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  #16 (permalink)  
Old 03-17-2008, 08:59 PM
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Quote:
Originally Posted by TheCiscoKid
Crap, just got it together before winter.I'll do a leak down test, I think it's probably valves as motor doesn't smoke.Motor had 70,000 on it.
BTW ....Picton is in Ontario,Canada.I work in the town Avril Lavinge comes from.If it gets much warmer my 30 x 40 igloo garage will melt soon. :oP
Cisco
Napanee! My Aunt and Uncle live there!

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Old 03-17-2008, 09:04 PM
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'76 sbc build , need more head advice

I can't get the car out because there's 2 feet of solid ice in front of the garage.What happened to global warming? I've had stuff growing this time most years. Cisco
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Old 03-17-2008, 09:06 PM
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At least the ice fishing is good!
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Old 03-17-2008, 09:54 PM
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'76 sbc build , need more head advice

Are your Aunt and Uncle related to Avril? LOL The fish moved to deeper water after the Zebra mussels cleaned the water, not as much ice fishing now.Used to be lots on the ice in front of the house, haven't seen anyone in years now.Besides who likes frozen fish?I don't even feed my cats fish and I have 13 ,oops 16 of them.have to include the German breeding stock
too. Cisco
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Old 03-18-2008, 09:50 AM
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Cisco,
those numbers are fine and the good news is you very likely can burn "elcheapo" brand 87octane with maxed timing...

nah, leave it together..... rule of thumb is if all cylinders do test within 10%....keep on driving....135 X 1.10% =148= close enough

when you "can" test drive and downshift with the vac guage...the vac guage is likely to read 24Hg+ and steady...when it does read <23Hg after alot more miles tear it down (and likely you will be adding a qt of oil every 1,000 miles at that point)

on any motor "some" cylinders live a much harder life (do more work with a less than best A/F mix) so the do wear faster

if this is a fresh build.....ignore the comp test results and vac readings till you get 500+ road miles on the motor (and re-torque and re-tune the whole motor)
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Old 03-18-2008, 10:30 AM
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Cisco,
the "catch 22" of building a street (low) rpms performance motor is that there is not a hell of alot of power (TQ) there to begin with to add onto....

the rv 204/214 cam will make almost as much TQ at 2k as the stock 190/202(?) cam for good normal acceleration....and a bit quicker "wind up" for passing a truck (with your relatively tall 2.73 gears good for mpg)

any cam much bigger kills that 2k street rpms number.... DD example from another thread on a 8.5CR motor:

222/222 vette cam=72ft/lbs @1k, 243ft/lbs@2k
same motor with a oem 190/209= 160ft/lbs @ 1k, 309ft/lbs @ 2k

243ft/lbs vette cam x2.73 gears=663ft/lbs at the tires
309ft/lbs stock cam x 2.73= 843 ft/lbs at the tires= roughly 30% more actual force twisting the hides at 2k rpms

bottem line is the "stock" motor build (250hp?) is the most and soonest maxTQ possible in the street rpms range...stock small 2V, stock intake, stock cam, etc....takes alot of careful planning and tweeking to actually get more TQ at street rpms than a plain vanilla 8.5CR 87octane 350

a year of planning and 2 years worth of tweeking my 208/214 cam 302 motor and I do know it would perform better driving normal with a stock 289 cam...but I don't want to give up 0-60mph in just a tad over 5 seconds with 3.55 gears and chirping the tires on the 1-2 shift with a automatic

Last edited by red65mustang; 03-18-2008 at 10:44 AM.
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  #22 (permalink)  
Old 03-18-2008, 02:03 PM
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'76 sbc build , need more head advice

The engine that is in my car is 70,000 mile 1976 4 bolt sbc out of a truck,487 heads.I put a new RV cam, oil pump,stock timing set,Edelbrock manifold & carb.It is the one with 2 cylinders down.My 74 Vet had 3:08 and it was way quicker and had nothing done to it.3:08 vs 2:73 aren't that far apart are they?I just don't think this motor has the balls it should.
My friends motor that I'm thinking of using is the 10:1 sbc with the big cam.I'm wondering weither to use my RV cam or something else in it.I want mpg not tire burning torque.
I guess what I have to decide now is if to change the motor or not.I'm keeping my th350. How much of a lower gear can I use without hurting mpg?Using a axle calculator ,car doing 2000rpm ,car is 60 mph.
Cisco.
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Old 03-18-2008, 04:28 PM
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re-curve the dist will help it grow some gonads...

sorry my post wasn't clear...for a really responsive motor on the street you do want to have way more than the minumum needed TQ available...so that just a little pedal the rpms jump very quickly when accelerating normal (hard for me to keep my car steady at 2k=40mph=320ft/lbs x 3.55 gears=1136ft/lbs in a 3400lb car=1ft/lb per 3lbs of car weight)...touch the gas and it jumps to 60mph!
(and when the grand kids are in the car you can light'em up)

each additional full compression point added only adds "up to" 4% to the power...your at roughly 9/1 and say 260hp....put a rv cam in a 10/1 motor would be only 10hp more "possible" AND require 92-94 octane likely

