Valve cupping? why? Anyone?

[John_S]

Re: Valve cupping? why? Anyone?

Do you have recessed pistons? You should, but make sure before buying heads. Also, make sure that Holley is not a street carb. If it is marine, it should have promenent J style vent tubes. If it is an auto carb, it was probably jetted too lean, along with being an explosion hazard. You need electric choke for vortec heads. The Edelbrock marine 1409 that Bondo recommends, would be good.

I purchased assembled vortec heads from Jegs. Free shipping (which is expensive) but, they have a single order handling fee. If you boat in freshwater or you have freshwater cooling, you can get the Edelbrock performer or performer rpm intake manifold there, too.

I believe valve train is the same, but look it up. The vortecs require self-aligning rockers, which should be on your 305 heads. Keep all valve train components to re-install in the same locations.


PS: the 305 heads are around 58cc compared to 64cc of vortec.

 

[rude50]

Re: Valve cupping? why? Anyone?

Pistons are cupped with four valve divits. carb is street but jetted up one size. Techs at merc spec.'ed the jets for me with some begging and flyingfish carbs did the deed.

 

[John_S]

Re: Valve cupping? why? Anyone?

"carb is street but jetted up one size. Techs at merc spec.'ed the jets for me with some begging"

I am not sure who you are talking to at Merc, but doubt they would provide that info given the liability of using a car carb in a boat. As Bondo said, Merc never used a Holley 4brl on standard production engines. Also, I can tell you that Merc was more than 1 step richer than typical car carbs for both Weber and Q-jet 4brls. Sell that Holley and get the 1409. You are lucky that carb only wasted your engine, and not you or your family.

As far as pistons, look at the pic of my engine posted above. They should look like that.

heads, intake, and carb... total will be over a grand, plus all gaskets, etc. Make sure engine is worth the expense.

 

[Bondo]

Re: Valve cupping? why? Anyone?

heads, intake, and carb... total will be over a grand, plus all gaskets, etc. Make sure engine is worth the expense.

Ayuh,....... I'm Agreein' with about Everything said since My last post,......

Somebody was very Misguided, putting that Head,+ Carb package together,.......

What do the Pistons look lke in #3,+ #6,..??..???

3) reprop for better than 4500 rpm WOT, say 4501 rpm

Nope,....... More like 4600/4800rpms @ WOT............

should I scrap the heads and intake and go back to vortec?

Ayuh,.......... That's the path I'd take..............

And don't forget the Carb....

 

[rude50]

Re: Valve cupping? why? Anyone?

Thanks all for your time and experience.

The pistons appear to be in great shape. The cyliner walls look great. I have to look real hard with a bright light to see even the slightest scores. With my bore micrometer I can't even measure a top ridge to bore difference. I think its worth another round. But I'll have to check rist pins for play in the two Tuliped cyliders. On my way back to dock there was a tapping around 3500 rpm.

What do you guyes think of Rochester carbs. I've got a new rebuild quadrajet for 5.7l that I was thinking about trying before this sad state of affairs.

Action time!

Plan A:
new cast iron vortec heads $470 (with stock springs caps and seals)
milodon stainless valves $200
Gaskets and seals $200
Intake manifold $350 (use rochester)
total $1220

Plan B:

New cast iron NON vortec heads $370 (stock springs)
Milodon stainless valves $200
gaskets and seals $200
Use old intake and Rochester $0
total $770

Would the extra $500 be worth the vortec? power? fuel economy? Less chance of valve cupping? Resale value? (with troubles like this these things creep into your mind)

Import john s your single posed pic is with heads on, no piston shot.
OK IMPORT JOHN S; IT WAS A CONTRAST ISSUE. YES THEY ARE MY PISTONS!

 

[MikDee]

Re: Valve cupping? why? Anyone?

Don't know if you really need stainless valves? as long as you have the right heads, & valves now. Do the vortec, or stock style heads, come with the valves? If so I'd use the stock valves, that come with them. I prefer the Edelbrock (Carter AFB) over the Q-jet carb. Although the Q-jet will get the job done, probably better then the holley, but I hope it's marine rated?

 

[John_S]

Re: Valve cupping? why? Anyone?

"Import john s your single posed pic is with heads on, no piston shot."

No, one head on, one off, but given the resolution, its hard to see. Here is a better shot:

Q-jet should be fine, just more of a pain to tune, than the 1409. Make sure it is marine. Post what primary/secondary jets and rods are, and will let you know how it compares to the one I run.

I think stainless valves are overkill. Stock mercs don't run them. But, understand why you want them.

The difference in heads, is about 30hp. I am assuming you are using a 64cc version of the standard head. A 76cc head would drop the compression too far (assuming recessed pistons).

What intake are you looking at for $350?

 

[rude50]

Re: Valve cupping? why? Anyone?

I don't have stats on q-jet. I purcased it from eBasicpower.com as a mcm 5.7l reman. when I was toying with the holly in case the holly bombed. So it should be water ready.

