Help: Clatter box - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Long Knight · 04-02-2003, 01:15 PM

Need some advice.

Whenever I get on the gas I hear this persistant clatter. I checked the exhaust and everything is tight. I had my valve covers off a few days ago and checked the rods. They were good except for one thing, they had some play from side to side. Is that normal?

I started the engine and the valve clatter didn't seem bad at all. But, I get the covers back on and head out the following morning and there it is again. I have good oil pressure. Adjusted the timing couple days ago. Any ideas or suggestions? Thanks everyone!

Ro

sam's 72 · 04-02-2003, 01:20 PM

Is it the valve train clattering or is it detonation from the pistons?
Sam

Long Knight · 04-02-2003, 01:31 PM

That's what I can't narrow down. I just put headers on not too long ago and maybe they just give off a hollow clatter vibration. Mostly what I need to figure out is if it is something bad that I need to fix or if it is something that doesn't really matter, because my truck is a daily driver that goes over 50 mile/day.

It only does it when I really get on it.

lpaine · 04-02-2003, 01:31 PM

If your timing is not too far advanced it shouldn't be detonating, I was thinking maybe you had a lifter not pumping up; but if it's only clattering when you get on the gas, that probably would not be a lifter. I think you need to give us more details about this particular sound you're hearing. Also, does it idle well? And do you have a vacum gauge to check the engine with?. They will tell you a lot about whats going on inside the engine.

Long Knight · 04-02-2003, 01:35 PM

No vac guage, engine runs slightly rough at idle. Can't seem to even out the idle. Could a bad vac. advance cause the clatter?

sam's 72 · 04-02-2003, 01:41 PM

I would take it easy till you get the problem pinned down. What octane gas are you useing in it and tell me about your engine, ( size, high performance, stock etc)
Sam

tom hand · 04-02-2003, 02:14 PM

Quote:

It only does it when I really get on it.

It could just be a header leak

Long Knight · 04-02-2003, 04:21 PM

Engine was rebuilt 7k miles ago. Only upgrade was an RV cam and a Edl 1406. All new pumps. Heads were re-built along w/ engine. Put headers on recently, can't find any leaks.

What would happen if you plugged the end of the tail pipe and shot compressed air up the pipe from an air compressor? That wouldn't mess anything up would it? I figure that would be a sure way to check for leaks, right?

sam's 72 · 04-02-2003, 04:32 PM

No that would not work like that, when the engine is sitting there off, some of your intake and axhaust valves are open, and you would just blow air out the carb. If it is detonation, try going with a higher octane of gas, or back your timeing down a little. If it is in the valve train, go back and readjust the valve, see if that helps. When you rebuilt the engine, how was the clearence in the bore/ piston? The pistons could have too much clearance and cause the rattleing, but go after the easy things first. It could just be you need to go with a higher octane. That would be a quick fix, I have a completly stock 305 in my truck ( 86' ) and it does not like any thing but 92 93 octane, if I try to go with 89, it clatters bad, if I back my timeing down any at all, I loose a lot of power and the truck is hard to get rolling. LOL! So I keep my timing a little on the advanced side. It is hard for us to say what it is with out hearing this.
Sam

Longhorn Man · 04-03-2003, 12:47 AM

Quick way to see if it is detonation, fill up with 92/93 octain, or what ever is high test at your fillin station. If it stops doing it, you found the problem.
and at 50 miles a day, you should be able to fill up in a couple days.

spinning wheels · 04-03-2003, 12:57 AM

When you mentioned clatter and that it gets louder when you get on it, I thought for a minute that you ended up with my ex-girlfriend, but then she clattered before she even got in the truck.

On your problem, check the timing, but it may be too much piston clearance. Sounds like my tired Z28. Damn thing almost sounds like a diesel when the timing is too advanced.

O'l Buck · 04-03-2003, 01:58 AM

Check your torque converter bolts, if they work loose, it will give a good clatter......sounds about like a rod bearing spun.

Long Knight · 04-03-2003, 09:58 AM

I'll check this stuff out this weekend. Thanks for the input everyone! It's always good to have an idea of what to look for instead of going in blind. This is such a great site for information! Thanks again.

04-02-2003, 01:15 PM	#1
Long Knight Spank 'em if you got 'em! Join Date: Nov 2002 Location: Kansas City Posts: 628	Help: Clatter box Need some advice. Whenever I get on the gas I hear this persistant clatter. I checked the exhaust and everything is tight. I had my valve covers off a few days ago and checked the rods. They were good except for one thing, they had some play from side to side. Is that normal? I started the engine and the valve clatter didn't seem bad at all. But, I get the covers back on and head out the following morning and there it is again. I have good oil pressure. Adjusted the timing couple days ago. Any ideas or suggestions? Thanks everyone! Ro __________________ Long Knight '71 C-20, 350ci, TH350, Edl. 1406 Carb w/elec.choke, Ignitor ignition, Viper Tires, Orange Dipstick

04-02-2003, 01:20 PM	#2
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	Is it the valve train clattering or is it detonation from the pistons? Sam __________________ 72 LWB chevy truck. Pasadena, Texas

