GT40P heads - Stock exhaust manifolds

[Stock Farm]

I thought I read on this site that the stock exhaust manifolds could be used with GT40P heads, now I can’t find it. Any info would be appreciated.

I have the shorty headers from BC Broncos but would prefer to use stock manifolds, my exhaust system is new and would rather not replace the Y-pipe.

I’ll be tackling this tomorrow and curious what needs to be trimmed to make them fit and if there are any heat issues (on the plug wires).

Thanks in advance

 

[bronco loco]

Just some shaving is needed.

 

[JKH67302]

BC does not advertise it, but BC told me the headers will fit the P heads. I almost went that route but decided to save some money. I used stock explorer manifolds from my donor instead.
James

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[Stock Farm]

Yes the headers fit the GT40P heads. I just want to use the stock manifolds if i can. If it’s simple shaving, I’ll do it tomorrow.

 

[JKH67302]

Yep simple shaving to make the stock manifolds fit. I found some pics on a Mustang site, it looked easy.
James

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[Eoth]

I shaved them to fit but kept melting spark plug caps. I suppose i could have kept shaving them but I was uncomfortable with how thin the walls were getting. Tried heat shields, insulation, different caps, etc.... After a couple of grinds i just gave up and bought a set of Bronco Hut headers. Should have done it from beginning..

 

[thegreatjustino]

I thought I read on this site that the stock exhaust manifolds could be used with GT40P heads, now I can’t find it.

https://classicbroncos.com/forums/showthread.php?t=211468

 

[1buckeyefan1]

I'm at the same crossroads.. tempted to use my stock GT40P manifolds vs. buying the BC or Broncohut shorty headers..

If you decide to sell your headers, let me know

 

[ScanmanSteven]

BC Broncos headers can work with P heads but burning plug wires will happen. I went through probably 5-6 sets of wires before I changed heads. There are hard ceramic plug ends that probably would have worked but I didn’t discover them until after I changed heads. I bought Allen head cap bolts so I could use the rounded allen wrenches. PIA still.

 

[Teal68]

I used shorty FMS stainless headers in my wife's automatic transmission Bronco, and manifolds in my stick shift Bronco.. I ground the stock manifolds a bunch! Seem ridiculous thin in spots, but been fine for 4,000+ miles now. The boot on one plug is slightly charred, but not a problem.

I swear hers seems to perform better. Both engines are identical aside from the manifolds/headers. Hers does have smaller tires though.

 

[theshadow]

A good thread for all things GT40P - includes header brands that fit (doesn't address Bronco drivetrain issues - Mustang thread)

https://r.tapatalk.com/shareLink/to...7&share_fid=1819&share_type=t&link_source=app

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[Stock Farm]

Thanks for the info. I went with the headers. Anyone know the simplest way to adapt a flange/reducer to the Y-pipe?