The question is a matter of journal size; as long as you have a "large journal" (2.45") 327 block any "large journal" crank will fit. Given that you have a '68 engine, I'd be 99 and 44/100ths sure you have a large-journal block; a quick check of the block casting number and a visit to http://www.mortec.com/castnum.htm will verify this. I don't know of any stroker cranks for the pre-1968 "small journal" (2.30") block.

There are many, MANY 2-bolt, cast-crank strokers out there - it's not at all unusual and I've built many - including my current LT1 383 project. The practical limitations are about 400 HP and 5500 RPM assuming ARP main studs (and an align-hone) vs. main bolts.

If you decide that a 4-bolt conversion is required, you can buy a BRAND NEW 4-bolt, roller-ready block from GM for about $700...so we're back in crate engine/engine swap territory IMHO.

 

1) You're exactly right - the compression height is different i.e. the pin is higher in the piston.

2) From a pure engineering perspective, SBC rods are too short. There are a bunch of reasons why (piston velocity, piston dwell, rod angularity, etc.) and a seach of the 'net will give a ton of background. I don't recalll (or on review find) that I said 5.7 and I generally recommend 6.00 rods if you can afford them for a stroker. A 6" rod will generally provide more torque than a similar engine with a 5.7" rod...although the extent of the gain is subject to significant debate

3) 400 cranks have a 2.65" main journal size vs. the 2.45" journal that (we hope) is in your block. The old stroker trick, before the ready availability of quality aftermarket cranks, was to turn down the journals on a 400 crank to the 2.45 size.

It's not an easy process to make these decisions, is it? I've had some very long discussions over the dinner table doing this type of planning, and it's always a compromise between budget and power...and you have the added complexity of preserving originality. I give you major props for the research you're doing and the questions you're asking!

 

Your right. You did not say 5.7" rods. Sorry about that!
I will take it at face value that the 6.00 are better. I can imagine though that a 6.00 will require slightly more clearance machining than a 5.750 will.

I am also just about positive that I have the large journals but will measure when I get home.

thanks!

 

Whats the difference between balanced internally and balanced externally?
Which is better?
Maybe it's better to buy an assembly unbalanced and let a good shop balance it?

 

This is another one of those questions where there are a lot of opinions about what's best so should be an interesting thread. An external balance engine uses weights on the balancer and/or flywheel/flexplate to create balance, where an internal balance engine matches all of the rotating components so that they are neutral. This is a gross simplification, but hopefully makes some sense

For a performance engine, IMHO internally balanced is a good investment - especially for a stroker. For a stock rebuild, the bobweights (weight on each rod throw) will be close enough.

Your BEST bet by far is to buy a complete, balanced rotating ***'y from a single vendor - ideally balancer to flexplate if it's not internally balanced. Balancing from the supplier is cheap...balancing at the shop is not (~$400).

 

Yep, 2.450 main journals!

 

I wonder why there is controversy. It seems better to me to balance each of the rotating components vs off setting the unbalance internals by adjusting the balancer or flexplate on the end of the crank. I would think the external balancing creates stress on the crank by setting up a twisting motion. But I know zero about balancing.
I think my current balancer has holes drilled in to balance instead of adding on the other end.

 

Many of these debates reflect that engine building is a science and an art - and that personal experience drives preferences. For example, some will say an align hone is not needed - others will say it absolutely is. In the end you need to weigh the comments, your research and your machin shop's advice and make your own decisions - as you're doing

 

Go find yourself a small block 400. Make sure it is either std bore or 30 over. The most you want to go with these is 40 over. After that, they run hot on you. Ditch all the internals except the crank, flex plate, and balancer.

Get a decent set of 5.7 rods (scat, eagle, LT1, etc), a set of Vortec heads (drilled for steam ports) and a set of Keith black kb-147 pistons for 10:1 compression, or KB126 for 9:1. Edelbrock's performer rpm cam/intake package would be a nice street setup for you. You can adjust up or down depending on your preferences. Around here, a balancing job is $250-$400. By using your stock crank, it won't be out of balance very much so you should be on the low end of the spectrum. The stock crank is nodular iron and is quite strong enough for street applications. I've ran them to 6500 rpm w/o any problems. Your stock 750 cfm Qjet will work quite well in this application. The block you find will likely be a two-bolt variety. Install a set of ARP studs in the bottom end for added strength.

Although this isn't the 'cheapest' option; it will be about $3500 discussed if you have a reputable shop assemble the short block; less if you do. It will also have nice street manners since the 400 SB is pretty torqie(sp) motor. Plus, it will eat the comparable 383 for lunch. I've never understood the 383 juggernaut anyway when you can build a 406/408 for essentially the same money

-Lurkin

 

Lurkin,

All sounds pretty good but I want to use my original 327/350 hp block and heads so it is stock looking on the outside.

