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TBI 350 problems

 
beaukulele
V-6 Camaros rule!
Posts: 27
Joined: 06/11
Posted: 01/21/13 07:30 PM

Let me start with a little bit of background. I rebuilt an engine over this past summer. I started with a stock 350 core and had the cylinders honed and crank refurbished. The crank is .010 over. I did not have the pistons or rods reconditioned as they all appeared to be fine to me. I also checked just the pistons in the bore without the rings and it fit perfect. When I reassembled the motor it was very difficult to rotate just the rotating assembly, but possible with a strong arm so I figured that once the engine started and ran for a while it would break in fine. That leads us to now.

The engine is more or less stock with just the addition of a Summit Racing 1102 Camshaft. Nothing special. It is in a 1995 Suburban with the stock Throttle body injection. The problem is, even with a known good 800 CCA battery, the engine will barely turn over and does so slowly enough to where I am legitimately concerned it is turning too slowly to start. Could the lack of reconditioning the rods cause this to happen? I didn't think so, but I am confused as everything else has been done to prevent this.  

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waynep71222
I have an SS396 tatoo
Posts: 448
Joined: 03/12
Posted: 01/21/13 07:44 PM

as you installed the parts... where did it start getting harder and harder to rotate??


or.. do you have a bad ground wire...

i have a great idea.. just to check... either take a thick jumper cable or both sides of a thinner set and clamp both of one end on the negative battery terminal... and the other ends on the engine block so you are doubling the ground connection...  if it starts then.. you have a bad ground connection to the block...

i had to start a jeep last week that an engine install tech.. NOT ME did not connect the ground wire from the battery to the engine block...    an OOPS moment... but the street sweeper was coming ..

Battery Negative To Block Ground Test

this allows the engine to be properly grounded with enough current to allow the starter to crank the engine...  

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beaukulele
V-6 Camaros rule!
Posts: 27
Joined: 06/11
Posted: 01/21/13 08:11 PM

The Engine started to get tight when pistons 7 and 8 were installed but all of the pistons had to be installed and removed with a rubber mallet and a considerable amount of force. The rings on the pistons seemed to make a lot of resistance but they were standard rings from a rebuilt kit. The pistons all at some points seemed to "jump" from spot to spot instead of sliding. I applied a generous amount of assembly lube to all cylinders before installation but it still did the same. I even had the pistons in and out multiple times. The second time I put them in I made sure to clean the ring grooves extremely well in an effort to let the rings have some play and it made little to no difference.  

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waynep71222
I have an SS396 tatoo
Posts: 448
Joined: 03/12
Posted: 01/21/13 10:00 PM

well its totally possible that the one or more of the rings might have been oversized... mixed in the stock rings..

once in a GREAT while that happens...

might have been file to fit stock size rings..     .004" end gap per inch of bore as i recall..      so 0.04 x 4" = .016" ring end gap..

the oil rings might also have been assembled wrong...  where the ring expander slipped under the oil control rings...  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 01/22/13 01:51 AM

A.Are the Rod Caps in their respective positions.

B.Are your bearings with the correct under-size.

1.Did you mark all the rod caps?

2.Did you mark the main bearing caps?

3.When they machined the crank did you mike the crank and check it for the proper bearing clearance. Both for the mains and the rod bearings. Or use plasti-gauge

4.You'll need .0015 to .0025 on the rod bearings.

5.On the mains .0015 to .0025. you can use Plasti-gauge for your application

6.As Wayne has said: on your piston rings. Go with .004 per inch of bore. Your 350 has a 4.0" of bore so .016 to .020 on the top ring.

7.Second ring. .016 to .018

8.Oil Ring .016 to .018  No wider..

It sounds to me as the engine was harder to turn: You should have STOPPED!

HOW MUCH OIL PRESSURE DO YOU HAVE?

1.You should have stopped and posted on our Forum.

2.Either the caps are not positioned correctly

3.Or the bearings are not the correct size.

4.I would pull the engine  out. Don't be surprised at what you find. If you didn't clean, and rehone or even break the glaze on the cylinder walls, you need to get that done.

5.JUST PULL THE ENGINE, AND GET BACK TO US!

Bob  

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beaukulele
V-6 Camaros rule!
Posts: 27
Joined: 06/11
Posted: 01/22/13 09:47 AM

I checked all the clearances on everything and had everything mic'd before assembled. The rings were at the .018 spec you listed. Everything was kept in correct order as I removed the pistons one at a time and put the cap on the piston it came off of. Pistons were kept in order. I also had the cylinder walls rehoned. Machinist told me everything was .010 over and I got bearings to put in it that were the correct size. No reason it should be this tight. I'll probably wind up pulling everything back out unfortunately.  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 01/22/13 04:02 PM

Don't look at it that way. If it did run and spit a rod out and windowed the block then you would have a pile of Junk.
  I would just pull the engine and recheck all your clearances. Something has to be obvious.

Bob  

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beaukulele
V-6 Camaros rule!
Posts: 27
Joined: 06/11
Posted: 01/24/13 01:52 PM

Kind of embarrassed to say this but it wound up being that the battery sat on concrete too long and was drained  Blush

I seem to be having another problem now however, while I was trying to break in the cam (2500 RPM for 30 Minutes), the truck will run for about 2 minutes then its almost as if it leans out. No matter how much fuel I give it, it won't stay running. Does anyone have any ideas as to why this may be happening?  Confused Before I swapped the motor I had been noticing a bit of hesitation, so I have considered low Fuel Pressure could be the problem and possibly the fuel pump needs replaced. Any ideas?  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 01/24/13 05:49 PM

Don't be embarrassed about the battery. At least you didn't pull the engine to find that it was the battery.....What that said.

