breaking in motor - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69ChevySB · 11-10-2003, 10:52 PM

hi i just got my new tranny and motor in and my truck is cruising, it shifts very nice and sounds good...the only problem is when i am going there is a sort of tapping sound when i accelerate and then it stops and gets slower when i idle...its not very loud but i can still hear it, do you think it may be one of the rocker arms, a small exhaust manifold leak, or maybe my timing is off... its at about 10 degrees advanced, but some people say set it until it stops pinging or knocking, is that the noise that they are referring to? also how should i go about breaking in my motor...

some people say get on it and drive it like you want and some people say after the first 500 miles then its ready to rock
what do you guys prefer. should i atleast change the tranny fluid and oil after 250 miles?i use supreme gas its a 350/400
should i just cruise and keep it under 2500 rpms for 500 miles or what any help would be nice thanks.

69ChevySB · 11-10-2003, 10:56 PM

also, how important is my kickdown switch for the turbo400 transmission? i dont have it hooked up, should i hook it up as soon as possible or what...and one more thing what is better for the motor and tranny, just put it in 3rd and cruise or go through my gears 1,2,3 i have a b&m megashifter so its kinda fun to go through them but what is recommended?

*Randy70C-10* · 11-10-2003, 11:00 PM

It definately sounds like your timing is advanced too far..... Your kickdown isn't that important.

I should ask, does your engine still tap at idle? Pinging normally occurs during acceleration.

Cat Fuzz · 11-11-2003, 01:15 AM

You broke in the cam, right?

71GMC_3/4T · 11-11-2003, 01:45 AM

The best thing you can do when breaking in an engine is to speed up and slow down often. Don't drive steady state until you hit 500 miles or so. Get out on the highway and go up to 65 and back off to 55, then speed up moderately to 65 again and repeat. This helps seat the rings correctly.
Your tapping could be many things, like you said.
I'd recheck the rocker settings again if I heard any tapping noise. With the valve covers off and it running, you may hear it better. Use the splash clips on your rockers.
Noise is your enemy. That means something is getting hammered to sh!t. Find it now, before it's too late.
You *did* break in your cam, right? At least say you smeared the lobes with Moly-d before you installed it, right?

lukecp · 11-11-2003, 02:11 AM

When my motor was rebuilt, i just stayed out of the throttle for the first 500 miles. I didn't go over half throttle. When the engine hit 500, i took it to machine shop for a check up, changed the oil, and floored it that day (i had to see what the new 350 had

)

JJFRANKIS-72 · 11-11-2003, 08:42 PM

71GMC_3/4T
WHAT DOES IT MEAN TO BREAK IN THE CAM?

**FRENCHBLUE72** · 11-11-2003, 08:52 PM

When you fire up a new motor you usally run it at about 2000 rpm for 20 minutes and this provide's a seating area for the lifter's to ride on the cam shaft lobe... I may not be 100% on that so if I am wrong some one please step in..

shuttermutt · 11-11-2003, 10:51 PM

Quote:

Originally posted by FRENCHBLUE72
When you fire up a new motor you usally run it at about 2000 rpm for 20 minutes and this provide's a seating area for the lifter's to ride on the cam shaft lobe... I may not be 100% on that so if I am wrong some one please step in..

Yeah, that's about right. The trick is to get that engine fired up to between 2,000 and 2,500 rpm so that there's plenty of oil splashing on the lobes as the break-in lube wears off (and it does... quickly). Double-check everything and triple-check your timing and valve lash before you fire it off for the first time.

69ChevySB · 11-12-2003, 12:56 AM

well i didnt keep it at 2000 rpms at first but i've kept it below 2500 rpms and i have about 120 miles on it now

the noise is when i idle too but you can barely hear it but when im in the truck i can hear it better than i can outside. it gets faster when i accelerate and slower when i am braking. i tried to make the timing slower but it sounded like it was going to die and it also was still tapping. maybe it is a rocker arm? what is the correct way to tighten these down? some people say just tighten it until its snug then loosen it 1/2 turn? how is this performed? thanks.