You mentioned 5.700 rods. Why not 6.00?

 

I have not read all these posts but there is another way of
increasing acceleration other then in the engine compartment.
you are lucky enough to have 3.70 gears but you do have a small
327, why not consider a big increase in torque multiplication by using
a 5 speed trans, the M21 you have with 2.20 low has a pitiful
overall first gear ratio of 2.20 X 3.70= 8.14 I believe 2nd gear is around
1.60 or 1.64. so you shift to another pitiful (for acceleration )
1.60 X 3.70 overall 5.92 2nd gear. Consider a five speed trans instead
of spending a lot under the hood say one with around a 2.77 low
gear 2.77 X 3.70 = 10.24 . Then you would have four better acceleration gears plus an overdrive for the freeway. Now you may
spend $3500 to $4000 for an all new much stronger then stock trans,
but it is not cheap to buy good heads and build another engine, You
will get more good out of the trans for yourself then engine changes.
if you want to spend a small amount on the engine, spend around
$250.00 to $300.00 for a more modern high lift cam/lifters. timing
gear/chain and gaskets.

 

I missed the part about using the original block/heads though I doubt the vast majority would notice. I have my original LS5, but it is going to be sitting on the engine stand in the corner pretty quick when the 496 gets dropped in. I'm not the purist that some are when it comes to this stuff.

You can certainly use 6" rods. The disadvantages are the pin sits higher up in the piston (tighter ring pack) and it decreases dwell time at TDC and BDC. This is usually offset by the more favorable rod/stroke ratio though. Your off the shelf piston selection also goes down w/a six inch rod. You can always get custom made pistons. For a street engine though this quickly reaches the point of diminishing returns.

Oh, for the sake of clarity, another issue with longer rods in the sbc 400 is clearance between the rod shoulders and the cam lobes because of the longer crank throw. There needs to be 0.020" min clearance between these two or it will happen only once!

Good luck on whatever you decide.

-Lurkin

 

I agree that a longer rods make for a more tightly packed piston (compression height of 1.125 vs. 1.560), but it increases - not decreases - dwell time, which is one of the reasons 6" rods generally produce more power.

.050 is a better clearance to shoot for with rod/cam clearance - most aftermarket I-beam and some H-beam rods are clearanced for a mild (383) stroker...but you do still need to check I haven't had a problem with the SCAT I-beam rods to date...but you do still need to check.
Small base-circle cams are available if you get stuck, and the shop can take quite a bit off the rod shoulder if you've got good rods and ARP bolts.

My only observation regarding the 400 blocks is that they're getting very hard to come by these days and take a fair bit of machining to get them into shape - including adding steel caps in place of the lousy stock caps. If you've got one, great - but IMHO I wouldn't go looking for one. If you need the displacement, buy an aftermarket block.

 

Well I received some books.
Vizard - How to rebuild your Small Block Chevy
and
John Lingenfelter on modifying small-block chevy engines.

Great books so far. Lingenfelter says you have to determine where the rpm's will be most of the time and optimize for that. For me, a street engine, that means under 3000. So the 383 is great for that. I need the low end torque.

I like the comments little mouse is making on transmissions. If I make a change there, and I probably will, it will be in addition to the engine build.

I am taking information from everywhere I can and when there seems to be a pattern I am gaining confidence that the info is right.

As of right now, today:
1) Using my 327 medium journal (2.450) block and 64cc camel hump 350HP heads. 1.9/1.5 valves
2) Not sure if I should open the valves up to 2.02 /1.6 or not because I now understand that velocity is important and if the valves are too big along with the runner area, the fuel/air mix gets lazy. Bigger is not better if it doesn't match the rest. BUT I tend to think 2.02/1.6 might be the right number for my RPM range.
3)6.0 rods. 5.7 is ok but if there is a slight advantage to 6.0 and only minor clearance issues.
4)cast crank is more than strong enough for my 400 hp. goal.
5) Another post has Mahle and SRP pistons leading by about 3 to 1. But I am unclear if I need to used forged of same brands or is cast ok?
6) Have a surprising amount of choices in local machine shops.

Having fun. Hope you guys are too, lets keep it going till I have a plan. Then I will get into the build and keep you posted along the way.

 

When I rebuilt the low-horse/auto 327 in the wife's 62, I wanted to give it a little more umph. First, I replaced the PG with a stock TH350, which made the car quicker off the line.

