Air injection tube removal....now what?

mean81GT · 02-15-2003, 01:47 AM

A friend and I just finished installing a freshly rebuilt 351W into his truck. But, we removed the air pump, and the tube that connects to the backs of each head. Does anyone know how to plug those holes now? They are really annoying leaks. We chased our tails for two weekends looking for the exhaust leak, but we found the holes, and then slapped ourselves in the foreheads.

horsesnake95 · 02-15-2003, 05:16 AM

I've heard of people taking and threading a bolt into the holes where the tube connects to the head..... not sure if it works or what size and thread pitch to use but it's worth a try.

BLACK85GT · 02-15-2003, 07:56 AM

yeah, just put a bolt in each hole. same size as the matching holes in front of the head(where accesories bolt up). thats why the heads are interchangable, left and right cause the hole goes all the way thru and is tapped the same on both ends.

HiFlow5 0 · 02-15-2003, 08:19 AM

They sell special plugs that fit directly into the thermactor holes in the back of the heads. You can also get bolts at any hardware store too, thats what I did. The size your looking for is a 5/8" thread about 1" long.

mean81GT · 02-15-2003, 09:07 AM

The threads are not the same as the accessory holes. I know this because the ******* engine builder put the heads on backwards, and wouldn't fix the problema after it was discovered. The owner of the vehicle doesn't want to rip everything back apart, so we kept the heads the way they are. We were able to fabricate new ways of mounting the front accessories, but the holes are gaping, and we need to seal them up. After all the work, JB quick weld isn't too appealing, but we're almost at our wits end with this project. Are there any caps for these holes that sit flush with the head? If so, where would I be able to pick them up? I tried getting something from Ford, but they claimed "Ford won't help a customer hinder the operation of the emissions system".

BLACK85GT · 02-15-2003, 12:26 PM

well, I am looking at the new holley heads on my engine stand and the holes for the air intake are the same as the front ones for the accessories. the driver side head has smaller holes for everything else though. but if you swap them the other head comes out the same. there is no left and right head as far as i know, but your friends heads might have inserts in them to make em work with his accessories? I have a pair of 351 heads in my shed i will look at. I know they have bolts blocking the air intakes also.

mean81GT · 02-15-2003, 12:40 PM

OK, thanks. Any info you can give would be great

HiFlow5 0 · 02-15-2003, 02:24 PM

Quote:

Originally posted by mean81GT
The threads are not the same as the accessory holes.

That's partly true. When set up properly the holes in the back of the heads will be larger. That's cause the holes in the front have reducer plugs in them to fit the accessory mounting brackets in. So yes, when that is done the holes are different sizes. If the engine builder didn't plug the rear holes and knew you were eliminating the smog equipment, then yes he messed up. But if you took it upon yourself to do remove the smog pump and did so with no lack of knowledge then your to blame, not the engine builder.

There are no difference in left to right of heads, just the reducers make the hole size different, not the way the head is manufactured making it different.

I'll say it again, go to the hardware store and get a 5/8" thread bolt, with and allen head (if you want it to sit flush with the head) and install them in the back of the heads. That's the thread size in the head before the reducer is installed.

mean81GT · 02-15-2003, 05:40 PM

I am going to get the 5/8' flush bolts. But the engine builder did screw up. These heads weren't new, or aftermarket. They came off of this engine, and the backs of the heads now have the reducers for the accessory bolts. Yes, the heads are interchangeable, but the heads are now on the opposite side from where they were when he received the engine. Thanks for your help guys.

HiFlow5 0 · 02-15-2003, 10:38 PM

See now that makes more sence! When the builder did the motor, did he install new reducers in the front for the accessories. Something sounds fishy about this builder, he should have noticed something like that when he was re-assembling the motor. I don't remember the thread size off hand for the reducers. I think its 7/16's, but don't quote me on that.

02-20-2003, 02:40 PM

Don't forget to coat those bolts to plug the heads with high-temp RTV silicone.

drudis · 02-20-2003, 04:03 PM

On a stock head...

02-15-2003, 01:47 AM	#1
mean81GT Registered Member Join Date: Nov 2001 Location: NY Posts: 299	Air injection tube removal....now what? A friend and I just finished installing a freshly rebuilt 351W into his truck. But, we removed the air pump, and the tube that connects to the backs of each head. Does anyone know how to plug those holes now? They are really annoying leaks. We chased our tails for two weekends looking for the exhaust leak, but we found the holes, and then slapped ourselves in the foreheads. __________________ I'm a glutton for punishment.

