Mismatched SBC build up, 327 crank, 6" rods, 350 block.

Well I work at a machine shop and through the years I have "collected" many engine parts, and have lots of left overs, and while going thru the garage this past week, I have come up with enough items to build a complete motor for free, BUT am not sure how it would perform and I know that if I got other things I could build something "normal" but like I said this is all free leftovers... SO here is what I have...: Block: 4 bolt 350, 4"@.030, pistons: 383 strokers @.030, crank: late(large journal), steel 327, rods: powder metal-6" (not 5.7",but true 6" lenght) heads: camel hump 194's cam:292 hydr. Isky. So mocking it up, the crank,rod, and piston combo works out to put the piston at .020 below the deck!!! Which I figure this is basically a "long rod" 327, but I am wondering if the longer stroke of the rod would have ANY advantage, to compensate for the shorter stroke crank?!?!?!? Any "desk top dyno" guys here? Of course I WOULD have this balanced before I put it together,Thanks...Ken

 

I think the long 6" rod would benefit you very little on the combination you have.

More benefit would be realized if you had a 400 crank or even a 350 crank.....Gues it allows you to runt the pistons ya got.
The deck height being as it is at -.020 below ,would lose you a minimal amount of compression,Id say you'd be allright there.
should run ok. will rev freely....
If you have another set of small chamber/runner heads such as 305 4 BBL or 2 BBL stock heads- OR=take em and have em milled/surfaced IF large chambers-to increase their compression ratio...
That way you keep the DoubleHumpers for later and the small chambers and small runners will add to the engines low to mid range response.
A 327 will rev irreguardless- it just wil be "snappier" at lower and mid levels.

 

Hot Rod Mag built a 400 block with a 327 crank and a 6.2" Ford 300 rod in 1997. They got 413 HP with AFR 190cc 305 heads and a 270HR10 cam. The heads had a 56CC chamber so they could get 11:1. The best part is it did this on 87 octane.

 

Yes that is exactly the reason for the 6" rods. the compression height on the 383's let it work, like I said I am just trying this out because these are all my "left overs"! everything is either new or machined. The whole engine, intake to oil pan, would cost nothing, ..zip, ..zero, ..NADA!! Oh -I would have to pay $35.00 for the balance job!! I do have a set of 305 heads, but know that they are so "unfriendly" on any performance level I didn't consider them?!?!?

 

Actually, yes. A 6" rod is a LOT closer to an optimal rod ratio with the storter stroke than it is in a 350. (Remember, in a 350, optimal rod length is something like 6.4", 6" is just all you can do easily). Powdered rods should be OK up to 7000 or so, ***uming a good balance job.

With the big cam, you'll have the potential to rev, IF you can get the heads to flow. Your smaller displacement helps a lot here, you should be OK with flow in the ballpark of 240-250 cfm (@ .600 lift, flowed at 28"), whereas with a 350 you'd need 270ish, which is all the best head guys in the world can get out of the double hump castings.

Also, I'd seriously consider decking the block to 9", getting your pistons close to zero deck height. It'll help a ton with flame travel, and getting compression that way doesn't casuse detonation as readily as tiny chambers.

Done properly, with attention to all the tiny details, it's a 400 Hp motor with decent torque. Certianly nothing to sneeze at, and more than a little potent, especially for a budget build.

 

If you run the double humps they are 64CC right? also a little loss of compression[020 under deck height].....prob a tossup as to which would run better.....Id bet the increase in compression from the 305 heads[#450 is good] would increase the end I suggested and if its a driver with street gearing or a heavy car THAT would help more than the top end gain of your 327 heads now.

 

I love that article.

 

hmmm. am i missing something,


your 383 stroker pistons are gonna have a pin height for the 3.750 stroke crank, and you are gonna be using a 327 [3.250 stroke] crank? thats gonna put you.030 out of the hole without the gasket on a standard deck height block.

 

6" rods. Using a 383 piston with a 327 crank and a 6" rod makes the deck height close.

 

ok

i guess my question should have been which piston do you have?


383stroker for 5.7 rods pin height is 1.430

383 stroker for 5.85 rods pin height is 1.250

383 stroker for 6 inch rod pin height is 1.125

 

Now that you have basicly a free motor, take some of the cash you saved and buy some good heads.

World Products, Dart and Brodix all make heads that would mop the floor with even the most radical set of double humps for under a grand.

Check out ebay and Racingjunk.com for good used stuff.

A free motor is cool though...


-Abone.

 

ok

i just dont think those pistons will work in that combo, but i could be wrong


most 383 stroker pistons using a 5.7 rod have a compression height of 1.430, and some have a height of 1.425

if your block is "decked from the centerline" my math shows you would need a compression height of 1.375 to be at "zero" deck height. If its .020 in the hole, wouldnt you need .020 less than that?.


if the block is standard deck 9.025

the math would be

deck height "9.025" minus [rod length "6.0" plus half the stroke of the crank "1.625"]


9.025 - 7.625 = 1.4


i may be tired but i still think the piston is gonna be poking out the top of the cylinder and not .020 in the hole

 

Well I didn't do good in math in school, BUT I layed the crank, hung a piston, installed it on the crank, put in the cam, and turned it over several times, to make sure the piston skirt cleared the lobes on the cam, and then at TDC. I put a depth mike on the deck and measured the piston "drop" in the bore...exactly .020 below the deck. Are you using your formula with a large journal 327 crank?? 3.250 stroke. the pistons are Sealed Power :H860CP, with a comp. height of 1.425, like you said.

