barrman : Big Block Blues

Big Block Blues
Post by barrman on Jul 21, 2006, 12:47pm

I had a local machine shop do the heads on my 1966 396 Chevy Big Block 2-1/2 years ago. I assembled the engine in March 2005 and installed it in the M715 2 APR 06. Less than 200 miles later, I started hearing a ticking noise. I thought it was valve adjustment and got very good at valve cover removal/instalation.

I still had a tick

The 1965-1966 Chevy Big Blocks had a different way of oiling the lifters and engine upper end than all 1967-present engines. A groove in the rear bearing of the cam had to be cut in my cam and 1966 only bearings had to be used. The same shop did the groove to my Edelbrock Performer cam.

I was getting oil to the top of the engine. Some push rods where spraying oil and some just pulsing a little. I suspected the groove. Out comes the cam. The shop looks at it and compared to the original, everything looks good. With the cam in the engine and the lifters pulled I could use a drill to turn the oil pump and still get oil blasting out the front of each lifter gallery. Oil was getting to the lifters. Engine goes back together. The machine shop and I start looking at the push rods and rocker arms. They are kind of worn, so I buy 16 of each.

I still hear the tick.

The shop tells me "Big blocks do that sometimes, just drive it."

I narrow it down to the #3 exhaust valve. I can put my hand on it while the engine is running and the noise stops. If I tighten it down more, I loose compression. So, I think the lifter is bad.

Edelbrock sends me a new one. I install it.

I still hear the tick.

Al Nelson at the Texas FE convinces me that it could be the lifter bore is oversized and we both agree nothing can be done without a complete tear down. I drive it.

I think up something else last month. Inner vavle spring. I put air to the cylinder to hold the valve up while I pull the spring. I can hear air flowing around the springs. I jiggle the valve and the air flow changes. Not good.

I call the machine shop up and tell them my guide is shot. He agrees to look at it and take care of it.

I pull the head on Wednesday night and take it to him on Thursday. He tells me all 4 exhaust valve guides are shot along with the valves. He said it is because I ran the engine too rich and that he won't charge me labor, but I have to buy the valves and guides.

I tell him that my air/fuel mixture was 14.8:1 last week acording to my fancy Snap-On flexible gas analyzer and it has never been richer than 14.2:1 or leaner than 15.1:1 over the last year. Which is basically all of the engines 3124 mile life. He says that it couldn't be the guides because the all went and that it had to be driver induced. He also said to bring in the other head.

I pulled it off last night and took it to him this morning. They are bad too.

I called a few other machine shops up and talked to them about this. They can't think of any reason why my driving slow or a rich start up condition would cause the guides to go. They tell me that the guides where probably installed wrong or the seats weren't properly matted to the valves and that my shop is just not wanting to accept blame. I agree.

but, the other shops all want at least $250 to fix it now. My shop is going to charge me $70 and have them both ready next week. The guy who did the head work doesn't work there anymore. The guy who did my block and cam work is a big block fanatic and is a good guy.

I don't like it, but I will pay the $70 to get them back and the truck running next week. I know if I throw a big fit, they might "accidentally" slow down my work or break something else. But, I send a lot of business their way and influence about 400 people on where to get work done.

Can anybody think of a reason all 8 exhaust guides would go in the first 3000 miles that wasn't workmanship related?

Anybody think it is because I use 5th gear a lot and lug the engine around at 1000-2000 rpm a lot?

How would a rich mixture cause the valve stems to tear up the seats? I still haven't figured that one out.

Should I throw a fit and threaten his future business or just let it be and not refer people to him anymore?

Thanks.

Re: Big Block Blues
Post by tacomainoh on Jul 21, 2006, 1:37pm

well lugging the engine is no good, but I always thought that was harder on bearings than valve seats..... The only other thing that I can think of that would hurt them is overheating the motor, which I'll assume you haven't done.

I would let it be and not refer any more business to them.

Re: Big Block Blues
Post by robertcowan on Jul 21, 2006, 2:35pm

I,D HAVE THE GUY FIX IT THEN TAKE THE HEAD TO ANOTHER MACHINE SHOP AND HAVE THEM PULLED DOWN AND CHECK THERE WORK. I BET THEY JUST REUSED THE SAME GUIDES OR KNURLED THEM. BETTER CHECK YOUR SEATS TOO. IF THE VALVES WE WALKING AROUND THE SEATS ARE BAD TOO ! ALSO BETTER CHECK YOUR INTAKES BET THERE THE SAME WAY. 1000 RPM,S WONT HURT A 366

Re: Big Block Blues
Post by wrecker on Jul 21, 2006, 2:49pm

I really think what Bob said is probably going to be right. I've gotten so pizzed off at hill billy workmanship, that I insist on doing almost everything myself. If it were my truck, I think I'd live with the heads as is and save up for some high quality aftermarket heads/cam/carb/intake combo that some company's engineers have dyno tested and documented. That way you'll know EXACTLY what you have and how to tune it. Of course, I don't have access to the diagnostic equipment you have either.

Re: Big Block Blues
Post by barrman on Jul 21, 2006, 3:54pm

I just talked to them again and asked about the intake valves on the head I took them this morning. He said all the intake guides are worn a lot. He told me it was because I make too many short trips with the truck. I told him that 5 miles to town everytime I drive it isn't really all that short. Plus, since I live at the end of a dirt road and idle the 1/2 mile length of it, the engine is normally warmed up before I get above 1000 rpm every time I run it. He returned to his "I don't know" comments.

Tacoma,
The engine did get up to 215 degrees a few times last summer before I put in the Summit Aluminum radiator. The noise was present before that though. That reminds me. The machine shop guy asked me this morning if I had a 160 thermostat in it because he said it looked like it had been running too cool. I told him I was very happy to to have it as low as 180.

