Dart 408 Build Progress thread...

TweekedGT · Mar 28, 2008

Well I've been amassing most of the parts for the Dart 408 for the past few months. Started the build yesterday. Started checking the block over and chamfering the cylinder bores for the stroker so it won't chew up the pistons. Set the main bearings in ..... and what the hell, bearings don't fit. I had ordered a forged rotating assembly with Eagle 4340 forged crank, Eagle forged rods, SRP pistons (.030) over. They sent me Windsor main bearings with it. A Dart 351 Block is a bastard, it's a Clevor basically. It uses Cleveland bottom end components and Windsor top end components. So order new Cleveland main bearings. They got here today so i test fit them and they fit perfect. We plastigauged them and everything looks good, .002 clearance. Can't wait to get to actually buttoning up the bottom end for real not just test fitting. I have to work tomorrow so me and my buddy will start the actual assembly Sunday. Can't wait. I'll keep the updates coming, with pics hopefully. I want to document every part of this build.

fastford91 · Mar 28, 2008

sounds good! should sound really good once done! ya pics !!! lots and lots of pics!

87foxstang · Mar 28, 2008

sick dude
definitely get some pictures up. Now I cant wait to start my 408, now all I need is the block

Rick 91GT · Mar 28, 2008

Actually you can get the 351 with the 2.749" or the 3.00" main, have the align hone checked, plasti guage is not the most accurate and I would want a little more then .002" on those mains.

TweekedGT · Mar 29, 2008

87foxstang said:
sick dude
definitely get some pictures up. Now I cant wait to start my 408, now all I need is the block

Get going on it already would ya!!!! You won't be disappointed. The numbers i've seen be put up by 351 based small block motors is amazing. Check this out.

http://sangharacing.com/

TweekedGT · Mar 29, 2008

Rick 91GT said:
Actually you can get the 351 with the 2.749" or the 3.00" main, have the align hone checked, plasti guage is not the most accurate and I would want a little more then .002" on those mains.

I've never seen a Dart 351 block without Cleveland mains. I'm happy with .002. I would only go as high as .003.

Bullitt347 · Mar 29, 2008

Is that .002 measurement Canadian, or US? Actually .002 is fine for a street car. A drag only engine might go a bit looser, but then with a drag only engine you rebuild every 100 to 200 miles (1/4 mile at a time) while the street engine has to last just a little bit longer.

Rick 91GT · Mar 30, 2008

Right now I believe DART is only offering the Clev main, although the older castings were both. You'll like the Clev mains, it will help keep the bearing speed down and solve some on the issues associated with a 3" main. Since it's a DART as long as you set it up for prioirty oiling the mains will be fed nicely, .002" is just a little low for what I like to set them up, even on a street car...will it be fine? Yes. The reason I mention the clearance is I have NEVER had a DART block in my shop that was not tight on the mains, they are always on the low end of O.D, and I have to align hone them. I check everything with a dial bore however and mic's, not plasti gauge. Just have your local machine shop check it to verify your clearances... You'll find you'll need to deck the block as well, the surface finish is just no where close to having a good sealing surface, plus if it was me you'll want it "0" deck.

Here's a couple things to look out for on the DART... The threaded plug that will go into the front of the oil galley right behind where the dist gear sits, make sure you use a shallow 1/4" plug, they are actually NPS threads and if the plugs sits out it will not clear the dist gear. With a 4.00" stroke and a 6.00 or 6.25" rod you may not even have to clearance the bores for the rod bolts, although it is always best to check. Just don't be surprised if you don't have to.

Although this is standard block prep make sure you deburr the edges of core plug holes aka "Freeze plugs" really well, along with the rear cam plug and the ouside surface edge of the rear cap where the 1 pc seal will go if using a 1 piece seal crank. They are sharp and always a little tight, if you do not chamfer or deburr it will shave the edge of the seal and plugs upon final assembly. Check the rear cap for rough metal above ther journal in the oval holes, there is usually slag there as well. The rear cam plug if your installing is a reverse taper plug, so the hollow side goes in first (this is the reverse of a standard Windsor motor), they can be fun, if your installing it I suggest getting 2 just in case.

If it is the IE block, radius the edges (the edges facing the rear of the block) of the 5th main cap to prevent pan clearance issues, and on most 1 pc gaskets you'll have to notch the gasket to fit around the 4 bolt cap.

If you run into anything specfic and need help let me know...

TweekedGT · Mar 30, 2008

Rick 91GT said:
Right now I believe DART is only offering the Clev main, although the older castings were both. You'll like the Clev mains, it will help keep the bearing speed down and solve some on the issues associated with a 3" main. Since it's a DART as long as you set it up for prioirty oiling the mains will be fed nicely, .002" is just a little low for what I like to set them up, even on a street car...will it be fine? Yes. The reason I mention the clearance is I have NEVER had a DART block in my shop that was not tight on the mains, they are always on the low end of O.D, and I have to align hone them. I check everything with a dial bore however and mic's, not plasti gauge. Just have your local machine shop check it to verify your clearances... You'll find you'll need to deck the block as well, the surface finish is just no where close to having a good sealing surface, plus if it was me you'll want it "0" deck.

Here's a couple things to look out for on the DART... The threaded plug that will go into the front of the oil galley right behind where the dist gear sits, make sure you use a shallow 1/4" plug, they are actually NPS threads and if the plugs sits out it will not clear the dist gear. With a 4.00" stroke and a 6.00 or 6.25" rod you may not even have to clearance the bores for the rod bolts, although it is always best to check. Just don't be surprised if you don't have to.

Although this is standard block prep make sure you deburr the edges of core plug holes aka "Freeze plugs" really well, along with the rear cam plug and the ouside surface edge of the rear cap where the 1 pc seal will go if using a 1 piece seal crank. They are sharp and always a little tight, if you do not chamfer or deburr it will shave the edge of the seal and plugs upon final assembly. Check the rear cap for rough metal above ther journal in the oval holes, there is usually slag there as well. The rear cam plug if your installing is a reverse taper plug, so the hollow side goes in first (this is the reverse of a standard Windsor motor), they can be fun, if your installing it I suggest getting 2 just in case.

If it is the IE block, radius the edges (the edges facing the rear of the block) of the 5th main cap to prevent pan clearance issues, and on most 1 pc gaskets you'll have to notch the gasket to fit around the 4 bolt cap.

If you run into anything specfic and need help let me know...

Thanks man, I appreciate it. The block is actually a DSS level 10 Dart Block, it is already clearance for a 408, the only thing it didn't have done to it was the cylinder chamfering, it comes with all the screw in freeze plugs and oil gally plugs. I am using a dial bore gauge and a 4-5" micrometer to check everything. The only thing I am unsure of is main bolt torque specs. Any suggestions? I'm running a blower or turbo after so I am looking to set the ring gap at about .024- .028. Sound about right?

Rick 91GT · Mar 30, 2008

TweekedGT said:
Thanks man, I appreciate it. The block is actually a DSS level 10 Dart Block, it is already clearance for a 408, the only thing it didn't have done to it was the cylinder chamfering, it comes with all the screw in freeze plugs and oil gally plugs. I am using a dial bore gauge and a 4-5" micrometer to check everything. The only thing I am unsure of is main bolt torque specs. Any suggestions? I'm running a blower or turbo after so I am looking to set the ring gap at about .024- .028. Sound about right?

Stock DART main bolts? DSS should have provided the tq they used when align honing, but I can give you the DART recommendation.

With a 4.03" bore I'd run .024"-.026" top (depending on how much boost you will run, and what material the top rin is made from), and I'd run .004" larger on the second ring.

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