02-15-2003, 07:56 AM	#3
BLACK85GT Registered Member Join Date: May 2002 Location: Tampa,FLORIDA Posts: 340	yeah, just put a bolt in each hole. same size as the matching holes in front of the head(where accesories bolt up). thats why the heads are interchangable, left and right cause the hole goes all the way thru and is tapped the same on both ends. __________________ 5.0, Holley heads, 1.7 Scorp Rockers, Stealth intake, Holley 600 carb, Holley Mech. Fuel pump, MSD 6Digital, MSD distributor, Hotchkis upper/lower rear control arms, FMS B Springs, 3:73 (8.8) rear. Production # 9,377

02-15-2003, 08:19 AM	#4
HiFlow5 0 Registered Member Join Date: Mar 2000 Location: Springfield, Ma, usa Posts: 706	They sell special plugs that fit directly into the thermactor holes in the back of the heads. You can also get bolts at any hardware store too, thats what I did. The size your looking for is a 5/8" thread about 1" long. __________________ NewEngland Auto www.baystategearheads.com -91 Mustang Coupe, ex 4cyl (sold) -99 F150, 3" lift, 35" Procomps, Magnaflow exhaust

02-15-2003, 09:07 AM	#5
mean81GT Registered Member Join Date: Nov 2001 Location: NY Posts: 299	The threads are not the same as the accessory holes. I know this because the ******* engine builder put the heads on backwards, and wouldn't fix the problema after it was discovered. The owner of the vehicle doesn't want to rip everything back apart, so we kept the heads the way they are. We were able to fabricate new ways of mounting the front accessories, but the holes are gaping, and we need to seal them up. After all the work, JB quick weld isn't too appealing, but we're almost at our wits end with this project. Are there any caps for these holes that sit flush with the head? If so, where would I be able to pick them up? I tried getting something from Ford, but they claimed "Ford won't help a customer hinder the operation of the emissions system". __________________ I'm a glutton for punishment.

02-15-2003, 12:26 PM	#6
BLACK85GT Registered Member Join Date: May 2002 Location: Tampa,FLORIDA Posts: 340	well, I am looking at the new holley heads on my engine stand and the holes for the air intake are the same as the front ones for the accessories. the driver side head has smaller holes for everything else though. but if you swap them the other head comes out the same. there is no left and right head as far as i know, but your friends heads might have inserts in them to make em work with his accessories? I have a pair of 351 heads in my shed i will look at. I know they have bolts blocking the air intakes also. __________________ 5.0, Holley heads, 1.7 Scorp Rockers, Stealth intake, Holley 600 carb, Holley Mech. Fuel pump, MSD 6Digital, MSD distributor, Hotchkis upper/lower rear control arms, FMS B Springs, 3:73 (8.8) rear. Production # 9,377

02-15-2003, 05:16 AM	#2
horsesnake95 Registered Member Join Date: Oct 2002 Location: illinois Posts: 26	I've heard of people taking and threading a bolt into the holes where the tube connects to the head..... not sure if it works or what size and thread pitch to use but it's worth a try.

02-15-2003, 12:40 PM	#7
mean81GT Registered Member Join Date: Nov 2001 Location: NY Posts: 299	OK, thanks. Any info you can give would be great __________________ I'm a glutton for punishment.

02-15-2003, 05:40 PM	#9
mean81GT Registered Member Join Date: Nov 2001 Location: NY Posts: 299	I am going to get the 5/8' flush bolts. But the engine builder did screw up. These heads weren't new, or aftermarket. They came off of this engine, and the backs of the heads now have the reducers for the accessory bolts. Yes, the heads are interchangeable, but the heads are now on the opposite side from where they were when he received the engine. Thanks for your help guys. __________________ I'm a glutton for punishment.

02-15-2003, 10:38 PM	#10
HiFlow5 0 Registered Member Join Date: Mar 2000 Location: Springfield, Ma, usa Posts: 706	See now that makes more sence! When the builder did the motor, did he install new reducers in the front for the accessories. Something sounds fishy about this builder, he should have noticed something like that when he was re-assembling the motor. I don't remember the thread size off hand for the reducers. I think its 7/16's, but don't quote me on that. __________________ NewEngland Auto www.baystategearheads.com -91 Mustang Coupe, ex 4cyl (sold) -99 F150, 3" lift, 35" Procomps, Magnaflow exhaust

02-20-2003, 02:40 PM	#11
Simi Stang Guest Posts: n/a	RTV Don't forget to coat those bolts to plug the heads with high-temp RTV silicone.

02-20-2003, 04:03 PM	#12
drudis Moderator Join Date: Dec 1999 Location: Livonia, MI, USA Posts: 1,194	On a stock head... __________________ Darius Rudis, Moderator Corner Carvers Delight 1989 Mustang LX - Open Track Car http://www.dariusrudis.com

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