Cast iron valve seats and LPG

[Pinger]

Are valve seats cut directly into a cast iron head - ie, no inserts - durable enough to withstand LPG?

[Gilbertd]

No. They need to be cut and inserts fitted. In fact, they are not even hard enough for unleaded petrol. When unleaded first came out people were horrified that it couldn't be used in the original BMC A series engine due to the seats being cut in the cast iron heads. Later A series in things like the Maestro and Metro had different heads.

[Pinger]

Thanks GilbertD. I only saw your reply today - missed it before the forum went down.
This is a strange one. My Chevrolet L31 Vortec engine is known to be durable in terms of tolerating LPG. I asked about valve seats on a Chevrolet forum and was told with the exception of some of the engines in 1 ton trucks and engines for LPG, the Vortec has seats cut directly into the cast iron head. The exceptions have either inconel inserts or, induction hardened (parent metal - ie, cast iron) seats and then only for exhausts. While I assume the standard (cut directly into the cast iron) seats are durable to LPG, for certain they are compatible with unleaded petrol. But I don't dispute your comments on BL's A-Series (and many other) engines.

[jon_gulliver]

I have heard of enlarging the contact area of the valve considerably to allow cast iron seats to be used. Never thought it was a very good idea though.

[Pinger]

I have heard of enlarging the contact area of the valve considerably to allow cast iron seats to be used. Never thought it was a very good idea though.

It would add durability I suppose.
What confuses me is that small block Chevys are happy on LPG despite cast iron seats. Maybe induction hardened exhausts but not inlets.

[Gilbertd]

I'm in the process of rebuilding a Mercruiser 4.3 V6 boat engine that was run out of the water and badly overheated. That is nothing more exotic than a Chevy 5.7 small block Vortec with a couple of cylinders missing and I can confirm, having spent days grinding the valves in, the exhaust seats are hard, very hard.....

[Pinger]

I'm in the process of rebuilding a Mercruiser 4.3 V6 boat engine that was run out of the water and badly overheated. That is nothing more exotic than a Chevy 5.7 small block Vortec with a couple of cylinders missing and I can confirm, having spent days grinding the valves in, the exhaust seats are hard, very hard.....

Reassuring!
has your engine survived without cracking of the heads? A Vortec susceptibility apparently or as I saw it put: ''Vortec heads are great - until they're not.''

[Gilbertd]

I have no idea how long it was run for without any coolant but both heads were cracked, one piston burnt, 2 others damaged, scoring on the 3 affected bores but that has honed out and still left enough meat that it doesn't need reboring. I got a pair of replacement, secondhand, heads from a company that refurbishes the Mercruiser engines and a set of new valves to fit in them (hence the valve grinding). The engine is identical to that fitted to smaller Chevy trucks, only difference on the marine version is brass core plugs and different gaskets. Haven't ordered the new pistons yet but I'm torn between a couple of secondhand ones or a full set of new ones.

[Pinger]

Hi Gilbertd. From here I can't tell whether you are an old hand with this engine or it's new to you - so forgive if if the former and I blurt what you already know.
The heads cracking is no surprise and you have replacements. Where are you sourcing the incidental parts? I use Rock Auto. Some stuff is available in the UK but for the same money, there's better quality on Rock Auto. Here >> https://www.rockauto.com/en/catalog/che ... 533,engine is the engine page for a 1997 4.3. as fitted to a 1500 (half ton) pick-up. Pistons (with rings) are £20 or £47 each - but I didn't check if individually available or in sets only.
Much of what I have to say about OEM rubber-on-plastic inlet manifold gaskets is probably moot here - suffice to say, avoid a gasket so constructed. Given the heads are the same Mercruiser and truck - that gasket can't be very different. Differences in SBC manifold gaskets tend to be related to channels left open or blanked for eg, heater by-pass, etc.

I've not had the heads off mine but I think there are bolts that enter waterways that require a sealant. Did you mark the dizzy's position prior to removal - or do you have the scan tool to set the timing? There is I believe another method if neither of the aforementioned are appropriate.
As I said, I don't know your depth of experience with this engine but for sure the guys (and girls) on the American truck forum I'm a member of know these motors inside out. Any questions you have I can bring to them for answers - including recommending a quality inlet gasket. (A failed gasket can allow a cylinder to fill with water when parked up and bend the con rod to oblivion on first turn of the starter. If your engine had a separated fresh/sea water cooling system, a failed inlet gasket could have caused the loss of coolant - the pistons do have something of a 'steamed clean' appearance).

