350 build,heads

[Truckedup]

I'm starting the build on a 350 Chevy that's for my 50 Chevy PU .Nothing too radical,the truck weighs about 3300 pounds,4 speed with 3.42 gears.The engine is a 010 2 bolt main block with a cast crankshaft.
The local machine shop ,I do the assembly, says forget any stock GM heads,he suggests a set of Dart or similar aftermarket 180 cc intake port fast burn heads,about 9.5 compression with about .040 quench,and ,218-224 degrees duration at .050 hydraulic flat tappet cam will give an honest 330 hp and great mid range torque at reasonable rpm's.Getting this power with most stock GM heads will require more cam and less low speed power.Rebuilding stock heads might cost 400 bucks and for another 400 bucks the new better flowing heads are a bargin.In addition this swap limits headers to short tube "street rod" or the set of 2-1/2 outlet Ram Horns I have on the shelf.So it's better for power to come on at lower rpm's due to exhaust type.
400 dollars won't exactly break my budget and this shop gives better prices on heads than Summit ot Jegs.
So...do you thing the shop's advice is good for a hot rod that's never going see a race track?

 

[grumpyvette]

it sounds like your dealing with a reasonably honest and knowledgeable machine shop

thats the type of engine that gets built for a great many of the street rods and cars , the second time ,AFTER the owners wise up and get tired of driving over camed and under researched engine combos, where guys basically stuck a large cam in a stock engine and wonder why its a dog.

Ive had very good results, building street/strip engines that were designed mostly for street use and durability with the emphasis on durability and no need to constantly tweak or tune the combo , like your looking to build,starting with a 350
with the brodix 180cc heads ,
http://www.jegs.com/i/Brodix/158/1021004/10002/-1
with a mild pocket port, clean up
http://garage.grumpysperformance.com/index.php?threads/port-speeds-and-area.333/
a weiand air strike intake
http://www.jegs.com/i/Weiand/925/8501/10002/-1
and
a decent 650cfm-750 cfm carb

http://www.holley.com/0-3310C.asp
and
a cam like this
http://www.crower.com/misc/cam_spec/cam ... 2&x=34&y=5

and a decent set of rockers like the erson 802-16 rockers

keep in mind your rear gear and 4 speed will allow that slightly larger duration cam,(like I posted above) that gives you a bit more punch without much if any sacrifice in drive-ability,
btw if your building a 383sbc in the future, select 10:1 cpr pistons and
a simple cam upgrade , will make it a P.I.T.A. to drive on the street but add a good bit of hp in the upper mid rpm range should you choose to go that route

http://www.crower.com/misc/cam_spec/cam ... 2&x=51&y=1

 

[Truckedup]

I see from your post you like aluminum heads...a few hundred bucks more,less weight and so on.And like you said,aluminum heads may reduce detonation.But some guys say although an aluminum head may allow more compression without detonation,the aluminum head takes away more head from the combustion chamber and reduces power,heat is power.So the increased compression is necesssary to make up for this and overall,the aluminum head makes the same power as an iron head,all else being equal.
The shop feels that anything over 9.25 compression with a fast burn iron head is pushing the detonation limit for 89-91 octane fuel with a carburetor. 93 octane is readily available around here but I would prefer an engine to run on 91 if possible.

 

[grumpyvette]

I prefer aluminum for TWO MAIN reasons,
they are far easier to repair when damaged
read thru this thread
viewtopic.php?f=52&t=389&p=7266#p7266
they are lighter in weight

theres almost no measurable difference in power either head material will produce at the same compression ratios,despite what you hear about aluminum needing a higher cpr to function correctly, aluminum does cool, and transfer heat to the coolant faster but under high rpm and cylinder pressure that's not as big , of a factor , in lowering the combustion chamber temperatures as many people would have you believe it is, and while it does tend to reduce the tendency to get into detonation, its certainly not going to prevent your engine temps from becoming critical if your ignition timing or fuel/air ratio, is less than ideal, it just may delay the onset of critical temperatures a bit longer than iron heads and if your concerned, with aluminum heads running too cool, theres thermal barrier coatings that can be applied to combustion chambers and piston domes

read thru these linked sub links in this thread

viewtopic.php?f=52&t=389&p=6855#p6855

 

[anderson3754]

I have a set of cast World Heads, SR Torquer on a 406 sbc approx 450 hp in my 70 chevelle and I just love them.

Have a second set of SR torquers on a 355 almost like your motor like 325 hp similar cam and again i think there great.
Hope it helps

 

[grumpyvette]

NEW/HEADS, you should NOT just bolt them on!

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=389&p=7266&hilit=aluminum+iron#p7266

http://www.carcraft.com/techarticle...luminum_cylinder_heads_test/dyno_results.html


now Ill probably tick some guys off here, but I see enought heads come thru the shop to point out a comon problem, and its NOT limited to one or a couple manufacturers, Ive seen it on nearly every brand and type of cylinder head!, what Im refering to is bits of casting flash, bits of aluminum or cast iron chips from machine work or sloppy assembly, burred threads, threads that are not cleanly cut,ETC. on new out of the box cylinder heads, I won,t name brands BUT some of the top names have bits of aluminum chips/dust/crud left in the ports in as shipped heads and dis assembly and use of a stiff tooth brush, high pressure air and carb cleaner spray along with reassembly with the proper lubricants and running a tap thru threads and cleaning all machined surfaces with solvent,is almost mandatory if your don,t want bits of crud washing around in the engine during first starting the engine. it sure doesn,t hurt to check the spring bind and other clearances, and that the valve seals are correctly installed either
IM sure the manufacturers used a high pressure air hose to blow out the ports and water passages, but theres com only some crud remaining so inspect carefully, and clean those new heads BEFORE installing them
, yes the cheaper brands seem more prone to this problem but even the best brands are commonly seen to be received in less than stellar condition, and need some basic clean-up

BTW, one of these tools comes in handy during the inspection process

http://store.summitracing.com/partdetail.asp?part=WMR-W89409&autoview=sku