 

are you using a factory GM crank?

 

Still sounds like it is .025 out of the block. 6 inch rod plus 1.425 comp distance plus 1.625 crank pin offset (3.25 stroke) is 9.050 on a 9.025 deck height. Tho sometimes my 2 cents are worthless.

 

I think I figured out where the problem is. If you are using GM factory pm rods, they measure at 5.94 not 6.00. Right there is .060. So if you add it all up, you get this: 1.625+5.94+1.430=8.995, which would be close to your 20 thou piston depth.

 

Yep Mikey, i thought about that scenario too,


what was throwing me was he stated they were true 6 inch rods and a decked block..


Fred

 

YES, thats it!!! I just ***umed (yeah I know) evryone would know what I meant by 6" rods (knowing they are not ACTUALLY a true 6" rod) when I said they were the P/M factory rods in my first paragraph!! My mistake, working in the industry I guess just kinda makes you think that everyone knows what you are meaning!! The rods are actually 5.9's , and they are origainally out of a '93-'95 265 caprice!! Its a large journal factory steel 327 crank. Anyways with all the carrification, does it seem like this motor is worth putting together??? I am getting nothing but **** at work about it!!!! Ken

 

"leftovers... SO here is what I have...: Block: 4 bolt 350, 4"@.030, pistons: 383 strokers @.030, crank: late(large journal), steel 327, rods: powder metal-6" (not 5.7",but true 6" lenght) "



yea i guess i missed the part where you said they were factory rods, I have 4 sets of true 6 inch PM rods on the shelf right now, so i apologize if i ***umed they were true 6 inch rods, you guys in the "industry" should take it easy on us common folk.

 

WOW.. I just picked up a SJ 327 yesterday and was doing some research and found this thread.

WHAT EVER HAPPENED!!
I also just happened to have a few decades of 'parts' laying around.
383 **** crank, a few roller blocks, box of 6" H-beams and a set of .020 over 383 pistons..

Like the guy on Dirty Harry said: I gots ta know..

e

 

A 10.75 year old zombie post dredged up.... do we have a record?

 

i want to know what happened also........

 

Did someone say 327

 

This should be a fun combo- over on the Camaro forums, a few have built long rod 302 and 327's. The longer rod will slow the piston head speed as it travels through TDC and it will be a revving machine and help with combustion. If you run the thin steel shim head gaskets, you'll be right at about the perfect quench height according to some of the experts like David Vizzard who have wrote books on this stuff. Going by memory, the steel shim gaskets are .016" and with the Pistons .020 in the hole, you have about a perfect .036" quench height.

A nasty, high revving solid cam would be the ticket here!

 

Shhhhhh
I wanna know too

 

BUT.. All this is VERY VIABLE information that 'we' can use NOW. (me and others..)
By that I mean just a couple years ago I was told and heard that one could
"Pick up a 5.3 or 6.0 for 'dirt cheap' prices" Well, I don't know where or who sells them that cheap, but around me just for a 4.8 with harness runs around 1200.00.!! Now add for : LS intake, F-body oil pan etc (all the other **** that they 'shoulda' come with) and you're knocking on 3-5K

I've got several engines/motors/parts in various states of 'investigation' you might say.

SO, since now the youngins are a bit bigger and have more money than time (not as much as it sounds) I think this IS more of a reality AND attainable!
I read Smokey's book about 10-15yrs ago and always remembered him saying that to get the longest rod in an engine that you could. It just makes more sense to dwell at top and bottom more for combustion and filling.
I dug in my shop and found my '97 roller block that was slated for a .020/383 build that's been sitting in plastic for about 10yrs, and now this 2680 327 crank that I picked up Friday, This Might Actually HAPPEN!
I just need to mock up the crank in the roller block with spacers and try to find that box of 6" H-beams that I squirreled away and see if Im in the hole or pokin out.
I can't remember if the 383 pistons are for 5.7's or 6's though. Oh, and just last week pulled off a fresh set of Ported Vortec 5.7 heads that I had on a .060 283.
If all I need is a set of 6" rods, well I'm VERY close to this. (Bullet Cams is just up the street aways, and if you can wait a few weeks, can regrind my roller cam for 1.6 or 1.7's..

OOOhhh. Im gettin excited (the ADHD doesn't help either)
E

 

The OP hasn't posted anything since May 2015 so good luck.

 

That's why I PM'd him.
Thanks though.

 

I saw that too and wondered how he did with his little project. For every HAMB success story, there are 19 that have unfortunately failed.