Hello everyone, I have done some searching on this site and others about at 383 or 421 stroker motors. I wanted to see if I could get some thoughts on some of my questions. I have a stock block 400sbc that I would like to stroke to 421. I am not sure if I can get anymore than that out a stock block... I also have been told that the 350 block may be the best small bock (OE) to use(400 overheat or so thats the wives tale). I guess I have a few questions. What would be better a 383 or 421. the application would be a daily driver but driven hard. I may take it to the strip once in a great while but I would really need it to be a great mannered street engine. If anyone could help with telling me the pros and cons to a 383 over a 421 then great let me know. One other thing is that either one would end up being a roller motor. What would the cost difference be and the amount of machine work that would need to be done. Thank you in advance.
A 383 has a 400 crank as you know. A 421 needs a stroker crank which costs money. As per Lingenfelters SBC book "why build a 383 when you can build a 406" (,030 over 400) for the same money and get 23+ cu. in. As far as overheating built right with sensible stuff they run great. I have and have had several in all different configerations and the 383 just didn't make sense unless you have a 350 block and a 400 crank sitting around. If you have a complete 400 laying around that makes sense. Pat
If you all ready have a 400 block, neither bore it .030 over for a 406. These make real nice street engines. If you need a block and have a good 400 crank use a 350 block for 383 cubes. If you are starting from scratch, get a dart SHP block and build a 427 cube motor. These are all proven combonations and when properly built work well. Keep in mind that a 375 HP 350 is very doable, cheap to build, easy to live with, and will make more power than most folks will ever use. 1934 Coupe-another fast fingered New York feller
"1934 coupe" Thank you for the input. You said you made a few 400s. Am I correct that 421 is all I I can stroke it without doing any machine work to the block. I agree with no replacement for displacement that is why I would look to stroke it the 400. Also, I have looked around and it looks for some reason a stroker kit for a 400 to is a lot more than one for a 350. Is this true or am I not looking things up correctly.
Since you have the 400 I would go 406 also. Will be much cheaper. Especially for a street and sometimes strip use.
don't know about the 421 400 stroker ...i guess i would have to say, "Why bother????" the overheating is a myth spread by those who either never owned a 400 sbc or they didn't have the propper steam relief holes in the heads....the 400 is a baby bbc when it comes to torque..and anyone will tell ya if ya want a fun, hard drivin sbc, ya want one with torque....lots of it.a 400..building a 383 stroker is another statement when i would say it again.....:"Why bother?" below is my last 400 sbc...had 4 different ones in this same car...ot 72 vega wagon....and yes i was a hard core, non-400 sbc chevy guy for many many years,,,,till i dropped the first of the 4 different 400's into the vega why 4 different ones...i had a job working at a place that dealt in re-man engines...i could buy em, mod them and sell them for way more then i had in them....too easy to yank it and sell it then to tear it down and start over...besides, the extra paid for the new version of the next one.... the blower motor above dynoed out at 580 hp and right at 604 ft lbs of torque...drove it every day to work....cruised it on the hiway from michigan to cincinnati ohio...several times....in the dog days of summer....never ever got above 200....and that was sitting in traffic during 98* temps during woodward dream cruise..which isn't hot for a 400...it was also 40 over on the bore...2680 weight of the car..non tubbed....dunlop gt qulaifers for rear tires,,,very hard, not much bite....i could roll into it and carry the front end..easy.... yeah i had a few bucks into it....had a friend o-ring the block for the blower...ran a lunuati cam at 540 lift, 330 duration..over the counter bowtie angle plug iron heads....good headers and the blower....funny part was that i rarely pushed the motor much beyond 3800 rpm,,,,,,generally by then, on the street i was gone...tail lites to ya...but i also had it beatin the drum at just a hair over 7 grand many times.... so again, why ??? 400 is just as cheap to build as any other sbc....and i love em so much, i still have the motor before the blower 400 sitting on the stand in the garage...right at 500 hp motor that is 40 over...ran a single t ram on it...think it's going to go into the boat this year.... ya, they are torquey.....and it happens really quick
I don't know how you wound up with 421" but .030" over comes out to 406 A .030" over with a 1/8" stroker crank is around 420.3". If you wanted to spend money it would be better to use a 5.7" or 6" rod instead of the 400s 5.565 then get pistons to match the new piston pin location. When you add it all up a 406 sounds pretty good. Pat
Stock crank, 7200 to 7400 pretty much max. Stroker crank for 421 or 434"? Then you need to start looking at rod to cam interference and rod to block and oil pan interference more than with the stock 400 crank.
