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View Full Version : 351 Cylinder Head Replacements


mmpol30
09-28-2011, 09:21 PM
My new to me 1992 Prostar 205 turned out to have a cracked exhaust valve on the number 6 cylinder. Even with 0 compression on that cylinder the engine ran very well the entire season. I took one of the heads off this past weekend, to find a casting number, and found E8JL, which seems to be a 1988 Industrial head. From reading this site, everybody seems to like the upgrade to the GT-40p heads, however, I am just looking to replace mine with stock heads. However, this casting number seems like it is hard to find, are there any other casting numbers that would fit my 1992 Ford 351 Windsor engine. What about E7TE?

My other option is to get my heads rebuilt at a machine shop.

Any help would be great

milehigh970
09-28-2011, 09:25 PM
So why a whole new head? Exhaust valves are like 6 bucks. A nice valve job at a good machine shop and that head is as good as new for around 100 bucks.

mmpol30
09-28-2011, 09:51 PM
Well my thinking was re-built heads from a few places on-line are 155 a piece, if I could find the casting number. I checked with a machine shop and they would do both heads for 250 plus parts. My thinking is with remanufactured heads I already know they are good, if I get mine re-built, I am concerned with what else they will find. I also figured since the intake manifold is off I might as well do both heads.

j.mccreight@hotmail.com
09-29-2011, 12:05 AM
You would need to replace both heads if you can't find a replacement for the e8jl head you don't wanna have different heads. E7 or E5 are a good stock replacement head. If your not looking for more horsepower I would take the damaged head to a shop and have them rebuild it, and put it back together, 200 bucks and your back on the water.

gr82bgreen
09-29-2011, 08:56 AM
Find a set of used gt 40's. Get a valve spring compressor and some lapping compound. Check the guides and replace the valve seals. Lap the seats and your good to go. Your there already so why not go for the extra HP.

Kevin 89MC
09-29-2011, 06:34 PM
Another vote for GT40 heads. I found a set in a local junkyard off a mid 90's Explorer for $35 each. Needed to have the shop drill out the headbolt holes and install brass freeze plugs, and they also replaced the valve stem guides. But they were a definite improvement in HP and torque. I got great heads for about $500 including shop cost, gasket set from Ski-Dim, head bolts from Summit and a fair amount of wrench time, but it was way worth it. I posted all about it here a few months ago. But you should also be able to find stock heads if you go that route, but I would think it would cost you almost as much.
Good luck,
Kevin

mmpol30
09-29-2011, 09:29 PM
I sure like the idea of extra horsepower, but using a different set of heads concerns me if everything is going to work. I guess I need to educate myself more. What is the difference between GT-40 heads and GT-40p heads? Does every Explorer have GT-40 heads, I guess I can look at the 3 lines on the side of the head?

Does every machine shop know how to install brass freeze plugs, or do I need to look for one that deals with marine engines?

Thanks to everyone for sharing their knowledge

j.mccreight@hotmail.com
09-29-2011, 09:47 PM
Swapping out the freeze plugs is no problem, explorers from late 97 to 2001 had the p heads and 95-97 had gt-40, the p heads flow a little better than the regular gt-40 heads due to the smaller exhaust valves and slightly better combustion chamber, p heads will have 4 bars not 3 like the std gt-40, also the p heads have a different spark plug angle a non- issue for using it in a boat but reaks havoc for the fox bodies. You would also have to have the head bolt holes drilled out to 1/2" because the 302 had smaller bolts(7/16"). Your prolly looking at a 15-20 hp increase for the gt-40 and 25-30 hp for the gt-40p just bolting them on.

TRBenj
09-30-2011, 11:51 AM
Swapping out the freeze plugs is no problem, explorers from late 97 to 2001 had the p heads and 95-97 had gt-40, the p heads flow a little better than the regular gt-40 heads due to the smaller exhaust valves and slightly better combustion chamber, p heads will have 4 bars not 3 like the std gt-40, also the p heads have a different spark plug angle a non- issue for using it in a boat but reaks havoc for the fox bodies. You would also have to have the head bolt holes drilled out to 1/2" because the 302 had smaller bolts(7/16"). Your prolly looking at a 15-20 hp increase for the gt-40 and 25-30 hp for the gt-40p just bolting them on.
That is accurate, except I would say that the P heads flow better despite having smaller exhaust valves. The smaller combustion chamber also does not cause them to flow better, though it does give a small bump to the compression ratio, which is a good thing. I would simply say that the runner design is slightly better than the GT40 heads.

