Disappointing 408 Results - Sad No More!

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jimmyray

jimmyray

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Well, I've whined like a cheap amp with a ground loop about my disappointing drag ET's from my 408 equipped Duster. I started with a 408, eddy heads, hooker comp headers, M1 single plane, 3000 rpm stall, 727 manual reverse with a 4.10 sure grip 8.25 rear turning 275/55 17's Nitto 450's.

Baseline:

1. 3/14/08 - 14.17, 93.75 MPH
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Changed plug wires (bad), installed new fuel pump (starving top end)

2. 3/28/08 - 13.58, 99.96 MPH
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Changed Edel 1406 600 CFM for a Holly 750 DP, proform center

3. 4/05/08 - 12.97, 104.6 MPH
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Changed float levels, backed timing off about 2 degrees

4. 6/06/08 - 13.36, 105.3 MPH
NOTE: ET slower, but speed up. Severe traction issues, unprepped track
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Added SS springs, long shocks, adjustable pinion snubber, 28x10.5 slicks, frame ties welded in, uncorked headers.

5. 6/30/08 - 12.38, 108.67 MPH
NOTE: Car launched much better, best 60' of 1.684, down from a previous best of 1.898
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I think there is more left! I was only running 1/2 to 3/8's of a tank, and may have uncovered the pickup on the top end of the last coupl of runs. Also, we have not played with jetting at all, and only made 1 adjustment to the timing. Finally, the tranny is getting tired, and needs freshened. Shifts are a little slow, and converter may be getting loose on the top end. Also, I need to get a better tach and experiment with shift points.

All said, I am quite pleased that my pump gas, street Duster with full interior. Your excellent advice and experience have helped me to realize more of the potential of this combo. Call me one Happy Camper!

Thanks A-Bodies!!!

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Vast improvements in 3 months. I would guess the slicks were the single most significant modifications of those you made.
 
I bet an Air gap or Performer RPM would pick it up a bit.

Nice work on getting it turned around. Feels good, huh... 8)

There's more there, keep at it. :thumblef:
 
Mancini Racing also has adjustable snubbers for an 8 1/4 rear end.
 
Nice Job. My last 422 justwent 13.40s @105+ in an E body with a slipping trans, 3.23s, and low profile 17"wheel radials. A 2.6 60' was the best he could get...lol. Also pump gas, hydaulic cam, ported 587 heads, and a Crosswind.
Love those 4" engines.
 
heres a few questions i have.

are the eddy heads ported??
if so,any flow numbers??
is the M-1 ported??
whats the specs on the cam??
hyd/solid??
what did you launch at??
what did you shift at??
what did you trap at??
 
mikesduster said:
heres a few questions i have.

are the eddy heads ported??
if so,any flow numbers??
is the M-1 ported??
whats the specs on the cam??
hyd/solid??
what did you launch at??
what did you shift at??
what did you trap at??
Click to expand...

If you want to know how inexperienced I am at Drag Racing, just read the below responses...
newb.gif


1. Yes, they are ported/polished by Indy (lightly) with a Gasket match on the intake
2. Don't know, I bought them used
3. Gasket match only
4. Comp Cams .544/.541 236/242 110 centerline
5. Hydraulic Roller (89 truck block)
6. Revving to 2,500, but nailed it off the line with the slicks
7. Hopefully around 5500, but things happen fast in a 12 second car (at least for me!)
8. Not sure about trap RPM, I never think to look...#-oAgain, that happening fast thing.

I need to get a better tach, with a shift light, and be more disciplined about my launch and shift points, this I know.

What would you recommed?
 
I'd recomend shifting at a higher point in 300rpm jumps. Then when the times fall, back down in 200rpm jumps till it picks up. then back up in 100 rpm jumps. Keep at it till you find the best point of shifting by going back and forth in this manor.

I'd also do this on launch. But ethier test launch rpm first or shift rpm, not both at the same time. (I think launch should be first to test for lowest 60 ft. times)

Any shift light that is easy to see is a good canidate. Mount it right in front of you.
 
Try to find out at what RPM you push through the brakes. That's your high limit for launches.

Do the same thing that rumble mentioned about shift points for launches. Up it 200-300 RPM til it starts blowing off the tires, then back it down. Another possibility, your car may not like launching against a loaded convertor. Try going the other way, down in RPM, and flashing it hard.

The fuel pump and carb change shows just how much your mill was starving for fuel. Bump up the secondary jetting 2-3 steps until the MPH falls off, then back it down to get your best trap MPH.

You might be investing in a rear end soon...

Nice job on the changes.
 
crackedback said:
You might be investing in a rear end soon...
Click to expand...

Funny you say that. I bought a set of cut down BBP axles and an original 8.75 housing to mate with my 3.23 sure grip. I asked the guy to package it well, to proetect the housing studs. FedEx lost the housing, then finally found and delived it. He shipped it with only shrink wrap around it! All of the studs were busted out of the ends of the housing, and half of the housing studs for the pumpkin were either busted in or broken off.

The studs may have only been knocked loose, but then again the housing may have been destroyed. Don't know, I refused to accept the shipment. I have an old B-Body that I can get cut down, but I'm concerned the perches won't be put in the right place.

I think I'll just run the 8.25 til it dies, which I am sure it will do at the most inopportune moment, and then either put in a pieced together 8.75, or just spring for a Dana, and be done with it.
 
with the body all you have to do really is move the perches, but if you want to cut it you can. The B Body will be a good back up. Maybe have the perches moved in 1/2 inch as soon as possible so when you need it all you have to do is bolt it in
 
74Burntorange said:
with the body all you have to do really is move the perches, but if you want to cut it you can. The B Body will be a good back up. Maybe have the perches moved in 1/2 inch as soon as possible so when you need it all you have to do is bolt it in
Click to expand...

And just a bit more offset for the wheels. Otherwise stuff sticks way out of the fenderwells.
 
not much maybe 1 inch to 1.8, but ya with some thats alot
 
Hi guys just readin the threads.I was running a 8 1/4 rearend 372 stroker(450hp)dynoed.Also 4 speed,410 gears.I ran [email protected],ve been scared to dump the clutch,thats why low e.t. Anyway last time i was at the track I thought i,d rev er up a bit. Well??? SNAP there goes the axel.Thank the mopar gods i didn,t cave in my 1/4 panel.I,m putting in 8 3/4 with strange axels and swapping 3.23 for 4.10.My advice if your running 8 1/4 rearend with a bit of hp.c-clip eliminators it may save your investment.I just got lucky because i would have cryed at the track that day.shootin for high 11,s now.Get my launch down:Where is your other 2 lug nuts?Very brave!!!!
 
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