boost/driveability problems

[bobwieser]

hey everyone, i have a STOCK 79 sport coupe, when boost pressure just illuminates the red dash light i experience a popping from the carb and a serious power loss, I checked all vacuum lines but got no further, any ideas?

 

[charlief1]

First thing I'd check is your timing Bob. Do you have any type of boost gauge on it now or are you going on the seat of the pants feel.

 

[bobwieser]

i am going by the popping from the carb, (its loud) and the car jerks when this happens, i did check the esc circuit and its functioning per the buick manuals test

 

[charlief1]

Not talking about the ESC Bob. Check what the timing is doing. You may have a timing chain going out which is causing the timing issues. This would be the poping sound, or back fire.

 

[FlintBuick4Life]

Oh man, I hope its just the timing and not a blown gasket. I blew both my head gaskets a few months ago and mine was doing the same thing.

 

[mat231v6]

Oh man, I hope its just the timing and not a blown gasket. I blew both my head gaskets a few months ago and mine was doing the same thing.

wow i didn't know you blew a head gasket that stinks.

 

[FlintBuick4Life]

wow i didn't know you blew a head gasket that stinks.

Yeah, both of them. I think one was blow for awhile, but never had any problems unless I went out of town and I would have the same problem as Bob. When the other one went, I diffidently noticed it... It would backfire out of the carb just like Bob here, only mine was really bad and hard to keep running. Did a compression test, turns out I was only running on 2 1/2 cylinders The 1/2 was the distributor caps fault:biggrin: Wasn't fun, had to rebuilt the top half of the engine

 

[mat231v6]

Yeah, both of them. I think one was blow for awhile, but never had any problems unless I went out of town and I would have the same problem as Bob. When the other one went, I diffidently noticed it... It would backfire out of the carb just like Bob here, only mine was really bad and hard to keep running. Did a compression test, turns out I was only running on 2 1/2 cylinders The 1/2 was the distributor caps fault:biggrin: Wasn't fun, had to rebuilt the top half of the engine

sorry to hear that. did you port the heads while they were off.

 

[WarWagon]

i am going by the popping from the carb, (its loud) and the car jerks when this happens, i did check the esc circuit and its functioning per the buick manuals test

Like Charlie suggested, have to check the base Ignition timing, being too lean on fuel will cause this too along with burnt valve/seat. I'm going with Ignition timing and fuel delivery problems.

 

[FlintBuick4Life]

sorry to hear that. did you port the heads while they were off.

Yeah, but not much... didn't have time to go all out on them, but I will on the old ones:biggrin: I`m betting its just an timing, ignition or fuel problem too, blown head gaskets where the last thing on my list to check... but sure enough When did you change the fuel filter last? Might also be your pump going out, but that`s another last check thing along with head gaskets, seals...

 

[charlief1]

Yeah, but not much... didn't have time to go all out on them, but I will on the old ones:biggrin: I`m betting its just an timing, ignition or fuel problem too, blown head gaskets where the last thing on my list to check... but sure enough When did you change the fuel filter last? Might also be your pump going out, but that`s another last check thing along with head gaskets, seals...

Very good point about the fuel pump Jase. Rich had a simular issue this past fall and it turned out he needed to rejet the secondaries if I remember right. I found him a high performance pump to try and it didn't fix the problem but it was better than the original design. I don't know if he kept it on there or not though.

 

[mat231v6]

Very good point about the fuel pump Jase. Rich had a simular issue this past fall and it turned out he needed to rejet the secondaries if I remember right. I found him a high performance pump to try and it didn't fix the problem but it was better than the original design. I don't know if he kept it on there or not though.

where do you get the jets at?

 

[Ttype83]

where do you get the jets at?

Rochester Carb / Quadrajet Parts Page

 

[mat231v6]

Rochester Carb / Quadrajet Parts Page

thank you by any chance do you know what the stock jet are.

 

[charlief1]

Which Q jet Matt?

 

[mat231v6]

Which Q jet Matt?

78 carb

 

[charlief1]

64's in the primarys for the one I have here Matt. Kind of small but it's all stock. I'll probibly go up to 75's or maybe a little bigger depending on how she runs.

 

[Ttype83]

I never changed my primarys. I changed the secondaries and hanger for quicker opening. Junkyards are your friend too for these

 

[charlief1]

If you're using an E4ME and not a 4M or 4ME you can't change the primaries. You can on the on the earlier ones but not after 81 unless it's non CCC.

 

[bobwieser]

i checked the timing, it is ok, so i am hoping it is a lean condition. engine has about 15000 on a stock rebuild, so hoping no valve/gasket issues. I will change the fuel filter next, its been awhile since i did that. the car runs smooth and strong, no misfire , this only occurs when you want to really stomp on it. I also checked vaccume hoses, pevr, etc;