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Canadian Poncho Homepage -> Canadian Poncho -> 1970 + Canadian Pontiac Power Train Forum -> Finally replaced my cracked manifold
Post Info TOPIC: Finally replaced my cracked manifold
73SC


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Finally replaced my cracked manifold
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I have been dreading this job but the other night 65 Camino came over and we tackled the cracked drivers side exhaust manifold on my LeMans. I had purchased 2 pre-smog manifolds for $10 at a swap meet.

The 73 sbc had an AIR system and I had plugged the manifold ports but it never sealed well.

I never knew how easy this was going to be, We got the down pipe flanges off without raising the car, then the manifolds unbolted  and basically fell off. The drivers side came off in two pieces, it was cracked right through. I never realized how much flow these smog manifolds with AIR ports going right into the heads blocked. Each port has a tube the thickness of a stick pen about 3" long blocking the flow in each exhaust port. I was surprised that there were no gaskets between the manifolds and head.

New studs, new gaskets, cleaned up the repalcement parts and finished bolting it all together earlier today. Does the car ever sound nice now, I didn't realize how much it was leaking from those plugged AIR ports not to mention the huge crack.

The engine runs smooth and feels stronger too. Just took it out to the Applewood Cruise which is a pretty good 30 minute run on the QEW to Mississauga. I was amazed at my new found power. Just goes to prove what a bad exhaust system can rob.

-- Edited by 73SC at 23:42, 2008-06-11

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Ray White, Toronto ON

Formerly - The one and only 1973 LeMans 454 "Astro-Jet"

Built March 9, 1973 - Oshawa ON

1993 Corvette Convertible LT 1

Built January 10, 1993 - Bowling Green Kentucky 

 
4SPEED427


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As far as I know, small block Chevys (Pontiacs!) never used a gasket between the manifold and head from the factory. I think the first application I have ever seen one used is in the Vortec days, or somewhere around there. Same goes for the big blocks.

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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
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73SC


A Poncho Legend!

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It seems to work well without any, I did notice that my Vortec in the GMC has a metal mesh type gasket there. I just cleaned up both surfaces before bolting up. I did change the "donut" gaskets on the down pipes, 2 for $25, made in Mexico! Anyway, I like the results, if weather holds I'll tighten up the bolts tonight after that hour or so on the highway.



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Ray White, Toronto ON

Formerly - The one and only 1973 LeMans 454 "Astro-Jet"

Built March 9, 1973 - Oshawa ON

1993 Corvette Convertible LT 1

Built January 10, 1993 - Bowling Green Kentucky 

 
macsleuth


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Applewood, I used to stop by there on Wednesday nights, I'll look for you next time I'm down there on a Wednesday.
Worked mostly on Chevy. I always remember exhaust gaskets, at least when I put them together, I remember using gaskets.

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65 Catalina 2+2 421 4bbl,  Auto, White, w/red interior, Buckets w/column shift.

66 Grande Parisienne, 2dr HT, 327 4bbl, Auto.

Had the 66 since about 83 and the 65 since 88.
Both still require a lot of work.
73SC


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There was a Mayfair Maize 1965 Custom Sport there last night, 327 car. Also a 73 4 speed Grand Am, we parked opposite each other, an 86 2+2 Grand Prix, and a 67 Firebird 400, that was it for Pontiacs, no Beaumonts or Acadians either. Applewood is a bit of a drive for us in Toronto rush hour so we only go a couple of times a season, always a good turnout there and a mix of current performance models, muscle cars, rat rods and bikes.



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Ray White, Toronto ON

Formerly - The one and only 1973 LeMans 454 "Astro-Jet"

Built March 9, 1973 - Oshawa ON

1993 Corvette Convertible LT 1

Built January 10, 1993 - Bowling Green Kentucky 

 
73SC


A Poncho Legend!

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A couple of photos to show the job and nasty old smog manifolds.

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Ray White, Toronto ON

Formerly - The one and only 1973 LeMans 454 "Astro-Jet"

Built March 9, 1973 - Oshawa ON

1993 Corvette Convertible LT 1

Built January 10, 1993 - Bowling Green Kentucky 

 
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