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Old 09-24-2008, 09:35 PM
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need advise finishing up my 355 sbc

hi everyone , ok, im building a 355 in my 72 nova . starting out i have a 2 bolt standard crank , pistons , no decking done to the block . it has been bored +30 over. i have a set of cast dart iron eagle heads, they are 2.08 1.6 49cc heart shaped chambers . lifters are already installed running an Elgin .501 cam , eldebrock performer single plane intake . next im needing to know what push rods to use ,studs, offset roller rockers , 5/16 ect.... this is my first build thanks , Danny

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Old 09-25-2008, 12:11 AM
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Race car or streeter?? ....and if you're building this engine why not at least have the block surfaced? You don't have to take a lot off, just kiss it a little.
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Old 09-25-2008, 12:12 AM
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Wow, 49cc chambers? Seems a bit unusual to have such large (2.08) intake valves on heads with chambers smaller than most stock 305 or 327 heads were. Just out of curiosity, what are the duration and lobe sep. specs of this elgin cam? It's kind of beginning to possibly look like a bit of a mismatch of intake/heads combo to stock bottom end, but then again I could be wrong. Just seems a bit funny to have a bottom end good to about 6k max, and such different/peculiar choice of intake and head components. Not trying to judge, just seems a bit "unusual choice of components". So anyways...What are the cam specs, and how fast were you planning to spin this powerplant? That would help for folks on this site to provide you with additional guidances that could prove helpful to you. -Jim
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Old 09-25-2008, 01:42 AM
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I agree with Jim. Whats the intake runner size of the heads? How high do you plan to rev it? A edelbrock performer is a dual plane intake, the torker is a single plane. The pistons are "stock" as in what way? stock replacement? forged or cast?
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Old 09-25-2008, 03:23 AM
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double post
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Old 09-25-2008, 03:24 AM
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yeah i'm starting to think jim is me. what you got there buddy is a 9.0 sec dragster topend on a grandma sunday driver bottom end. i'd sell those heads. honestly. i'm not trying to be a jacka$$. your going to sling your bottom end apart trying to turn the rpms that head/cam combo is going to want to turn. the cams not so bad though. i'd get some nice 67 cc heads from summit (less than 700 bucks, assembled) and i'd sell those heads you got for about 900 on ebay. the light duty stuff like stamped rockers will work for a while, in fact i would say keep those for good while, but i would invest in a good set of hardened push rods. btw if you go cheap on roller rockers your going to think your motor is knocking cause they make so much damn noise. just please dont build your motor around "those" heads, to build the motor those heads need to be on your going to spend about $6K-$7K more than you already have.
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Old 09-25-2008, 04:08 PM
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cont.... camshaft specs.

sae duration is as follows 287 intake , 297 exhaust. cam lift is 336 intake 336 exhaust, vavle lift .504, lobe centers , 99 intake, 111 exhaust. the cam is a Elgin pro stock . i want this to be a street car , but like to take to the track a couple times also. and thanks for the info : sounds like i'll be starting all over .
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Old 09-25-2008, 05:07 PM
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Quote:
Originally Posted by rude 72
sae duration is as follows 287 intake , 297 exhaust. cam lift is 336 intake 336 exhaust, vavle lift .504, lobe centers , 99 intake, 111 exhaust. the cam is a Elgin pro stock . i want this to be a street car , but like to take to the track a couple times also. and thanks for the info : sounds like i'll be starting all over .
Unfortunately this doesn't have the bottom end to put up with the power the top end can make. This thing is a ticking bomb waiting to go off and it will take all your expensive heads with it.

Compression unless you're running some pistons with really big dishes in them the compression will be way beyond anything you can get at Chevron to burn in this engine that won't blow the pistons out the bottom in pieces.

You're putting a competition cam and top end on a grocery getter bottom end, This won't last for long.

Bogie
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Old 09-25-2008, 07:02 PM
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old bogie- question

what heads at the most can i use , to make it run like a beast .
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Old 09-25-2008, 07:57 PM
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Are you dead-set on utilizing this stock bottom-end? If so, there's only so much it's gonna handle, -Both in terms of compression ratio, maximum rpm, and so forth. You will not make a "Monster" out of it, but you can get "respectable" performance out of it if you CAREFULLY PLAN your choice of components. If building from that stock bottom end, then plan to keep compression ratio below *about* 9.7:1, the rpm band (USABLE range) between *about* 1200-5600 {thru cam choice;duration and lsa}, and valvesizes no larger than 2.02/1.60 {at most, with 1.94/1.60 being more suitable}, intake runner and chamber size of heads more like 170-180cc intake runners, 58-64cc combustion chamber size {depending on exactly which +.030 pistons are in it now}. These are basic starting points from which to work. Some of the REALLY knowledgeable people on here can, and likely WILL, give you more detailed info as to what components will be best suited for your tastes that realistically are do-able and fit within your parameters (budget/intended driving patterns/etc...) -Jim
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Old 09-25-2008, 08:40 PM
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about 355 lower half

