Project 6-71 340 Demon

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Coyote Jack

Coyote Jack

Member #55, I'm old
FABO Gold Member
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Baxters Corner N.B. Canad
I have officially started building my 340 blower engine. The plan is to build a 340 up to withstand about 8 lbs coming from a 6-71 roots blower. Hopefully I will end up with 650 to 700 HP and 600 ft/lbs of TQ.
I got the block and heads back from the machine shop, (Thanks Rinaldi's), back in November and had it sitting in my garage waiting for me to finish hunting for this year.

I expect this will be a slow process as you have to pick your days to warm up the garage during the winter up here.

I finally got to it today. I used degreaser to get the layer of WD40 off of it, then washed it down and dried it with compressed air. After that I sprayed it with carb cleaner and taped it up.

The first pic is when I started. I then got 2 coats of high heat primer on it. The last pic is after I sprayed it with 3 coats of gloss black high heat enamel.

Jack
 

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i m gonna have to follow this one.. i m gonna be building something similar for my demon. looks good so far
 
Thanks Mad Dart,

I'm still trying to find a blower on the cheap. I'm beginning to think there is no such thing. LOL

Jack
 
Coyote Jack said:
I sure hope so. It has been kind of painful trying to get all the stuff needed on the cheap. LOL

Next on the list is installing the crank, rods and pistons over the Christmas holidays.

Jack
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Coyote Jack said:
Thanks Mad Dart,

I'm still trying to find a blower on the cheap. I'm beginning to think there is no such thing. LOL

Jack
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Sorry to say, but there is no such thing.

And 8 pounds of boost out of a 671 on a 340 is a lot, you definitely need a good girdle or 4 bolt main caps installed. You also need to make sure that your final compression isn't too high with that much boost.
 
Blownfish said:
Sorry to say, but there is no such thing.

And 8 pounds of boost out of a 671 on a 340 is a lot, you definitely need a good girdle or 4 bolt main caps installed. You also need to make sure that your final compression isn't too high with that much boost.
Click to expand...

I agree that I am going to have to keep an eye on the boost level. 8 lbs is borderline according to the BDS charts. I may have to keep it down to 6 or 7 lbs.
You are the first to say I might need a girdle. For the most part the info I am getting is go with ARP bolts and I should be fine.

Jack
 
Blownfish said:
Sorry to say, but there is no such thing.

And 8 pounds of boost out of a 671 on a 340 is a lot, you definitely need a good girdle or 4 bolt main caps installed. You also need to make sure that your final compression isn't too high with that much boost.
Click to expand...

I disagree. That block will take 8PSI Easily without any 4 Bolt caps. If the 4bolt caps are Aftermarket it will actually weaken the block in those areas when you drill for them. A Girdle is also a Myth though it may make you feel better, it does almost nothing on a SBM. Most of the big engine builders "YES even the ones on this site" do not drill their blocks for 4 bolt mains or use a girdle on their radical small block builds.

I know of a guy that built a SBM with over 20psi, stock block & Crank that wound it up to over 7K and made over 900HP at the wheels. It lived no problem for a very long time. It is all in the tune.

Use studs on the mains. Studs on the heads with Cometic gaskets and you will be good to go. If you get worried about Detonation throw a Meth Injection kit on it. That blower would probably love some cool mist sprayed through it!:D
 
I've never used studs in an engine before. One of the things I heard is if you go to studs you have to get the mains align bored to match them. It didn't make sense to me as the bolts or studs don't actually touch the caps on the sides only on the vertical. Hope that makes sense.

Jack
 
Coyote Jack said:
I've never used studs in an engine before. One of the things I heard is if you go to studs you have to get the mains align bored to match them. It didn't make sense to me as the bolts or studs don't actually touch the caps on the sides only on the vertical. Hope that makes sense.

Jack
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Yes that is true when using studs. You will be fine with the bolts. Carry on and get that engine together!! haaa:D
 
"I know of a guy that built a SBM with over 20psi, stock block & Crank that wound it up to over 7K and made over 900HP at the wheels. It lived no problem for a very long time. It is all in the tune."

What failed?
 
dilley340 said:
"I know of a guy that built a SBM with over 20psi, stock block & Crank that wound it up to over 7K and made over 900HP at the wheels. It lived no problem for a very long time. It is all in the tune."

