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  #76 (permalink)  
Old 08-13-2010, 06:46 AM
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Originally Posted by dry
Long time Lurker and now need your expertise!!

Ok here is the deal, My Corvette is a 74 L82 4 Speed car 73k original miles with the 3:72 rear end I have not been happy with the performance of the L82's Bottom End Torque so some changes were made.

Block was line bored .30 over and decked. the rotating assembly was balanced, forged flat tops, Crane Fire Ball II 290H Cam (1800-5200 rpm)-224/224 duration, 107 lobe centers,454/454 lift, Performer aluminum intake, Holley 4160-600 cfm single line, 882 stock heads professionally massaged and rebuilt with bronge guides etc, stock rockers, crane matched springs,Mallory unilite mechanical advance electronic ignition factory 20 degree mechanical advance "No Curve" timing is set at 18 btdc idling at 800 rpm, nice even compression across all cylinders, runnning 92 octane.......

Here lies the problem the car starts right up no timing drag hot or cold and runs great,no pinging, no stumbles or hesitations, temp stays about 190 drives great on the road 3500 rpm at 70 mph and runs well stop light to stop light when just driving it normal.........PROBLEM is when you try to stand on it from a stop light it doesn't have enough torque to even break the tires loose....this rebuild has about 5,000 miles on it so its broke in well and i am ready to find the right tune the car sounds awesome at idle but the torque performance didn't seem to change from what it was before the rebuild!!!

What am i missing here i just can't seem to figure it out, why have i not realized a torque increase etc...

All opinions and suggestion welcome!!
After looking at all 5 pages there is a lot of good info and yes the 882 smoggers are the worst. You can build a engine that will roast the tires at will but keep in mind these older vettes where made to hook up. With the independent rear suspension and a weight ratio of 48% front and 52% rear its tough to spin em from a dead stop. My 81 has 882 smoggers on a rebuilt engine from the previous owner. With the auto trans I can get the rears to burn but it takes some doing. Hooken up with street tires is a good thing

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  #77 (permalink)  
Old 08-13-2010, 08:35 AM
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OK I didnt read every comment but here is my 2 cents worth,and if someone else said this then by accident Ill repeat it.
First thing I would do is to snatch intake dizzy and heads, bring pistons(every one of them) to TDC and measure deck height, this will tell u if the eng has to pulled or not,ok so lets say you find 0 deck and a reasonable c.r. piston.
Now youll know weather problem is in top end or not.
If deck is at or close to 0 and you have flat tops,then get rid of that cam,n choose another when u put cam in,time cam "straight up",this is not just aligning timing marks and if u dont no ,ask.
2nd thing I would do after cam ,is, get rid of heads n use somethig close to mid 60s c.c.
I think the carb is no problem for now,you may want to change this to a larger carb later,650 or so,although 50 c.f.m. are really not gonna make a lot of difference.
Your timing sounds right, I take it total (mech+ initial)is about 38 or so,of course check pointer when u time cam.
With 0 deck,flat tops,good cam ,ign initiated properly,and correct intake,this engine should make that vette go pretty good,headers would definetly be a big + too.
accolades to bogie,very,very knowlegable eng builder.
Hope this helps.
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  #78 (permalink)  
Old 08-13-2010, 11:04 AM
dry dry is offline
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There has been alot of good information passed along here and my question in the beginning was why did i not gain enough torque to break the tires loose and appreciate all of the responses.

I believe that has been answered and the answer is because of my cam choice,comp ratio, and choosing to keep stock heads along with the close ratio 4 speed. The car sounds old school good and runs extremely well from 3k up which is a good thing that the original L82 didnot do well before.

I appreciate everyones input and suggestions and think i may just rebuild the 71 rectangular port big block 454 i have in the corner over the winter to L88 standards or better (with input from the folks here) and eventually swap engines.

So for the time being it is what it is and i will just try to fine tune what i have in order to get it running as crisp as possible for what it is. I am sure it can be cleaned up a little more by way of carb tuning, initial and advance timing along with headers and exhaust.
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