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1970-72 - 455 intake manifold ( crack )

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Old April 5th, 2023, 12:16 PM
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1970-72 - 455 intake manifold ( crack )

Hi All, Long story short i did some bartering for this intake manifold not for sure what i was even going to do with it, so i sent it in to get boiled out went this morning and was told the news on it, here are a couple of pics, he told me the only way it could be used is to plug off the intake heat riser's, i see they have them on ebay, i know that the choke wont work proper with that closed off, Any suggestions would be most appreciated, Thanks john....




, thanks john...

Last edited by john mann; April 5th, 2023 at 02:20 PM.
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Old April 5th, 2023, 01:09 PM
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I'd find another manifold to use.

I run a blocked cross over on mine. Converted to electric choke so that can be overcome.

It's my opinion, there is no gain to be found in a stock street cruiser and cold weather drivability will be compromised. If you're looking for every HP you can get, sure, block off the cross over.

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Old April 5th, 2023, 02:18 PM
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Hi Don, Thanks for chiming in on this issue, john.....
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Old April 5th, 2023, 07:20 PM
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Does the crack actually go all the way into the heat riser, or just between the two secondary bores? If the latter, I wouldn't worry about it. There won't be any meaningful flow through that crack.
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Old April 5th, 2023, 08:03 PM
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Hi Joe, Hard for me to explain, what you have just told me i say it might be ok, looking at it standing in front of it the crack on the drivers side is all the way down but does not run across the bottom of intake, the pass side is all the way down to and about 1" heading towards the heat riser, Joe i can send better pics tomorrow if you would like, thank you joe !! john...............
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Old April 5th, 2023, 09:51 PM
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Agree with Joe, determine the extent of the crack and go from there.
In any case a 404521 casting is not that rare and you should be able to find one pretty easily. Look to buy locally as shipping costs would be high for this item.
The loss of the crossover can be somewhat compensated by installing an electric choke.

What car were you looking at installing the manifold on?
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Old April 6th, 2023, 05:46 AM
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Hi Al, That's just it, I have a 1970 455 and a 71 455 on stands, I thought i would get the manifold just to have because it would work for either one, iam going to take 2 more real good pics today and post them here, thanks for your input, john..
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Old April 6th, 2023, 06:30 AM
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Even if the crack goes all the way into the exhaust crossover it would be worth taking it to a competent welder to get a quote on repair. It might be cheaper to weld up vs. buying an OE cast iron intake.
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Old April 6th, 2023, 06:31 AM
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Originally Posted by john mann
Hi Al, That's just it, I have a 1970 455 and a 71 455 on stands, I thought i would get the manifold just to have because it would work for either one,
It will work on any BBO, but casting 404521 is correct for 1970 and 407567 for 1971-72.
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Old April 6th, 2023, 09:07 AM
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Hi Joe, Here are those xtra pics, the black is marker outline, The yellow is the crack on both sides, looks like the one side is just in the divider, the other side as you can see comes down and goes flat for about 1" iam thinking more than likely without a repair it s no good, hope this helps john..


Last edited by john mann; April 6th, 2023 at 09:34 AM.
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Old April 6th, 2023, 09:20 AM
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Originally Posted by john mann

Yeah, unfortunately this looks like a crack into the exhaust crossover.
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Old April 6th, 2023, 09:23 AM
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John,
The second pic looks like it is right above the crossover so you guy is probably correct. It could be fixed but by the sounds of what others are saying the manifolds are not that hard to find so I dont know if it would be worth it. If I was going to fix it I would use Loc-n-stitch pins but I dont know if it is thick enough at that point. Welding cast iron in my experience rarely works long term. Besides I dont know about your area but around here any welder worth talking to is not going to even turn on a torch or welding machine for less than $150 I dont think that manifold is rare enough to try and save.
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Old April 6th, 2023, 09:28 AM
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Thanks so much for helping me out on this Joe after i took these last pics and by your reply above i was pretty sure it was over, Also many thanks to everybody else who came to the rescue for my intake issue john.........................................Thank you all !!!!!

Last edited by john mann; April 6th, 2023 at 09:32 AM.
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