Question on GT 40 heads

[wizard12]

Was lucky enough to pick up a pair of GT-40 heads and the complete intake from a 1996 explorer at pick-n-pull last week.
My plan is to install the intake, heads, and cam in a 1993 F150 5.0 and run it all with a stand alone Ron Francis MAF harness, both of which I already have.

I have never gone this in depth into engines, so I am going to have lots of questions along the way.

1. Here is a picture of the heads. Any idea on what would cause the one combustion chamber to be so carboned up compared to the rest. Anything I should be concerned about or look for?

2. Been looking on youtube for different ways to clean/de-carbon the heads. Any first hand experience is appreciated.

 

[OX1]

Plug not firing, injector leaking like crazy..........

 

[DirtDonk]

You going to have the heads refurbed? Or are you planning to use as-is?
Assuming getting a full valve-job and if so they would clean them and during that process would be able to highlight and fix any issues that are with the heads themselves.

If not (and you did ask about cleaning them yourself) then after cleaning you'll want to make sure that all valves seal against their seats. You can do that with air pressure or liquids poured into the port, or the combustion chamber.
My first set of heads I worked on were in great visible shape, but when I was cleaning them with kerosene and scrapers, I noticed that the kerosene would run past some of the valves very quickly while I was scrubbing and scraping. A sure sign that the valve seats and/or the valve faces needed some TLC.

For scraping, the old school tools still work well. Even a screwdriver with a decent sized head that's not too sharp will do the trick. Because the head is cast iron and not aluminum, gouging is much harder to do.
Dedicated scrapers, those air-chisel mounted scaler thingies, or similar scraping tools work well, but with today's modern garage usually sporting at least one angle-grinder and a bunch of wheels and flap-discs, there are lots of ways to skin that cat.

But there's a lot more to heads than just cleaning, which is why most of us still let the shops do it. Valve spring pressures and heights, valve stem and guide wear and trueness, valve face and seat facing, hardened exhaust seats (if machining is extensive, otherwise it's good from the factory on your heads) and magnafluxing are all things that a shop can make short work of.
If those were low-mileage heads (could you see the mileage on the Explorer?) you might be in luck all the way around. But it's not worth the trouble to me to do it twice.

How did the cam look?

Paul

 

[rjrobin2002]

Most machine shops will freshen the valve surfaces up for like $100 or so.

 

[wizard12]

OX1 - That makes sense. I guess I will need to check the injectors.

Paul - Plan is to refurbish the heads before using them. I initially thought about trying/learning to do it myself, but now leaning towards taking it to a shop and letting the experts do their magic. Want to make sure I don't have issues after I put them on, and I am as far from an engine expert as you can get.

Unfortunately I didn't get to see the mileage. I would be surprised if it was low mileage. Most 5.0 explorers are in the 300+ km range (180K miles) and they still demand a premium. It was pretty dirty and beat up, so I think it was ran pretty hard.

I am hoping to go and get the cam out in a couple of days when the weather is supposed to get above freezing again. I started to get the front dress off after I got the heads, but only got as far as the power steering pump, AC, and bracket before I had to call it a day. Hoping the rest of it is there and I can get it all off in one day.

 

[DirtDonk]

Cool. Good donor and hopefully the cam is in good shape still. They usually are, but you never know.

Doing the heads yourself is really not technically difficult. A few specialty tools can come in very handy, but even they are not always required. It's just the time taken to do it the right way that gets most people in the end. Taking the time to do it yourself, is time well spent. But sending it to the shop to be done is time not spent!

Paul

 

[onebadd73]

I just had a set of GT40 heads off a 93 Cobra rebuilt for $120.00. I also added a set of TFS valve springs and port matched both the intake and exhaust gaskets and cleaned up the bowls for my build.

 

[Broncobowsher]

The carbon could be from a bad ring on that cylinder. That would be my first guess. Since you didn't take the short block, you left the bad part for someone else. How did the cylinder look?

 

[wizard12]

Update

Broncobowsher - I was back today and had a look at the cylinders. They all looked very similar.

