[strokin]

I'm planning a 400 sbc blown build, using eagle internal balance kit with je 36 dish piston all forged,
Using a dart shp block, carburated, haven't picked cam yet or heads, probably go with afr 220's with a 75cc chamber and a solid roller cam. Plan to run around 9 psi.
Question is, I've built many small blocks up to 450 hp but never built over that and never in a blown application. Are there any tricks for tolerance? Specs? Or any special details I should be watching for when building blown short block? I have a good speed shop here that can do all the machining. Also never done a 400, do I have to worry about steam holes with all these after market pieces?

And no I'm not interested in having my speed shop build it.

Thank guys

[496CHEVY3100]

On a street engine you will need the steam holes drilled in heads you are using,you can get by on engines no turning Less than around 3000 rpm such as circle track ,we ran Late Model Modified on dirt with alumimum block and Brodix # 7 heads prepared by Race Engine Design .we drilled heads just to be sure,some did not,but some had problems in pack out and during caution,I am assuming you will need all the help you can get to cool blown engine, I have built hundred or so racing engines But Never a blown engine ,will be building BBC with 671 crager blower later this year ,Just my opinion someelse might help us both ,Good luck

[vinniekq2]

your ring gap needs to be increased.
spin or fbird can give exact specs when they see this thread.
dont be shy with the heads,227s might be nicer

[F-BIRD'88]

Build a 7.5:1 cr 355 cid sbc and supercharge it. 6-71 or 8-71

Keep it simple with off the shelf parts. It will make all the power you will ever need.

[cobalt327]

Originally Posted by strokin

I'm planning a 400 sbc blown build, using eagle internal balance kit with je 36 dish piston all forged,
Using a dart shp block, carburated, haven't picked cam yet or heads, probably go with afr 220's with a 75cc chamber and a solid roller cam. Plan to run around 9 psi.
Question is, I've built many small blocks up to 450 hp but never built over that and never in a blown application. Are there any tricks for tolerance? Specs? Or any special details I should be watching for when building blown short block? I have a good speed shop here that can do all the machining. Also never done a 400, do I have to worry about steam holes with all these after market pieces?

And no I'm not interested in having my speed shop build it.

Thank guys

You'll have good air/fuel homogenization, but still I'd recommend a reverse dome D-cup dish if possible (example JE Extreme Duty inverted dome p/n 131633-1). Run the quench measurement as you would NA.

[496CHEVY3100]

I contacted BDS They recomend cutting a second keyway in crank snout to keep hub from stripping key and spinning crank hub and destroying crank snout,also Must run run forged cranh and forged 8.1 or less pistons for street with 7 lbs boost or less,Is this just a recomendation or a Must,anyone had any experiance wiyh this ,It is a 454 stroker=496 i have steel crank forged pistons ,but stock rods with arp bolts in rods and mains are arp studs ..671 blower i have a crager and a weiand ,which would be better.have already purchaced Comp Cam Blower Cam.roller rockers pushrods roller chain,115cc aluminum heads 225/188 valves do not want to change these

[cobalt327]

496CHEVY3100, why not start a separate thread, that way things won't get confused between your questions and the OP.

[spinn]

My god, blowers are nuts.

The power is awesome.

[techinspector1]

Originally Posted by 496CHEVY3100

have already purchaced Comp Cam Blower Cam

I'll bet your Comp "blower cam" is cut on a 114 LSA. Read this from Blower Drive Service...110 works best for gasoline...114 works best for ALCOHOL...

"Choosing the proper camshaft would be the most important requirement for a blower motor. An improper cam will cause a variety of problems that can easily be avoided by following a few simple guidelines. Hydraulic cams are recommended if you intend to drive the vehicle frequently, requiring little or no maintenance, and the maximum engine RPM's are kept around 6500 or lower. Roller rocker arms are recommended. Flat tappet and roller cams are recommended for high performance applications especially where the engine will see high RPM's. Exact camshaft specifications vary depending on the performance level you wish to attain. BDS offers different types or stages of cam grinds specifically made for blower motors. Refer to camshaft specs listed in tech info for BDS' individual engine camshaft specifications and their intended uses.
If you wish to purchase your cam from one of the many fine camshaft manufacturers, we suggest using our camshaft specs as a guidline. Extremely high lift and long duration cams are recommended for high RPM, high performance racing only.
The lobe center of the cam will play an important role in determining the performance characteristics of an engine. Wide lobe centers (112 to 114 degrees etc.) will create higher cylinder pressure providing more horsepower with cooler burning fuel such as alcohol and methanol. We have found 110° lobe centers to produce the best overall power on gasoline.
Whatever cam you choose, make sure that it will operate and perform properly in the RPM range required for your application."

