Thread: Pat McCarthy and others......

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Need some advice from some of you who know engines. I mention you Pat, because you said you worked on marine engines as well as car engines.

How do you adjust the valves in a counter rotating Chevy 350 marine engine. I know how to do the actual adjustment, I just don't know the sequence. Last night I helped my Son install a pair of new heads on one engine in his boat. (Well, I drank his beer and ate his Doritos, he did the actual grunt work) When it came time to adjust the valves the manual we were using ONLY discussed a regular rotation engine, and it had been very descriptive on everything else up to that point. So, our assumption was that you do the counter rotating one just the same (bring # 1 to TDC, then adjust certain intake and exhaust valves in that position, then rotate it 180 degrees and adjust another group of intake and exhaust valves.

The manual was telling us that when # 1 was up we should be doing # 1 intake valve, and some other intake valves, but when I looked at one lifter it was telling us to adjust, it was obviously not on the heel of the lobe, because the lifter was up somewhat.

What I am asking is, do you use the same sequence for running the valves in the counter rotating one as you do in a regular rotating one, once you have estabished TDC for # 1???

Thanks,

Don

Heck Don, I believe I mentioed on another site that there were other options then selling the T Bucket , eg. sell Don Jr boat and get both young lads to buy you a bigger workshop that you could use rent free, and if you had followed my advice, and sold his boat instead of putting new engines in it.
Sorry apart from the cheek, I really can't help you on the other little problem.

i do it when the ex is at all most max lift and do the intake and do the ex the same way .i know some may say this will not work and that may be true for them but i been doing it this way for 20years .that way you do one side at a time and firing order will not matter

So let me get this straight Pat. You bring the exhaust on any given cylinder all the way open, and then you set the intake valve on that one? Do you then turn the crank and do the same to every other cylinder in sequence? It makes sense, if the exhaust is all the way open the intake HAS to be all the way closed.

Whiplash. Great idea, now if I can just sell it to them.

DOn

Originally Posted by Itoldyouso

So let me get this straight Pat. You bring the exhaust on any given cylinder all the way open, and then you set the intake valve on that one? Do you then turn the crank and do the same to every other cylinder in sequence? It makes sense, if the exhaust is all the way open the intake HAS to be all the way closed.

Whiplash. Great idea, now if I can just sell it to them.

DOn

yep thats how i allways done it. you are going to crank the engine more. do one bank no hopping around so theres less of a chance of a screw up .like i said. some may say it not the right way .but i done all my builds this way .i long block over 7 engines a year never had to relash any solids .or hyd lifters ever

Thanks Pat, that is what we'll do. I never worked on a reverse rotation one, it had me confused as to which way things moved internally.

Don

Set #1 at TDC firing stroke, then turn the crankshaft in whichever direction it goes, 1/4 turn, and set the next one in the firing order, whatever it may be. Continue around the engine two turns and you are done!

That's the problem we were having. When we tried to turn the crank bolt with a rachet, the bolt kept breading loose, as we were turning the engine to simulate the reverse rotation. So we bumped the starter, but that is very hard to hit the exact spots correctly, especially standing on your head in a tight twin engine bilge.

Don

you should of done it before you put the sparkplugs in then the bolt wouldn't of loosened

There were no plugs in and the intake isn't on yet. No belts or pulleys on either yet. It is just a tight motor for some reason. Part of the problem is, the engines are jammed right up against the forward bulkhead, with very little room to get in there.

Don

Ha! Sell the boat to buy a shop for dad huh???? Actually that is starting to sound like a good idea right about now with all the trouble I have had with the STB engine. Hopefully this will cure the issue.

Found the intake manifold gasket had given way and was allowing a small amount of seawater to enter the combustion chamber of the front two cylinders on the passenger side bank. Both intake valves were rusty. Luckily, I caught it before it filled the engine with sea water eventually

Thank you for the recommendations. Reverse rotation is just confusing because only the crank spins in reverse (to the right if you are behind the engine at the flywheel looking forward)

The cam and distributor spin normally (Even though the cam is specially ground to accomodate the reverse firing order)

Ok I need a beer now.........To confusing

Louey, I agree it should be that easy, BUT you can end up on the side of the lobe of the cam instead of the heel which gives you a false adjustment.


OK now i need another beer

Is there something you can do with the pulley bolt holes, long bolts, and a bar. Bump it with the starter get it close than finish with the bar. Aint gonna be easy!

Originally Posted by Louey

There were no plugs in and the intake isn't on yet.

In that case, does it really matter which way you rotate the motor ? I mean you can see when the lifter moves up and down, so you can go either way to adjust the lash. Just do one at a time is all.

That is what we did before we quit the other night. We watched both lifters on each cylinder and when both lifters were totally down flush with their bores we did the zero lash, then 3/4 turn thing, then moved to the next cylinder and did exactly the same thing. I figured that was close enough, but Don is tired of climbing around in the bilge of this thing and wants to make sure it is done right before the intake goes on.

Don

Yeah, I called it good, but told Don we would ask people who know more just to be sure. From where I was sitting, drinking my beer and eating Doritos, it seemed fine.

Don