Thread: early 80's 350

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im not familiar with the Chevrolet side of motors. i have it in my boat and it is a engine out of a suburban that i rebuilt and had it bored to a 383. I'm getting water on top of the pistons on #1 & 7 cylinders. just built the motor and on the test stand everything checked out. put it in the boat and it runs shitty. the head doesn't have dowel pins they look to be filled or either broke off and machined smooth. could i have missed a plug or something and causing water intrusion? idk how it could be a head gasket and i hope it isn't a cracked or warped head. thx for any input guys. the compression is around 160 on all cylinders and there is enough water that when i pull the sparkplug out i can pour the water outta the plug. i took the hoses off the risers on the port side and run it trying to eliminate the riser malfunctioning and still got water in the plugs. i removed the heads and took these picture. the picture with the studs in backwards is to show the placement of the gasket and all the open holes. also when i was taking the heads off alot of water went all over all the pistons but the sludge that you see is after i wiped the pistons off a little bit so im assuming that all the cylinders arent running correctly. any ideas?

First, I'd get the dowel pins replaced! Only way to get the heads and gaskets positioned correctly on the block. Seeing as how the heads are now off, I'd suggest having them pressure tested and the block surface checked for squareness. Might want to do the straightedge and feeler gauge check on the block surface where the heads bolt on, too.

the deck at best looks weak . i see were the head gasket is weak heads need a clean cut .like dave said fix the deck pins . but like dave said check the heads they are very thin casting and crack under an threw the head chamber seen many that were FNG . was it leaking in the boat ? if so check the ex logs could be busted in side and water getting in threw the EX valve

Is this boat running in salt water? The finish on the head and block surfaces leads me wonder what the condition might be for the rest of the cast pieces. While it was out being bored, was any internal inspections completed?

Originally Posted by 34_40

Is this boat running in salt water? The finish on the head and block surfaces leads me wonder what the condition might be for the rest of the cast pieces. While it was out being bored, was any internal inspections completed?

did say the engine came out of is truck? ..... BUT ....... if the ex boat logs have ever been in salt water there a good place to start looking. they rot out . has for the deck on block and heads every job i do at my shop gets a cut its a big deal them chevy sbc have a very bad deck finsh from Gm many guys seem to think they can fix it with a 3m wheels on a die grinder they do nothing but make the head gasket work harder to seal it up. you realy have it down this far if evey thing get a pass and checks out i would deck the block and cut the heads . BRM hone rering check bearings .just for the hell of it check rods that they are not bent

Originally Posted by pat mccarthy

did say the engine came out of is truck? ..... BUT ....... if the ex boat logs have ever been in salt water there a good place to start looking. they rot out .

have it down this far if evey thing get a checks out i would deck the block and cut the heads . hone rering check bearings

Those are the first things I'd look at since I live on the Atlantic ocean it's what I'm most familiar with. And I agree with you regarding the other procedures while the block is at the machine shop. If his block was milled at that time it's living a hard life now!

Originally Posted by 34_40

Those are the first things I'd look at since I live on the Atlantic ocean it's what I'm most familiar with. And I agree with you regarding the other procedures while the block is at the machine shop. If his block was milled at that time it's living a hard life now!

when i worked at the boat yard it was not very hard to know when a boat was in salt water boat. just the smell in the bilge . salt is very hard on them on boats we had to cut the out drive gimble housing off to get the out drive off rotted and locked every thing up on it .... salt is nasty stuff. lucky for me i did not work on many salt water boat . fresh water is so much better

Originally Posted by pat mccarthy

when i worked at the boat yard it was not very hard to know when a boat was in salt water boat. just the smell in the bilge . salt is very hard on them on boats we had to cut the out drive gimble housing off to get the out drive off rotted and locked every thing up on it .... salt is nasty stuff. lucking for me i did not work on many salt water boat . fresh water is so much better

Cutting the drive out of the transom? I've done dozens of them. Fresh water might be better for the drive gear.. BUT, salt water is so much better for the fishing!

This particular engine hasn't even seen any water beside hose water. I just built it and put it in the boat, the risers are off the old engine that blew up. This is a fresh build, you can still see the cross hatch from being bored over. Idk how water would just get in 1 & 7. I'm going to test the risers with some pressure, that's all I can think it is. It was not leaking in the boat, I assembled the other side that isn't leaking the exact same way and it isn't leaking

My bet is the exhaust manifolds They leak even in fresh water after awhile. Been there done that.

Just rebuilt??????????? Awful lot of oil/carbon fowling on top of those pistons!!!!!!!!!!!!!

looking at the pics---it appears that there is an sizable amount of inexperience work on this engine---

What hasn't been addressed is that on cylinders #1 and #7---the intake port is next to a water passage in the intake manifold---a poor gasket /sealing match between the manofold/head surface would/could cause the oil fouling present and also fill 1 & 7 with water from the water passage port

well yes and so are 2 and 8 can you say ... It is a head slide...... with no deck pins for head to locate it... if it was down with out pins ????? that would open up the intake gap on that side ????......Yes... she is no looker ....jerry

You can drive those dowel pins on thru the deck and replace them with new ones---

You can also drill them out with a drill a little smaller than the pin which will release pressure on them and remove them----

well i installed 2 dowels on that side, gotta get new pushrods, for some reason with this motor the intake bolts are long enough to hit the pushrods and bend them. and get shorter bolts. and yes jerry i wasnt born with experience like you i guess. just a guy trying to learn sorry im not as basa$$ as you---------------------------------------------------thanks for your input though. im going to untorque the other head a littlebit and tighten the intake down evenly with both heads then retorque the head so its matched up. the head gasket on the side i took off was still slick and not made a permanent press on yet being the engine hasnt even been to operating temp yet

when you put your shorter intake bolts in make sure you use sealer on them just the end hole s on the heads are blind so all others are open bolt holes and will leak oil out of them as well if no thread sealer is used