**FRENCHBLUE72** · 11-12-2003, 01:00 AM

Are you sure it is not an exhaust leak???

rickh · 11-12-2003, 01:06 AM

Rocker adjustment requires a specific sequince to complete. I do not have a book in front of me and if I did, I would not have the time to type it all out. Your objective would be to do each cyl with both valves closed, you can only insure they are closed by timming marks, or a pencil in the cyl while turning over the engine BY HAND and noting the top dead center of the piston. At that point, both valves should be closed. Go through each cyl and see if you notice a rocker loose enough to make noise when you wiggle it. They should be snug, but you should also be able to twist them.
If you have a repair manual, I am sure the procedure is in it.
Rick H...

RussTburb · 11-12-2003, 01:09 AM

There is a procedure for adjusting the valves that makes it real easy but someone will have to help me with it.
First put the engine at tdc #1 then you can adjust some of the intake valve and some of the exhaust, then you roll to Tdc #4? then adjust the rest. The way I do it is loosen the rocker arm nut until you can spin the push rod. keap spining in in your two fingers while tightening the rocker arm nut. When you cannot spin the pushrod any more tighten the rocker arm nut 1/2 a turn more. (oppinions very on this step I actually go 3/4 of a turn and never had a customer complain). Inspect the studs that hold the rocker arm in as some are pressed in the head and I have seen a lot of these pull out.

11-10-2003, 10:56 PM	#2
69ChevySB dropped69 Join Date: Jan 2003 Location: Grand Canyon State Posts: 120	also, how important is my kickdown switch for the turbo400 transmission? i dont have it hooked up, should i hook it up as soon as possible or what...and one more thing what is better for the motor and tranny, just put it in 3rd and cruise or go through my gears 1,2,3 i have a b&m megashifter so its kinda fun to go through them but what is recommended? __________________ "And yet I find, yet I find...repeating in my head. If I can't be my own, I feel better dead." -Layne Staley (R.I.P)

11-10-2003, 11:00 PM	#3
Randy70C-10 Account Suspended Join Date: Mar 2001 Location: Virginia Beach, Va. U.S.A. Posts: 15,320	It definately sounds like your timing is advanced too far..... Your kickdown isn't that important. I should ask, does your engine still tap at idle? Pinging normally occurs during acceleration. Last edited by Randy70C-10; 11-10-2003 at 11:03 PM.

11-11-2003, 01:45 AM	#5
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	The best thing you can do when breaking in an engine is to speed up and slow down often. Don't drive steady state until you hit 500 miles or so. Get out on the highway and go up to 65 and back off to 55, then speed up moderately to 65 again and repeat. This helps seat the rings correctly. Your tapping could be many things, like you said. I'd recheck the rocker settings again if I heard any tapping noise. With the valve covers off and it running, you may hear it better. Use the splash clips on your rockers. Noise is your enemy. That means something is getting hammered to sh!t. Find it now, before it's too late. You did break in your cam, right? At least say you smeared the lobes with Moly-d before you installed it, right? __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

11-11-2003, 02:11 AM	#6
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	When my motor was rebuilt, i just stayed out of the throttle for the first 500 miles. I didn't go over half throttle. When the engine hit 500, i took it to machine shop for a check up, changed the oil, and floored it that day (i had to see what the new 350 had ) __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

11-11-2003, 08:52 PM	#8
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,600	When you fire up a new motor you usally run it at about 2000 rpm for 20 minutes and this provide's a seating area for the lifter's to ride on the cam shaft lobe... I may not be 100% on that so if I am wrong some one please step in.. __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