04-02-2003, 01:31 PM	#3
Long Knight Spank 'em if you got 'em! Join Date: Nov 2002 Location: Kansas City Posts: 628	That's what I can't narrow down. I just put headers on not too long ago and maybe they just give off a hollow clatter vibration. Mostly what I need to figure out is if it is something bad that I need to fix or if it is something that doesn't really matter, because my truck is a daily driver that goes over 50 mile/day. It only does it when I really get on it. __________________ Long Knight '71 C-20, 350ci, TH350, Edl. 1406 Carb w/elec.choke, Ignitor ignition, Viper Tires, Orange Dipstick

04-02-2003, 01:31 PM	#4
lpaine Registered User Join Date: Oct 2002 Location: Parksville, B.C. Canada Posts: 637	If your timing is not too far advanced it shouldn't be detonating, I was thinking maybe you had a lifter not pumping up; but if it's only clattering when you get on the gas, that probably would not be a lifter. I think you need to give us more details about this particular sound you're hearing. Also, does it idle well? And do you have a vacum gauge to check the engine with?. They will tell you a lot about whats going on inside the engine. __________________ 1969 G.M.C 3/4 Ton 920 (Canadian Version) 307 3 speed, currently apart 1998 Chevy 1/2 ton ex cab V-6 5 speed 1967 Chevy SWB - project truck; not started just yet

04-02-2003, 01:35 PM	#5
Long Knight Spank 'em if you got 'em! Join Date: Nov 2002 Location: Kansas City Posts: 628	No vac guage, engine runs slightly rough at idle. Can't seem to even out the idle. Could a bad vac. advance cause the clatter? __________________ Long Knight '71 C-20, 350ci, TH350, Edl. 1406 Carb w/elec.choke, Ignitor ignition, Viper Tires, Orange Dipstick

04-02-2003, 01:41 PM	#6
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	I would take it easy till you get the problem pinned down. What octane gas are you useing in it and tell me about your engine, ( size, high performance, stock etc) Sam __________________ 72 LWB chevy truck. Pasadena, Texas

04-02-2003, 04:21 PM	#8
Long Knight Spank 'em if you got 'em! Join Date: Nov 2002 Location: Kansas City Posts: 628	Engine was rebuilt 7k miles ago. Only upgrade was an RV cam and a Edl 1406. All new pumps. Heads were re-built along w/ engine. Put headers on recently, can't find any leaks. What would happen if you plugged the end of the tail pipe and shot compressed air up the pipe from an air compressor? That wouldn't mess anything up would it? I figure that would be a sure way to check for leaks, right? __________________ Long Knight '71 C-20, 350ci, TH350, Edl. 1406 Carb w/elec.choke, Ignitor ignition, Viper Tires, Orange Dipstick

04-02-2003, 04:32 PM	#9
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	No that would not work like that, when the engine is sitting there off, some of your intake and axhaust valves are open, and you would just blow air out the carb. If it is detonation, try going with a higher octane of gas, or back your timeing down a little. If it is in the valve train, go back and readjust the valve, see if that helps. When you rebuilt the engine, how was the clearence in the bore/ piston? The pistons could have too much clearance and cause the rattleing, but go after the easy things first. It could just be you need to go with a higher octane. That would be a quick fix, I have a completly stock 305 in my truck ( 86' ) and it does not like any thing but 92 93 octane, if I try to go with 89, it clatters bad, if I back my timeing down any at all, I loose a lot of power and the truck is hard to get rolling. LOL! So I keep my timing a little on the advanced side. It is hard for us to say what it is with out hearing this. Sam __________________ 72 LWB chevy truck. Pasadena, Texas

04-03-2003, 12:47 AM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Quick way to see if it is detonation, fill up with 92/93 octain, or what ever is high test at your fillin station. If it stops doing it, you found the problem. and at 50 miles a day, you should be able to fill up in a couple days.

04-03-2003, 12:57 AM	#11
spinning wheels Registered User Join Date: Sep 2001 Location: Hacienda Heights, California USA Posts: 474	When you mentioned clatter and that it gets louder when you get on it, I thought for a minute that you ended up with my ex-girlfriend, but then she clattered before she even got in the truck. On your problem, check the timing, but it may be too much piston clearance. Sounds like my tired Z28. Damn thing almost sounds like a diesel when the timing is too advanced. __________________ '72 GMC custom camper 350/350

04-03-2003, 01:58 AM	#12
O'l Buck Recovering Truck Driver Join Date: Mar 2002 Location: Orleans, NE USA Posts: 1,883	Check your torque converter bolts, if they work loose, it will give a good clatter......sounds about like a rod bearing spun. __________________ 67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska

04-03-2003, 09:58 AM	#13
Long Knight Spank 'em if you got 'em! Join Date: Nov 2002 Location: Kansas City Posts: 628	I'll check this stuff out this weekend. Thanks for the input everyone! It's always good to have an idea of what to look for instead of going in blind. This is such a great site for information! Thanks again. __________________ Long Knight '71 C-20, 350ci, TH350, Edl. 1406 Carb w/elec.choke, Ignitor ignition, Viper Tires, Orange Dipstick



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