[Gilbertd]

This particular engine is new to me but I've been working on and rebuilding engines of all types for the best part of 45 years. Distributor was marked before being removed with the engine at TDC number 1. I agree the pistons look clean but from the state of everything else, it has been run very little, I think the previous owner used it moored up for posing rather than actually taking it out and going anywhere in it. It's a '96 engine so the page you linked to is spot on. I've been getting some parts from either realsteel.co.uk but the heads came from Repower Marine. Not sure where I'll get the pistons, I'll compare prices and specs. Repower may be willing to supply me with 3 used ones, or it will be a full set of new ones. I've got the Mercruiser engine manual and that gives full rebuild details including the need for sealant on the head bolts. It is a pretty pathetic piece of design if you ask me. Head bolts going into the block I don't have a problem with but rather than them going into blind holes they go right through into the water jacket. So if you don't put the sealant on the bolt threads, coolant can work its way up the bolts and fill up the rocker covers. Crude, but it is American after all.....

The marine inlet manifold gaskets are aluminium with rubber inserts around the ports. Obviously there's no heater channels as there's no heater. It doesn't have a separated cooling system, it uses the water the boat is in for cooling. An impeller in the outdrive (a Mercury Alpha One) sucks water in either side, just above the propeller, pumps that to the engine where it is circulated by the water pump (not sure if this is different to the one used when the engine is in a truck or not) and outlets through a coaxial exhaust manifold so it cools the manifold and exhaust gases, before exiting, with the exhaust, out through the centre of the propeller. So if it is run out of the water, there is no coolant there at all. Any coolant left in there from when it was in the water, will be pumped out in a very short space of time so it will be running completely dry. Dashboard temperature gauge won't show anything untoward as the sensor needs to have coolant around it, not air.

[Pinger]

I've read of issues where the cyl head bolts let coolant out when sealant hasn't been used - not that you'll do such a thing! It's not ideal the way it's configured but there's worse - MB V8s with the tensioned part of the bolt in the water jacket. Yep, they corrode and lose clamping tension.
Around about 1996 is the transition year for trucks between the TBI (throttle body injection) and Vortec with sequential injection with the injectors in a block (aft of the throttle body) and feeding poppet injectors located in the manifold runners - the so called 'spider' system. Yours will have the different manifold and external injectors I suspect. Not sure of any changes with the marine engines around this time but definitely so with the truck motors. Possibly the changes between TBI motors and Vortec is only above the block (ie, bottom ends the same) but the ignition systems are different. TBI takes its ignition timing from the dizzy. Vortecs have a reluctor wheel on the nose of the crank and use the dizzy as a cam sensor. The importance though of getting a Vortec dizzy correctly timed is to avoid the spark jumping to the wrong lead within the rotor cap. The V6 is probably less susceptible with wider spacing on the dizzy cap and not having a cylinder half way into its compression stroke to catch an errant spark.

What I found with Real Steal and USAutomotive is (apart from the lack of quality choice) is that they carry limited stock and though they can get anything you want, the lead time is as per Rock Auto - where the prices are keener despite shipping costs. Typical lead time is ten days (economy option) and if you are ordering multiple items, consider trying different permutations such that they all ship from the same place to reduce carriage costs. The 'truck' icon is the symbol for that.

Sounds like you have decent gaskets. It's the rubber on plastic ones that are frail. The Vortec's only true weakness. There was a Ford V6 that suffered what you describe. If it lost only a little coolant the temp sensor was in air and didn't register the problem.

[Gilbertd]

From '96 onwards the Mercruiser engines used the Vortec V6 block, the one with the balance shaft (which they refer to as the Gen+ motor), but with differing fuel and ignition systems. The 4.3LX Gen+ with a 2 barrel carb and standard dizzy with electronic ignition (designated as the 190hp version, which is the one I have), the 4.3LXH Gen+ with a 4 barrel carb (designated as the 200hp version) but still with a dizzy and electronic ignition and the 262 Magnum EFi Gen+ with TBI fuel injection but still uses a dizzy although without an advance mechanism as that is dealt with by the ECM. Dizzy on all of them uses the standard method of driving it off the oil pump drive which is driven from a gear on the camshaft.

The new valves came from Real Steel as they were a fair bit cheaper but were available from stock so came next day. I got the secondhand heads (and a marine gasket set) from RePower Marine (they also trade as Bradford Grinders). I assume they do engine rebuilds on other types but they specialise in refurbished V6 and V8 Chevy small block engines used as Mercruiser and Volvo Penta badged marine engines. In fact, a friend with a C3 Camaro needed a replacement 350 engine and bought a refurbished marine engine from them and only had to swap the sump with the one from his old engine, everything else was identical.

