Okay so i got the backfire issue solved under no load. But i have another problem. It spits out the carb when i try to start it warm. And then if i put it under load it has exhaust backfire. Any reason it'll do both? Carbs are mostly a mystery to me so any suggestions will help. Thanks it's a 670 street avenger btw
I just cant get away from timing can i? Hah i thought i had fixed that... Maybe I'll take another look at it
Are you still trying to run this engine with a Performer RPM cam and roller lifters ? If you are, this is your problem. You cannot run roller lifters on a flat tappet cam. It just will not work.
Yes i am but it ran perfectly fine before the carb. And from what i am told the roller lifters will work fine with the cam with proper push rod length, which i did
http://www.mustangsplus.com/xcart/Ford-Mustang-Edelbrock-RPM-Hydraulic-Roller-Cams-for-289-302.html Preformer rpm cam for hydraulic roller lifters....
Is that the cam you have? All cams arent the same is why i ask. It could have a wear issue if its a flat tappet cam.
No, they will not. The lobe profile is different between the two types of cams. If you'll compare the lobes on the two types, you'll see that the flat tappet cam's lobe "peaks" have a more pointed profile, roller cam peaks are more rounded to allow the rollers to maintain contact with the lobe after the "peak" is passed. This needs to happen because of the heavier weight of the roller lifters to avoid having them "bounce". Roller cams open the valves faster, then close them more gently than a flat tappet cam does. Try to run flat tappet lifters on a roller cam profile and the lifters will dig into the lobes as the lobes try to lift the lifter. Roller lifters on a flat tappet cam, and you have the lifters bouncing with the sharper peaks, this would cause misfires with the valve springs loosing control over the lifters actions. If you have the cam you linked to in there, then fine, look for another cause. It's also possible that you have the wrong valve springs too, allowing the valves to float with the lifters bouncing, that's something to consider here too.
where is the old carb? if you are sure its the carb replace it with the old one see if the problem goes away.
okay, so the whole cam thing was really starting to worry me, so i pulled the cam. turns out i got lucky, heres mine. http://www.edelbrock.com/automotive/mc/camshafts/locator.php?part_number=2221&submit=go backed up by engraved numbers and all. which is nice to know that ive been going by the wrong cam card the whole time lol. so thats settled. roller cam for my roller lifters. and as far as the old one, i have it still. when i put this back together ill try that.
