Ventilated Piston Question
09-26-2002, 07:33 PM
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Ventilated Piston Question
Tonight I tore down the engine that blew on Memorial Day and found several new holes in the #1 piston. Also found the addition of a meandering crack in the cylinder sporting many tributaries. What an ugly scene. Not to mention the underside of my $2k Aluminum heads. Ouch. Oh yeah, and I seem to be missing the exhaust valve head as well in #1. Maybe just a coincidence?
Oh well. The question I have is, not knowing the valve material used to build these heads, is there any way to tell what they are? I suspect automotive. All cylinders were burning a nice tan color, including what is left of #1. None of the other exhaust valves appear tuliped. The only other notable problem was the bent pushrod. I was running about 4500rpm when it let go. 454magnums. The other motor failed in what I learned to be a similar fashion during my pre purch sea trial. Guess I should have ran screaming at that time.
Thoughts?
BT
Oh well. The question I have is, not knowing the valve material used to build these heads, is there any way to tell what they are? I suspect automotive. All cylinders were burning a nice tan color, including what is left of #1. None of the other exhaust valves appear tuliped. The only other notable problem was the bent pushrod. I was running about 4500rpm when it let go. 454magnums. The other motor failed in what I learned to be a similar fashion during my pre purch sea trial. Guess I should have ran screaming at that time.
Thoughts?
BT
09-26-2002, 07:47 PM
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I hate the winter!!
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BT:
Sorry to hear of your trouble. I am sure that they were not Inconel valves. If they were, I don't think you would be having this problem, unless you experienced valve float which can break off the valve. Is it possible for you to post a few pictures of the carnage??? It would be alot easier to get some real opinions that way.
Sorry to hear of your trouble. I am sure that they were not Inconel valves. If they were, I don't think you would be having this problem, unless you experienced valve float which can break off the valve. Is it possible for you to post a few pictures of the carnage??? It would be alot easier to get some real opinions that way.
09-26-2002, 07:55 PM
#3
Oh man, bummer, Is #1 the only one hurt? What did the head gasket look like? Compression ratio? I wouldnt think #1 would be the one to get hit by reversion problems so I doubt that. Are they high flow necked down valves? It may have just popped the head off the valve and then the rest happened.
09-26-2002, 08:11 PM
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Sorry Checkmate.. no got digital camera. Suffice it to say it is dam ugly!!! Definately not valve float. In fact, I think the moron I bought the boat from got the heads off a drag car. The valve springs were so strong I broke my spring compressor trying to remove a valve before this happened. I was having a oil temp problem in this engine before it blew, and I believe this was from excessive seat pressures. Not sure though. Asking these questions because I want to salvage the $4k in two sets of Edelbrock heads (6055).
Formula31... Long time no talk to bro. How you been? Yes, only #1 was hurt. You may remember I was having a problem with #2 toasting spark plugs just before this happened. I in fact did replace the risers on this side when I assembled the new long block because I thought it was a water problem. No washing of the cylinder evident though now that I have it appart. I'll have a closer look at the valves to see if they are necked. I believe they are.
The good news is, I had the new motor up and running within three weeks of this blowing, and then had a rompin good summer. Put about 50 hours on the two new long blocks. Unfortunately I switched to the oval port cast irons on both engines at that time looking for reliability. Lost 400-500 rpm in the process and am working on a plan to get that back (and then some) over the winter.
Thanks fellas,
BT
Formula31... Long time no talk to bro. How you been? Yes, only #1 was hurt. You may remember I was having a problem with #2 toasting spark plugs just before this happened. I in fact did replace the risers on this side when I assembled the new long block because I thought it was a water problem. No washing of the cylinder evident though now that I have it appart. I'll have a closer look at the valves to see if they are necked. I believe they are.
The good news is, I had the new motor up and running within three weeks of this blowing, and then had a rompin good summer. Put about 50 hours on the two new long blocks. Unfortunately I switched to the oval port cast irons on both engines at that time looking for reliability. Lost 400-500 rpm in the process and am working on a plan to get that back (and then some) over the winter.
Thanks fellas,
BT
09-26-2002, 08:25 PM
#5
Ive had a pretty good summer so far, a couple of scares on the new engine but nothing of consequence. Boat running strong and I cant wait to do the other engine this winter and I expect a clean 70 out of my barge. Need bolsters real bad.
I wouldnt think that large oval port heads would have hurt power at all. The aluminum heads may have been smaller combustion chambers (110) and the ovals are usually 119. That would have changed compression but I still wouldnt have expected a 500 rpm loss. I know everybody likes inconnel valve ( I do too) but this is the first year I have run them and I have never lost an exhaust valve before on my mild 450 hp motors. Although I didnt have inconnel's on my big motors on my formula either and never hurt them. I wouldnt ever use necked valves and make sure the seat is at least .100 wide for cooling. I have seen car head seat widths that looked like a pencil line. Im surprised the cam survived with those valve springs.