You can get rebuilt GT40p heads from a few different places in the $400 per set range. That includes fresh brass freeze plugs and drilled out bolt holes. That is the way I would go, without question. I would not be interested in swapping out or repairing a single head- the other one may be ready to suffer the same fate as the first. I also would not spend a dime on the stock heads, nor would I entertain rebuilding used heads (GT40, GT40p or otherwise). You can get the P heads (already rebuilt) for cheaper than it would cost to buy+rebuild used ones, and you dont stand the risk of getting something thats cracked or has a bent valve. Been there, done that.

TRBenj
09-30-2011, 01:29 PM
Whoops, double post.

thatsmrmastercraft
09-30-2011, 04:09 PM
Whoops, double post.

Helping out and trying to get the post count up. :rolleyes::D:D

mmpol30
10-02-2011, 08:59 AM
So I found a place on-line that sells sets of rebuilt GT-40p heads already drilled for a 351 for around 400 dollars. Still need to check about the brass freeze plug. Do these heads also have casting numbers? Or is GT-40p the casting number?

Thanks, this site is great

CantRepeat
10-02-2011, 09:15 AM
Swapping out the freeze plugs is no problem, explorers from late 97 to 2001 had the p heads and 95-97 had gt-40, the p heads flow a little better than the regular gt-40 heads due to the smaller exhaust valves and slightly better combustion chamber, p heads will have 4 bars not 3 like the std gt-40, also the p heads have a different spark plug angle a non- issue for using it in a boat but reaks havoc for the fox bodies. You would also have to have the head bolt holes drilled out to 1/2" because the 302 had smaller bolts(7/16"). Your prolly looking at a 15-20 hp increase for the gt-40 and 25-30 hp for the gt-40p just bolting them on.

Visual inspection point. These are located on the end of the head.

j.mccreight@hotmail.com
10-02-2011, 11:16 PM
So I found a place on-line that sells sets of rebuilt GT-40p heads already drilled for a 351 for around 400 dollars. Still need to check about the brass freeze plug. Do these heads also have casting numbers? Or is GT-40p the casting number?

Thanks, this site is great

"GT40P" is stamped on the head, note the bars

http://www.google.com/m/search?site=images&gl=us&source=mog&aq=f&oq=&aqi=p1g5-k0d0t0&fkt=140&fsdt=17785&cqt=&rst=&htf=&his=&maction=&q=gt40p+

TRBenj
10-03-2011, 01:45 PM
Clearwater Cylinder Head (http://cylinder-heads.com/details.cfm?itemid=1890) will install the brass casting plugs and drill your bolt holes out to 1/2" for no extra charge. I know several people who have purchased GT40p heads from these guys with good results.

sam196370
10-03-2011, 04:56 PM
While changing my oil yesterday I found the old oil to be brown and murky which I think means that water has mixed with the oil....it has rained a ton around here so I'm hoping it's rainwater that has gotten into the crankcase since the boat was outside and the cover is ancient.

After changing the water pump last month I realized it was in backwards b/c the engine got really hot; might have blown a head gasket and if that is why the oil was brown and murky then I'm going to go the GT40 route and sell mine. I have the PCM 351W ('79 Stars & Stripes) - will the '95 - 97 Exploder heads work on this block?

Please god let it be rainwater in the crankcase.....

Kyle
10-03-2011, 08:52 PM
While changing my oil yesterday I found the old oil to be brown and murky which I think means that water has mixed with the oil....it has rained a ton around here so I'm hoping it's rainwater that has gotten into the crankcase since the boat was outside and the cover is ancient.

