SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: ArborDude133 on June 29, 2021, 06:59:29 PM
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Just picked up a new boat. 455 Olds 71 tahiti hull. Took out for a shakedown. Had oil coming up the dip stick noticed there's no o ring. Fixed that fairly quickly. Later on boat ran good get hot spots in the center of the intake manifold and smokes slightly. Temps jump at idle to close to 200. running stands solid at 150 to 160. No pressure reg on it. Thinking that will help with temp issues. Any one have any idea why the manifold getting hot spots I'll post pics soon.
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These are the two valleys heating up. I was thinking gasket issue but they are both located in the center of the block which has me thinking.
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Hi there, if I remember correctly, those are for egr valve/choke related parts which come off the exhaust ports. I assume that’s a street manifold?
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Yeah its and edelbrock torker. Previous owner said he did the gaskets. The motor looks fairly freshly painted. Has new oil pan and dip stick hence why the dip spit oil he never put in the o rings. Figured he re painted ran it and sold.
Any suggestions on a better manifold. Never had a Olds motor before not as familiar with them.
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I would figure out my rpm range and buy accordingly. I’m sure there are nice used ones for sale.
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I would figure out my rpm range and buy accordingly. I’m sure there are nice used ones for sale.
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Boat runs good between 3k and 4k haven't pushed it past that. Smooth at about 45mph to 50 at 3500. Give or take. I'd like to build a hotter motor at some point but again. Not much experience with Olds blocks. It's running Hardin headers wet. Holly 750 I believe. And a mild cam. Pervious owner replaced the oil pan and gaskets. Supposedly. I feel the manifold to head gasket has a leak but again just speculation. It does have a small leak at the oil pan so I'm assuming it was thrown together quick. I get a very small amount of oil after a run. Enough to notice. And can't visibly spot the leak.
If you or anyone else has some advice Performance or reliability wise ot would be greatly appreciated.
Looking to build another motor or this one. Don't want to go crazy but I would appreciate the get and go portion of that
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Just picked up a new boat. 455 Olds 71 tahiti hull. Took out for a shakedown. Had oil coming up the dip stick noticed there's no o ring. Fixed that fairly quickly. Later on boat ran good get hot spots in the center of the intake manifold and smokes slightly. Temps jump at idle to close to 200. running stands solid at 150 to 160. No pressure reg on it. Thinking that will help with temp issues. Any one have any idea why the manifold getting hot spots I'll post pics soon.
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Those are exhaust crossover ports. They sell plugs or you can have them filled. Here is a link to a similar thread. I posted a link to an Olds build article that is very informative about building and Olds. They can be great engines, they just need the right kind of love.
http://www.socaljetboats.com/the-no-wake-zone/455-olds-help-cross-over/?PHPSESSID=giu311bnni0urcolauek6k2082
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I have a 455 bored 40 over cam and c heads I put the Edelbrock air gap on there with a Edelbrock 800 avs2 carb so ignition is the Petronix to replace the points and is very reliable. I have no hot spots and my temp never gets above 130 and usually runs around 100 I have it paired with a jacuzzi when that has been converted with the xlertator kit aggressor 8 vane bowl hph droop and a manual diverter
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I have a 455 bored 40 over cam and c heads I put the Edelbrock air gap on there with a Edelbrock 800 avs2 carb so ignition is the Petronix to replace the points and is very reliable. I have no hot spots and my temp never gets above 130 and usually runs around 100 I have it paired with a jacuzzi when that has been converted with the xlertator kit aggressor 8 vane bowl hph droop and a manual diverter
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Thanks for the info. I'm still trying to figure out the route I'm going to go. Will probably pull the motor this weekend. Most likely go through a complete rebuild. I've got Hardin headers now. But I feel like they were rigged to the motor. Original owner has tabs that hold the headers together like they were rigged to fit the heads.
Any idea on a good exhuast header route. I have a through transom setup now with the snail collectors at the ends. Feel like this motor was just slapped together
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These are the hokey poke mounts I had mentioned. I feel like they were made to fit. You can also see the hot spots from The head to the header. I'm assuming there is a bad gap between the two causing the heat build. And the headers were pretty much rigged to fit. I don't know enough about marine headers and the fitment. But I assume that these headers are made for a different application and were modified to fit and the valleys don't nessicarily agree with each other. Am I wrong?
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Those are Hardin Logs and snails. Pretty common original stock power plant applications for all jet boat motor makes. I still have mine on my 79 460 Avenger
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Those are Hardin Logs and snails. Pretty common original stock power plant applications for all jet boat motor makes. I still have mine on my 79 460 Avenger
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Is that bolt configuration universal or unique for those headers. I feel like those tabs were added In to make them fit the application. Previous owner said he replaced the gaskets recently but what worries me is the hot spots and the tabs that I feel were modified to the original bolt pattern on the header.
Is that a common mod or am I one of a kind. Any idea on a good replacement?
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They’re an exhaust manifold not a header and should be water cooled. Mine stay pretty cool compared to the other style manifold/risers I had on my other boat. I’d take them apart and make sure they aren’t all corroded inside and investigate a bit more about the fitment you’re concerned about. I’m sure they were intended to be used on a 455 if they bolt up.
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They’re an exhaust manifold not a header and should be water cooled. Mine stay pretty cool compared to the other style manifold/risers I had on my other boat. I’d take them apart and make sure they aren’t all corroded inside and investigate a bit more about the fitment you’re concerned about. I’m sure they were intended to be used on a 455 if they bolt up.
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Are those tabs normal for those manifolds. I feel like the gap and the tabs are kind of a band aid fix
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They’re an exhaust manifold not a header and should be water cooled. Mine stay pretty cool compared to the other style manifold/risers I had on my other boat. I’d take them apart and make sure they aren’t all corroded inside and investigate a bit more about the fitment you’re concerned about. I’m sure they were intended to be used on a 455 if they bolt up.
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In the third picture you can see where the original milling almost looks twisted upwards and the opposite side is still in line. Also the other passenger side doesn't have the gaps between the bolts that the driver side has
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Are those tabs normal for those manifolds. I feel like the gap and the tabs are kind of a band aid fix
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It is common for the log manifolds to crack there. People cut the flange to keep them from cracking and use the washer for clamping, its a little more "roughly" done then others i have seen. Just run them down to a machine shop and they should be able to true them on the big belt sander for like $20
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These are the two valleys heating up. I was thinking gasket issue but they are both located in the center of the block which has me thinking.
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As mentioned, these are the exhaust crossover designed to heat the carb for cold weather. There are ways to stop that but most people just dont paint the manifold and you would never notice.
Also the torker is a fine manifold for a jet boat especially since you already own it. if you are looking to just spend money, performer is good for the RPMs you are running now, or a performer rpm would be for a hotter motor.
Good luck, let us know what you do
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As mentioned, these are the exhaust crossover designed to heat the carb for cold weather. There are ways to stop that but most people just dont paint the manifold and you would never notice.
Also the torker is a fine manifold for a jet boat especially since you already own it. if you are looking to just spend money, performer is good for the RPMs you are running now, or a performer rpm would be for a hotter motor.
Good luck, let us know what you do
Will do. Thanks for the info. Much appreciated.
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