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Username Post: Sudden backfireing?        (Topic#355870)
HotRodg57 
"12th Year" Silver Supporting Member
Posts: 973
HotRodg57
Loc: San Marcos CA USA
Reg: 06-04-01
04-01-19 07:11 PM - Post#2763450    

For some reason for the last 2 weeks my truck has started to backfire whenever I get off the throttle, or decelerate. (52 1/2 ton 235-6 4spd)It runs great, and has been for a couple of years. It never did this before. Sounds kinda like twice pipes. My choke and throttle cables are all the way in. I haven't changed anything.
And it's getting irrigating. Any ideas?
Thanks
Rodger

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Shepherd 
Frequent Contributor
Posts: 1761

Loc: Lake George, NY
Reg: 11-11-15
04-02-19 08:08 AM - Post#2763482    
    In response to HotRodg57

A vacuum leak can cause that, it's thru the exhaust or intake?



 
HotRodg57 
"12th Year" Silver Supporting Member
Posts: 973
HotRodg57
Loc: San Marcos CA USA
Reg: 06-04-01
04-02-19 04:04 PM - Post#2763511    
    In response to Shepherd

Thanks, from the exhaust. I'll try checking with some carb spray for intake leaks.
Rodger

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HotRodg57 
"12th Year" Silver Supporting Member
Posts: 973
HotRodg57
Loc: San Marcos CA USA
Reg: 06-04-01
04-04-19 04:48 PM - Post#2763655    
    In response to HotRodg57

Looks like I need a new manifold gasket. It's leaking big time. Thanks for the tip.
Rodger

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HotRodg57 
"12th Year" Silver Supporting Member
Posts: 973
HotRodg57
Loc: San Marcos CA USA
Reg: 06-04-01
04-10-19 11:13 AM - Post#2763965    
    In response to HotRodg57

*Update- * Turns out my intake manifold bolts had come loose. The gasket "slipped" out of place a little. I tapped the gasket back into place and retightened the bolts. Purrs like a kitten again.
Rodger

Check out my Car Pics


 
wagonman100 
Super Senior Member
Posts: 14243
wagonman100
Loc: Baltimore, MD
Reg: 11-27-04
04-10-19 07:42 PM - Post#2764017    
    In response to HotRodg57

It’s always nice when a fix is easy and free.

Jay
Friends don’t let friends drive Fords.

1999 Silverado Z71 4X4 extra-cab short bed
1983 Malibu Fauxmad - tubbed
1978 El Camino Kustomized
1972 Monte Carlo
1957 210 handyman wagon
1957 Nomad sport wagon
1957 Cameo Carrier


 
Bel Air kiwi 
Deceased Member RIP
Posts: 4558
Bel Air kiwi
Loc: New Zealand
Reg: 04-24-14
04-17-19 06:07 PM - Post#2764432    
    In response to HotRodg57

Hi HotRodg57, The intake manifold gasket should not drop down when the manifold comes loose.
As built these engines had a short tubular sleeve that went in the intake ports and the gasket fitted over them so it cant drop.

This isn't just an install issue. Chevy put them there for exactly this reason. They support the gasket and align the manifold.

Have a look at a manual as there is a bit more to the proper sealing of the intake/exhaust combo than just tight.
A number of alignments matter.

Cheers Kiwi

48 3100 RHD, 51 Deluxe 4DR RHD, 51 Bel Air parts car, 52 Bel Air P-Glide LHD. Others 23T, 32 Tudor, 58 Edsel pacer 4DR HDT, 79 F250 351C RHD. 69,70,82 Capri. No mobile, no TV, and no Jap cars.

"They made a desert and called it peace." Tacitus


Edited by Bel Air kiwi on 04-17-19 06:08 PM. Reason for edit: No reason given.

 
HotRodg57 
"12th Year" Silver Supporting Member
Posts: 973
HotRodg57
Loc: San Marcos CA USA
Reg: 06-04-01
04-26-19 06:16 PM - Post#2765116    
    In response to Bel Air kiwi

Actually, it kinda slipped up. It was sitting about 1/4' above the manifold. I barely tapped it and it fell into place. Tightened up, and bingo
Rodger

Check out my Car Pics


 


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