I have a '99 Ram Slt with a 408 stroker. This is my first TBI stroker and I am running into some problems. First off the heads are stock, the intake is stock and I have added a Fastman 52mm TB (got it on Ebay dirt cheap). The cam is a MP purple Roller #5007551. This is one step up from the R/T cam. PCM is stock but I have added a Jet chip #90002S. I have installed a low temp thermostat and I am having a problem with light detonation under W.O.T. I am using premium fuel. I was wondering if anybody could tell me if the stock injectors may be causing this problem due to fuel starvation. I read somewhere that I should be running 28-30 lb. injectors. Can anyone verify any of this info for me. If you have a 408 Magnum I would like to hear from you.[&:]

 

Id definately up the injectors (i dont know jack about dodges, but from a general standpoint, thats a gooooood start). Id also get the comp tuned.

 

you need to call an expert. i'll bet you need a custom flash on the pcm for the 408 motor. KRC performance or Hughes engines.

 

The Fastman uses 24lb injectors in his 500 hp motors. I would go with some 24 lb injectors and send the comp to be reflashed with hughes engines. Got my injectors from comp cams and my comp tuned at hughes. love it!

 

Just for grins, take out the Jet chip and try running it a while. I have read in a number of forums pinging can be a common problem with these. You can always plug it back in.
I doubt if its an injector issue, but how warm is your engine running with the 180 T-stat? Preignition or pinging, can be caused by the internal combustion chamber temps or poor spark preigniting the air fuel mixture. It can be caused buy too lean a fuel mixture, but your stock injectors will easily handle 400 hp. Usually under injected enigines will run hot, even with a 180 stat.
Your cam overlap may be causing some issues too. Lazy low end airflow is an occasional culprit.

I caught your post because I was doing research on 408 strokers, I'd like to do this to my ram. Are you running premium fuel beacuse of the compression ratio?

 

The engine runs at 180 all day not much change there. Check out the cam specs below and let me know what you think. I am going to take the Jet chip out and run over it. I think it is causing a problem too. I'll get a flash on the PCM. The premium fuel was to get rid of the ping but that has not seemed to help much. Compression is 9.25:1. I don't think that is too high for premium fuel but the gas here (in Canada) is crap anyway. Pulling the tranny this weekend to install a transgo kit and replace the low/reverse I just burnt up..ooops! So you think that the stock injectors are fine for now? I was thinking of going bigger on the cam...not sure on that yet. I WANNA BUILD SOMETHING![8D]

[IMG]local://upfiles/49984/FCD7DC612A7A4BE088D76E498F84E629.jpg[/IMG]

 

I looked up your cam in the MP catalog, and I think its a bit stout for a heavy truck but should be ok in a stroker. It recommends a performance PCM.
Another issue with timing is that Mopars don't run a knock sensor system that retards timing when the sensor hears it. Since your engine is most likely knocking on the top end, I suspect your PCM has way too much advance built in. A custom flash will cure this...but I'd talk to someone like Hughes engines about it.
One of the Jet chips functions is too speed up this advance rate, which may cause it to ping even faster... [:@]

 

I did some research before selecting that cam and decided that because a stroker builds good torque down low by design I would broaden the TQ bad a little and go with a bigger cam. This is only a step up from the R/T but in a stroker the low-mid grunt is awsome. The stock intake will be replaced with an M1 along with new heads this winter. I will look into the PCM flash. Thanks.

 

I re re did the post AFTER reading the catalog (Blush)! But you had responded to my first draft! [:@][&o]

 

Seriously though, how do you like your 408?