small block build for me!
08-28-2008, 10:11 PM
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small block build for me! well, im a 3800 V6 guy moving to the big boy's feild. i want to build a small block. i've always loved third generation camaros, and when a friend of mine got a white one, i decided i had to have a black one. he's built around a 326ci engine. 400 block with an old school 302 crank. im going the opposite direction. i've got a few parts chosen, but am looking for help and options for others. i know, you some of these things (like the only things i've got picked out) shouldnt be chosen before you choose heads, but i was bored, and found about what i think i want. anyway, here we go
400 block. i dont have it yet, but i'll get one. shooting for an old school 2 peice rear seal block, as i've found more cranks for this motor.
a lunati Voodoo Mechanical Roller Camshaft
Lift: .566''/.578''
Adv. Duration: 267°/273°
Duration @ .050'': 237°/243°
RPM Range: 2500-6800
speedpro powerforged pistons
flat top with valve reliefs
will give an 11.6:1 cr with 64cc heads... i know, that's race gasish compression area.
so i have a few questions. first, i dont have $1500 to spend on heads. im looking for a cheapish, iron head that will allow me mid .500's in lift and have cose to, possibly a little larger (but not 76cc large) combustion chamber. im already planning on the shop doing the work to the block to do P&P work on the heads. but if i could get a casting number or year or something to start out with, that'd be awesome. also, can SBC valve guides be milled to give more clearance for lift?
second, how important is a forged crank in this application. im only looking to get around 500 hp when all is said and done (not neccesarily with these heads) is a cast crank ok for that? i know forged is preferred, understandably, but it's also over twice as much. 3800 cranks arent forged, and they can put down 700 whp.
i think that's about it for now. remember, before you start ripping into me, im a noob to this V8 stuff. so go easy on me.
400 block. i dont have it yet, but i'll get one. shooting for an old school 2 peice rear seal block, as i've found more cranks for this motor.
a lunati Voodoo Mechanical Roller Camshaft
Lift: .566''/.578''
Adv. Duration: 267°/273°
Duration @ .050'': 237°/243°
RPM Range: 2500-6800
speedpro powerforged pistons
flat top with valve reliefs
will give an 11.6:1 cr with 64cc heads... i know, that's race gasish compression area.
so i have a few questions. first, i dont have $1500 to spend on heads. im looking for a cheapish, iron head that will allow me mid .500's in lift and have cose to, possibly a little larger (but not 76cc large) combustion chamber. im already planning on the shop doing the work to the block to do P&P work on the heads. but if i could get a casting number or year or something to start out with, that'd be awesome. also, can SBC valve guides be milled to give more clearance for lift?
second, how important is a forged crank in this application. im only looking to get around 500 hp when all is said and done (not neccesarily with these heads) is a cast crank ok for that? i know forged is preferred, understandably, but it's also over twice as much. 3800 cranks arent forged, and they can put down 700 whp.
i think that's about it for now. remember, before you start ripping into me, im a noob to this V8 stuff. so go easy on me.
08-28-2008, 10:18 PM
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get a set of aftermarket iron heads to begin with. you can find them cheap and they are better than stock heads. personally, i'ld go with a 350 block and then stroke that. if you get a cast crank, then atleast buy a scat 9000 or equivilent.
08-29-2008, 01:34 PM
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they hold up better than stock gm 400s though. if i went 400 route i would buy a dart world prod. block, unless i just had one laying around that was ready to go.
08-29-2008, 02:27 PM
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Ok, there are a few things I see here that might be an issue. If you use a 400block (they're all 2 piece seals) you have two things to watch for. First, the main journals are larger than the journals on the crank you plan to use (302) unless you buy a custom crank, so you'll have to use bearing spacers to compensate for the difference. Second, the 400 has siamesed cylinders and you'll have to drill steam holes in whichever heads you decide to use or have the manufacturer or machine shop do it. Without the holes you'll have cooling problems.
I don't see a problem using a mechanical roller cam, but you'll have to have some pretty decent spring pressure to run it, so make sure whichever head you choose is set up properly or you'll float a valve. As far as your 11.6:1 compression, I don't see it being that high with flat tops. If I'm understanding your post, it seems to me that you're planning on de-stroking the 400 which will lower the compression ratio as compared to the catalog listings. Also, if you destroke you'll have to order a custom piston to change the compression height or use a longer rod to bring the piston to the top of the bore.
