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Discussion Starter · #1 ·
my friends stock lt1 started knocking and was basically a big hunk-o-junk....so he had Jasper build a 383 stroker as a replacement. the original motor they set him had the wrong length rods in it and they were hitting the oil pan, so we sent the motor back and they rebuilt it and sent it back. that one started experiancing blow-by and was smoking on deceleration, so we sent that one back. Now he has a brand new motor and its supposedly running like it should. he has ported heads, tb, headers....pretty much every bolt on, and a cutout in the Y. the thing sounds like a beast w/ the cutout open. but for some reason, it has no topend whatsoever. driving in 1st gear, he can tap the gas and it feels like it will pull the tires, so the torque is definately there.

but we raced on the highway from a 20 roll in 1st gear and my front bumper was at his door and he went first, and i still beat him. really bad too. i went for a ride with him yesterday, and it seriously has zero topend. he can drop it in 2nd at 55 and it will start to pull, but then it just slows down. the motor is screaming and it sounds like youre hauling ass, but if you looks at the speedo, youre not. and for some reason, 1st gear goes to 40-45 (not sure which, but thats about normal), second to about 70, but then 3rd only goes to 80 or so. wtf is up with that? i watched him while he was shifting and looked at the speedo and thats what it says. i take first to 45, 2nd to 70-75, and i shift into 4th at almost 100....

were both 6 spds with stock 3.42s, im on stock clutch and he has a new spec stage 2.

anyone know why his car is such a slug? :poke:
 

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We need some details.

What heads? Ported stockers? How much porting? What are the cam specs?
 

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Discussion Starter · #3 ·
ill see if i can get a build sheet, i know the cam is fairly large, and the heads might be ported stockers, but ill see what the build sheet says.

i mean, my mods are pretty much cam and exhaust with a tune....so he should be beating me, right?
 

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No, not at all 383 sounds great but its the heads/cam that make the power. Ported LT1's won't feed a 383 up top...it will be a midrange tq monster but will peak early.

That's part of the problem I bet. So to compensate you have to run a massive cam...on a high ICL. I bets its an off the shelf job with a 108 ICL and its peaking hp-wise at like 5300.
 

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Discussion Starter · #5 ·
down low its definately a beast, im not sure what size cam it is, but ill talk to him today and check out the build sheet.

at first he was worried about the motor, since the first one Jasper sent was fubared, but i didnt think that was it
 

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If you're saying it's got a big cam in it and ported LT1 castings, my first inclination is going to be that the heads just aren't cutting it for the setup. A 383 needs a lot of air up top, and ported LT1 castings just don't have the capability to give that air. Couple that with a cam that is a top end revving cam, and that motor is going to run out of steam real quick.
 

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Is it floating the valves? Are the springs matched up with the cam?
 

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i agree with fastbird heads make all the differance.try joggig with your hand covering your mouth your not gonna run for long.but if you walk it dosent matter.make sence?
 

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santa_rosa_lt1 said:
i agree with fastbird heads make all the differance.try joggig with your hand covering your mouth your not gonna run for long.but if you walk it dosent matter.make sence?

LMAO! GREAT Analogy there! :lol:
 

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Fastbird said:
If you're saying it's got a big cam in it and ported LT1 castings, my first inclination is going to be that the heads just aren't cutting it for the setup. A 383 needs a lot of air up top, and ported LT1 castings just don't have the capability to give that air. Couple that with a cam that is a top end revving cam, and that motor is going to run out of steam real quick.
Took the words right out if my mouth.
 

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Discussion Starter · #11 ·
well, i asked for the build sheet, but its all numbers and codes and shit from Jasper. and i would think that the heads would be fine, since they built the entire motor, its not like he grabbed a big cam and just tossed a set of heads on...they built it all together, so it should run fine.

on another note....that thing def isnt running like it should. we were out racing last night, and we went from a dig and i took him...
 

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wow this is really making me not wanna order an engine from jasper. i would agree with everyone else that the heads are not flowing enough to support the cam and the rest of the engine. id be interested to see what heads they put on it, and did they give you a dyno sheet?
 

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Discussion Starter · #13 ·
i dont know if anyone here likes jasper or not, but i will say DO NOT BUY A MOTOR FROM JASPER. that motor has been the biggest headache ever. we only wanted to buy a built motor to speed up the down time, but we couldve built the motor quicker than them. they always had delays and pushed delivery back, then the motor had rods that were too long, then it was smoking and popping and blowing off oil caps, then after the sent a new motor, they sent the wrong harmonic balancer with it so it was eating belts. now it just isnt running right....we were racing last night and the 383 was having trouble with a near stock lt1. sure, it sounds mean....but the motor isnt making the power it should be
 

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Discussion Starter · #15 ·
the motor is tuned, it hasnt been dyno'd and we wont know the a/f until its dyno'd. the place around here with the dyno is closed or something, so we need to find somewhere else to go.
 

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Shoulda done a tree fiddy five
 

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Discussion Starter · #18 ·
well, a 383 should be just fine....if its built right...Jasper wouldnt have been the company i wouldve went to if i was looking for a motor, but i wasnt aware he went to them until after he made the transaction. i base my business on word of mouth and results i can see in person. apparently this was jaspers first lt1 383....
 

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Discussion Starter · #19 ·
and not to mention they lied to him right to his face. they said every motor is dynod and ran before its sent out....but if thats true, then how the hell did they not notice the rods were too long in the first motor. it sounded like someone was banging on the oil pan with a hammer when we started it...if they ran it then they wouldve noticed something was wrong...
 

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I was saying that because from what I see...355s tend to be faster than the 383s...you gotta pump a LOT of air into those 383s and 396s...only way I would do either is if I was doing forced induction personally...
 
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