After changing the water pump last month I realized it was in backwards b/c the engine got really hot; might have blown a head gasket and if that is why the oil was brown and murky then I'm going to go the GT40 route and sell mine. I have the PCM 351W ('79 Stars & Stripes) - will the '95 - 97 Exploder heads work on this block?

Please god let it be rainwater in the crankcase.....

The Explorer gt40p heads will work on any 351w. You need to drill head bolt holes to 1/2" though. The head is 7/16" before drilling. Have a machine shop drill out head and the 1/2 bolts will be fine. Always keep in mind it's a good idea to replace head bolts when doing the swap. I have arp bolts in mine. Very nice upgrade with the "p" heads. Consider a cam too. More than likely you have a very mild cam and you can increase lift and duration and get some more bump.

thatsmrmastercraft
10-03-2011, 09:34 PM
The Explorer gt40p heads will work on any 351w. You need to drill head bolt holes to 1/2" though. The head is 7/16" before drilling. Have a machine shop drill out head and the 1/2 bolts will be fine. Always keep in mind it's a good idea to replace head bolts when doing the swap. I have arp bolts in mine. Very nice upgrade with the "p" heads. Consider a cam too. More than likely you have a very mild cam and you can increase lift and duration and get some more bump.

Good words of advice on the cam, but where do you stop? I was playing that game in my mind the other day and I ended up stroked to 427 CI..........:rolleyes:

Kyle
10-04-2011, 03:19 AM
Good words of advice on the cam, but where do you stop? I was playing that game in my mind the other day and I ended up stroked to 427 CI..........:rolleyes:

Peter I'm considering a stroked 351. Right now mine is a 359.3ci and want more. You can never have too much HP.

thatsmrmastercraft
10-04-2011, 10:58 AM
Peter I'm considering a stroked 351. Right now mine is a 359.3ci and want more. You can never have too much HP.

I hear you there. Would make a fine winter project.

TRBenj
10-04-2011, 11:41 AM
While changing my oil yesterday I found the old oil to be brown and murky which I think means that water has mixed with the oil....it has rained a ton around here so I'm hoping it's rainwater that has gotten into the crankcase since the boat was outside and the cover is ancient.

After changing the water pump last month I realized it was in backwards b/c the engine got really hot; might have blown a head gasket and if that is why the oil was brown and murky then I'm going to go the GT40 route and sell mine. I have the PCM 351W ('79 Stars & Stripes) - will the '95 - 97 Exploder heads work on this block?

Please god let it be rainwater in the crankcase.....
I doubt its rainwater. Oil only turns into a milkshake with water if the engine is run with both in the engine. If the engine isnt run like that, then the water and oil will stay separate (water will sit at the bottom of the pan).

The overheat is the likely culprit- but I would not necessarily point to the head gaskets. Other potential issues could be cracked exh manifolds, intake manifold or heads... or even block. Better do a compression test for starters... that should rule out the block and heads if it comes back clean.

sam196370
10-04-2011, 01:58 PM
Since I was changing the oil I did run the motor with both in there, didn't find out that it was brown until drawing the oil from the crankcase. Once I get my gas tank back I'm going to change the oil again while it's in the water (like manual says) after running it pretty good. If it is a cracked block/head/valve/etc I'm impressed the motor still runs very smoothly.

thatsmrmastercraft
10-04-2011, 02:08 PM
Since I was changing the oil I did run the motor with both in there, didn't find out that it was brown until drawing the oil from the crankcase. Once I get my gas tank back I'm going to change the oil again while it's in the water (like manual says) after running it pretty good. If it is a cracked block/head/valve/etc I'm impressed the motor still runs very smoothly.

If you suspect water in the oil I would not run it. I would drain as is. If there is water in the oil you will find out right away when you start to drain it. Without warming the oil it will take a little longer to drain, but it's all in the pan, so just let it sit for a few hours.

sam196370
10-10-2011, 10:58 AM
So I changed the oil and it was still brown, changed it again and ran it for a few minutes - no brown murky stuff on dipstick; although I'm eager to pick up some GT40p heads I'd rather it be a voluntary project. Took boat out yesterday and ran like a champ.

