408 timing
03-01-2014, 06:56 AM
#21
All those cams are way larger than his.
Well there is always some a hole that comes along to try to prove you wrong. Apples to Microsoft I say.
03-01-2014, 12:16 PM
#22
Now on to your issue. I think 23* is very low and is a reason for a good bit of the power loss. Your cylinder heads will dictate your final timing. Most stock casting heads will be around the 28* mark some aftermarket heads, depending on the chamber, will have a lil less. Your 9 inch rear isn't helping any either. That is one of the most power robbing rears out there. No matter though, you need it to take the abuse and get the power to the ground. Unlocked is another issue but usually Vigs are pretty efficient even unlocked. Just a side note, you will need more converter for that motor with those cubes and cam.
I would like to know what exhaust is on the car. Ideally, I would like to see a 1 7/8-2 inch primary with a 3 inch collector and a true dual setup for max power.
IMO, I have never been a fan of the Dart LS heads and Larry Meaux is local to me but in the LS world, I have not been impressed with some of the local cars I have seen with his heads on.
Where did you get it tuned at? Do you have a dyno sheet? Did you run it down the 1/4 yet?
03-01-2014, 02:33 PM
#24
You have alot of factors hindering you and we just need to nail them down one by one.
As for your camshaft, you spent alot of money on your heads and having them ported and then money spent on stroking a bottom half, why would skimp and use off the shelf cam? At that point, it would of been wise to get a cam spec'd out by one of the sponsors on here and its not much more money. Some of them are Martin@Tick, Geoff Skinner@EPS, and Pat G. It costs an extra 25 bucks for them to get you one custom to work with your setup. Not saying the TSP giant is a bad cam but it has been around for awhile and there are alot of newer lobes and cam technology out now.
03-01-2014, 03:15 PM
#27
Well, I don't see anything wrong with the FTP lid but I would take that cross flow spintech off and see what it would do.
I dyno'd a 3rd gen with a 355 with the same spintech piping you have but it had a 4 inch in and a 4 inch out muffler. I took the muffler off and I thing it gained 2 hp. That could of been anything though.
You on the other hand have a bigger motor flowing way more air. You would need the same muffler or run it straight off the y pipe. There was a thread on here a long time ago and a bunch of guys put up their specs and what cat back they were running and if they had a cutout. The consensus was that the magnaflow catback was the least restrictive but nothing beat a cutout.
I dyno'd a 3rd gen with a 355 with the same spintech piping you have but it had a 4 inch in and a 4 inch out muffler. I took the muffler off and I thing it gained 2 hp. That could of been anything though.
You on the other hand have a bigger motor flowing way more air. You would need the same muffler or run it straight off the y pipe. There was a thread on here a long time ago and a bunch of guys put up their specs and what cat back they were running and if they had a cutout. The consensus was that the magnaflow catback was the least restrictive but nothing beat a cutout.
03-01-2014, 03:38 PM
#28
But also silver, I wouldn't say aftermarket heads will not also be able to use 28* to their advantage. That is an assumption that doesn't always hold true. I have seen some aftermarket heads take 30* and make very good power. Would I run that on the street? Probably not, but still, it happens.
03-01-2014, 03:50 PM
#29
Than the person I was specifically talking about. That is what you were trying to prove me wrong on.
But also silver, I wouldn't say aftermarket heads will not also be able to use 28* to their advantage. That is an assumption that doesn't always hold true. I have seen some aftermarket heads take 30* and make very good power. Would I run that on the street? Probably not, but still, it happens.
But also silver, I wouldn't say aftermarket heads will not also be able to use 28* to their advantage. That is an assumption that doesn't always hold true. I have seen some aftermarket heads take 30* and make very good power. Would I run that on the street? Probably not, but still, it happens.
03-01-2014, 04:10 PM
#32
The graph is in mph. I wish it would of been in rpm. Going by other graphs, those start at 2500 rpm and increases at 500 rpm per vertical line. If that is the case then this motor peaked at roughly 5500 rpm and that is all wrong for a 408 with a 248/254 cam.
With 23* of timing and the AFR at 12.6 alot of work needs to be done.
03-01-2014, 04:19 PM
#33
The entire combo seems wrong to me though.
Even the original graph is odd. Almost plateaus then takes off. The red numbers cross at different intervals. Either it has an odd converter or it was in the wrong gear?
Too many questions. Although that huge dip LOOKS like knock it doesnt show on the AFR so idk how to explain that one. A stalled auto during a shift would show a large torque spike and a change in mph a bit.
Silver that is likely why they have the graph in mph. A 3600 stall in rpm...the graph would last 2 seconds lol.
Even the original graph is odd. Almost plateaus then takes off. The red numbers cross at different intervals. Either it has an odd converter or it was in the wrong gear?
Too many questions. Although that huge dip LOOKS like knock it doesnt show on the AFR so idk how to explain that one. A stalled auto during a shift would show a large torque spike and a change in mph a bit.
Silver that is likely why they have the graph in mph. A 3600 stall in rpm...the graph would last 2 seconds lol.
03-01-2014, 04:46 PM
#34
It could also be that they started the pull too early and the converter flashed at that point too. We could go on for days about this graph, the OP needs to look over his combo and check thru the whole engine to make sure every thing is kosher.
This car should be making about another 40 horses easy with this setup.
OP, I would check compression to make sure everything is good on that part and that will tell you also if the cam might be off. You're missing roughly about 5* of timing which is good for some power right there. Take that muffler off and see if the car puts down a better number too. Check to see if you throttle blade is opening up all the way with the pedal pressed to the floor. I have seen that before with the cable adjusted wrong. Check your plugs and make sure they are good. You could possibly have a weak coil. Check that converter and make sure its coupling right and putting your power to the ground. I have seen converters that were back yard pieces of junk that couldn't hold the power of a lawnmower, let alone a 408.
I think that list should keep you busy for awhile. Check back with us and let us know what you find.
This car should be making about another 40 horses easy with this setup.
OP, I would check compression to make sure everything is good on that part and that will tell you also if the cam might be off. You're missing roughly about 5* of timing which is good for some power right there. Take that muffler off and see if the car puts down a better number too. Check to see if you throttle blade is opening up all the way with the pedal pressed to the floor. I have seen that before with the cable adjusted wrong. Check your plugs and make sure they are good. You could possibly have a weak coil. Check that converter and make sure its coupling right and putting your power to the ground. I have seen converters that were back yard pieces of junk that couldn't hold the power of a lawnmower, let alone a 408.
I think that list should keep you busy for awhile. Check back with us and let us know what you find.
03-01-2014, 04:46 PM
#35
Than the person I was specifically talking about. That is what you were trying to prove me wrong on.
03-01-2014, 04:55 PM
#37
Your ideas do not seem realistic as to advantages of a 408 vs a 364. He should be at 460 or a tad over with the correct combo and quite a bit more tq. Nearly all the dynos you quoted had afr heads and mostly.....custom cams....hmm....on one part your links seem right. And most of those were done by patg.
And as long as it is a new vig and locked to remove some fluid coupling loss, it should be good.
And as long as it is a new vig and locked to remove some fluid coupling loss, it should be good.