1.The first thing I would do is change the fuel filter.
2.Then check the fuel pressure.
3.If the pressure varies its probably time for a fuel pump.
4.It could be the IAC is dirty.
5.EGR

Follow the fuel first...

Bob  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 01/24/13 06:09 PM

What threw me a curve, was the part when you said the engine was hard to turn when the engine was out. But anyway thats that problem.

My brother had a 1964 Ford Galaxie 500 XL with the 425/427. He wanted to put Crane Fireball Heads on it. Back in the day those heads were the hot set-up. For most Hi Po engines. The Chevy 435/427. The MoPar 440 engine. So he decided to pull the engine. We did everything by the book. Every piston we put in the engine was getting tighter. I can't tell you how many times we pulled it a part. I went through (3) Rear Main (rope) Seals. Thats what it was. The engine didn't have many miles on it. But we blue printed, and balanced that bad boy. Once all the parts were back. We had a small group of guys that ran BBF's. Anyway we used the same parts. We replaed the wear parts. Holman&Moody were the Gurus of the Fords back then.
  Ford Had (3) different versions of the 427. They had a Medium Riser, High Riser, and a Tunnel port. (I wish we had that engine today)!If I told you what we paid for a camshaft in 1968/69 we would all have a good laugh. How about list for P/N C8AX-6250-D was $42.10. I paid $36.70.
  Ford had a rope seal for the rear main. That was really a hard to turn over by hand. I told my brother, I'm not sticking the engine in. We have to find a way a get the starter on it. Well we did. The starter turned the engine over like a hot knife threw butter.
  That side oiler was a power house, when we were done with it, the heads, made a 50 to 60 horse power gain..... That car was an animal. He put the sliding rear traction bars on it like the state police had it hooked up hard. for a big car it moved. It wasn't a light weight, but it ran.

Bob  

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beaukulele
V-6 Camaros rule!
Posts: 27
Joined: 06/11
Posted: 01/26/13 10:56 AM

Pepsi, I am a bit confused by your first line. Are you saying you think because the engine is tight that is why it won't stay running? At startup the engine seems great, it runs really well WHILE it runs, but it dies shortly after that.  

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beaukulele
V-6 Camaros rule!
Posts: 27
Joined: 06/11
Posted: 02/01/13 06:48 PM

Just wanted to let everybody know I'm getting closer to finding the exact gremlin going on with my truck.

Got it running and it shut off and when I went to turn it back on the temp gauge read that it was overheating. Started to remove the radiator cap and it burped out into the overflow container. Filled the radiator back up, let it sit for a while and then added as needed. Turned it back on and it idled beautifully for twenty minutes. I did drive it up to my mechanic after this because it still has a bad stumble and on the way there it died three times until I turned the heat up all the way. I'm suspecting the water pump is going bad as I was forced to recycle the one off the running engine I pulled out. I also noticed my injectors are more dripping then emitting a pulsing spray.

At any rate, I appreciate the wisdom you all have shared with me. I am still learning a lot about engines and some things escape my thoughts in trouble shooting and you all have been really good at offering suggestions for my problems.

P.S.
Had to draw in my harmonic balancer more with an installer tool in order to fix a problem with the serpentine belt. When re-installing the bolt into the crankshaft, I was able to turn over the motor with a 3/8 drive craftsman ratchet. The engine still feels really good and taught all around but also feels well broken in and I am SO RELIEVED that it is.  

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68scott385
I mow my lawn and find Chevys
Posts: 1994
Joined: 10/09
Posted: 02/01/13 07:18 PM

The balancer will only go in so far before it hits the crank gear of the timing set. That IS how far it is supposed to go in, no more, no less. The crank gear is also supposed to go on until it hits the raised lip on the crank but shouldn't have to be pushed on with the balancer.  
68scott385 68scott385 68scott385

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pepsi68
I love my Chevy Chevette!
Posts: 4
Joined: 02/13
Posted: 02/01/13 10:12 PM

beaukulele

I'm back sorry it took so long. Website problems. AKA. Pepsi68 now.

I think because the engine was so hard to turn, and if it is tight it won't keep running until you get the RPM up and Hold it there ie breaking in the CAM.

Thats another thing to remember if the lifters are adjusted to tight the engine won't stay running either. The valves won't close to make compression, and you can actually rub the lobes off the cam.... A tight engine will have a hard time running. I won't get into what could happen. I didn't mean to confuse you.

Bob  

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beaukulele
V-6 Camaros rule!
Posts: 27
Joined: 06/11
Posted: 02/03/13 12:41 PM

About the balancer yes I know. I simply had tried to get the balancer on by tapping around it with a rubber mallet which seemed to be fine. When everything was assembled however, it was very apparent that it wasn't on all the way so I went and rented the appropriate tool from a parts store.

And yes, the engine was tight, but seems basically normal now. I did clean the piston grooves very well but as I'm sure you all know well, the carbon in the corners of the groove are hard to get, and I'm thinking that was the problem because after running for a while, the engine turns over just fine.

The valves if anything are slightly too loose. I followed the instructions of tightening until there is minimal play in the pushrod when the lifter is at its lowest point, and then about 3/4 turn from there. The lifters all seemed fine even when I was building the engine. It didn't really get much tighter when I installed the pushrods.

I noticed with the air filter element off my injectors are basically just spraying all the time instead of the pulsating bell shape that is most desirable so I've narrowed it down to a sensor problem or a need for new injectors. These components have a lot of mileage on them so anything is possible. As I said I got it to a point where it was running enough to where I got it to my mechanic and I'm going to see if he is a better troubleshooter than myself  Smile

Hopefully I will have an update for you all within the next day or so.  

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