I called a engine/machine shop today and they want $300 per head to glass blast them, magnaflux, redo the seats, and something to do with the stem that I don't recall. That didn't include the parts, I would have to bring in new seals or he could order and add the price on top.
Unfortunately I haven't worked since Jan 2018 so I am going to use my spare time to pick away at them.

2 follow up questions:
1. I was able to get the rest of the front dress today, but wasn't able to get the cam out more than 2 lobes. I gave up after 30 minutes and then thought on my way home that I didn't remove the cam sensor - duh. Before I head back tomorrow, want to check with you guys on whether or not the cam sensor has to be removed to get the cam out, or if I have another problem (I did remove all the lifters)?

2. Anything else I should take that might be useful down the road?

 

[Broncobowsher]

Yes, the cam sensor has to be removed to get the cam out.

$300 per head, plus parts. That means at least $600 and that is of nothing was wrong. Add parts and you will be at least $700 and depending on what they feel is wrong it can be a lot more. That is too much. Either the machine shop has so much business that they can do this, or it is a sign that they don't want to mess with it. I bought a set of swap meet trickflows that had a dozen passes on them for $700 at one time. They were like new, needed nothing, and are a way better head.

I just checked Summit to price brand new aluminum heads. Trickflows are now ~$660 each and Blueprint has a head for $500. With rebuild prices like you are getting, the performance potential of aluminum heads is very much in reach.

Those Explorer heads are old school heads. They should not take $300 for basic work. There are still machine shops around that do good work on old iron at fair prices. If there are none left in your area, save a few more pennies and just get the aftermarket heads. Maybe go looking for a better set of heads that don't need rebuilding.

OK, scratch that. I was about to hit post. I had a quick thought, scrolled up. You are in Canada. I'm pricing things here in the states. I was just talking to someone up there about the exchange rate. Your dollar has gotten stupid recently. That $300 per head isn't as over priced as I was thinking. I still think it is high (even at the conversion rate), and I don't know what other options you have locally.

 

[wizard12]

Thanks

Awesome, thanks for the confirmation on the cam sensor. It's about a 45 minute drive each way and wanted to make sure I wasn't missing something else.

I thought the price was a bit steep as well. They have been in business for 40+ years, but think they might be used to doing larger engines for the oil patch and therefore can be choosey with their prices. I will definitely be checking around, even in smaller communities.

I guess I have nothing to loose with giving it a go myself. If I mess it up, or I discover something wrong then I can look at another set or some aftermarket as you pointed out, the prices aren't that much more.

Yes our dollar does suck. About a 35% premium on the US. Unfortunately there are no bronco dealers up in the great white north, and even most Jegs/Summit I end up ordering from the US and get it shipped to Montana where I road trip down to pick it up twice a year. The customs and duties to get it shipped all the way up is astronomical.

 

[OX1]

Yeah, for that kind of money, you can get another set already re-manufactured.

https://www.ebay.com/itm/PAIR-5-0-S...846443&hash=item3fb778fd99:g:C80AAOSwHF1cKmv1

 

[Broncobowsher]

Do you have the Tom Monroe How to Rebuild a Small Block Ford book?
Might be worth it, buy a valve spring compressor. Take the heads apart yourself and just check everything out. If the guides are good and the valves and seats are usable, clean the carbon and change the valve seals. Lap in the valves and it is minimal money and a fair bit of your time. Valve springs can even be tested with a bathroom scale and rig yourself a controlled lever to compress them.

 

[Joe473]

Yeah, for that kind of money, you can get another set already re-manufactured.

https://www.ebay.com/itm/PAIR-5-0-S...846443&hash=item3fb778fd99:g:C80AAOSwHF1cKmv1

I spent $500 on my GT40s but that was all new guides, seals, valve grinding, and new spring set up. 3 yrs ago most cheaper heads would have needed new springs or buy unassembled to work with roller cam over .500" . That plus $400 for the block machining and the about $1400 for scatt rotating assembly and I had a nice 347 that looks stock.

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