I need help bad!!

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Jonnylightening

Jonnylightening

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Hi guys, now I know this forum is for A bodies but I need help badly. over the winter I started building a 400, its in and ready to go but it's very sluggish. Here's the list of whats done to it:

Mopar 400 (.030 ovr)
Edelbrock 850
1" Moroso spacer
Mopar M1 Intake
Stock heads
Champion Copper Plugs
Crane 1.6 Roller Rocker
Lunati Custom ground flat tappet cam
Lift Int./ext.-(.525)
Dur. @ .50 Int./ext.(235)
Adv. Dur. Int./ext.(264)
Lunati Double Valve Spring
Lunati FT lifters
Cloyes Billet Dbl. Rollr. Time Chain
Mopar HV oil pump
Mopar HV pump drive
KB Pistons
Stock Rods
Factory Forged Crank
MSD 6AL Box
Stock Coil
MSD Pro Billet Dist.
MSD Wires
ARP Bolts (rod/Main)
Headers

So anyway we got this thing all broken in and it sounds amazing, but it's a dog off the line. I have a NP435 trans and in second gear it tries to stall out. We tried adjusting timing(not too sure with this type of dist. yet), adjusted the rockers(.012) and repeated. I'm hoping and praying someone on here could lead me in the right direction. I'm using this motor in my 2WD pulling truck and have a week to have it ready. So if anyone can help It'd be really appreciated. Thanks a bunch! Jon
 
.012 sounds too tight. Have you checked compression? I would run a vacuum and compression test to get some insight. What do the plugs look like?
 
One of the biggest problems with the 400 as far as performance was the low compression due to the fact that the pistons were so far down in the hole at TDC that they lacked compression. That and the fact that your probably bleeding off more with the large cam.
 
What KB pistons are you running?
What is the true compression ratio?
My guess is the stock heads have you choked off.
What type of fuel pump / tank are you running?
We need more info.
 
I agree with the previous posts, a true comp. ratio needs to be determined before we can give a resonable response to your issue. It's possible you have 8.1 or less and if that is the case that cam is killing your performance.
 
Are you running the kb 240's? Is the block zero decked to the pistons? Even with the large chambers of the stock heads you would have over 9 to 1 compression without the the zero deck with those pistons. I would go over all the basics before you start condemning your combo. Make sure you have the timing set to 36/38 degrees. Make sure the carb and fuel system are working properly. Check for vacuum leaks.
 
If this is strickly a pullin' truck i'll assume you have hi-comp pistons. Iv'e never seen a solid cam with that tight a valve settings. Could be when at full operating temp. the valves are hanging open a little. Just throwin' out a idea?
 
What gear and tire size you running? Any work done to the heads? Whats the fuel pressure under load? And is it just stalling out with a load?
 
Im running the KB240 which should put me @ around 9:1. Im running a holley black reggulated to 7psi. Im running 356 gears with 33" tires. Im gunna piss with the timing a bit more. When I did order my cam lunati accually suggested this grind. I told him exactly what my combo is.
 
you probably need 4:10's in the back, especially with 33" tires

shift point is probably 5500 or so?

also i'd run a little bit hotter coil than a stock.

your power band for that camshaft is significantly higher than a stock cam. it's not for low-end torque, but higher rpms she will kick up lots of mud
 
perhaps a single plane intake would give you more lower end torque. Also your gear ratio compaired to the tire size. heck my explorer is a 29" tire and came with 3.73 stock.
 
what size fuel line and where is the tank or cell located? don't be afraid to add more timing than the afore mentioned 36*-38*. did you degree the cam in or just line up the marks? what does lunati's lash spec call for? do you have the fuel pump running off a relay? on that m1 intake the phenum is fairly large and you might epoxy the sides of it to a nice curve or arch top to bottom from the cylinders 3&5 and 2&6. this will improve it's response a heap. plus you might want to give around a 4.89 gear set a try. also try a better coil, that maybe part of your problem. what size headers are you using?
 
I have a 5 gal fuel cell located in the bed. Im using 3/8 fuel tubing from cell to carb. Timing chain was installed 4° adv. On the cam. Headers were used so not to sure. Im wondering if the carb is too much and also if I should remove the carb spacer.
 
Your posts say "stock pistons" and then later "KB240". Which is it? Second, the gear ratio you said it 3.56? With 33s? With that much tire you need at least 4.56s, preferably 4.88s or steeper if you're serious about getting the engine in the rpm range where it will work for you.
 
i agree with moper 100% that a 3 56 with a 33 inch tire is not helping at all. you want rpms. a higher gear will help tremendously. hell even my jeep cherokee has 3.55s and 33s and that dogged it out where it would burn off a 235/75
 
OldmanRick said:
If this is strickly a pullin' truck i'll assume you have hi-comp pistons. Iv'e never seen a solid cam with that tight a valve settings. Could be when at full operating temp. the valves are hanging open a little. Just throwin' out a idea?
Click to expand...

THis is why i urged him to do a compression check. If valves are hanging open he will have low numbers. If exhaust is hanging open he will have an erratic vacuum gauge. Compression and vacuum gauge are handy diagnostic tools. Start with the basics. I also agree 4.56 to 5.13 ratio wouldnt hurt. But the ratio would hurt his bottom rpm more than top.
 
I looked up the np435 gear ratios
1st - 6.69:1
2nd - 3.34:1
3rd - 1.66:1
4th - 1:1
Is this reason for the 3.56:1?
Are you experienced at setting up carbs and timing curves for performance engines? Maybe get it dyno tuned. I'd start with what Daredevil says compression test and check for vacuum leaks and don't take for granted if something new that it's good like coil, plugs, wires etc...
Start with the basic Fuel, Air and Spark and maybe more gear.
 
Get an O2 sensor on the tailpipe as well.It'll help you tune that puppy.
 
I just reread the thread you mention playing with timing and valve lash but not the carb.
Is it stalling during a pull or just when give it by itself?
Can you see the fuel pressure gauge when it's under load an engine uses alot more fuel under load than free reving.
 
Lol didnt even get 2 pull yet. When free revin it seems to stutter. I thought I had it runnin 2day, got it outta the garage went down the drive way and it just fell flat. Even in granny first it stumbles.
 
if it has a solid lifter cam .022 on intakes and .026 on exhaust valves will wake her up......Just sayin :)
daredevil said:
.012 sounds too tight. Have you checked compression? I would run a vacuum and compression test to get some insight. What do the plugs look like?
Click to expand...
 
Jonnylightening said:
Lol didnt even get 2 pull yet. When free revin it seems to stutter. I thought I had it runnin 2day, got it outta the garage went down the drive way and it just fell flat. Even in granny first it stumbles.
Click to expand...

if it is crapping out on you when you hit the gas , im going to say that you are having carb or fuel issues . a little better description of whats going on would help. does it idle good? is it hesitating? boggin out ? high rpm misfire? all around misfire?
 
Is it a new carb, freshly rebuilt or been sitting around?
and 850 ain't too big for your engine.
 
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