[Pinger]

From '96 onwards the Mercruiser engines used the Vortec V6 block, the one with the balance shaft (which they refer to as the Gen+ motor), but with differing fuel and ignition systems. The 4.3LX Gen+ with a 2 barrel carb and standard dizzy with electronic ignition (designated as the 190hp version, which is the one I have), the 4.3LXH Gen+ with a 4 barrel carb (designated as the 200hp version) but still with a dizzy and electronic ignition and the 262 Magnum EFi Gen+ with TBI fuel injection but still uses a dizzy although without an advance mechanism as that is dealt with by the ECM. Dizzy on all of them uses the standard method of driving it off the oil pump drive which is driven from a gear on the camshaft.

Only the TBI mentioned there is recognisable as a truck set-up in the mid 1990s. I can see why the required gasket set differs so much.

The new valves came from Real Steel as they were a fair bit cheaper but were available from stock so came next day. I got the secondhand heads (and a marine gasket set) from RePower Marine (they also trade as Bradford Grinders). I assume they do engine rebuilds on other types but they specialise in refurbished V6 and V8 Chevy small block engines used as Mercruiser and Volvo Penta badged marine engines. In fact, a friend with a C3 Camaro needed a replacement 350 engine and bought a refurbished marine engine from them and only had to swap the sump with the one from his old engine, everything else was identical.

Fair play to Real Steel - they sorted you out with what you wanted - ditto RePower.
If, you decide to buy from Rock Auto, I believe this is a valid (5%) discount code: 235212578188298673. Valid until end of July and goes into the box labelled:
“Where did you here about us”

[Pinger]

Crude, but it is American after all.....

Americans are very good at building to a price and still attaining the required objectives. The end result isn't always aesthetically pleasing, glamorous in it specification and may well include downsides re maintenance but they are good engineers. They pioneered thin wall casting without which the ability to meet weight objectives with iron blocks may have caused GM to retain, not release, its alloy V8 that became the mainstay of the Land Rover line-up. When GM next returned to an alloy block (Cadillac 4.1, 4.5, 4.9l V8s) they paired it with iron cylinder heads (to avoid having to install separate valve seats) - which is where this thread started!

[Gilbertd]

When GM next returned to an alloy block (Cadillac 4.1, 4.5, 4.9l V8s) they paired it with iron cylinder heads (to avoid having to install separate valve seats) - which is where this thread started!

That's something I have never come across, iron block with alloy heads yes, but never the other way round!

Maybe I was just lucky with realsteel having the valves from stock and Repower actually supplied me with 3 heads. They sent the first two and one was in pretty good condition but the other was pretty well rusted (there's something about these engines, leave them overnight and the following day all gasket surfaces have a coating of rust on them, I've got it slobbered in grease at the moment.....). That one needed the valve seats re-cutting so I took it in to get it done and they found a crack actually on the valve seat. Phoned Repower, told them and they sent me another by next day courier free of charge. So I've actually got 5 heads but only 2 don't have cracks.

I'm leaning towards a full set of pistons from Rock but the ones that look the same as the originals are the Mahle, more expensive, ones.

The main reason why the gaskets on a marine version are different is that they have to be able to cope with sea water being used as coolant. A good reason why they use all iron engines, I suspect an alloy one would dissolve after not much use.

[Pinger]

I have never come across, iron block with alloy heads yes, but never the other way round!

Yep, American engineers weren't scared to innovate. I'll post a photo of the engine at the bottom of this post. Note how little actual material there is in the heads so despite being iron, they are still pretty light. Another example of production line cost saving is the duplicated valve cut-outs on the pistons you are working with.

Maybe I was just lucky with realsteel having the valves from stock and Repower actually supplied me with 3 heads. They sent the first two and one was in pretty good condition but the other was pretty well rusted (there's something about these engines, leave them overnight and the following day all gasket surfaces have a coating of rust on them, I've got it slobbered in grease at the moment.....). That one needed the valve seats re-cutting so I took it in to get it done and they found a crack actually on the valve seat. Phoned Repower, told them and they sent me another by next day courier free of charge. So I've actually got 5 heads but only 2 don't have cracks.

Chances are those exhaust valves are the same as fitted to every SBC from the 1950s!
I wonder if salt water has permeated the sealing surfaces - or maybe it is just what GM engines do.
RePower have been very fair with you. That said, Vortec heads have a rep for cracking.

I'm leaning towards a full set of pistons from Rock but the ones that look the same as the originals are the Mahle, more expensive, ones.

