riverdogs00 Posted December 23, 2022 Share Posted December 23, 2022 Group, one of my project cars is a 70' SBC/350/10 bolt that is being converted to a mid 70's 454 LS-7 / M23 / 9" / AC delete. I read the various forums, but didn't recall seeing the difference between the SBC/BBC fan shrouds. I always presumed the tunnel was different as well as the shroud, but read otherwise. I ordered a BBC shroud from the parts place, and when I compared it to the SBC shroud I had, I could see the height difference. The SBC shroud is much taller. I removed the staples from the tunnel, found the appropriate drill bit size for the wire I had (5/64"), and mocked it up. I used the existing holes on the tunnel and it went together in about an hour. I should have taken pics of the new shroud before the tunnel install, but didn't think about it. The engine pic is my other car - SS454 and factory shroud for comparison. I should note the SBC shroud was from an AC car, and I understand there are 3 different shrouds for our cars. Hope this is of help to the group 3 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted December 24, 2022 Share Posted December 24, 2022 Yes, small block with hd/ a/c cooling, big block and the standard non-a/c cooling. The first 2 can be identified by the 4 bolt upper radiator plate and the 3rd has a 3 bolt upper radiator plate. All tunnels are the same. The shrouds, that bolt to the upper plate is where the differences are. Just like you noted in your project. 3 Quote Link to comment Share on other sites More sharing options...
Canuck Posted December 30, 2022 Share Posted December 30, 2022 Good info. I have a non-AC small block 1970 Monte with the small shroud that is fairly uncommon. The whole rad support is different for this application also. 1 Quote Link to comment Share on other sites More sharing options...
stangeba Posted December 30, 2022 Share Posted December 30, 2022 I found these pictures a long time ago, if it helps. Quote Link to comment Share on other sites More sharing options...
stangeba Posted December 30, 2022 Share Posted December 30, 2022 I remember turning my ac lid over for fun years ago. Good times! I did have the police turn their lights on behind me, just after I had done a burn out with the lid upside-down but they drove away when I pulled over. Lucky day for me and last time I turned the lid over. 3 Quote Link to comment Share on other sites More sharing options...
sbarnette Posted December 31, 2022 Share Posted December 31, 2022 When I was 16 years old and bought my 71 Monte Carlo, the first thing I did was flip the air cleaner lid. That’s the way it stayed until I put a chrome open element filter on it. I learned this from my dad. The family car was a 72 Buick station wagon with a 455. The AC lid was always flipped on it as well. That one really sounded mean when you opened the secondaries. 1 Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted December 31, 2022 Share Posted December 31, 2022 I changed out my stock air cleaner when I put the 4 barrel on, it was a 14x2 then went to 14x3 now I have the flow through top also and you can really hear the q-jet when the secondaries are kicked in. Although I was trying to avoid it the last couple years because of gas prices. As we all know kicking in secondary is like flushing a toilet 🤣 but it does sound so good. 2 Quote Link to comment Share on other sites More sharing options...
stangeba Posted December 31, 2022 Share Posted December 31, 2022 There is a TV show, Engine Masters, where they run tons of different performance products on different engines on a dyno to verify H.P changes. I think it would be cool to see the actual HP gain running all these different air cleaners. Yes, the lid upside-down would be cool also! Quote Link to comment Share on other sites More sharing options...
jft69z Posted December 31, 2022 Share Posted December 31, 2022 1 hour ago, stangeba said: There is a TV show, Engine Masters, where they run tons of different performance products on different engines on a dyno to verify H.P changes. I think it would be cool to see the actual HP gain running all these different air cleaners. Yes, the lid upside-down would be cool also! They did do one on air cleaners, but good luck trying to find it. Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted December 31, 2022 Share Posted December 31, 2022 2 hours ago, stangeba said: There is a TV show, Engine Masters, where they run tons of different performance products on different engines on a dyno to verify H.P changes. I think it would be cool to see the actual HP gain running all these different air cleaners. Yes, the lid upside-down would be cool also! I found it on YouTube but not sure how to put it on here but you can look it up. They tried 5 different air filters and each one made it better the best is the flow through top but I guess we could probably assume that. Quote Link to comment Share on other sites More sharing options...
stangeba Posted December 31, 2022 Share Posted December 31, 2022 https://www.facebook.com/watch/?v=153247265330893 Try this link 1 Quote Link to comment Share on other sites More sharing options...
stangeba Posted December 31, 2022 Share Posted December 31, 2022 Results: Quote Link to comment Share on other sites More sharing options...
riverdogs00 Posted December 31, 2022 Author Share Posted December 31, 2022 On 12/30/2022 at 8:35 AM, stangeba said: I found these pictures a long time ago, if it helps. much better info than what I had - never saw this post before. Quote Link to comment Share on other sites More sharing options...
riverdogs00 Posted December 31, 2022 Author Share Posted December 31, 2022 2 hours ago, stangeba said: Results: I follow Engine masters, roadkill and roadkill garage on the motortrend app. I'm in the middle if scheduling my LS-7 for a visit to Westech to help dial in my tunnel ram, and see what this motor ACTUALLY will make. Quote Link to comment Share on other sites More sharing options...
Steve G Posted January 6, 2023 Share Posted January 6, 2023 So what’s the harm in just running a small block shroud? You got me worried. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted January 6, 2023 Share Posted January 6, 2023 If you have a big block and install the small block shroud, you may have to cut the shroud for alternator clearance, the fan will be too deep inside to cool properly and may also need to be clearances for the lower crank pulley. This is what I have been told. I've always done the conversions correctly and have not run into those issues. 1 Quote Link to comment Share on other sites More sharing options...
Steve G Posted January 7, 2023 Share Posted January 7, 2023 5 minutes ago, MC1of80 said: If you have a big block and install the small block shroud, you may have to cut the shroud for alternator clearance, the fan will be too deep inside to cool properly and may also need to be clearances for the lower crank pulley. This is what I have been told. I've always done the conversions correctly and have not run into those issues. Hmmm.... I will send ya a pic this weekend. Quote Link to comment Share on other sites More sharing options...
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