I am building a 406" sbc 4bolt main engine for my c-3 .my corvette engine building days are from 1960 1980 era. So when I read " quench area" I get confused we set top of piston to deck height to .005 thousands plus or minus one.now I never see deck height written they use quench area dimension . Assumed this is the same parameter however they are including the compressed head gasket to make a total dimension.i see you present day engine builders are shooting for .045 thousand broken down into the same .005 thousand deck height plus head gasket .what do you do to change ??????use thinner gasket which changes your compression ratio or deck block. Second question is .045 optimum or do you use another dimension. 406" with forged pistons,H beam rods and SCAT crank.with roller cam. Car is used for street only a 0 to 100 mph run on occasion.

 

I know this subject was discussed a short while ago but my question or observation says attempting to measure block height ( centerline of crank to deck) will give you all sort of wrong measurements .taking into account bearing clearances ( big end,piston pin,crank bearings). Why not assemble without rings bring each cylinder to TDC. And check each cylinder to deck with dial indicator? What if block is decked on slant front to back or opposite way what good is your block height measurement taken from one cylinder.to many variables I feel assemble without rings tells the real story if you want dead nuts slide feeler gauge at 1/2 piston to bore dimension at 90 degrees to pin to eliminate piston rock without rings.might be old school but it is the only way (with pre- lubricated bearings) to get real dimensions, now the original question what do guys like for quench dimension for above engine.

 

.035 is what I usually shoot for especially with aluminum heads. So if you're .005 in the hole you'll want a .030 compression thickness head gasket.
The quench or squish as some call it creates a lot of turbulence as the piston gets close to the flat part of the head. Forcing the mixture out with great force into the open part of the chamber right as its being fired by the spark plug. Its worth a lot of horse power when set correctly!

 

If you're running iron heads .045 is ok but you are leaving HP on the table especially if you are running 93 octane and can keep your motor under 200 degrees

 

Thank you finally a explanation! So .035 is perfect ok that means I cannot use 040 SS laminated head gasket which I would have like to use with the aluminum heads.i will shoot for 035. Using the assemble and check method.

 

Yes exactly get your play doh out.....LOL

 

I have not purchase heads yet but I was set on dart 2.20 and 1.60 on exhaust 210 flow combustion chamber either 64cc or 76cc with probe forge flat top I would like to stay under 10.5 CR. running on street with 93 octane gas .

 

If you're just getting up to speed with quench after a 30 year absence from the scene, then you might want to check into something called dynamic compression ratio. Or maybe you guys were aware of it back in the old days, and I just think it's something new because I am new on the scene. Anyway, if you're getting back into engine building, and aren't aware of DCR, it's worth learning about. Please don't take offense if you're already up to speed with it, just making sure. It's something that was pretty new to me not too long ago. Good luck on your build,

Scott

 

Scott I am not familiar with DCR .this term is new to me ,and I was there with the best in the north Zul engine building and S&k speed shop.they shocked the world when they beat the best and won the NHRA nationals in pro stock. Undefeated in A class,B class and won the World Series of offshore boat racing. A little off subject when I built my 427" corvette motor for my 67 coupe I remember decking only one side of block! .005 on drivers side and .012 on passenger side made then even that's what struck my funny with you guys installing crank and then measuring block height from I guess front of block. center of crank has dot to to deck really what are you using a ruler! I cannot see this method too many errors built in.zul pulled 712 hp out of what would be a stock 270hp 350" corvette motor don't forget no headers in stock class and protested every race.the key; he severely angle mill the heads .the judges use to comment how " sloppy the intake manifold gaskets look( we snicker ). Running at 7000 rpm we were over 1500 rpm more then the competition crazy but true Never loss a engine!!!those were the days!

 

i agree richie zul is a great engine builder, those were the days. i knew Richie a little bit General Lee Edwards was as good as any too.and of course Sonny Leonard, both Virginia guys like myself.

 

oh, CAPT BOB don't let new words get you down they just came up with a name for something that was done waaay back.

 

The nice thing about aluminum heads and forged piston is they are more forgiving if detonation occures

64 cc chambers will put you @10.5 - 11:1 compression and will need 93 octane and it will be fast!!!

DCR is a variable. It can be changed by the camshaft you choose directly related to the duration. Or the closing of the intake valve. This intern bleeds off compression so an 11:1 motor will crank and idle like a 9:1 motor.

Without getting into it to deep, I would advise any cam with .230 duration at @.050
Lift can vary but @ .450 is a good range.

When your engine is assembled, call comp cams and tell them what you got and what you intend to do and they will choose the right cam for you. If they give you a choice, always go with the smaller cam on a street motor!!! It will save you headaches and you'll enjoy the drivability of your car!

