Ram horn manifold - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Breadstick · 06-07-2021, 10:03 AM

If anyone was wondering what size bolts to get for the OEM 350 exhaust manifold, the thread size is 3/16 24 and the middle size is 2 3/4. I found this through trial and error and I only found ONE bolt this size between Lowes, O'reilly, Napa, and Advance auto parts. I have lots of 3", so I'm going to have to cut them down. Apparently no one wants to run the original manifold anymore.

**MJN** · 06-07-2021, 10:44 AM

which bolts- manifold to cylinder head? They should be 3/8-16 thread size. I've never seen a fine thread manifold bolt and 3/16" diameter is much too small.
I've ordered manifold bolt kits from Corvette Central. https://www.corvettecentral.com/c3-6...f%3fcount%3d18

LNP · 06-07-2021, 11:23 AM

I run the original ram horn manifolds on my LT1 350 and use the stock bolts which are 3/8" x 16 national coarse thread. In all my 30yrs in garage work I've never seen a bolt smaller than 3/8" on a small block Chevy. If someone broke the original bolts off maybe they drilled and tapped them a smaller size. I would be worried about a 3/16" bolt not being able to hold the exhaust manifold in place for very long.

**Grumpy old man** · 06-07-2021, 12:20 PM

Don't forget to use anti-seize when installing the bolts , Someday you'll need those bolts to come out .

Breadstick · 06-07-2021, 01:03 PM

Sorry everyone, I meant the correct length is what I'm having trouble getting. My 72 had headers and a terrible, too short exhaust when I got it. Going back to stock-type, so I didn't have the original manifold bolts to bolt to the engine, just the short ones for the headers.

LNP · 06-07-2021, 03:10 PM

Quote:

Originally Posted by Breadstick

Sorry everyone, I meant the correct length is what I'm having trouble getting. My 72 had headers and a terrible, too short exhaust when I got it. Going back to stock-type, so I didn't have the original manifold bolts to bolt to the engine, just the short ones for the headers.

Ok cool. Do you still need to know the correct lengths? I could always pull a few of mine out and measure them.

Breadstick · 06-07-2021, 03:34 PM

Quote:

Originally Posted by LNP

Ok cool. Do you still need to know the correct lengths? I could always pull a few of mine out and measure them.

No thank you. I know the correct lengths, I just can't find them. I can get 2 1/2" and 3" length everywhere but I can't find 2 3/4" anywhere in grade 5 or 8. I have some 3" grade 8 in the right pitch so I'm going to try to grind the last 1/4" off and see how that goes.

72c20customcamper · 06-07-2021, 06:17 PM

Quote:

Originally Posted by Breadstick

No thank you. I know the correct lengths, I just can't find them. I can get 2 1/2" and 3" length everywhere but I can't find 2 3/4" anywhere in grade 5 or 8. I have some 3" grade 8 in the right pitch so I'm going to try to grind the last 1/4" off and see how that goes.

I would cut rather than grind off a 1/4 inch I got one of these a few months ago it works great for chamfering bolts tubing and rods

LNP · 06-08-2021, 09:32 AM

Quote:

Originally Posted by Breadstick

No thank you. I know the correct lengths, I just can't find them. I can get 2 1/2" and 3" length everywhere but I can't find 2 3/4" anywhere in grade 5 or 8. I have some 3" grade 8 in the right pitch so I'm going to try to grind the last 1/4" off and see how that goes.

https://www.mcmaster.com/hex-bolts/m.../length~2-3-4/

fatbass · 06-08-2021, 11:10 AM

I've cut bolts off before and found that if you run a thread die down the bolt, make the cut, then unscrew the die, the burr come off and the bolt will thread into the head easier.

firedemon · 06-07-2021, 08:47 PM

try ARP they usually have everything probably not cheap though

**Accelo** · 06-07-2021, 11:55 PM

Fastenal has them.

**Grumpy old man** · 06-08-2021, 01:08 AM

Bolt depot .

https://www.boltdepot.com/Hex_bolts_...ow_3_8-16.aspx

**Richard** · 06-08-2021, 02:37 AM

McMaster Carr is another source.

72c20customcamper · 06-08-2021, 08:50 AM

Fastenal

https://www.fastenal.com/product/fas...egation=Length

06-07-2021, 10:03 AM	#1
Breadstick Registered User Join Date: Mar 2012 Location: Scott AFB, IL Posts: 210	Ram horn manifold If anyone was wondering what size bolts to get for the OEM 350 exhaust manifold, the thread size is 3/16 24 and the middle size is 2 3/4. I found this through trial and error and I only found ONE bolt this size between Lowes, O'reilly, Napa, and Advance auto parts. I have lots of 3", so I'm going to have to cut them down. Apparently no one wants to run the original manifold anymore.

