so i'm currently running a 87 trans am with a 305 tpi, it has 140,000 miles on it, and i have just replaced the stock fuel filter, i have replaced the cat with a exhaust cut out and i have year old spark plugs and stock spark plug wires...these are all reasons why when i rev up between 4500-5000 i hear popping, like its sorta backfiring even when the exhaust valve is closed...oh i also have a cool air induction system on it so i know its breathing right, what can be causing this popping sound? is it the old wires or is it cuz i dont have headers to complete the no resistance air pump that is my engine?....thanks guys

-brian

 

spend $60 on some wires and plugs and see what happens

 

By stock plug wires, do you mean they're original?!

Does it only pop when you let off the throttle, or is it all the time?

 

yeah i was thinking about that... he said it does it when the "exhaust valves are closed" maybe you have the timing off and are pinging the motor?

i would check the fuel pressure, and swap the plugs/wires and see what happens

 

well i meant the electric dump valve for the exhaust pipe...and it only pops when i rev it up real high, like 4500-5000 and keep revving until it shifts, i also seem to lose some power with that too, adn yes, by stock wires i do mean original....i suppose it wouldnt hurt to swap them out lol

 

dude i wouldnt be suprised if you picked up 20rwhp from putting a set of crap wires on there

get some 8.5mm MSD Superconductors, and some new plugs... and be prepared to be amazed at the difference a set of wires can make.

also, the popping noise is just the exhaust allowing air into the piping at the dump valve, causing it to make that sound. and you dont want to rev your motor over 4500rpm... its pointless, because your peak hp is deffiently nowhere over 4500rpm. save up and get a shift kit and a ratchet shifter, youll be very happy with it

 

well i'm going to return a pair of balljoints which i got (i paid 75 for the pair and my dad picked up a pair for 50, so i'm gonna just return the 75 one) and return a set of brakepads that i got cuz ithought my front brakes were bad but theyre not, i'll pick up some wires and i guess a nice set of double platinum plugs too...i am about to order some hooker shorty headers and so hopefully that'll help with the power...i dont want to do too muchto this motor cuz after the headers i'm going to save up for a 350 long block from the junkyard and build it up a little and put that in, then save up for a t5 trans...i have seen a 6 speed rebuild kit for it but thats for a different forum...but what is the peak rpm for power though with these cars?

 

Don't waste your money on those double platinum plugs. They're more of a gimmick than anything. Just get some standard platnum plugs.

 

just get some ac delco plugs, like $1.50 a piece. that will be more than sufficient for you.

also, a T5 (unless its a world class) wont really hold up to a 350 for very long, if at all. they were meant for a 4 and 6 cylinder motor, they worked ok in a 305 and not at all in a 350... thats why the 350 cars came only automatic from the factory

 

oh true, well then waht did they use in vettes for that time whenthey had manuals? and good to know about the double plats, i got some cheapo plugs a year ago when i did the valve seals...its still burnin oil whenever i start so i dont think they did a very good job haha but the plugs are probably alraedy fowled haha

 

From '84-'88, the Corvette used the goofy 4+3 transmission. It was a 4-speed manual coupled to an automatic overdrive on the top three gears. From '89 on they used a ZF 6 speed. Not sure if these will swap to a third gen because I've never heard of it being done before. Doesn't mean it can't be done though. But if you really want a manual trans, I'd stick with the T56 you mentioned above. If you're having fouling problems, go with some quality platinum plugs. They'll resist fouling because they fire hotter than regular copper plugs.

 

I did this a while ago, but i got 2 of my wires backwards. #5,7. The car was hard to start, and seemed to run ok, but gave me a popping sound.

Took me a while to realize, cuz i USUALLY dont do this.

Popping happens for 1 main reason. A plug isnt firing, and the gas builds up and eventually the compression is too much so it explodes.

Another reason is late spark. So the explosion occurs in your exhaust pipe not your cylinder.

Its odd that it only occurs in THAT rpm range.

Change your plug wires (if they are in the right order).


As for plugs. these cars LOVE the cheap AC delcos. Dont get bosch or anything too fancy. The regular AC delcos, champions, or if you wanna get a "performance plug" get the rapid fire or split fire, or something like that.

 

+1 for Champion platinums.

 

so today i did some work, ithink i may have found the culprit for the popping problem and i have deffinately re-gained some h.p....so remember how i told you i had the original 1987 spark plug wires? well apparently this thing has never seen a tune up because not only was i able to rip a plug wire by my own hands (i'm weak, and i was pretty pissed off at all the clips holding the wires in) then when managed to over think the firing order so i called my dad...he went to take off the wire to the coil, and the damn plug came right out of the distributor cap...come to find out the cap was cracked, the rotor was worn like hell and one point on the cap was almost missing it was so worn, not to mention the plug wires were totally worn inside, so now that i know that its never been tuned up really in 20 years, i guess i have some work to do on it soon lol

 

Yep you bet. In a case like that, the problem could be anything, or in your case EVERYTHING

So get some champions or AC delco. If you dont want to spend $$$ on plug wires, just get stock ones. However, i would strongly recommend you buy a high performance wire, the 8.5mmones, and a colour of your choice. Its definately a good investment, and if you take care of it, will run you anohther $10 years. And the internals on the distributor arent that expensive, or hard to replace.

Your looking at around $100 for this tune-up. But remember that the plug wires cost around $40-80 depending on which you get.

Get this all replaced, dial in the timing, and you should be running much smoother probably much more powerful too.


DONT FORGET TO GAP THE PLUGS>

 

Many of the TPI Firebirds have the window and mirror switches mounted right behind the shifter. They don't even offer a ratchet shifter for My Formula. Just a thought...

 

my car has that like popping sound or w/e from the exhaust when i let off the gas and im in drive or i rev it up in neutral. I have no cats or anything. I think its just the exhaus. nothing wrong. It doesnt pop when drivig and it runs smooth.

 

yeah mine pops too when its decelerating, but i meant when i was still accelerating it would sound almost as if it was back firing

 

on the cap and rotor depending on the type if your cap is a bolt down or the twisty one STAY AWAY FROM CHECKERS nascar ones i had the rotor fly apart on my 86 ta with a 350 and on my 88 gta 350 the plastic they used on thoes were cheap and it always serprated near the bolts on the first one i has to repair the dis shaft becuse one of the tops of the rotor bolts went down into it lucky the lower screen caught it

 

I believe his should be a screw-down type distributor cap (if the distributor is, in fact, stock).

I have an '86 TPI 305, and it has a screw-down cap (Hell, I have a nice, brand new Summit Racing HEI Cap sitting here that I couldn't use because it is clamp-down-style).

 

mp81 you are correct, for a tpi it is a screw down cap...the rotor just slides on which i presume would be the same for every car