Drilling the snout out of a 250 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

NicoSlam · 12-10-2009, 06:44 PM

I'm getting ready to replace the dampner on my 250 which does not have a tapped snout. I have the tool to remove it but can't use it to re-install. From what I have read, there are two methods of installation, getting a BFH and pounding it or tapping the snout using 25/64 bit and a 7/16-20 tap going in 1". If you were in my shoes what would you do? I have the know how and the tools but I'm lacking the confidence. I do plan to remove the grill and radiator for the install so removing parts will not be a factor (will polish grill later

) I also made a jig to help me drill parrallel with the crank by utilizing two of the three threads on the old balancer as a guide for the drill bit. I am worried about damaging the engine using the BFH method. share your thoughts

thanks

louis

JimKshortstep4x4 · 12-10-2009, 07:03 PM

I had a "drill bushing" made up for use on drilling the "snout" on a sbc that was never tapped and it turned out well. It sounds like you know what you are doing and as long as the hole and tap are concentric with the "snout" you should be good.

I believe that you are better off pulling the damper on with an installment tool so my vote would be to drill and tap the hole.

Jim

68gmsee · 12-10-2009, 09:05 PM

I had mine tapped on my 68 since I didn't have the tools to do it with. In your case, you have all the tools and know how so I'd give that a try.

But... if you're still leery about doing it, I've installed several with the big hammer method and didn't hurt the engine. Other guys have done the same thing. What you need to do is first tap it in all the way around to get it started as much as you can since it's going to be a very tight fit. Then get a block of wood and finish tapping it in. I've used a piece of 2X4 on them before. Just remember that it's a tight fit.

mike16 · 12-10-2009, 09:29 PM

the big hammer method may damage the damper but it will also possibly damage you thrust bearing inside the motor.

low'n slow · 12-10-2009, 10:29 PM

Get a narrow step bit from HF and go for it. It goes in real quick then you can follow up with the coorect bit and tap. It worked for me.

hayhauler71 · 12-10-2009, 10:52 PM

Quote:

Originally Posted by mike16

the big hammer method may damage the damper but it will also possibly damage you thrust bearing inside the motor.

Use the bfh and you will lose the thrust bearing not a good idea.

AusTx68 · 12-11-2009, 12:32 AM

I just went thru this myself when I attmepted to install the dampner without the tool. I would have never considered using a BFH. Just too risky for me. I drilled, tapped and used a .750 helicoil. Worked like a charm. The 1" didn't work for me. Probably because I didn't tap it deep enough.

I still have the Helicoil kit. PM me if you need it.

NicoSlam · 12-11-2009, 09:56 AM

Thanks for the advice. I'll try the drill method as the only difficulty would be staying on center. If I jack this up I guess I have the BFH as a last resort. Is the a reason for the helicoil?

thanks

AusTx68 · 12-11-2009, 11:12 AM

The helicoil is what gives you the new bolt threads. Tapping and inserting a helicoil will make it stronger than just tapping and will allow you to use the correct size bolt. The helicoil kit comes with the correct drill bit, tap and coils.

My kit is for a BBC so it won't be of much help to ya.

woodridge · 12-11-2009, 11:31 AM

Looked it up in an old Chiltons manual. Said to drive it on.

AusTx68 · 12-11-2009, 12:11 PM

Quote:

Originally Posted by woodridge

Looked it up in an old Chiltons manual. Said to drive it on.

I doubled checked using my GM Chassis Manual for 1968. It shows two methods. One using the bolt and the other using a drive tool. Just depends on whether you have threads or not.

So according to the manual you can drive it on. Even shows a photo of the BFH.

PanelDeland · 12-11-2009, 04:05 PM

If you use the BFH method.Do it on a cold day.Let the engine become very cold.Put the Harmonic balancer in the oven at 150* and get your oven mitts ready.This way you will have the largest tolerance to drive on the balancer.

68gmsee · 12-11-2009, 08:25 PM

I think some are getting the impression that a BFH is a 9 lb sledge hammer.

I used a short handle 3 pound hammer when I did this and basically work it in by tapping with authority but not slamming the living daylights out of it. After it's in a little ways, I use a wooden block and hit harder until I drive it in.

The heating method mentioned above might work better now that it's cold.