I don't know if it's your money being spent here or a 'customer's' but either way I'd veer towards the Mahle/Clevite ones despite the additional cost - which will be relatively small in the overall rebuild costs, represent better value when carriage costs are included, appear to be a closer match, and will be of a known quality. Rock Auto offer parts from suppliers for all budgets and generally the advice is: 'don't buy the cheapest'. This feeds into my earlier comment and by way of an example. From either Real Steel or US Automotive (I forget which) the cheapest oil filter RA sell costs the same as the best (Wix) filters RA sell. For the same money - better quality.

The main reason why the gaskets on a marine version are different is that they have to be able to cope with sea water being used as coolant. A good reason why they use all iron engines, I suspect an alloy one would dissolve after not much use.

That explains why the inlet manifolds are cast iron but alloy on the trucks. The marine manifold (despite its extra weight) is a sought after item for the V8s as it allows fitment of more conventional injectors. The spider system gets a lot of flak but as mine is only for start-up I don't let it worry me.

[LPGC]

Wahey! I'm back on the forum again thanks to Dave.

I have similar boat problems at the moment Gilbert. Sent you a link to a thread I started on a US boating forum which explains all, I'm getting some good info from users on there. Just off the phone to Repower marine myself. My boat has an Volvo Penta (read OMC Cobra, read Ford 5.0) engine / setup, a knock from the engine, I've just gone to do a compression test and cranked the engine with no plugs in... only for loads of water to spit out of all the starboard side spark plug holes . The same side marine exhaust manifold looks cracked (and bodged on the outside by someone trying to use sealant), I'm guessing it's cracked on the inside too so allowing water to get to the exhaust valves (and into cylinders), further expect the knock is due to engine damaged caused by hydraulic lock... not sure if the knock will be valve train related (bent pushrod / valve / collapsed follower / etc) or bottom end related (broken piston / rings / bent conrod / broken big end bearing). Bah!

[Gilbertd]

As it happens a friend in France had a boat with the same engine, Ford Windsor 351. I don't remember how or why but he ended up with a spare, good, cylinder head that he gave me and suggested I put it on eBay. I did and everyone that asked about it wanted a pair and not just one, so it sat in my garage for years and moved with me when I moved house 4 years ago and it still sits on a shelf in the garage. So, if it will be of any use to you.....

@Pinger, this is my engine not a customers. I bought a little 13.5 foot Fletcher speedboat with a 40hp outboard not long into lockdown as a bit of a project. It was on a trailer but the guy selling it was moving house and wouldn't have anywhere to keep it, so I got it at the right price. It needed paintwork, the engine fitting properly and a bit of cosmetics (not usually my thing). Partway through doing it, I managed to throw a 600cc Yamaha down the road at about 40mph resulting in lots of bruises and destroyed Shoei crash helmet, leather trousers and right boot. Not too much damage to the bike surprisingly, but I was looking at £600 to replace the gear, so decided, as it was only a weekend toy, my biking days were over. Anyway, got the Fletcher finished (despite only having one working leg for a time) and we took it to the local river to try it. That was a bit of a failure as the engine wouldn't idle so had to be started and immediately slammed into gear but the main problem was that the lower engine mount holes in the transom were below the waterline and had 16mm holes with 12mm bolts going through them so it started to fill with water at a worrying rate. Anyway, after finding some suitable conical rubber bungs to fit over the bolts to seal the holes in the transom and adjusting the carbs (with the bottom of the motor in a plastic dustbin full of water) we were ready to give it a second try. This time it was a success. Engine ran perfectly, it didn't fill with water and everything seemed pretty much spot on. See https://www.youtube.com/watch?v=Xo2I9dlDn80 and https://www.youtube.com/watch?v=klwemf0gB18. On the way home, the missus said, "I know you are going to miss having the bike, but for me, the bike was only fun when we got to where we were going. Getting there and back was either boring or scary, but this is fun. I know you bought it to sell on but why not keep it?"