06-07-2021, 10:44 AM	#2
MJN Registered User Join Date: Feb 2000 Location: Maquoketa, Ia/ Orr, Mn Posts: 3,052	Re: Ram horn manifold which bolts- manifold to cylinder head? They should be 3/8-16 thread size. I've never seen a fine thread manifold bolt and 3/16" diameter is much too small. I've ordered manifold bolt kits from Corvette Central. https://www.corvettecentral.com/c3-6...f%3fcount%3d18 __________________ '51 South Bend Model "9A" '56 Chevy 3600 NAPCO '74 Chevy Cheyenne Super K20-restored on 37's '72 GMC Sierra Custom K2500- in progress '08 GMC Envoy Denali '12 GMC Sierra 2500HD Denali '17 GMC Yukon XL VCCA member #58596 http://www.nohrco.com

06-07-2021, 11:23 AM	#3
LNP Registered User Join Date: Mar 2014 Location: Pekin, Illinois Posts: 442	Re: Ram horn manifold I run the original ram horn manifolds on my LT1 350 and use the stock bolts which are 3/8" x 16 national coarse thread. In all my 30yrs in garage work I've never seen a bolt smaller than 3/8" on a small block Chevy. If someone broke the original bolts off maybe they drilled and tapped them a smaller size. I would be worried about a 3/16" bolt not being able to hold the exhaust manifold in place for very long.

06-07-2021, 12:20 PM	#4
Grumpy old man Senior Member Join Date: Dec 2013 Location: Gods country East,Tn Posts: 8,545	Re: Ram horn manifold Don't forget to use anti-seize when installing the bolts , Someday you'll need those bolts to come out . __________________ 1967 Factory short bed - Old school '71 - 350 / 4bolt / 487 heads / Edelbrock C3BX Muncie M-22 4 speed / Hurst Comp plus Factory 12 bolt posi 3.73 / 255-70-15 Smoothed firewall / Factory cowl induction Power disc brakes / power steering / 3.5-5" drop

06-07-2021, 01:03 PM	#5
Breadstick Registered User Join Date: Mar 2012 Location: Scott AFB, IL Posts: 210	Re: Ram horn manifold Sorry everyone, I meant the correct length is what I'm having trouble getting. My 72 had headers and a terrible, too short exhaust when I got it. Going back to stock-type, so I didn't have the original manifold bolts to bolt to the engine, just the short ones for the headers.

06-08-2021, 11:10 AM	#10
fatbass Registered User Join Date: May 2012 Location: South Ogden, Utah Posts: 172	Re: Ram horn manifold I've cut bolts off before and found that if you run a thread die down the bolt, make the cut, then unscrew the die, the burr come off and the bolt will thread into the head easier. __________________ '71 C/20 350/T350.

06-07-2021, 08:47 PM	#11
firedemon Registered User Join Date: Jun 2015 Location: @ Posts: 890	Re: Ram horn manifold try ARP they usually have everything probably not cheap though

06-07-2021, 11:55 PM	#12
Accelo Senior Member Join Date: Mar 2015 Location: washington Posts: 2,301	Re: Ram horn manifold Fastenal has them.

06-08-2021, 01:08 AM	#13
Grumpy old man Senior Member Join Date: Dec 2013 Location: Gods country East,Tn Posts: 8,545	Re: Ram horn manifold Bolt depot . https://www.boltdepot.com/Hex_bolts_...ow_3_8-16.aspx __________________ 1967 Factory short bed - Old school '71 - 350 / 4bolt / 487 heads / Edelbrock C3BX Muncie M-22 4 speed / Hurst Comp plus Factory 12 bolt posi 3.73 / 255-70-15 Smoothed firewall / Factory cowl induction Power disc brakes / power steering / 3.5-5" drop

06-08-2021, 02:37 AM	#14
Richard Senior Member Join Date: Dec 1999 Location: Southern California Posts: 2,896	Re: Ram horn manifold McMaster Carr is another source. __________________ Richard 1972 K10 Custom Deluxe SWB Fleetside My build https://67-72chevytrucks.com/vboard/...d.php?t=800746

06-08-2021, 08:50 AM	#15
72c20customcamper Registered User Join Date: Jul 2018 Location: Catskill Mountains,NY Posts: 8,739	Re: Ram horn manifold Fastenal https://www.fastenal.com/product/fas...egation=Length __________________ Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary.



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