Need opinion on engine build-up!!

[Zoso240z]

Hello all, it's been a while since I've posted but I'm finally starting on my 73 sbc Z after about 6 years. I've been looking at parts to buy and just wanted some opinions.

 

I have a SBC 350 with 4-bolt mains and a cast crank.

 

 

 

 

Parts I'm looking at:

Eagle SIR I-Beam 5.7 Connecting Rods

Connecting Rod Material: Forged 5140 steel

 

Keith Black Hypereutectic Pistons

 

Bore (in): 4.030

 

Piston Style: Dish

 

Compression Distance (in): 1.561

 

Dish Volume (cc): 18.00

 

Valve Reliefs: Two

 

Wrist Pin Style: Floating

 

 

I've tried some compression ratio calcs. and get a ratio of 9.05 Vortech Heads. Does this sound about right. What's a good ratio? Any help will be greatly appreciated

[jt1]

The first thing to do is define the intended usage of your motor. Grocery getter, weekend driver w/ a few trips to the strip, occasional driver w/strip or open track use, or serious race engine.

 

The KB's and cast crank will be OK for the first two, but not the second two categories. If you're in the second two groups, you want to go forged with both crank and pistons.

 

In order to determine your compression ratio, you need to know your head cc's and deck height, both of which can vary from the factories published figures, plus bore, stroke, gasket cc, piston height and cc. Once you get all this info there's a good CR calculator on KB's site.

 

General rule of thumb for 93 pump premium is 9.5:1 for iron heads, 10.5:1 for aluminum heads. BUT when you start pushing the limit, dynamic CR becomes important along with static CR. Your cam has a big effect on DCR. Lots of good reading on DCR at http://cochise.uia.net/pkelley2/DynamicCR.html.

 

Do a lot of searching and reading here in the chevy V8 forum. There's tons of good info here and you will learn a lot about what you need to do, without making bad decisions based on what some internet genius or street racer rocket scientist tells you.

 

I highly reccomend David Vizard's books "How to rebuild your SBC" and "How to hot rod your SBC", available thru B&N or Amazon. LOTS of good info there.

 

John

[grumpyvette]

http://www.diamondracing.net/cocalc.htm

 

http://www.newcovenant.com/speedcrafter/calculators/compressionratio.htm

 

heres an old post that will help

 

its obvious some of the guys on this site need to understand the differance between static and dynamic compression ratios, and thats understandable as its a difficult concept to grasp at first

but you need to understand it before selecting a combos components

 

the differance between STATIC COMPRESSION RATIO AND DYNAMIC COMPRESSION RATIO is where the piston is in the cylinder when the valves close and the piston can accually start compressing the REMAINING VOLUUM IN THE CYLINDER VS the STATIC COMPRESSION THAT ASSUMES THE PISTON STARTS COMPRESSING THE INSTANT IT LEAVES BOTTOM DEAD CENTER AND STARTS UPWARD ON THE COMPRESSION STROKE!

 

let me try and explain, the short version is that the PISTON COMPRESSES NOTHING untill BOTH VALVES ARE CLOSED, .......thats the only compression ratio that matters,.... since its the only compression ratio the engine ever sees.

 

static compression is simply the differance between the cylinder volume at BOTTOM DEAD CENTER(BDC) and its compressed volume at TOP DEAD CENTER (TDC), into the combustion chambers,... dynamic compression takes into account that on the pistons upward compression stroke the valves have not yet closed and nothing gets compressed by the piston untill they do, that of course depends on the cam and rockers, pistons and connecting rods, the cylinder voluum, the rod/stroke ratio, ETC.,used, in the combo, and the rpm levels to some extent BTW, ALUMINUM HEADS can usually operate at a higher dynamic compression simply because ALUMINUM releases heat to the coolant much faster than iron, its the lower heat levels that remain in the cylinder that help prevent detonation..when you increase the dynamic compression the heat levels in the heads combustion chamber rise , the differance in the RATE heat leaves the cylinder allows a slightly higher dynamic compression level from aluminum before the same HEAT levels are REACHED & MAINTAINED in the combustion chambers

 

heres a calculator for static cpr, which you need to figure first

 

http://www.newcovenant.com/speedcrafter/calculators/compressionratio.htm

 

let me point out a few things

first look at this chart

 

http://www.iskycams.com/ART/techinfo/ncrank1.pdf

 

then lets assume your 350 sbc engine has a static compression ratio of 11:1 but youve installed this cam

 

http://dab7.cranecams.com/SpecCard/DisplayCatalogCard.asp?PN=114681&B1=Display+Card