I wouldnt think that large oval port heads would have hurt power at all. The aluminum heads may have been smaller combustion chambers (110) and the ovals are usually 119. That would have changed compression but I still wouldnt have expected a 500 rpm loss. I know everybody likes inconnel valve ( I do too) but this is the first year I have run them and I have never lost an exhaust valve before on my mild 450 hp motors. Although I didnt have inconnel's on my big motors on my formula either and never hurt them. I wouldnt ever use necked valves and make sure the seat is at least .100 wide for cooling. I have seen car head seat widths that looked like a pencil line. Im surprised the cam survived with those valve springs.
09-26-2002, 08:43 PM
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If you were toasting plugs prior to blowing the #1 piston, chances are you were experiencing the big D. Detonation could have caused the exhaust valve to get very hot. Loosing center and ground electrodes in plugs is a serious problem that needs to be fixed quick before major damage occurs. Detonation is usually the culprit. Just my opinion.
09-30-2002, 03:20 PM
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hi BT,
6055 heads are edelbrock performer rpm 454-r race heads with rectangular ports. 315cc intake port on long runners, 300 cc on short runners and 110 cc exhaust runners. the combustion chamber is 118 cc with 2.19/1.88 stainless valves with 11/32 stem diameter with undercut stems. the bare heads are # 6054. they are automotive valves. undercut stems are a bad idea for marine engines even more so when the stem is 11/32 as opposed to 3/8 already. the great thing about aluminum heads are that they can almost always be repaired. cast head cracks, throw it away. get some marine valves and a big fat seat and your back in buisness. i have tulipped an inconel valve before though but i still think they are worth the money. i have a nice spring compressor your welcome to use anytime.
Fran
6055 heads are edelbrock performer rpm 454-r race heads with rectangular ports. 315cc intake port on long runners, 300 cc on short runners and 110 cc exhaust runners. the combustion chamber is 118 cc with 2.19/1.88 stainless valves with 11/32 stem diameter with undercut stems. the bare heads are # 6054. they are automotive valves. undercut stems are a bad idea for marine engines even more so when the stem is 11/32 as opposed to 3/8 already. the great thing about aluminum heads are that they can almost always be repaired. cast head cracks, throw it away. get some marine valves and a big fat seat and your back in buisness. i have tulipped an inconel valve before though but i still think they are worth the money. i have a nice spring compressor your welcome to use anytime.
Fran
09-30-2002, 05:51 PM
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I just got my Dennis Moore BBC Marine book tody, so maybe I will find answers there, but do marine engines like 3 angle valve seat grinds? That is what these 6055s have presently.
WetteVette... I think my problems with number 1 plug surrounded a cracked intake runner causing vacuum leak. It was just a matter of time before that caught me.
What I did after blowing that motor was purch a remanned 330hp long block. I bought performer oval intakes to match up with the cast heads and removed the al heads. The new motor matched the other replacement motor (the prior owner) installed after dropping a valve in the other engine during sea trial. I took the al heads off that engine as well at the same time. I was going for reliability.
Formula31... you are right about not loosing so much rpm just due to the head/intake change. There were probably other differences in cams and such that I am unaware of, which contributed to my loss in hp. Did I read somewhere your weekend sucked with a blown motor? If so, that bites!! I blew the splines out of another coupler, so my season is done also. Believe I am needing new gimbal bearings.
Excaleagle42... Thanks for the specifics and the offer of tools!! I really need to find a good marine engine shop in our area to get these heads squared away. To many unknowns at the moment. Do you know of any you would use? Sorry I won't be able to buy the first round this year at the Chesepeake Inn, due to my coupler problem. Probably start pulling motors this week. Hopefully we can get our **** together next year and hookup on the C&D.
Any more thoughts are greatly appreciated. Thanks,
BT
WetteVette... I think my problems with number 1 plug surrounded a cracked intake runner causing vacuum leak. It was just a matter of time before that caught me.
What I did after blowing that motor was purch a remanned 330hp long block. I bought performer oval intakes to match up with the cast heads and removed the al heads. The new motor matched the other replacement motor (the prior owner) installed after dropping a valve in the other engine during sea trial. I took the al heads off that engine as well at the same time. I was going for reliability.
Formula31... you are right about not loosing so much rpm just due to the head/intake change. There were probably other differences in cams and such that I am unaware of, which contributed to my loss in hp. Did I read somewhere your weekend sucked with a blown motor? If so, that bites!! I blew the splines out of another coupler, so my season is done also. Believe I am needing new gimbal bearings.
Excaleagle42... Thanks for the specifics and the offer of tools!! I really need to find a good marine engine shop in our area to get these heads squared away. To many unknowns at the moment. Do you know of any you would use? Sorry I won't be able to buy the first round this year at the Chesepeake Inn, due to my coupler problem. Probably start pulling motors this week. Hopefully we can get our **** together next year and hookup on the C&D.
Any more thoughts are greatly appreciated. Thanks,
BT
