Car dying in 4th Gear

[mustangLover281]

Hello Guys. I will try to make a quick explanation of what's happening with my Mustang. here is the engine set up: Motor is a 0.30 over 302 with forged pistons a new std. crank and bearings,the cam is an x303 with a 224 dur,and 542 lift roller with new lifters,felpro gaskets,melling hv oilpump,edelbrock intake,750 vac sec holley and bbk longtube headers,the heads are stock castings that have been ported and polished with comp cams springs, stainless ferrara valves185 in. The car made 281hp at the rear wheels on a dyno.

Now, the car is dying in 4th gear. what I mean by dying is that the engine is shutting down and not taking any gas, it feels like the engine just chokes up. this only happens in 4th gear. Also it only happens when I am "pedal to the metal". If I role on the gas in 4th gear, I have no problem whatsoever and the car pulls hard. I don't have that problem in any other gear. Basically this problem happens when I am "dragging". It doesn't feel like an Electric problem. I just changed the distributor cap and wires, and I have a K&N air filter. The only thing I am suspecious of is the Gas. Has anyone had this problem? or what do you think the problem might be?

 

[mustangLover281]

Anybody???

 

[86bluecobra]

a 750 on a 302 is way over kill. Odds are you are killing the engine with fuel. It would be worth finding out what your afr is. That will help you to narrow it down.

 

[86bluecobra]

also what gears do you have? When I installed my 351w into my car I had 2.73's. The car would buck and you could not punch it in 5th. Once I got 3.73's and brought the rpms up the car was much better. Perhaps your engine just needsa higher rpm range. What rpm in forth is the issue at? Can you slowly accelerate in fourth with no issues?

 

[mustangLover281]

I have 373 gears. the car does that only in 4th gear when I am completely on the gas. Ususally this happens when I am draggin the car. I will be fully on the gas in 1st, 2nd, and 3rd, and when I shift to 4th and dump it again, it just does what I explained in my first post which seems like the engine is choking and not taking any gas. if I am in 4th gear and I punch it without having dragged every gear before, I get no problems, the car pulls strong, so the answer to your question is Yes, if I accelerate slowly in 4th I get no problems. As for the RPM's, Almost as soon as I shift to 4th when I am draggin and dump the gas all the way down, I get that problem.

 

[TheUser]

Let me preface this by saying that I don't know anything about carbs.

It kinda seems (like 86BlueCobra said) that you're getting too much fuel. Perhaps its more of a sequence-of-events issue rather than a 4th gear issue; as you know, there really is nothing - especially on a carbed car - that links the tranny gear to the ignition of fuel. What I'm saying is that it's just a coincidence that it happens in fourth gear...that's just the point that the engine has gotten too much fuel, so if you don't mash it, it can maybe burn some of the fuel off, but when you do mash it in fourth, of course it just dumps more fuel in and maybe that's the point.

I wonder what would happen if you run out first and second at WOT, skip 3rd and go straight to fourth and go WOT? Obviously it won't accelerate as quickly and you'll drop quite a bit in the rpms from going from 2nd to 4th, but if it doesn't have the problem, then you'll know it's not necessarily a 4th gear issue.

I may be way off target, it's really just a guess.

 

[86bluecobra]

Another thing it could be is dirt in a jet or a needle seat. I had an issue like that and my secondary's would fill with gasoline. Once you stomped on it the gas would pour from the secondaries into the engine and die. It usally happened to me in first when I was trying to go throuh an intersection.