I thought about it but decided that 13.5 ft wasn't big enough to safely take out on the sea (and it would get boring pretty quickly at 7 knots on the river except for a 1 mile stretch known locally as water ski mile) and 40hp wasn't enough to realistically tow a water skier. I used to water ski a lot and the plan was to teach the missus to drive the boat so she could drag me around with a couple of planks on my feet and I could teach her to water ski too. As she is originally from Latvia (which was still part of the Soviet Union when she was at school), her games lessons included biathlon, skiing and shooting, so she can snow ski and everyone says that if you can snow ski you will easily pick up water skiing. But not easily with only 40hp to do the pulling. So she suggested selling the little Fletcher and getting something a bit bigger. I started looking for something around the 17-18 ft mark with 100hp but all I could find was either overpriced, out of my price range or described as a project which would likely take at least 10 years before it could be got into a state where it would even float! Then I found something right up my street, a Bayliner Capri 2050 Bowrider. Complete with trailer and described as cosmetically perfect but with a blown engine. Got it for around 30% of what it would have cost me if it was all ready to go. The seller had taken it to a marine engineer who had started taking it apart and had quoted the owner £9-10,000 to replace the engine with a new one, hence it being sold. The small matter that it was 20.5 ft with 190hp didn't seem to make that much difference. Even though I'd shown the missus pictures of it before collecting it, her first words when I got it home was, "bloody hell, I know I said get something a bit bigger, but it's huge!!).

Initial checks revealed a lack of compression on 3 cylinders and a bit down on 2 others but no nasty noises (in fact, it even tried to fire on what was left in the carb). So off with the heads and the cracks were immediately obvious. Got the replacement heads, fitted new valves and spent hours with the grinding paste. Got one head ready so fitted that to the RH bank. After a delay when I found the other head was cracked and had to start again from scratch on the replacement until that was ready to bolt on. Then I saw something odd. While cleaning up the block face, I noticed what almost looked like filler around the top of the bore on the LH bank rear cylinder. As the engine had been left at TDC on number 1, that cylinder was at BTC so not easy to see (not without standing on your head inside the engine bay anyway). A mirror showed the full damage, so the engine was going to have to come out (if it was in a car you'd just drop the sump but you can't do that when it is in a boat as you can't get underneath it). That is where the delays started. With the boat on the trailer, the sides are around 6 feet off the ground and the engine has to be lifted over that. I've got an engine crane but there is no way that is tall enough and the 4 post lift in my mates workshop doesn't go up high enough to be able to lift it out on that and tow the boat out from underneath so I had a problem. That was last year so it got ignored over winter. The rear mounts are 1/2" bolts through rubber bushes but were seized solid too. I ended up having to drill them out which from start to finish took 2 days (cobalt drill bits very slowly, lots of lube, started with a 3mm drill and went up in 1mm increments until I got up to 12mm and the remains of the bolt came free)! But I still had the problem of how to lift it out. Then, I was asked to do an air con install in an old house with 10ft ceilings and pipework that had to come out through the loft. No way was I putting a 65mm hole in a brick wall from a ladder at that height so had to hire a towable cherry picker. Customer paid for it but the company said that if I hired it on a Friday and got it back before 9am on Monday, I would only be charged for 1 days hire. That meant I would use it on the Friday to do the AC install and have it sitting at home for the weekend. The platform was rated at 250kg SWL so a 1/2 tonne chain block was attached to the underside of that, manoeuvre it into place over the boat and hook up the chain. As the lifting eyes are bolted to the heads, I'd had to fit one of the cracked heads to the LH bank so I had something to attached the chain to but out it came. Dropped it into my little 4x3ft trailer and used that like a wheelbarrow to move it to in front of the garage where I then had to use my engine crane to lift it out of the trailer and attach it to an engine stand. And that is where it is now. The one piston is well and truly fubar'd, two others have scuff marks on them but the bores seem good and should hone nicely. I've got 3 done, 1 part done and 2 more to go. Bottom end bearings were perfect so all I really need is a set of big end bearings (crank is still in place with masking tape over the big end journals to keep them clean and to stop them rusting) and a set of pistons. The only problem I have now is time. The sun came out a week or so ago and I'm inundated with people wanting me to install AC systems for them......

[LPGC]

As it happens a friend in France had a boat with the same engine, Ford Windsor 351. I don't remember how or why but he ended up with a spare, good, cylinder head that he gave me and suggested I put it on eBay. I did and everyone that asked about it wanted a pair and not just one, so it sat in my garage for years and moved with me when I moved house 4 years ago and it still sits on a shelf in the garage. So, if it will be of any use to you.....

Yes please mate!

I'll just say that for now, off to bed soon, but very interested in the rest of what you've written about your boat/engine too.

[Pinger]

Gilbert: Very sorry to hear of your mishap with the bike (I've ran bikes on the road in the past - I know the dangers) and trust you are fully recovered now, but congrats on finding a new hobby. And hat's off for the repurposing of the cherry picker - genius! Way back before I'd even reached my teens neighbours had a boat with a BL A-Series engine that had to come out. The lifting 'apparatus' (which also deployed a functioning telegraph pole as support!) was probably my introduction to resourcefulness.

PS. This thread is morphing nicely! Not at all what I expected - all good!