Now we get to the heads. I would try to go with a nice set of aftermarket aluminum heads. There are a bunch out ther that'll fall into your price range. Patriot Performance just came out with a nice aluminum SBC head for under $800 a pair. I'd maybe look into those or something similar. If you plan on driving the car it'll give you a little more detonation resistance on pump gas. As far as you crank goes, if you're going to be turning 6800 RPM, I'm not sure I'd be too comfortable with a cast crank. It's not necessarily horsepower that breaks parts, it's RPM and that's pushing it in my opinion. Hope this helps!
I don't see a problem using a mechanical roller cam, but you'll have to have some pretty decent spring pressure to run it, so make sure whichever head you choose is set up properly or you'll float a valve. As far as your 11.6:1 compression, I don't see it being that high with flat tops. If I'm understanding your post, it seems to me that you're planning on de-stroking the 400 which will lower the compression ratio as compared to the catalog listings. Also, if you destroke you'll have to order a custom piston to change the compression height or use a longer rod to bring the piston to the top of the bore.
Now we get to the heads. I would try to go with a nice set of aftermarket aluminum heads. There are a bunch out ther that'll fall into your price range. Patriot Performance just came out with a nice aluminum SBC head for under $800 a pair. I'd maybe look into those or something similar. If you plan on driving the car it'll give you a little more detonation resistance on pump gas. As far as you crank goes, if you're going to be turning 6800 RPM, I'm not sure I'd be too comfortable with a cast crank. It's not necessarily horsepower that breaks parts, it's RPM and that's pushing it in my opinion. Hope this helps!
08-29-2008, 03:03 PM
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it would, except i AM building a 400, crank and all ;-) it's my friend that built the 326, i was just using him as a reason why i wanna build somethin unique and not just another 383. if i could score some patriots for $800, that'd be nice. i was thinking 130# springs should be able to hold through upper 6000 rpm range with mid .500 lift with no float. what's not as strong in the 400's? the cylinder walls since it's a siamese boar?
08-29-2008, 09:34 PM
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Any thirdgen project is awesome...happy to see you starting one! Vortec heads are the only stock ones I'd do these days...Modified sets from SDPC2000.com can be bought as a combo with all the top end parts...good for big lift, etc...
Deals are out there if you look around...building is cool but so is cashing in on someone's great stuff being sold. A local guy here has a(brand new I believe) 355 for sale that I wish my friend would buy. check it out. it's built by URE Racing here in Michigan... http://www.yellowbullet.com/forum/sh...s+355+for+sale
He's been dropping the price like crazy and If I didn't have a back up engine, this would be my new backup!! Easily a 500-525hp pump gas engine with a decent parts list. I'd assume it's 7-8K worth of engine and I bet he'd take 4K for it...cash talks these days.. Goodluck!
Deals are out there if you look around...building is cool but so is cashing in on someone's great stuff being sold. A local guy here has a(brand new I believe) 355 for sale that I wish my friend would buy. check it out. it's built by URE Racing here in Michigan... http://www.yellowbullet.com/forum/sh...s+355+for+sale
He's been dropping the price like crazy and If I didn't have a back up engine, this would be my new backup!! Easily a 500-525hp pump gas engine with a decent parts list. I'd assume it's 7-8K worth of engine and I bet he'd take 4K for it...cash talks these days.. Goodluck!
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09-12-2008, 06:57 PM
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Check out the street/strip heads Summit sells, they're Brodix 1k200's with a Summit logo milled into the end. They're good heads. A little thin for porting, but as-cast they're still very good- you won't get a high quality thick-walled head in your price range anyway. You'll have to get them drilled for steam holes.
There's nothing wrong with building the 400. I've had 400's in street rods since the mid-80's, and I love them. These days, go with a Scat 9000 series steel cast crank, as Vizard says nobody seems to find the limit of what these can handle- 600+hp is no problem. The 6" capscrew rods with 7/16" capscrews are awesome and you can internally balance with the matching Scat 9000 crank.
Those pistons aren't great, but you can pick up some very good ones for not a ton more coin. I bought a whole rotating assembly from Scat last month for a .040" over 400 that I'm building in my garage now using these same parts. There are a LOT of good pistons out there for these, less so at .040" over (in my case) but you don't say what your overbore will have to be.
Don't worry about siamesed cylinders either. People seem to remember two things about Chevy 400's- "siamesed cylinders" and "overheat cracking". GM found that they needed to add the steam holes because in tests they ran in New York cabs, where the engines are idled for EXTENDED periods- sometimes hours- they can develop pockets of steam in these areas that can become entrapped and doesn't "shake out" when the car isn't moving. The steam holes take care of this, and except for this one field follow area they had no trouble when developing the 400's. Notice that the Bowtie block has siamesed cylinders and no steam holes!!!