 

looking at the cam specs we see that the effective stroke is not the 3.48" that the static compression ratio is measured from ,at BDC, BUT from about 2.6 inches from tdc where the valves close as the piston moves upward, so your true working compression is closer to 8.1:1 NOT 11:1

 

heres a longer more detailed explanation and access to the software to figure dynamic cpr with the cam your useing in your engine

 

http://cochise.uia.net/pkelley2/DynamicCR.html

 

keep in mind that you can easilly run a stattic compressio of 11:1 with aluminum heads if you keep the cam timing in a range so that the DYNAMIC COMPRESSION is CLOSE TO 8:1

take the time to understand the concept,it VERY IMPORTANT

 

read this

 

http://victorylibrary.com/mopar/cam-tech.htm

 

http://victorylibrary.com/mopar/otto-c.htm

 

http://victorylibrary.com/mopar/cam-tech-c.htm

 

http://kb-silvolite.com/article.php?acti...3117842f4eb4c49

 

http://victorylibrary.com/mopar/rod-tech-c.htm

 

http://victorylibrary.com/mopar/piston_position-c.htm

 

http://www.iskycams.com/techtips.html#2003

 

http://victorylibrary.com/mopar/rod-tech.htm

 

http://www.zhome.com/ZCMnL/PICS/detonation/detonation.html

 

http://www.chevytalk.org/threads/showfla...true#Post397334

 

if cams are a mystery please take the time to read these, it will get you a good start

 

http://www.newcovenant.com/speedcrafter/tech/camshaft/1.htm

(read LESSONs 1-8)

 

 

http://www.wighat.com/fcr3/confusion.htm

 

http://www.chevyhiperformance.com/techarticles/95298/

 

http://www.idavette.net/hib/camcon.htm

 

http://www.centuryperformance.com/valveadjustment.htm

 

http://www.totalengineairflow.com/tech/valvelashing.htm

 

http://www.chevytalk.com/tech/engine/Cam_Selection.html

 

http://www.chevytalk.com/tech/101/Cam_Theory.html

 

http://www.babcox.com/editorial/ar/ar119736.htm

 

 

 

http://www.symuli.com/vw/camp1.html

 

http://www.symuli.com/vw/camp2.html

 

http://home.wxs.nl/~meine119/tech/camqa.html

 

http://www.chevytalk.org/threads/showfla...true#Post200511

 

http://www.crower.com/misc/valve_timing_chart.html

 

http://www.speedomotive.com/Building%20Tips.htm

 

]

 

http://chevyhiperformance.com/techarticles/94138/

 

http://www.aera.org/Members/EngineTech/engine.htm

 

http://www.zhome.com/ZCMnL/PICS/detonation/detonation.html

 

you really should get these books and read them before going any further, it will help a good deal, while only the basic info is presented it still makes for a good knowledge base, and referance

 

DO YOURSELF A HUGE FAVOR

buy these books, FIRST it will be the best money you ever spent, read them, and you will be miles ahead of the average guy. youll save thousands of dollars and thousands of hours once youve got a good basic understanding of what your trying to do!

http://www.amazon.com/exec/obidos/tg/det...F8&v=glance

 

http://www.amazon.com/exec/obidos/tg/det...nce&s=books

 

HOW TO BUILD THE SMALL BLOCK CHEVEROLET by LARRY ATHERTON&LARRY SCHREIB

http://www.amazon.com/exec/obidos/tg/det...2699400-6836852

 

 

.

HOW TO BUILD MAX PERFORMANCE CHEVY SMALL BLOCKS ON A BUDGET by DAVID VIZARD

.

JOHN LINGENFELTER on modifying small-block chevy engines

[Guest Ground Rat]

If you are going to replace the entire rotating assembly, the best bang for the buck would be a 388 stroker kit. You can get a kit from PAW w/ forged pistons for less than $600. Gitrdun.

[Mikelly]

Forged rods you picked are good... The rest... bleh... Get a decent crank and forged pistons... Shop around and you can find excellent deals on forged "Kits" with rings for under $420. My whole 383 stroker shortblock ASSEMBLED, BALANCED, BLUEPRINTED using ARP bolts was less than $1400...

 

Oh, and having a 383 stroker, I'd not build another one... I'd keep it 350-355 and spin it a little higher, or go crazy and stroke it BIIIIIGGGG!

 

GIDRDONE.... BUT Get her done RIGHT!

 

Mike

[Mikelly]

...and I forgot to mention... grumpy is the bowtie GOD... Take notes, there will be a test later.

 

Cheers!

Mike