Been tweaking on my girlfriends new car (85 trans am, LG4 305, 262 cam, edle intake, headers, 3.42 gears, holley 600 carb) and the holley carb on there was tuned by a guy that really doesn't know jack about holley's........I"ve been too lazy to open it up and see how badly he ****ed it up, but I got it fixed so that now it doesn't bog.....problem is, sometimes when I race people the motor will pop/bog/stutter out the exhaust like its either running out of gas or just something's wrong. I figure its either valve float or running too lean. The motor pulls all the way to 6,000 rpms, but right when it gets that high its starts popping and really slows the car down. The valve train on the motor is probably the original 160K 1985 305 stuff since the guy that did the comp 262 cam said he didn't install performance valvesprings when he did the swap. Any ideas?

 

Popping in the exhaust = raw fuel passing through the motor
Popping in the intake = lean

Doesn't sound to me like it's lean.

I'd guess you have a combination of valve float and poor ignition. If one of those XE cams is under a set of worn-out stock valve springs, it's a time bomb, just waiting to drop a valve at that kind of RPMs.

Change the valve springs first, since that's an obvious, known defect. Then go from there.

 

Your old weased out valve springs are the cause of your problem. My recommendation would be to pull the junk 5.0 out and put in a healthy 5.7. quit foolin' around with slow weased out junk. Or else spend the couple of hundred to put in new springs. the choice is yours.

 

sounds like ignition to me....

 

Well if you read my sig........the camaro that my girlfriend wrecked had a newly installed crate motor 350 in it which is now sitting at my parents house (it survived the wreck)...........I'm mainly just seeing how fast I can make this old POS 305 go before it blows. I have that 350 with ported heads, 268 cam, Comp roller rockers, ect.......just waiting to be put into its new home. Hence the reason I'm beating the hell out of the 305

 

you and your girlfriend won't be beat'n it too much longer with those springs in there.. Spend a days pay and another day of your time and put some springs in there and then see what that motor can do.

 

Hell, if you rev it that high very often you wont have to worry about it for too long.

 

hell, the redline starts at 5000 , so six is really thrashing it!

if the top end dont blow then the bottom prob will

 

i hear a very familiar loud knocking noise...........

 

say hi to the rods when you see them for me!

 

u get like a pop/bog when ur trying to give it gas right? is the engine hot by then? if so replace the ignition control modula. i had the same probalem with my car. i didnt know it was that untile after i put a new fuel pump, fuel filter, spark plugs, coil, and a new edelbrock carb on. and it still gave me that problem even at low rpms and on day it died on me and well we replaced the control modula at work and to our surprise it was old and dirty and looked to be the only thing not replaced when everything else in the distributor was but after we took it out it only had 2 spots of that heat sink stuff on it. so we replaced it and put a crap load of the heat sink stuff on it and well too this day i have not had a problem since.

and now after driving for 15-20 mins i can still get on it with out worriing of anything poping or boging or anything.

 

I dont' think you guys are familiar with non-stock small block chevy's...........revving over 5,000 is no big deal. The factory red line has absolutely nothing to do with what a cammed motor with different intake, carb/headers can rev to. The stock redline on my firebirds truck 350 was 4,500.............I've taken it to 6,500 hundreds of time, nothing bad has happened. This motor in her car peaks at 6,000 rpms with this cam, so thats what i need to be shifting at.