The other semi-myth is about cracking- 400's are slightly more prone to cracking if you overheat the motor severely. This is mostly in the heads- not the block, but the block can be cracked if overheated (just like any other block). They can crack from the steam holes but this doesn't happen unless they're overheated, and they're no more difficult to cool than any other smallblock (when the steam holes are present, unless idling for those extremely extended periods).
Get the best pair of heads you can afford- AFR's are great, Canfield (Jegs) heads are very, very good (and come drilled for 400's according to Canfield), and the Summit street/strip heads are Brodix 1k200's without the Brodix label on the end- also very good heads. Patriot Performance is making a name for themselves too, but I don't have any experience with theirs. If you're running iron heads, Sportsman II's are great if you don't mind porting the wee out of them, and Vortecs can make a LOT of power- but compression will be awful high unless you use a piston with about 24cc dish- no problem using a shim gasket though, and this can give you a nice quench distance without the cost of decking the block.
Pick up ARP head & main bolts while you're at it and you're golden. As far as a cam, it should be picked to compliment everything else in your combo- it's a tuning device, not a tool to win a measurement contest!!! Call a professional and ask them to pick the cam once you know your combo. The above combos will give you great performance assuming you have a decent intake (RPM Airgap is perfect for street) and full-length, 1-5/8 or 1-3/4" at most headers with a 3" collector. If they fit the car, they'll do the job. Add a 750 or so carburetor and you're in business. You'll be smoking the tires through all three (possibly four with an O/D) gears, 3.40 or better rear gear, and 2200-2500 RPM stall converter.
There's nothing wrong with building the 400. I've had 400's in street rods since the mid-80's, and I love them. These days, go with a Scat 9000 series steel cast crank, as Vizard says nobody seems to find the limit of what these can handle- 600+hp is no problem. The 6" capscrew rods with 7/16" capscrews are awesome and you can internally balance with the matching Scat 9000 crank.
Those pistons aren't great, but you can pick up some very good ones for not a ton more coin. I bought a whole rotating assembly from Scat last month for a .040" over 400 that I'm building in my garage now using these same parts. There are a LOT of good pistons out there for these, less so at .040" over (in my case) but you don't say what your overbore will have to be.
Don't worry about siamesed cylinders either. People seem to remember two things about Chevy 400's- "siamesed cylinders" and "overheat cracking". GM found that they needed to add the steam holes because in tests they ran in New York cabs, where the engines are idled for EXTENDED periods- sometimes hours- they can develop pockets of steam in these areas that can become entrapped and doesn't "shake out" when the car isn't moving. The steam holes take care of this, and except for this one field follow area they had no trouble when developing the 400's. Notice that the Bowtie block has siamesed cylinders and no steam holes!!!
The other semi-myth is about cracking- 400's are slightly more prone to cracking if you overheat the motor severely. This is mostly in the heads- not the block, but the block can be cracked if overheated (just like any other block). They can crack from the steam holes but this doesn't happen unless they're overheated, and they're no more difficult to cool than any other smallblock (when the steam holes are present, unless idling for those extremely extended periods).
Get the best pair of heads you can afford- AFR's are great, Canfield (Jegs) heads are very, very good (and come drilled for 400's according to Canfield), and the Summit street/strip heads are Brodix 1k200's without the Brodix label on the end- also very good heads. Patriot Performance is making a name for themselves too, but I don't have any experience with theirs. If you're running iron heads, Sportsman II's are great if you don't mind porting the wee out of them, and Vortecs can make a LOT of power- but compression will be awful high unless you use a piston with about 24cc dish- no problem using a shim gasket though, and this can give you a nice quench distance without the cost of decking the block.
Pick up ARP head & main bolts while you're at it and you're golden. As far as a cam, it should be picked to compliment everything else in your combo- it's a tuning device, not a tool to win a measurement contest!!! Call a professional and ask them to pick the cam once you know your combo. The above combos will give you great performance assuming you have a decent intake (RPM Airgap is perfect for street) and full-length, 1-5/8 or 1-3/4" at most headers with a 3" collector. If they fit the car, they'll do the job. Add a 750 or so carburetor and you're in business. You'll be smoking the tires through all three (possibly four with an O/D) gears, 3.40 or better rear gear, and 2200-2500 RPM stall converter.