I don't know what it is that makes you guys jump up and buy the cam as one of the first items. Cam and torque converter should be the last 2 items bought, after you've finished the drivetrain and everything else.

[strokin]

Ya I've heard about running wider gap, but yet some say to run a second gapless ring?

[strokin]

So you don't see any advantage to running a 400 vs 355 even though they will all be brand new parts? Obv we've all heard of typical problems with a 400 but even with dart block and all aftermarket parts?

[vinniekq2]

after market dart blocks are great. 400 is a good starting point for your engine

[496CHEVY3100]

Originally Posted by techinspector1

I'll bet your Comp "blower cam" is cut on a 114 LSA. Read this from Blower Drive Service...110 works best for gasoline...114 works best for ALCOHOL...

"Choosing the proper camshaft would be the most important requirement for a blower motor. An improper cam will cause a variety of problems that can easily be avoided by following a few simple guidelines. Hydraulic cams are recommended if you intend to drive the vehicle frequently, requiring little or no maintenance, and the maximum engine RPM's are kept around 6500 or lower. Roller rocker arms are recommended. Flat tappet and roller cams are recommended for high performance applications especially where the engine will see high RPM's. Exact camshaft specifications vary depending on the performance level you wish to attain. BDS offers different types or stages of cam grinds specifically made for blower motors. Refer to camshaft specs listed in tech info for BDS' individual engine camshaft specifications and their intended uses.
If you wish to purchase your cam from one of the many fine camshaft manufacturers, we suggest using our camshaft specs as a guidline. Extremely high lift and long duration cams are recommended for high RPM, high performance racing only.
The lobe center of the cam will play an important role in determining the performance characteristics of an engine. Wide lobe centers (112 to 114 degrees etc.) will create higher cylinder pressure providing more horsepower with cooler burning fuel such as alcohol and methanol. We have found 110° lobe centers to produce the best overall power on gasoline.
Whatever cam you choose, make sure that it will operate and perform properly in the RPM range required for your application."

I don't know what it is that makes you guys jump up and buy the cam as one of the first items. Cam and torque converter should be the last 2 items bought, after you've finished the drivetrain and everything else.

Thanks Mine is 110 lc hydi do have roller rockers& All matching parts and only 540 lift ,the alum heads i buught are good up to 615 lift as recomended by comp far gas ,114 for alcohol, compresssion is 7.9 converter is 26 00-2800 from B&M for big block app,all i want is the whine of 671 ,will nerer be raced exept to gas station ,lol,probable never over 5000 rpm. just want look and sound thanks for advice.. i had the converter still in box 4 yrs and blower before i bought the engine

[F-BIRD'88]

Originally Posted by strokin

So you don't see any advantage to running a 400 vs 355 even though they will all be brand new parts? Obv we've all heard of typical problems with a 400 but even with dart block and all aftermarket parts?

Adds a lot of extra cost and complexity to the build which won't be returned
in real street strip performance gain.

The 355cid "keep it simple" blower motor is powerfull and reliable and more than delivers the goods.
A after market block is not required.
You could build a big block 454 based motor for the money it will cost you.
Way better return in both performance and reliabily, with a big block . VS a big cube SB w aftermarket block etc.
Again simple cost effective brute strength and reliable supercharged power with a BBC, when you need more than 650-700
hp supercharged street power. Its hands down better to go this path.

Is 650+ horsepower and 500+ ft/lbs torque enough?
The 7.5:1cr pump gas 355 6-71 or 8-71 delivers this. Real simple to build.
Remember, this is more than enough to shread a 9" rearend. And split a trans case in half.

why make it more complex and costly than it needs to be.?

How much power/performance are you really after? how will it be used? purpose....

[1932bantam]

thing about the 400 you got to run that big heavy crankhub for ex balanced that and pulleys for alt etc. puts alot of strain on the end of the crank. As far as quench no need to worry about it on a blown engine. We just had a crank hub twist off, bent end of crank on 383 idling was running a spacer behind blower pulley, not a good setup