intake manifold bolt size ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sactoC10 · 10-29-2003, 12:08 PM

What is the size of the intake manifold bolts on a typical 350 stock motor?

Old Dave · 10-29-2003, 12:45 PM

I'm 99% sure they are 3/8 x 16 but don't remember the length. They take a 9/16" socket or box end wrench.

sactoC10 · 10-29-2003, 03:10 PM

anyone know the length? I suspect that I have a short one, but don't really want to pull another to find out

**COBALT** · 10-29-2003, 04:29 PM

Can't be more than an 1" and a half. ARP intake bolts (that I use exclusively) are I think 1" in length and have a reduced 3/8" head on them. That, and they're stainless chrome plated.

crazy longhorn · 10-29-2003, 04:43 PM

be carefull not to go too long.....there are a couple places that the bolts will interfere with the pushrods

Off the top of my head, i think 1 1/4".......if you pick up an intake bolt set (Dorman or MR gasket), you will have the proper lenght. crazyL

sactoC10 · 10-29-2003, 06:41 PM

Did my frist oil change in this truck o' mine last week. Got it up to the proper level and (of course) my pesky leak that gives me a small pool oil on the intake manifold came back...with a vengeance.

What was for a short time a drip or two, is now a 3-4" stain.

A few weeks ago I was told here that the bolts on the manifold can be the reason for these puddles. I removed and cleaned my (long tall) oil filler neck and when I put it back I used a shorter bolt that what was there before, just for ease of re-installation.

If these bolts can be part of leaking problems, then I may have made the problem worse with the shorter bolt!

Also, now that the I can see this leak clearly, I am reasonably sure that it is the leak causing my drip, not the pan as I originally suspected. It actually leaks, burns and smokes (where burning) then drips after the truck is shut off.

J.Lance · 10-29-2003, 07:16 PM

1 1/4" is your max length on the bolts to avoid interference with the push rods. Try putting a little RTV on the threads before you install them to give em a better seal.

tom hand · 10-29-2003, 08:02 PM

The four bolts in the center of the manifold by the heat riser will always leak if you don't put sealer on them

Dean23 · 10-29-2003, 09:33 PM

By a set of arp intake bolts and new gaskets...then b sure to use some liquid teflon thread sealer on every set of threads. Its a sure fire way to prevent the oil and coolant from seeping upwards

sactoC10 · 10-30-2003, 11:23 AM

Don't know what this is yet, but I asked this question once before.

The driver's side of the intake manifold, just beneath the carb is where I have the seeping oil. Of those two bolts, the one toward the front of the truck is not a bolt at all, but it is a fitting. The fitting has a line attached to it, a rubber hose that extends over to the front of the engine, into the block, right near the water pump.

I'd really love to just block this line, but I don't know what the heck it is! Coolant line? Still have not been able to take a good picture of it.

10-29-2003, 12:08 PM	#1
sactoC10 71 DELUX Join Date: Sep 2003 Location: Northern CA / Sac Posts: 1,056	intake manifold bolt size ? What is the size of the intake manifold bolts on a typical 350 stock motor? __________________ 5/4 drop LWB wood bed - 15x8 front 235/60 - 15x10 rear 295/50 2003 FORD Escape 1998 Honda VTR1000

10-29-2003, 03:10 PM	#3
sactoC10 71 DELUX Join Date: Sep 2003 Location: Northern CA / Sac Posts: 1,056	length anyone know the length? I suspect that I have a short one, but don't really want to pull another to find out __________________ 5/4 drop LWB wood bed - 15x8 front 235/60 - 15x10 rear 295/50 2003 FORD Escape 1998 Honda VTR1000

10-29-2003, 04:29 PM	#4
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Can't be more than an 1" and a half. ARP intake bolts (that I use exclusively) are I think 1" in length and have a reduced 3/8" head on them. That, and they're stainless chrome plated. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

10-29-2003, 04:43 PM	#5
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	be carefull not to go too long.....there are a couple places that the bolts will interfere with the pushrods Off the top of my head, i think 1 1/4".......if you pick up an intake bolt set (Dorman or MR gasket), you will have the proper lenght. crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

10-29-2003, 06:41 PM	#6
sactoC10 71 DELUX Join Date: Sep 2003 Location: Northern CA / Sac Posts: 1,056	reason I am asking Did my frist oil change in this truck o' mine last week. Got it up to the proper level and (of course) my pesky leak that gives me a small pool oil on the intake manifold came back...with a vengeance. What was for a short time a drip or two, is now a 3-4" stain. A few weeks ago I was told here that the bolts on the manifold can be the reason for these puddles. I removed and cleaned my (long tall) oil filler neck and when I put it back I used a shorter bolt that what was there before, just for ease of re-installation. If these bolts can be part of leaking problems, then I may have made the problem worse with the shorter bolt! Also, now that the I can see this leak clearly, I am reasonably sure that it is the leak causing my drip, not the pan as I originally suspected. It actually leaks, burns and smokes (where burning) then drips after the truck is shut off.

10-29-2003, 12:45 PM	#2
Old Dave Is a bullfrog waterproof? Join Date: Nov 2000 Location: OLATHE, KANSAS Posts: 1,130	I'm 99% sure they are 3/8 x 16 but don't remember the length. They take a 9/16" socket or box end wrench.

10-29-2003, 07:16 PM	#7
J.Lance Too many is never enough! Join Date: May 2003 Location: Idaho Falls, ID Posts: 455	bolts 1 1/4" is your max length on the bolts to avoid interference with the push rods. Try putting a little RTV on the threads before you install them to give em a better seal. __________________ Jason 1968 K10 SWB Fleetside 1971 K2500 GMC LWB 1968 K20 (later frame, donor body) 1972 C20 LWB parts truck 1993 K2500 Suburban, tow rig, 454, 4L80E NEW!! 18' Siem's car hauler 2004 Honda Odyssey (family man!)

10-29-2003, 08:02 PM	#8
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	The four bolts in the center of the manifold by the heat riser will always leak if you don't put sealer on them __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

10-29-2003, 09:33 PM	#9
Dean23 68cst_ss490 Join Date: May 2001 Location: edmonton,canada Posts: 1,363	By a set of arp intake bolts and new gaskets...then b sure to use some liquid teflon thread sealer on every set of threads. Its a sure fire way to prevent the oil and coolant from seeping upwards __________________ Dean edmonton,canada a winter wonderland 2005 Chevrolet Avalanche LT cold air intake, performance exhaust, Comp cams cam, jba shorty ceramic headers. http://www.cardomain.com/ride/3090973

10-30-2003, 11:23 AM	#10
sactoC10 71 DELUX Join Date: Sep 2003 Location: Northern CA / Sac Posts: 1,056	still have mystery bolt though Don't know what this is yet, but I asked this question once before. The driver's side of the intake manifold, just beneath the carb is where I have the seeping oil. Of those two bolts, the one toward the front of the truck is not a bolt at all, but it is a fitting. The fitting has a line attached to it, a rubber hose that extends over to the front of the engine, into the block, right near the water pump. I'd really love to just block this line, but I don't know what the heck it is! Coolant line? Still have not been able to take a good picture of it.



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