I am chuckling because you started out asking for a 90% hwy cruiser "only" and 87 octane and mpg (=9/1CR 87 octane rv cam) ....now yer askin' fer "vette' performance (and 87 octane and mpg!).... that's a oxymoron... or.... go buy a $71,000 ZO6...505hp and 25(?)mpg hwy on 94 octane

ya gotta choose your priorities...or get out your wallet and buy a OD tranny and much lower gears....or just stick a simple NOS kit on it.... (and have 87octane and mpg and "vette" performance)

Last edited by red65mustang; 03-18-2008 at 04:39 PM.
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  #24 (permalink)  
Old 03-18-2008, 07:14 PM
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Does your 350 have a dished piston? If so the compression ratio is very very low with 487 heads. The chamber volume on 487 heads can be as big as 80cc. That, combined with a dished piston and .040" composite gasket= very very low compression. potentially as low as 7.50:1
If that is what you have now, you need a head swap.
Don't even think about moving the summit cam to another block. its a $78 cam with new lifters. If you want to re-cam, get a new one.
Your motor has mediocre performance cause you have very low compression, low flow, stock smogger heads.

A cheap, effective, low budget solution is to fully home port and modify a set of high compression #416 305HO heads and swap them onto your 350 block. If your 350 has a dished piston, use a thin felpro #1094 steel shim head gasket.
Modify the 305HO heads for a 1.6:1 intake rocker arm (lengthen push rod guide slot, drill and roll pin stud bosses) and fully port them. Rob the 1.94" intake valves out of your 487's and have a new valve job done on the 416's after all the porting is done (by you).
Your new compression ratio will be higher so you can now use a larger cam and still have a good bottom end pull and efficient cruising.
Use Comp cams #12-208-2 cam and get 8 1.6 rockers for the intakes.
specs with split rocker ratio
265-269 adv 211-221@.050" .471"in -.465"ex lift 110 LSA

The increased compression ratio + improved cylinder head port airflow+ new camshaft will add a significant amount of real usable torque and power.
Air flow, cam timing, compression, it all has to work together.
A moderate jump in rear gear ratio will help seat of the pants performance as well. If you have a short 26" rear tire a 3.42 is good. if you have a tall 28" tire use 3.73's
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Old 03-19-2008, 03:31 AM
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'76 sbc build , need more head advice

EXCUSE me if I expect more from what I have or for trying to build on a budget. Cisco
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Old 03-19-2008, 06:55 AM
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Cisco,
apology!
I was chuckling because you "clearly" stated your "priorities" in your post #15...
and repeatedly asked for "best mpg possible"...
then you compared the performance of this "truck motor" designed for low end TQ to a "vette" motor designed for high rpms performance (apples to oranges)

a car only uses around 40-60hp to maintain hwy speed depending on the car wt...so motor rpms @ hwy speed does pretty much determine mpg....go any deeper than about 3.08 gears and mpg will be less and that's not nearly enough to to give it some balls

best solution for best performance and best mpg on the "truck" motor is a OD tranny to keep it at 2k=60mph with much deeper gears to give it some gonads when it downshifts WOT
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Old 03-19-2008, 09:32 PM
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'76 sbc build , need more head advice

Thanks, Red.
74 Vette L48 ,2 bolt,piece of crap low CR, but burned out, chirps when shifts, doesn't glue you to the seat when accelerating,gets 25mpg.I drove it until everything went,then I sold it for almost what I paid new.
76 4 bolt truck motor ,487 heads, low CR,with my cam ,intake,headers,I'm saying it should run stronger,A 3:08 isn't that much dif than a 2:73 is it?
The truck motor doesn't pull, doubt it will burn and gets 15mpg and it should be the better motor.
The way it is here,I can't find a SBC in a wrecker.I found a camaros LS motor and trany for $6500 at a wrecker last week.If my motors dying ,it's gotta go.My cheapest opition is my friends motor,but with 10:1, I don't think I want it.A fresh build will be $5000 for a sbc.I'd like a cheaper solution.(dreamer)
My car sat at a hot rod shop for 2 1/2 years.I dragged it home,stripped it back to frame,re-did almost all the shops work in 4 months.I have some body issues and glass to replace,then I'll paint it myself.Once that's done I will not want to take it apart.The other issue is what do I paint on it.I raise pedigree cats(truth,see below).Do you think I'd get thumbs up for flaming cats on the fenders? LOL
Cisco
Kerakterkatz ( character cats )
Maine Coon cats with character
http://kerakterkatz.tubazaar.com
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Old 03-20-2008, 07:10 AM
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5000 seem very expensive. I rebuild my sbc or bbc for about 1000.00. That is with new pistons and all the machine work (block and head) and with bearings and gaskets. I do my own assembly but that would only be another 200 to put it together at the machine shop.
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  #29 (permalink)  
Old 03-20-2008, 07:48 AM
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'76 sbc build , need more head advice

hey 454 Buddie!!!! Build me a 383 please. LOL
I'm in Canada, we get reamed.Maybe I should post ,looking for a motor.
I spent this morning looking at crate motors on line,again way cheaper in the USA. Cisco
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Old 03-20-2008, 08:07 AM
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you already have a motor, right? so buying pistons and getting the machine work should be the same price, right?

how much to clean and bore a block? 130.00
install cam bearings and freeze plugs? 40.00
turn a crank? about 125.00
a basic valve job? about 150.00 for a V8
resize 8 rods? 60.00
engine bearings, pistons, oil pump, gaskets, 310.00 from summit racing
summit cam and lifters, 80.00
assembly, 200 to 300.
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