Re: poor dyno numbers from 408 :(
 

I looked at your build sheet. The xe284h cam is part number 31-250-4. Comp Cams site says any cam with a 31 prefix uses the old firing order 1-5-4-2-6-3-7-8. If you are useing 1-3-7-2-6-5-4-8 this is your problem. I've seen it before.

Re: poor dyno numbers from 408 :(
 

Andy669- I am thinking he would benefit most from a custom cam, which I think he will have no problems with purchasing. Even though it is a shelf cam, I really think this thing should be able to run decent with that cam. I also found the specs on the Edelbrock valve springs and can post them if they would help at all.


7DMach1- I checked the firing order and it was where "I" thought it should be. I looked all over Comp cams website and can not find where it talks about the proper firing order. Where did you find that? I can not remember what firing order I went with, so now I got to take a look at my notes if I can find them.

thanks,
Ryan

Re: poor dyno numbers from 408 :(
 

I'll second that. A representative at Comp cams told me this very thing. Prefix 31 is the old 302 firing order and Prefix 35 is the 351W and HO 302 firing order.

Re: poor dyno numbers from 408 :(
 

Here's where I found it. Ray
http://www.compcams.com/Technical/Cu...HTML/62-65.asp

Re: poor dyno numbers from 408 :(
 

I appreciate the help, but the cam card I have has a 35 prefix, so as I understand the replies that would mean I need the late style firing order??
Ryan

Re: poor dyno numbers from 408 :(
 

If the firing order was wrong, you would hear it. Plus, if that thing made 300 horses on only 4 cylinders? Holy shit! That thing would be a monster. 1-2-6-8 will still fire correctly either way. Good thought, but I dont think thats the problem.

It could very well be something timing related. 15 degrees of timing was worth exactly 100 horsepower in my car.

Andy

Re: poor dyno numbers from 408 :(
 

I really think it is going to be the timing. I have just gotten busy with work here (begining of my work week) and have not had time to put the advancement pieces back in.

I am hoping tomorrow to put it together correctly, which should give me atleast 20 more degrees total advancement (give or take a few). Will post when we do it.
Ryan

Re: poor dyno numbers from 408 :(
 

Heres a couple of my dyno pulls.

Andy

Re: poor dyno numbers from 408 :(
 

Andy669,
thanks for posting that....gonna be a few days before the car can do a pull again......see the other post. :(
Ryan

Re: poor dyno numbers from 408 :(
 

Well, the thing feels tons better since we have played with timing and fixed the broken timing chain cover :) The big rear tires dont seem big at all on this car.

I think a dyno is gonna show it is falling sooner then it should. Around 5,000 5,500 she still falls off. I believe the cam is designed to pull to 6,500. I am kinda thinking the high volume carter fuel pump (mechanical) may not be able to keep up at the higher rpms. Any thoughts?
Ryan

Re: poor dyno numbers from 408 :(
 

I may have found another problem. The car looks to still have 2.25 exhaust on it. I dont see how the thing could be breathing thru that with its cubes.
Ryan

Re: poor dyno numbers from 408 :(
 

I would imagine a 408 would be pretty choked breathing through 2 1/4. Its time for 3 inch.

Re: poor dyno numbers from 408 :(
 

Im not thinking that edelbrock performer head is gonna flow enough for 408 ci 6500 rpm pulls. Exhaust needs upgrading as well.