Seems like the problem was not having exhaust flaps and the motor overheading a little - have heard from other owners that this causes water to get sucked up into the crankcase somehow.

Kyle
10-10-2011, 11:56 AM
Seems like the problem was not having exhaust flaps and the motor overheading a little - have heard from other owners that this causes water to get sucked up into the crankcase somehow.

unless you are reversing very hard and you are running straight pipes this would be hard to do. Mufflers have baffles in them so those would keep water from flowing up your risers.

The engine back sucking water is due to a too big of cam. Your cam probably is not a race cam and is a factory cam eliminating this.

I will say if it keeps happening and you think it's the exhaust then replace the riser gaskets. If they are leaking then water could leak into the heads. If this were the case spark plugs would show water signs though. Hopefully this is not the issue because it's easy to bend valves, hydro lock, etc

Have you done a compression test yet. That's the first thing I would do. Second would be if you are running it in the driveway and water is in the oil then see if oily water is coming out exhaust. I'm guessing either a small crack somewhere or a blown head gasket.

mmpol30
10-13-2011, 12:29 PM
When reinstalling cylinder heads, as long as the head bolts look fine, could they be reused? Or just replace them all? Are 351W engines torque to yield bolts?

Thanks

thatsmrmastercraft
10-13-2011, 12:41 PM
When reinstalling cylinder heads, as long as the head bolts look fine, could they be reused? Or just replace them all? Are 351W engines torque to yield bolts?

Thanks

New head bolts every time.

Kyle
10-13-2011, 12:51 PM
New head bolts every time.

X2 for new head bolts EVERY TIME...

TRBenj
10-13-2011, 02:39 PM
I do not believe that Ford ever used TTY bolts on the 351w, and therefore they *can* be reused. That being said, I personally choose to replace with ARP bolts when I put heads on- theyre cheap enough and will give you some peace of mind.

DooSPX
10-13-2011, 03:31 PM
I do not believe that Ford ever used TTY bolts on the 351w, and therefore they *can* be reused. That being said, I personally choose to replace with ARP bolts when I put heads on- theyre cheap enough and will give you some peace of mind.

That's true... the head bolts are NOT torque to yield. But, when I replaced the gaskets, I did use new bolts for peace of mind.

mmpol30
10-14-2011, 02:34 PM
Thanks for the comments on the head bolts, I have decided to purchase new ARP bolts.

I think everything I need is on order. I decided to go with the GT-40p heads. They are getting drilled out to 1/2 inch and brass freeze plugs installed. The question I have is the engine circuit breaker and alternator are attached to the starboard cylinder head, are all these bolt sizes in the cylinder heads compatible with the old 351 heads, or will I need different size bolts for this too?

Thanks for all the information

Kevin 89MC
10-14-2011, 03:21 PM
Thanks for the comments on the head bolts, I have decided to purchase new ARP bolts.

I think everything I need is on order. I decided to go with the GT-40p heads. They are getting drilled out to 1/2 inch and brass freeze plugs installed. The question I have is the engine circuit breaker and alternator are attached to the starboard cylinder head, are all these bolt sizes in the cylinder heads compatible with the old 351 heads, or will I need different size bolts for this too?

Thanks for all the information

On mine I think I had to drill out the plate that held a relay in the back, and possibly the bracket that held the coil, or the dipstick, can't remember. Fortunately the alternator hole was the same, that's a long bolt! I think one of the lifting ring holes might have been different too. Had to make a run to the hardware store to get some bigger bolts for some of the bolt on items.
Good luck,
Kevin

Dino Don
10-15-2011, 03:31 PM
Thanks for the comments on the head bolts, I have decided to purchase new ARP bolts.

I think everything I need is on order. I decided to go with the GT-40p heads. They are getting drilled out to 1/2 inch and brass freeze plugs installed. The question I have is the engine circuit breaker and alternator are attached to the starboard cylinder head, are all these bolt sizes in the cylinder heads compatible with the old 351 heads, or will I need different size bolts for this too?

Thanks for all the information


if the bolts do not have sealer on the tips (think they do) get some Permatex silicone white sealer and seal them.