the bulk as we all know. Both tunnels are very close in length with the shroud portion creating the disparity in overall length. The pic's just show where those differences are and as I was curious, thought it could be useful for future referense. Measurements are approximate as a simple tape measure was used but do highlite those visual differences. Doug 1 Link to comment Share on other sites More sharing options...
70mcarlo Posted July 27, 2011 Share Posted July 27, 2011 Great photo comparison, Doug! The very slight difference in extension ("tunnel") diameters is probably due to the way the two sections (upper & lower) were stapled together on each car. Otherwise, they are the same part. The only difference between SB and BB is the width of the rectangular shroud "base." Your photos do a great job of showing the different widths - thanks for posting them! Link to comment Share on other sites More sharing options...
Monte7071 Posted July 28, 2011 Share Posted July 28, 2011 Thank you for taking the time to take referense pics. We should have an area showing the changes between BB and SB and a/c not a/c cars and any other differences. Link to comment Share on other sites More sharing options...
car poor Posted July 28, 2011 Author Share Posted July 28, 2011 Thanks Doug! That helps immensely. I agree with the others, a sticky highlighting the differences between SBC & BBC cars would be useful. Link to comment Share on other sites More sharing options...
Mikstudie Posted July 28, 2011 Share Posted July 28, 2011 Took time to supply pic's with some basic dimension differences between BB & SB Fan Shrouds. Essentially the length of each make up the bulk as we all know. Both tunnels are very close in length with the shroud portion creating the disparity in overall length. The pic's just show where those differences are and as I was curious, thought it could be useful for future referense. Measurements are approximate as a simple tape measure was used but do highlite those visual differences. Doug Great shots Doug... Link to comment Share on other sites More sharing options...
montefrazer Posted July 29, 2011 Share Posted July 29, 2011 Originally Posted By: car poor Ok, so if I understand this correctly... the "tunnel" is the piece closest to the engine? And it attaches to a standard Chevelle/Malibu fan shroud? I've never really paid much attention to the fan shroud to be honest. Ok so now I am scratching my head big time as my Big Block fan shroud in the chevelle that is a factory LS-5 454 looks nothing like a small block or big block Monte fan shroud.. Picture it with a Monte tunnel stuck into the engine side and stapled in place. Link to comment Share on other sites More sharing options...
dimitri Posted December 2, 2011 Share Posted December 2, 2011 my question is could you modify a small block shroud for a 454 or will it not perform correct Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted December 2, 2011 Share Posted December 2, 2011 I know a guy who had the SB Shroud tunnel shortened in his 72 Monte to have it fit his BB engine conversion. He simply trimmed the excess material from the engine end of the tunnel for the depth he needed. No other mods made! Works just great for him. Doug Link to comment Share on other sites More sharing options...
dimitri Posted December 3, 2011 Share Posted December 3, 2011 i just took a look at my shroud and am wondering if i should buy a new big block shroud or will this work by modifying it the bottom is cut already for what reason i have no clue Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted December 3, 2011 Share Posted December 3, 2011 Dimitri, The overall length of the SM Shroud is approximately 12 1/2". The overall length of the BB Fan Shroud is approximately 10 1/2". This would suggest that removing approximately 2" from the SB Fan Shroud tunnel section would provide you with the required spacing for the BB engine requirement you desire. Why yours has been notched per your pic I have no idea. If that notch removal is 2" in depth, then using that notched out area as a witness, removing the remainder of the material would give you the desired BB Fan Shroud dimensions you are after. If that notched out areas depth is significantly beyond 2", then may be wise to seek a original BB replacement. The difference between the 2 Fan Shrouds has someting to do with the performance the air flowing into the tunnel to aid cooling of the radiator. I don't know the actual dynamics but will affect the cooling performance of the radiator if the Fan Shroud sits to deep into or to far from the Fan Blade. As the BB engine sits closer to the radiator, the Fan Shroud needs to be shorter vs. the SB engine that sits further away from the radiator that requires a longer fan Shroud. Basically, if your Fan Shroud is original to the vehicle and is a SB Shroud, removing 2" material from it would provide you with the desired result acting as a BB Fan Shroud. No additional mods would be neccessary. Doug Link to comment Share on other sites More sharing options...
dimitri Posted December 3, 2011 Share Posted December 3, 2011 72-CLASSIC_RIDE i believe the notched out area is close to 3 and a half inchs now i might have a different distance as i replaced the fan blade . my next question is if i put a electric fan would i need a tunnel shroud at all Link to comment Share on other sites More sharing options...
Leghome Posted December 3, 2011 Share Posted December 3, 2011 No shroud needed with electric fans but you have a very large gap tween the radiator and water pump. I have seen a couple Monte's with electric fans and one guy had a stainless steel shroud made to take up half the space. It looked very nice and he had the stainless polished. Link to comment Share on other sites More sharing options...
monte70car Posted December 3, 2011 Share Posted December 3, 2011 a few years back I ran my monte without the shroud as I have dual elec. fans. This year we did alot of work most of it was body as it got a custom hood made for it, also did a fuel injection set that looks like a carb and I figured why not go for a stock look so the small block shroud went back in which was to long. I brought a big block chevelle shroud that mounts to the radiator support notched it around my elec. fans and put the tunnel back on and it looks good. 1 Link to comment Share on other sites More sharing options...
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