The new pics look just like my pistons only a bit blacker.

I was cosidering a holly marine manifold Commander 950 from jegs 9901-102-1 with an addapter to the q-jet. Or the Edm531170 from ebasicpower.com with the same addapter. The holly might be too tall but looks throaty. As always I'm open for suggestions. I have open cooling and run in salt once-in-awhile so I think I need something other than straight alum.

The heads I'm looking at are from Marinecyliderheads.com and come fully dressed. I could buy them bare for about $40 cheaper each but to add all the hardware would cost about $50 each. But with the cupped valves in my fear set, if I spend $200 I have a chance of loading up the boat now and again without a prop change and with some peace of mind. (I hope)

 

[John_S]

Re: Valve cupping? why? Anyone?

I looked at the heads at that website. They do not look like GM castings. If not, why try to save a few dollars on unproven heads?

GM Vortec:

MarineCylinderHeads.com vortec heads:

I looked at the small pic on Jegs of the Holley 950 commander. It looks to be a single plane intake. If it is, NOT recommended for your boat engine.

The Edm531170 looks to be a squarebore performer knock-off w/bronze lining. Much better than above. Make sure manifold, adapter, carb, and flame arrestor all fit under your dog house.

 

[rude50]

Re: Valve cupping? why? Anyone?

Import john s: Good Eye

I don't see casting #'s on the marinecylinderheads.com heads. I will investigate.

The old dog had 4.5 in. of head room ( carb center stud to insultaion) so I've got room but I will make sure.

Michiganmotorz also sells a vortec intake manifold 120-P that they use on there engines for $369.

 

[John_S]

Re: Valve cupping? why? Anyone?

That intake is like a Performer, as well. If you stay with that type of intake, it will minimize the carb jetting, etc that will need to be done.

99% certain they are not GM. I'd be leary of those heads, just because they were not forthcoming that they were not GM. While they do use screw in rocker studs, they apear to rely on casting vs machining around the head bolt areas. They provided no other specs or pictures of heads.

Other well known aftermarket cast-iron head suppliers, have near-vortec equivelents, but the cost is ussually higher than the GM. My recommendation is to stay with GM heads.

 

[JustJason]

Re: Valve cupping? why? Anyone?

It cracks me up with people with these frankenmotors have problems, i see it all to often. If you want to play Mr Engine Engineer then your bound to have a blow up. In fact that's what real Mr Engine Engineers do for a living is blow up motors at the factory and find out where they went wrong.
Whenever I hear the same old story I listen for key words, like "i think" or "it should" or "my buddy said that" "compression perfect" and my personal favorite is this post "my home made exhaust temp alarm never sounded"

That being said.

You cupped your valves because those cylinders ran lean, there is no other reason. (not for nuttin "lugging" usually melts pistons/exhaust valves, as it is a form of detonation, not preignition)
The valves overheated. It is the fuel itself that cools the intake valves. IE: no fuelie(or not enought of it)... no coolie... baaaa byeee (says the flight attendent)

Forget about the vortec this and vortec that (just a marketing term anyways for "hey us GM guys came up with a new block/head design that doesn't blow as often as the old ones")

If you want to do it right (ie:reliable) Take the merc serial number and order parts for that block. If you do it any other way, and i repeat ANY OTHER WAY... you are playing Mr Engine Engineer man. If the block came from merc vortec this or that, then buy those parts, if it did not, then don't.

Your Compression ratios are way to high, (120-140 being more normal) and that is 1 possible reason for the lean condition, I doubt the carb was jetted for and engine with 180psi. (180psi would be closer to race motor) And as Bonus said, possible to have a leak on the intake, also check the carb base and throttle shafts and anything else im not thinking of at the moment.

If you order all the merc specified parts, and assemble it all according to the merc manual (not some sealoc or clymer crapola, but the merc manual) you shouldn't have an issue. Whenever people have these issues I start looking at the parts that are not supposed to be there.

 

[John_S]

Re: Valve cupping? why? Anyone?

Jason,

I agree with the what caused this, and its always the safe bet to use genuine parts. In this case, the heads are discontinued from Merc, and maybe other parts as well. Not that he would want to buy them at Merc prices, anyway. A couple of G's just for the heads! I bet if you call Merc, they will give you a cross to a GM part

 

[rude50]

Re: Valve cupping? why? Anyone?

The list price for heads on the merc web is 1049.94 smackers, EACH! for a used engine... I don't know. They don't even list an intake manifold for the engine. Besides, where's the fun in that. If I wanted a sure thing I'd buy a new boat or wave from the dock. Of course you can't argue with a well beaten path, just ask any lemming.