I guess another question is who has put together a 406 or so together and what is the combo they have used compared to people that have put together a stroker 420/421. A head to head comparison about hp/tq and cost would be the thing to end this discussion. I have been thinking about if a roller motor is worth the money as well instead of stroking it or does the money not make much sense. I know it depends on where someone wants to draw the line on their build. So...any info on this would be great. Thank you
I'd build a 377 if I had a 400 block in good shape. Always worth the cost to build a roller motor. I don't usually do it for myself but I'm a cheap bastard, if I was building an engine for someone else I would strongly suggest the roller option.
Why go beyond the 3 3/4" stroke crank? The raised block Mopars (413, 426 & 440 engines) all came factory with the very same stroke! As has already been emphatically stated, the 406 is the best way to go on the street.
Whats the rest of the combo? trans , conv , carb, rear gear.weight of car its going in . more details please.
406 is the baddest little sbc out there, i run a 383 stroker, the 406 would run the balls off the 383
I agree completely. Don't spend the extra money on exotic cranks, rods , and pistons to build a 421. Plus, you're going to have to grind your pan rail area for counterweight clearance. Build a 406. You'll save a pile of money (vs. a 421), and use easy to find, off the shelf parts. Spend the money on a good flowing set of heads. 400s are the best bang for the buck when it comes to SBCs.
I went through three 400SBCs and none of the blocks were Ok to build so I called Jeg's and bought a Dart SHP block. I ordered the 4.125" bore and built a 400 using the following parts. Eagle forged crank with 3.375 stroke, Eagle H-beam rods, J&E forged pistons, coated Clevite bearings. For cam I bought a Comp Cams hydraulic roller 08-433-8 with their dual springs and GMPP lifters and push rods. Everything was balanced internally so I could use 6" balancer and cheap flywheel. Heads are off the shelf GMPP Vortec cut for the Comp springs. The rest is Melling oil pump, Edelbrock RPM intake with Holly 750 (4779-2) and a new GMPP HEI distributor. It is 400 CI and makes 437HP and 518FP at 5400RPM. I have about $6K in it since I bought everything brand new and only the best quality parts. I could have bought the 4" stroker crank for a little more money and made a 421" but I left room to grow if I need to later.
I am leaning more to not stroking the 400 but just doing a roller motor. Some you guys ask why I want to even stroke the 400? Because there is no replacement for displacement. However, one of the points of this post is to see where the lines should be drawn with time and money. The 400 had a blown head gasket so it will have to be rebuilt any how so I figure if I am going to do it once why not do it the best way. I know what is "best" depends on preference of a person.
I guess the other question is who has done a 421 stroker. Can it be done without messing with the clearances and other machining?
The 421 combo may have problems with cam to connecting rod clearance. Rods may hit pan rails but thats an easy fix. The camshaft issue depends on what rods you use and the profile of cam. On my drag race 434 even with Oliver rods and .850 base circle roller cam it's still mighty close. Plus advancing or retarding the cam timing also changes the clearance. My 2 cents. If you are going to buy a stroker crank get a 4" arm. 434 costs the same as 421 and has more power. Otherwise 406 is good choice.
good question, to get that many cubes don't you have to run a taller deck? I have a 406, and when I was building it I considered a 4" stroke and I was led to believe that it would only make it a 421
How about the crank from the 283 and install it in a small journal 327 block???...... I think Egge sells .125" oversize pistons for a 283... I gotta go to work...
$6000 and alot of issues to watch.....this is what i am to surmise to build a 421 or bigger???? hell why screw around, for a few more thou, i'ld have to call BME and just buy one of their 427 modified crate motors....hell they even have a warranty... i mean ain't this supposed to be a street motor???track maybe once in awhile????? your cash......my opinion????my 40 over blower 400 would eat the 421....and probably walk past the 434.....and costs is about half.......
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