 

Here's an article that does a pretty good job of describing what DCR is:

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

It may be something that you guys were aware of back in the day, but just called it by a different name. I am sure you are aware of the concept of an engine with a long duration cam needing more static compression, right? Well, all DCR really is, is just a way of quantifying that concept with a number. The article above has a pretty good calculator you can download at the bottom of the page, it works well for both static and dynamic compression ratio calculations. Welcome to the 21st century, Cap'n Bob!

Scott

 

Scott good article .ijust want to say we had good times and bad times mainly fellow racers hated us.who the hell is this idiot from Lindenhurst Long Island ,no sponsor on car starting out in17 place on rotation when the car came up to a 6 car field running same engine a southern guy told us they are going to shut you offat the line(NHRA shut off safety switch on outside of rear quarter) we disconnected the safety switch sure enough somebody switch it off while the car was staging.)car dies at line your out.beat warren Johnson 1 million dollar campaign car point leader. Never forgot they brought some strange looking small blocks into the shop from Oldsmobile high performance.block had no threads in outside of block every timing chain cover hole ,oil pan holes had to be threaded boring machine moan and groan ,block was as shiny as buffalo nickel and we put Buick valve covers on Pontiac heads the competition was baffle.we had those nickel blocks direct shipped always with chevy or Buick valve covers. Built a 1966 corvette coupe AHRA door slammer class ,427 turn 9000 rpm every run like clock remove power glide trans after every 11 passes.running in 9 sec never beat.yea those were the days

 

Step back and relax. 406 with Flat tops with 64 CC heads, .035 quench ends up about 11.8 to 1. He wants a hydraulic roller. If possible go AFR 195 or 210 on the heads. The dart actual measurement will be oversize. 75CC chambers with 5CC flat tops and .040 quench gets you about 10.4 to 1. Gearing has a lot of bearing on how radical you can go on a build. Need to post up your trans and rear differential info. Hood type. If your gearing allows it I would look at this with the 10.4 build. http://www.summitracing.com/parts/cc...make/chevrolet

 

I have turbo 400 with shift kit and.3.55 gears.

 

Mako I have L-88 long hood and will use existing performer manifold( duel plane with slight cut out in center divider (1/2").1.6 ratio roller rockers ,HEI/ MSD ignition. The block is a 1972 stock bore 400" 4 bolt main sitting in garage 40years. Took block to shop and remove every oil gallery plug ,freeze out and boiled then complete sonic test block is solid so put on centerline boring machine for proper index and exact 90 degrees. Bored .025 over and install torque plate each cylinder will be honed on Sunnen to it's respective probe forge racing piston. I even get to curse installing the B-locks in the free floating 6" h- beam scat rods and arp 7/16" rod bolts .the rings are special Hastings file fit with 1/8" oil ring . On the subject allways go for longer rod on your 406" build .zul try to explain in so many words spends more time at TDC. In addition to less angle at BDC. I will then take block home and do the deck height thing. I very important note the boys are all retired so no 50.000 engine secrets ( minimum of two in the day) cost you 100,000 to look inside !;. Hugie82 there is something to be said about your very important comment; zul angle mill the nickel block at least 11 degrees as well as cylinder head. He experimented with Dyno at 2 am by his self for a very long time changing angles every time with experimental combustion chamber changes. I recall 1809 hp from the 498" four barrel pro stock engine. Apparently he pull a lot of hp. From angle of quench area as well as redesign combustion chamber.compression was 14 to one with his own piston configuration not a regular dome.nothing was "out of box". When this rotating assembly is finish will gather all this cam choice information and apply it .once again thank you corvette brothers!

 

On the 6" rods. I would go with the 75CC AFR 195 eliminators. They will match up with your intake well and flow about the same as those Dart heads your looking at and get you 10.4 to 1 compression. The cam I posted will work great with your combo and a 2400 stall convertor. Operating RPM range of the cam will drop about 500 RPM vs a 350.

 

The probe industries pistons had calculation for 406" ; 64ccheads 11.52 comp. and 76cc at 10.14 cr so I will go with 76cc for street.will run on 93 oct. Shell gas. 63 Mako don't you feel the 195 flow heads are a little conservative considering this is a 406" motor with 1 7/8" primaries on long tube headers.plenty of fresh air thru L-88 hood.i would think 210 but you are up with these current engine specs.i do not know what deck height / gasket probe used to come up with cr figures.

 

The AFR 195 will flow more than the Dart 220. Your using a performer intake which will be a huge mismatch with the bigger head. Those AFR 195 will pull to 6000 + RPM easily on a 406. They flow about 300CFM. Check this site. http://www.users.interport.net/s/r/s...ehdc.htm#Chevy
Compare the flow on the AFR Eliminator 195 to any head 220 or under. You will be shocked. They will support 550 HP. Probe likely used a standard .025 deck clearance and standard .040 gasket.