What failed?
Click to expand...

Nothing ever did fail. When the engine was torn apart. The crank was bent. This engine seen at least 300 1/4 mile runs and a bunch of street miles which is a heck of alot more than most get out of an engine.
 
Coyote Jack said:
I've never used studs in an engine before. One of the things I heard is if you go to studs you have to get the mains align bored to match them. It didn't make sense to me as the bolts or studs don't actually touch the caps on the sides only on the vertical. Hope that makes sense.
Click to expand...

Install the studs, main caps with nuts, all to the individual correct torque values, then alignbore. This will correct any slight distortion caused by the installed studs. Same reason you align bore after installing main caps with bolts and finish bore and hone cylinders with torque plates installed.
Always better safe now than sorry later.
 
Well, it was already align bored with bolts, so it's staying that way. The cylinders were bored and honed with torque plates as well. It's not going back to the machine shop unless there is a major screwup on my part.

Jack
 
i will be watching this build jack i cant wait to go for a ride in july .
 
Mad Dart said:
I disagree. That block will take 8PSI Easily without any 4 Bolt caps. If the 4bolt caps are Aftermarket it will actually weaken the block in those areas when you drill for them. A Girdle is also a Myth though it may make you feel better, it does almost nothing on a SBM. Most of the big engine builders "YES even the ones on this site" do not drill their blocks for 4 bolt mains or use a girdle on their radical small block builds.

I know of a guy that built a SBM with over 20psi, stock block & Crank that wound it up to over 7K and made over 900HP at the wheels. It lived no problem for a very long time. It is all in the tune.

Use studs on the mains. Studs on the heads with Cometic gaskets and you will be good to go. If you get worried about Detonation throw a Meth Injection kit on it. That blower would probably love some cool mist sprayed through it!:D
Click to expand...

The boost isn't the problem, it's the 600 ft pounds of torque and the stress from the blower that will cause the mains to fail. You talk to anyone that has built a blower motor, and they'll almost all say the same thing, a girtle is a must with a small block with that much torque.

Coyote Jack said:
I've never used studs in an engine before. One of the things I heard is if you go to studs you have to get the mains align bored to match them. It didn't make sense to me as the bolts or studs don't actually touch the caps on the sides only on the vertical. Hope that makes sense.

Jack
Click to expand...

Unfortunately, you shouldn't of had it line bored, or any machine work done till you had everything needed for the build. Studs and a girdle is something that I wouldn't leave out if you want the engine to last, and if the girdle is installed correctly, you'll need to have the top of the caps machined to match so you can pre load them when the girdle and main caps are torqued down.

There is a lot more to a blower motor than people realize, you'll find yourself redoing some things as you go.

One other thing you'll have issues with is cooling, an Edlebrock water pump and a set of aluminum heads will be the best money you can spend.
 
Blownfish said:
The boost isn't the problem, it's the 600 ft pounds of torque and the stress from the blower that will cause the mains to fail. You talk to anyone that has built a blower motor, and they'll almost all say the same thing, a girtle is a must with a small block with that much torque.



Unfortunately, you shouldn't of had it line bored, or any machine work done till you had everything needed for the build. Studs and a girdle is something that I wouldn't leave out if you want the engine to last, and if the girdle is installed correctly, you'll need to have the top of the caps machined to match so you can pre load them when the girdle and main caps are torqued down.

There is a lot more to a blower motor than people realize, you'll find yourself redoing some things as you go.

One other thing you'll have issues with is cooling, an Edlebrock water pump and a set of aluminum heads will be the best money you can spend.
Click to expand...

i have studs and girdle in mine , the frist time i didnt and i had to much compression 9.1 now i have 6.5 j.e pistons i run around 7 to 9 lbs of boost and shes been together for16 years now it needs a freshing up but i still drive it about 500 miles a year still its a cool ride with a 4 speed spend the money take your time dont have to redo it
 

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jimjimjimmy said:
i will be watching this build jack i cant wait to go for a ride in july .
Click to expand...

I hope I have for this coming July Aaron. I will be getting a blower one way or another shortly after Christmas. Once I have it I believe I will be spending a fair amount of time out in the garage.

Jack
 
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