I also asked him about spark plugs. He says I have too much carbon build up on the valves and ports. I wanted his opinion about whether my plugs were too cold or not. I didn't ask him if an about to go bad coil would cause excess carbon build up. I really think he is just talking to cover his backside and that bad workmanship on his part is the problem.

Bob,
They are going to replace the vavles, guides and do a complete valve job because the seats need to be cut to the angle the guide holds the valves. Each guide is a little bit different according to the shop. I already have hardened seats from the last valve job.

Re: Big Block Blues
Post by drvnkaiserdaily on Jul 21, 2006, 4:26pm

It is true that the seats must be cut AFTER installing the new guides.The design of the canted valve head doesnt allow the guide to center itself,so the seat must be cut to match the new guide.Be aware that cutting the seat causes the installed height to increase.If these heads have ever had the seats cut before,and possibly milled for cleanup,you can be sure that you will be getting in to valvetrain geometry problems.Make sure that the contact patch on the rocker is correct upon re assembly.Most all hot rodding books show how to make sure the sweep of the rocker is correct.If too much of the contact patch is on the outside lip of the valvestem,RAPID wear of the guide will occur because of the side loading on the valve.This has possibly already happened on the previous valvejob.Not trying to be a know it all.This info came straight from a blueprinting book just for BB chebbys. Drvn

Re: Big Block Blues
Post by elliott on Jul 21, 2006, 4:26pm

Sounds like they are full of it, probably a good thing their "head" guy is no longer there. Bummer about the trouble, but for the $70 to have it gone through at least it's cheaper then taking the heads elsewhere (this time). I think they should be more honest with you then feeding you a line like that "too many short trips" crappola....

Re: Big Block Blues
Post by compexp on Jul 21, 2006, 5:17pm

Ask them how long they will warranty their work for. I've never heard of running the engine too little causing issues like that. I think they're full of crap.

If the engine is lubricating properly, it shouldn't matter how long or short the trip is. I think there was an issue to begin with.

Re: Big Block Blues
Post by jeepistdougiowa on Jul 21, 2006, 5:56pm

I'm guessing it's poor geometry as Drvn said...only other thing I can think of would be that the valves were set to tight.

Old machinist bud of mine always claimed some GM big blocks suffered from poor geometry from the factory, but they typically would make it to the 80,000 mile range before wearing to the state Tim's has now. He mentioned lifter bores being out of spec(bored off angle/result=excessive cam wear) and valve height being off as Drvn suggested(guide and seat problems).

Anyway you look at it, it sucks for Tim. I hope they get it right this time.

Re: Big Block Blues
Post by robertcowan on Jul 22, 2006, 2:30am

BARRMAN, heres a way to tell if you got a good valve job. as soon as you get your " finished " heads back. turn them on there side with all the intake ports up. fill the port with laquer thinner to the top of the port, look at the combustion chamber and see if its leaking, then do the same thing for the exhaust ports. the old thinner trick never lies. an old top fuel drag racer taught me this. thinner will seep when water wont. if its sealed it wont leak. also ask him to let you see all the work before its reasembled. he has no squirm room then !!!!!!
bob

Re: Big Block Blues
Post by barrman on Jul 28, 2006, 9:11am

I got my heads back yesterday. I of course, had to make them green along with everything else I unbolted when I took them off.
http://img221.imageshack.us/img221/8...adpaintly0.jpg

The shop owner stuck to his story that I was running too rich. I spent about 30 minutes with the tech who built them this time. He says there is no way the fuel mixture did this. 16 guides, 8 exhaust valves and 1 hardend exhaust seat had to be replaced. He is convinced it just wasn't put together right.

I had to pay $117.60 to get them back. That was "just the parts" according to the shop. I referred 4 people this week to other shops. I am going to call them up once I get mine back together and tell them about how much business they are loosing. I still have to buy an intake gasket set at NAPA tonight too.

Re: Big Block Blues
Post by brute4c on Jul 28, 2006, 9:32am

I sure hope its fixed now....

Re: Big Block Blues
Post by gimpyrobb on Jul 28, 2006, 10:46am

Good luck with it Tim. I was thinking of doing some work to the heads of my BBC, but now I think I'll just run it as is.

Re: Big Block Blues
Post by jeepistdougiowa on Jul 28, 2006, 11:09am

Been a while, but guides used to cost less than $2....that's one expensive seat!


Hope it's right this time Tim.

Re: Big Block Blues
Post by barrman on Jul 30, 2006, 4:01pm

I put it all back together Friday night and Saturday morning. I had just fired it up for the first time when Mark called. (Sorry if I was rude Mark, my cordless phone doesn't work inside my metal shop and I wanted to get off the phone so I could look for leaks and such as fast as I could.)

I can hear no noises and the thing has tremendously more power. I haven't had it on the open road yet, I finally got Jennifer to help me put the newly painted hood back on last night. I did have to use the truck to "herd" a runaway horse back to my land. Fast stops, starts, donuts and powerslides were needed. Along with some slow speed crawling through woods pulling a tied up horse that didn't want to follow. (It is amazing that a mad horse can make the entire truck slide sideways.)

I also had to put out a 2,000 pound round bale of hay out this morning. Never even knew it was there driving through the field in second gear.

I will drive it to work Tuesday and Wednesday this week and do the road test then.

I did figure out something weird on my timing though. 8-10 degrees advance makes it act like it is flooded when warm and hard to start. 10-12 degrees makes if fire up like a fuel injected engine. 12+ makes the starter chug. I have it at 10 right now and will see what happens as far as pinging and hot starting in town later in the week.