12-10-2009, 06:44 PM	#1
NicoSlam Registered User Join Date: Nov 2009 Location: San Antonio TX Posts: 251	Drilling the snout out of a 250 I'm getting ready to replace the dampner on my 250 which does not have a tapped snout. I have the tool to remove it but can't use it to re-install. From what I have read, there are two methods of installation, getting a BFH and pounding it or tapping the snout using 25/64 bit and a 7/16-20 tap going in 1". If you were in my shoes what would you do? I have the know how and the tools but I'm lacking the confidence. I do plan to remove the grill and radiator for the install so removing parts will not be a factor (will polish grill later) I also made a jig to help me drill parrallel with the crank by utilizing two of the three threads on the old balancer as a guide for the drill bit. I am worried about damaging the engine using the BFH method. share your thoughts thanks louis

12-10-2009, 07:03 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Drilling the snout out of a 250 I had a "drill bushing" made up for use on drilling the "snout" on a sbc that was never tapped and it turned out well. It sounds like you know what you are doing and as long as the hole and tap are concentric with the "snout" you should be good. I believe that you are better off pulling the damper on with an installment tool so my vote would be to drill and tap the hole. Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

12-10-2009, 09:05 PM	#3
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: Drilling the snout out of a 250 I had mine tapped on my 68 since I didn't have the tools to do it with. In your case, you have all the tools and know how so I'd give that a try. But... if you're still leery about doing it, I've installed several with the big hammer method and didn't hurt the engine. Other guys have done the same thing. What you need to do is first tap it in all the way around to get it started as much as you can since it's going to be a very tight fit. Then get a block of wood and finish tapping it in. I've used a piece of 2X4 on them before. Just remember that it's a tight fit.

12-10-2009, 09:29 PM	#4
mike16 Registered User Join Date: Dec 2009 Location: bisbee, arizona Posts: 1,529	Re: Drilling the snout out of a 250 the big hammer method may damage the damper but it will also possibly damage you thrust bearing inside the motor.

12-10-2009, 10:29 PM	#5
low'n slow Too Dumb To Know Better Join Date: Nov 2005 Location: Texas Posts: 883	Re: Drilling the snout out of a 250 Get a narrow step bit from HF and go for it. It goes in real quick then you can follow up with the coorect bit and tap. It worked for me.

12-11-2009, 12:32 AM	#7
AusTx68 Registered User Join Date: Nov 2008 Location: Italy Posts: 1,278	Re: Drilling the snout out of a 250 I just went thru this myself when I attmepted to install the dampner without the tool. I would have never considered using a BFH. Just too risky for me. I drilled, tapped and used a .750 helicoil. Worked like a charm. The 1" didn't work for me. Probably because I didn't tap it deep enough. I still have the Helicoil kit. PM me if you need it. __________________ '68 C-10 SWB 383 Stroker (Sold 3/2/2013) '87 R2500 LWB 454 TBI converted to Carb

12-11-2009, 09:56 AM	#8
NicoSlam Registered User Join Date: Nov 2009 Location: San Antonio TX Posts: 251	Re: Drilling the snout out of a 250 Thanks for the advice. I'll try the drill method as the only difficulty would be staying on center. If I jack this up I guess I have the BFH as a last resort. Is the a reason for the helicoil? thanks

12-11-2009, 11:12 AM	#9
AusTx68 Registered User Join Date: Nov 2008 Location: Italy Posts: 1,278	Re: Drilling the snout out of a 250 The helicoil is what gives you the new bolt threads. Tapping and inserting a helicoil will make it stronger than just tapping and will allow you to use the correct size bolt. The helicoil kit comes with the correct drill bit, tap and coils. My kit is for a BBC so it won't be of much help to ya. __________________ '68 C-10 SWB 383 Stroker (Sold 3/2/2013) '87 R2500 LWB 454 TBI converted to Carb Last edited by AusTx68; 12-11-2009 at 11:13 AM.

12-11-2009, 11:31 AM	#10
woodridge Senior Member Join Date: Feb 2005 Location: Maynardville, Tn Posts: 3,030	Re: Drilling the snout out of a 250 Looked it up in an old Chiltons manual. Said to drive it on. __________________ SEMA Network- Protect our Hobby! 71 C30 in pieces, starting to come together. Click here for A Place For Tennessee Truck Enthusiest To Meet

12-11-2009, 04:05 PM	#12
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,992	Re: Drilling the snout out of a 250 If you use the BFH method.Do it on a cold day.Let the engine become very cold.Put the Harmonic balancer in the oven at 150* and get your oven mitts ready.This way you will have the largest tolerance to drive on the balancer. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

12-11-2009, 08:25 PM	#13
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: Drilling the snout out of a 250 I think some are getting the impression that a BFH is a 9 lb sledge hammer. I used a short handle 3 pound hammer when I did this and basically work it in by tapping with authority but not slamming the living daylights out of it. After it's in a little ways, I use a wooden block and hit harder until I drive it in. The heating method mentioned above might work better now that it's cold.



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