11-10-2003, 10:52 PM	#1
69ChevySB dropped69 Join Date: Jan 2003 Location: Grand Canyon State Posts: 120	breaking in motor hi i just got my new tranny and motor in and my truck is cruising, it shifts very nice and sounds good...the only problem is when i am going there is a sort of tapping sound when i accelerate and then it stops and gets slower when i idle...its not very loud but i can still hear it, do you think it may be one of the rocker arms, a small exhaust manifold leak, or maybe my timing is off... its at about 10 degrees advanced, but some people say set it until it stops pinging or knocking, is that the noise that they are referring to? also how should i go about breaking in my motor... some people say get on it and drive it like you want and some people say after the first 500 miles then its ready to rock what do you guys prefer. should i atleast change the tranny fluid and oil after 250 miles?i use supreme gas its a 350/400 should i just cruise and keep it under 2500 rpms for 500 miles or what any help would be nice thanks. __________________ "And yet I find, yet I find...repeating in my head. If I can't be my own, I feel better dead." -Layne Staley (R.I.P)

11-11-2003, 01:15 AM	#4
Cat Fuzz My son, my joy. Join Date: Sep 2003 Location: Spokane WA Posts: 463	You broke in the cam, right?

11-11-2003, 08:42 PM	#7
JJFRANKIS-72 Registered User Join Date: Oct 2003 Location: Clovis, CA Posts: 10	71GMC_3/4T WHAT DOES IT MEAN TO BREAK IN THE CAM?

11-12-2003, 12:56 AM	#10
69ChevySB dropped69 Join Date: Jan 2003 Location: Grand Canyon State Posts: 120	well i didnt keep it at 2000 rpms at first but i've kept it below 2500 rpms and i have about 120 miles on it now the noise is when i idle too but you can barely hear it but when im in the truck i can hear it better than i can outside. it gets faster when i accelerate and slower when i am braking. i tried to make the timing slower but it sounded like it was going to die and it also was still tapping. maybe it is a rocker arm? what is the correct way to tighten these down? some people say just tighten it until its snug then loosen it 1/2 turn? how is this performed? thanks. __________________ "And yet I find, yet I find...repeating in my head. If I can't be my own, I feel better dead." -Layne Staley (R.I.P)

11-12-2003, 01:00 AM	#11
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,600	Are you sure it is not an exhaust leak??? __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

11-12-2003, 01:06 AM	#12
rickh Registered User Join Date: Nov 2001 Location: Bellevue Nebraska USA Posts: 74	Rocker adjustment requires a specific sequince to complete. I do not have a book in front of me and if I did, I would not have the time to type it all out. Your objective would be to do each cyl with both valves closed, you can only insure they are closed by timming marks, or a pencil in the cyl while turning over the engine BY HAND and noting the top dead center of the piston. At that point, both valves should be closed. Go through each cyl and see if you notice a rocker loose enough to make noise when you wiggle it. They should be snug, but you should also be able to twist them. If you have a repair manual, I am sure the procedure is in it. Rick H... __________________ Rick H.... 69 C10-CST Wood bed floor full power 70 SWB 425hp HOTROD! Full power 71 C20 Camper Special 402 full power, factory dual tanks with gauge switch. FOR SALE!

11-12-2003, 01:09 AM	#13
RussTburb Registered User Join Date: Mar 2002 Location: Blaine,Wa. U.S.A Posts: 261	There is a procedure for adjusting the valves that makes it real easy but someone will have to help me with it. First put the engine at tdc #1 then you can adjust some of the intake valve and some of the exhaust, then you roll to Tdc #4? then adjust the rest. The way I do it is loosen the rocker arm nut until you can spin the push rod. keap spining in in your two fingers while tightening the rocker arm nut. When you cannot spin the pushrod any more tighten the rocker arm nut 1/2 a turn more. (oppinions very on this step I actually go 3/4 of a turn and never had a customer complain). Inspect the studs that hold the rocker arm in as some are pressed in the head and I have seen a lot of these pull out. __________________ "Red-heads not war-heads, Blondes, not bombs, Brunettes, not fighter jets!" Fligh of the Choncords 72 burb 3/4 ton 2wd 06 2500 suburban 8.1L 4x4 84 chev 4x4 diesel 96 Geo Metro with the 4cylbb, lol! Almost 300k just won't die! 89 Honda Civic, runs on the smell of an oily rag! 2008 Aerolite 26qs Travel Trailer (aka "THE BARN")



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.