Dissapointing performance

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straightlinespeed said:
Im with what every one has told you so far. Listen to these guys and be open minded to what they have to say. Just because you spent money on heads doesnt mean its going to fix your combo, if it is not set up correctly. I for one am with the people that said you have to low of a stall converter.

Here is my set up for a reference.

LA360
Stock Magnum heads
XE268H cam
Air gap
750 carb
TTI's to 2.5" to 2.25" exhaust. Soon to be changed to 2.5" all the way
18* initial 34 total
9.5 SCR
14Hg.

My engine put down 380 on the dyno.

Now in the car Im running a 2800 stall converter and 3:23 gears. I can light the tires up for a block or more. I've even been playing around with a 600 cfm Eddy carb and I can still light the tires up for a block or more. Did I loose some horsepower, Im sure I did, but how often am I going to be driving in the 5200rpm range?
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That is a nice combo right there for street use and probably has a great "seat of the pants" feel.....

JW
 
Lustle said:
Well. It seems like you don't really want help. But I'm a sucker for punishment. So here it goes.

Yes, the exhaust is all wrong. And YES exhaust contributes A LOT to your power loss.
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Congrats. You've put an exhaust on there that can support a whopping 289 horse. What did you say you thought you ran at the track again? Oh right, about 300 horse. Put those headers to work and put on at least a 2-1/2 inch system.

Carb is wayyyy to small. 750 double pumper fits the bill nicely on something like this. Don't use a vacuum secondary on a car that has greater than 230@50 duration cam.

Piston to head clearance. How did you measure that? If your quench is actually .078, I would try and get it down. the .040 area is great.

Once you do all that. Re-tune and re-time. It will need it.

BTW this is the definition of mismatched combo. Hence why it's a dog.

Oh and try to be decent to other people on here that are offering help and such. We are here to help but not when you give us **** attitude in response.
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That table doesnt mean you output power will be limited to that. It starts making hp lost after that. I read and understand everything what you guys say and Ill take your succestions and ideas. I know that distange is too much.
 
My cousins rhs heads only flowed 270 after porting.
 
Im from finland and my attitude is good. I dont have that american style of writing and speaking.
 
racerdan80 said:
Is this drag race only? If more street than race i'd say dual plane. Race, single plane. Exhaust, 2.5-3" with x or h pipe to help scavenge and balance out the exhaust. Need more stall on converter. I have personally seen a second or two difference in et's at the track when a matched converter was installed in lieu of a factory tight one which did not compliment the rest of the drivetrain combo
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Street use.

Et surely better but how about trap speed?
 
The best solutions are gears, converter and larger exhaust as mentioned. The band aid things that are cheap and will improve performance are: X or H pipe, Advancing cam, adding a little slack to the valve lash, carb spacer, carb tuning.
 
Dusterguy said:
better heads? These flow 270 cfm and are high velocity heads. I thought that these are best heads what you can buy for street use.
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I was making reference to the upgrades you did. New (better) heads and cam. On advancing the cam, yes it can cause detonation. That's why the timing is important. Advancing it will help build more cylinder pressure which will help the low end. My last three engines have had the cams advanced four degrees, 102,103 and 104°.

BTW the intake you have is fine.
 
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How much hp I will gain from 750 carb and 2.5 exhaust? maybe 20. It still miss 80hp..
 
Confirm the pistons are .078" down in the hole? What's the cranking compression at now?
 
jbc426 said:
Confirm the pistons are ." down in the hole? What's the cranking compression at now?
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I had 0.5 millimeter deck distance and I use felpro regular gasket and it is about 1.4 millimeters. quench distange is something like .078" I didnt even try to make it good it is what it is. I havent done compression test yet.
 
Dusterguy said:
How much hp I will gain from 750 carb and 2.5 exhaust? maybe 20. It still miss 80hp..
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I'd say 35 or more, but it'll still be a pig with the converter and gears you have. Who told you that the upgrades you did would be worth 100HP?
 
justinp61 said:
I'd say 35 or more, but it'll still be a pig with the converter and gears you have. Who told you that the upgrades you did would be worth 100HP?
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I have talked to experts and I have seen 400 hp dyno numbers on much milder builds. Right now my biggest problem is engine hp.
 
Before swapping parts you have something not right first future that out. Should be able to do a burn out.
 
Dusterguy said:
I have talked to experts and I have seen 400 hp dyno numbers on much milder builds. Right now my biggest problem is engine hp.
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Heat the motor up, pull #1 spark plug and grab a quick compression reading.

My Magnum based 408 has zero deck pistons, closed chamber aluminum Eddy heads and a touch bigger cam w 247 IN, 252 EX @ .050"; and it cranks 195 to 200psi. It runs on 91 octane and puts out just over 500 hp.
 
More gearratio and a bunch more converterstall should make that engine come alive bigtime.
A bigger exhaust would be nice and free up a bunch of power but is not killing your ability to smoke tires.
 
jbc426 said:
Heat the motor up, pull #1 spark plug and grab a quick compression reading.

My Magnum based 408 has zero deck pistons, closed chamber aluminum Eddy heads and a touch bigger cam w 247 IN, 252 EX @ .050"; and it cranks 195 to 200psi. It runs on 91 octane and puts out just over 500 hp.
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Stock or ported heads? I assume ported ones. What carb you have?
 
Why did it run better with old heads? Port Velocity! The way you are set up right now smaller runners would give you the torque you are missing. HP is directly related to RPM and that is where the converter is kicking your butt.
 
unbolt your exhaust (open headers) mount two compact spare tires out back.
let her breath with the right gearing
 
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