I sent the stock heads to Mike Stark at CFM Performance www.cfmperformance.com I had him completely re-do the heads and give them his stage 5 port job. This was not cheap. Flow numbers and pics of the porting are in the link below.

http://www.picturetrail.com/gallery/...9897&members=1

I've always been a fan of torque motors, and since the wife didn't want a lot of cam, I would have to make the power with cubic inches. Our block is small journal, so I had a stroker crank for a 350 engine turned down to fit the SJ block. I used 6.00" Manley SJ rods, and Pro-gram engineering splayed main caps. I had pistons made with a calculated 9.5:1 compression ratio.

I already had a used Comp 262 XS cam. I had the cam reground by Ed at Camonics in North Hollywood since it was already on a reduced base circle, and had a 112* LS, which I wanted to help tame the idle. The cam, with 1.6 rockers, cam in at .520" I/E, 236* I/E, 284* adv, on a 112* LS, .012" I and .014" E lash.

I took it to LACR on 7-29-07 and went 13.2 @ 106 (12.88 @ 109 w/altitude correction). It was 95* when I made the first pass at 10:00 AM. The times were run on 235/70/R15 Radial TA tires. The car has a 3.70 posi. I run the cheap 87 octane gas, including our trip to the track.

I left the trans in "D" because the stock PG shifter was sloppy. The car would have ran quicker if I could have raised the shift points above 4500 RPM. A shift kit might have helped some too. The only tuning I did was to back the timing down to 35* total. The engine had less than 200 miles on it when I ran those times.

The car idles like a stocker, and the exhaust note wouldn't cause you to look at it twice. My wife takes it shopping and around town, without missing a beat. A crate motor would have been cheaper, but would not have been quicker.

NOTE: You can run your stock pan (if you use dedicated stroker rods), intake and valve covers. I would recommend a full port of the intake to match your heads if you go all out on the heads.

 

Best book ever

Price the upgrade and see; if the heads are receeded it might be almost a freebie...but it's not JUST about adding bigger valves as the chambers/bowls need to be swept and now you're into $750+ in machine work for the pair.

There are two types of cast pistons; cast and hypereutectic. Cast pistons are only suitable for low-performance rebuilds, hypers are fine up to about 450HP...and some say well beyond. Forged are absolutely not required in this application unless you're going to spray.

 

billla,
What does receeded mean in this context?
What would heads cost, iron, that would serve the purpose?
What's the value of Aluminum other than the weight off the nose?
Would the Vortec's or Bowtie fit the bill?

I have become gun shy of the hypers for no other reason than many people say they are no good. But I haven't heard why yet.

 

NOTE: You can run your stock pan (if you use dedicated stroker rods), intake and valve covers. I would recommend a full port of the intake to match your heads if you go all out on the heads.[/QUOTE]

wesmigletz
I am new to this so I don't understand this sentence. If you don't mind please provide more detail.

 

wesmigletz
I am new to this so I don't understand this sentence. If you don't mind please provide more detail.[/QUOTE]

Some stroker cranks or rods may hit the 327 oil pans. I stroked the 283 in our 59, and the 3.75" stroke crank and rods cleared a 6 QT 327 pan... the counterweights had been turned down and the rods had cap screws (which provide additional clearance).

Our 62's 327 used a 3.80" stroke Callies crank that was offset ground to fit the 327 main size. That crank and 6.00" rod combo just hit the 327 pan. With some judicious clearancing, it could have been made to fit.

I have aftermarket valve covers on my engine, your stock ones can be re-used. Your stock intake can be re-used. My heads were opened up to a Felpro 1205 size intake gasket. As such, it would be a benefit to have the intake opened up as while (the real world gain would probably be small though from gasket matching the intake).

 

I know money does not grow on trees, but if your going to the trouble
and expense of building a 383, don't use the around 165 runner 202/160
valve factory heads they do a poor job of flowing air. here is a
comparison of a bowtie chevy head 183 runner chevy bowtie head
that has been completely ported by a proffesional porter.
and the older afr 180 runner heads ( out of the box no porting, not the new 180 eliminators)
Chevy bowtie fully ported
int./ex. lift
.200=116/107
.300=169/143
.400=212/166
.500=239/169
.550=225/172
.600=228/174
out of the box AFR 180 runner
.200=140/112
.300=201/152
.400=244/190
.500=260/208
.550=262/214
.600=263/219
The later LS, Z06 350 size engines
runs good , the 350, Z06 heads flow close to 300 cfm at full lift. if you
put the 165 runner 202/160 factory heads on your 383 you will strangle it to death for air. sure with a 1/2 inch more stroke you will notice
some more torque, but with the old factory heads you will never no
how good the engine could have run. if you want the Iron head look
the 205 runner bowtie vortec head would flow enough air.