[delgadog]

i just installed gt40-p heads about 2-3 weeks ago. only after the heads were installed i started experiancing back fires and some hesitation in the car. when i get on the gas it starts to sputter and i can't stand it! i did some research and i read i have to retard the timing to reduce detonation... i was kinda hoping to find out what everyone with a similar set up as me has for timing??? i have a 306 with stock MAF and injectors and the last time i remember the timing was advanced. also, i keep hearing some metal clanking around in one of the cylinder heads, a mechanic told me it could be the lifters... i have stock springs and push rods with 1.7 roller rockers, is there a possibility that i have bad lifters and the timing needs to be retarded due to the higher compression??? and is retarding the timing something i might be able to do in my drive way with the proper tools??? or should i just go somewhere to get the timing retarded??? i'm racking my brain as to what it could be... also, vaccume lines are good. thank you for your help!!!

[WildWill]

when i first put my heads on I had this exact same issue. as it turned out my timing was waayyyy off!!!! I guarantee that you didn't put your dizzy back in correctly when you put everything back together. check your base timing. you do not need to retard your timing at all with your new heads, I actually advanced mine.

also... check your sparkplug wires. did you get 90 degree boots to go with your "p" specific headers? if not, then I can also pretty much guarantee you that you have burned up at least one plug wire and you are most likely only running on 6 or 7 cylinders. I made this mistake at first too.

clanking in your heads is a bad thing. try and get your timing right and check your plug wires before you do anything else... then update us and we will see where to go from there.

[WildWill]

oh and just so you know, I'm running base timing at 14* with zero problems.

[1slo5.0]

Like I said in your last thread, "Did you have the heads milled at all? If not then you haven't changed the compression ratio because the chamber size is the same as the original E7 heads.

When did the backfire and hesitation problems start? After the swap? Is the distributor phased correctly? What is the timing set at and was it set correctly? Did you check for vacuum leaks? Double check and make sure everything is connected properly. Scan for codes".

You also said in a previous post "new springs, which by the way were to stiff for my hydrolic cam". Until you put the correct parts together you are going to have nothing but problems and broken parts.

[delgadog]

ok, i'll check the dizzy and put the timing to 14* as a base line. yes, i have new plugs with the 90* boots with heat wraps so they don't get burnt up. i checked and rechecked for vaccume leaks, and nothing. i did port and polishing to these heads. when the mechanic put the springs i bought he said that the cam couldn't push up the rockers, so i had the new springs out with my stockers. the back fire only started after the head swap. so i don't get it...