I came up with the exhaust temp alarm after I found high resistance values accross the sealing compound of the thermostat housing and overtemp sensor. The sealing compond specified and used by Mercruicer. The resistance was so high that my searay overtemp alarm was unreliable. So I thought the first place a low water condition would be detectable would be the exhaust. I dusted off my MSEE and made an alarm. As soon as the gasses above either water shutter reach about 200 deg f a flashing light and buzzer goes off. Well before the block temp rises. If you need a cure for the giggles, I'll sell you the patent.

For me it's a cost vs. fun conundrum. Sure there's little risk in paying some else for what they have already figured out. But the risk of not having fun trying to figure it out is too high. (some of the time anyway, that's where all yous guys come in) Thanks all

Captjason: I "tryed" to check all gasskets and parts from the intake plenum down for failure and did not see anything obvious. But it's a good idea to give the carbs a going over for shaft leaks ect. Thank you.

For now my conclusions are this:

1) wrong intake manifold gasket thus no exhaust gas restriction thus higher temps for intake gallies of #6 and # 3
2) wrong heads thus higher compresion thus Higher temps and more force to cup
3) wrong heads thus smaller intake valve thus wrong mixture adjustment by rpm/vacuum method thus too lean thus to hot
4)Over proped thus more work and less air thus more heat.
5) stick to plans A or B above.

I'm still chrunching the number for plans A and B. But the vortec route is making me feel better.

 

[John_S]

Re: Valve cupping? why? Anyone?

"1) wrong intake manifold gasket thus no exhaust gas restriction thus higher temps for intake gallies of #6 and # 3 "

Your prior posts indicated the intake manifold gasket was open to these ports. That is the way it is suppose to be on standard heads. It is also open on vortec heads, just no place to go (intake or heads).

When I went back and checked, I found this: Plug type: ACMR43LTS. That is the wrong plug for your heads. It is the correct plug for vortec heads. It has too long of reach for standard heads.

 

[MikDee]

Re: Valve cupping? why? Anyone?

"1) wrong intake manifold gasket thus no exhaust gas restriction thus higher temps for intake gallies of #6 and # 3 "

Your prior posts indicated the intake manifold gasket was open to these ports. That is the way it is suppose to be on standard heads. It is also open on vortec heads, just no place to go (intake or heads).

When I went back and checked, I found this: Plug type: ACMR43LTS. That is the wrong plug for your heads. It is the correct plug for vortec heads. It has too long of reach for standard heads.

Whoa! That is the wrong plug for a normal small block Chevy!,,, heat range is right 43, but it's a long thread plug, not good! I agree on the gaskets.

 

[rodbolt]

Re: Valve cupping? why? Anyone?

hahahaahahaha
you guys are to funny.
captnjason is rolling me over with laughter.
he is another that did one school and remains clueless.
yes your valve over heated, that much is not in contest.
however now we ,mostly you, need to know why.
sit down, open a refreshing beverage and think.
the 2 main reasons an intake overheats is lean or lugging(over propped for that days hull load)
its not hard nor difficult. you dont have to redesign nor engineer the boat.
YOU have to figgure out what you wish fronm the hull and make corrections to the drive train to suit it.

a swalloed valve is simply a symptom, lie to your tech and you will swallow anoter.

the only reason an intake valve on a 5.7 tulips is due to valve overheat. the only 2 things that cause it are over prooping,creating excessive combustion temps or a lean airfuel mix in that cylinder creating the same over temps.

dudes, this aint rocket science. the technology is over 100 years old.

 

[moser42]

Re: Valve cupping? why? Anyone?

What is the recommended rpm's on a 350?
I know 4.3 V6's are 4400-4800, my dad has one and with just him and half a tank, WOT is 4350-4400, is this too low and may cause a tulip? With more load im sure the rpm's drop a few hundred.
Does this mean he needs a lower pitched prop or higher pitched?
If he got a 4brl carb would it bring the rpms up?

 

[rodbolt]

Re: Valve cupping? why? Anyone?

dont try to reengineer a high performance package, I get at least one a month that is so cobbled I simply close the engine box and politly say aint no way I will touch it.
some folks with years of experience can deal with it. most folks cannot.
the WOT on a 350 can vary all over depending on the options and who marinized it.
however regardless of who marinized it and the hull load the engine must be capeable of turning its WOT range.
if not its lugging and bad things can happen.
most modern EFI motors run a knock sensor that can detect pinging and attempt a corrective action.
carbed motors usually have no knock detect feature and you cant hear it in a boat so your first clue is loss of power.
I dont mean to bust anyones chops here but the company that marinized that GM product has all the guidelines.
if your not careful when mixing and matching parts it will snowball on you.
toss on a 4bbl and now you find the heads wont work well, toss on heads and now the cam profile isnt really correct, toss in a new cam and now the gear ratio/prop is wrong.
see where I am going with this ?
some folks have the skill and understanding to do it. most do not and spend large sums of money before giving up on boating.
most times the best course of action is reasseble it as the engineers designed it and operate it within the marinizers guidelines.

 

[Don S]

Re: Valve cupping? why? Anyone?

Red Spots....... I see em, Red spots on your forhead