thank you jim , i will sit down and think about beefing the lower half up.
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Old 09-25-2008, 10:04 PM
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I have done what you describe before, not recommended but it can work. I put
a set of heads with 49cc chambers on a stock bottom end. Two bolt main, cast
crank, stock rods with silv-o-lite hypereuthetic pistons. Did not deck the block,
ran a 0.026" thick gasket. Installed a isky flat tappet 259 degrees @0.050" with
0.550" lift.

Mine needed 100 octane fuel, ran real strong for a couple of years to 7000 RPM
till a starter bolt hole cracked. It's really a gamble, might run for a couple of
years, might break tomorrow. Run it into autoignition and it will break real soon.
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Old 09-25-2008, 10:24 PM
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Those small chambers/large intakes heads (depending upon what the runner sizes are) would likely be more suited to a very high revving and very high compression (12.0:1-14.0:1) "all-out drag" or "transam roadracing" motor, such as a 302 or 327 with highdollar/all-forged, balanced, and blueprinted internals. The cam you have, in a 350, wouldn't even begin making power until at least 3000 rpm. While it is possible that you might be able to have the chambers on those heads opened up a bit, say from 49cc to perhaps 54cc , that wouldn't be enough change to really "change their application", -just drop compression ratio a bit on most usages to a more "sane" level. I think (personally) that you'd be better off to do as one of the other guys has suggested, and try to find a buyer for them (in the form of someone whom would be building the aforementioned type of hi-rev powerplant). Without SERIOUS changes in bottom end platform, you'd be best to rethink cam choice as well, to something more in the range of UNDER 220 degrees duration (@ .050" - the standard most used for comparison), and probably no more than .520" lift-so as to avoid getting into the more complex issues involved with most commonly used cylinder heads springpockets. I'm not positive but I believe stock vortec heads will accept up to .525", and I'm sure someone on here can correct me if that is wrong. I'd say If it were me, I'd keep that shortblock you have and build a SIMPLE and RELIABLE powerplant that you can drive back/forth to work 5-6 days a week, and run a few passes each weekend at the strip. Save the IronEagles (as you currently have them configured) for a hi-revver or sell them to finance some upgrades to the current build. Save that Too-long duration cam as well, for a hi-revving motor, or utilize it in the future if you build a 434 stroker. (With the 84 extra cubes, it would have more of a 2600-6600 powerband, as opposed to the likely 3400-7400 that it would in a 350.NOTE; ...figures are APPROXIMATE!) To best utilize your existing shortblock, since it's just been freshed, get some heads as previously described (in last/prior post) , add a nice reasonable cam of 204-220* (max) duration @ .050", lobe sep.angle of 108-112*, lift of .465-.500" max (u can increase slightly with 1.6:1 ratio rockers instead of 1.5), put a decent HEI system with proper advance curve, some 1-1/2" or 1-5/8" longtube headers feeding to 2-1/4" or 2-1/2" duals with a x-pipe or balance tube, top it all off with a low to mid-rise dualplane intake rated idle-5500rpm, capped off with a well-tuned/adjusted q-jet or a vac.secondary of your choice 600-650cfm and YOU WILL BE VERY HAPPY -and have a reliable good performing engine that will be there for you day in and day out. Very easy to achieve this build. Time tested and proven. Won't overwhelm a stock but properly maintained bottom end. Save the other items for future build, or sell to finance this properly-designed powerplant and pocket the extra to buy the new rubber you'll be needing on a regular basis. It's a win-win situation for everybody. especially your local tire supplier! -Jim
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Old 09-26-2008, 08:12 AM
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Those heads were designed for circle track racing, they provide 12 to 1 comp with a flat top 350 with a zero decked block. You would probably be in the 10 to 1 range with stock dished pistons and .040 range gasket.Have to check to be sure.The stock bottom end is far more capable than most give it credit for it should easily survive 6500 rpm strip blasts.We have built these same type combos as claimer engines turning 7000 to 7200 all night long in circle track engines.I don't recomend over 6500 continuous but occasional blasts up there should be fine.
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Old 09-26-2008, 08:37 AM
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barnym17,
You make good points, small chamber heads combined with stock dish pistons
would be a inexpensive way to build compression and power. Also as you
mention an occasional blast to 6500 is nothing compared to the constant high
RPM like circle track engine sees.
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