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Replacing guides on the 944 head is nothing special. You need to get the machine shop a printout from the shop manual so they know the specs for setting up the springs & valve... I can scan something for you if you do not have access to the manuals or the little specs book.
Porting is a different story.
BTW the CMW intake is nice, I have the same on my track car. It's supposed to equalize the flow across all 4 runners.
The valve guides can be tricky in a 951 head. Mainly the exhaust valve guides because if they are pressed in to hard they will crack the ceramic ports. Spencer seems to have forgotten because he still has a N/A engine with a N/A head and they don't have the ceramic exhaust ports. Remember the 951 was the first head design I know of that was made with the head being cast around the ceramic exhaust ports. And if LR told you that then they are right, so would everyone else if they told you that. It can be tricky but only the exhaust valve guides. If the ceramic cracks then you have a wasted head because the ceramic exhaust port is in direct contact with the water passage.
good score BTW.
Thanks for the response, nobody likes to feel like a sucker! It wasn't Lindsey Racing it was a shop I had never spoken with before that came up somewhere as specializing in building Porsche Heads (including 944), they seemed knowledgeable, but I think I contacted them because the performance head springs and retainers pictured on their site looked like the ones on the last head I bought and if nothing else I was looking for a way to source matching parts if needed. I do appreciate your comments because the other individual had said that pressing the guides in was the part that required caution.
Thanks on the score comment, will see when it arrives, but I feel like a ported and o-ringed head with larger valves, matched ported intake, adjustable cam gear and the valve cover with a performance cam for $566 was a good buy. The cam is a real unknown, so not certain if I should mess with it or not, will decide on all of it after inspection, fingers crossed. Hey with the valve cover I can do the black paint job with the silver lettering and ribs before I tear into the car! always looking for a silver lining incase something else is bad.
Originally Posted by fast951
Replacing guides on the 944 head is nothing special. You need to get the machine shop a printout from the shop manual so they know the specs for setting up the springs & valve... I can scan something for you if you do not have access to the manuals or the little specs book.
Porting is a different story.
BTW the CMW intake is nice, I have the same on my track car. It's supposed to equalize the flow across all 4 runners.
John, thanks for the response and information. I do not have the shop manual set, I just have the 'Haynes Repair Manual', two actually and I leave one with anyone who is doing any work for me, so if you have some good head information that isn't in the weekend mechanic manual I have, I would love to have a scan/copy of it.
A big thanks on chiming in on the intake manifold, I didn't know what to think of it. Obviously it looked like a lot of work was done, but didn't mean it was the correct work, now I know. I guess I will see what can be done about the welds as the Frankenstein appearence will negate a bit my "Stealth Build", maybe a bit of clean up and heat dissappating paint will hide them for the most part.
The cam is probably the big unknown, one side of me thinks if they spent all the money to do this work they probably put a decent cam in it. The story behind it all is the gentleman I bouth it from bought the car with a sleeved 3.2 liter and raced it, but had oil starvation issues in the block and in the two years he raced it he had to rebuild the engine twice. He parked it for almost 10 years and raced a BMW M3, recently sold the M3 and wants to race the 951 again, but not deal with the engine so he is working out the kinks in his install of the Volkswagen/Audi 1.8 litter turbo charged engine and plans to race that. So he had top end parts that were good so he put them on eBay and I was hopefully lucky (I won the auction) enough to have the higest bid and now awaiting the arrival of the parts to have inspected.
The old guy that runs a local shop here (third generation family run) has been sick with the flu and then pneumonia and work has been piling up and he has no idea when he can get to it, so I am in the serch again for a shop as the weather has been so nice and I haven't been able to drive for so long, I want to get it going. I purchased used Arnwork timiming belt kit, etc. in case I do the work, but I am antsy to get it running and can't wait until fall to get the head. So I will either find someone around here or send out to someone reputable to go through things before I install it on my car. With that in mind, anyone know a shop in Seattle, WA (I live in Central WA) that does good head work on 951's?
Thanks again for chiming in, always appreciate the feedback and information I get here and working in a vacuum can suck some of the life out of a project, no pun intended!
Yea seeing how just the intake work itself is about $700 you got a huge score! Kinda hella jealous.
Thanks, makes up for a MAF and previous head I bought! LOL I figured the adjustable cam gear and even the aftermarket cam sweetened the pot to! I was just excited about the ported 48mm intake valve head! LOL Now I am teetering on doing it myself or having a shop do it as I am so busy with basically three jobs, I don't want it sitting apart because I can't get to it!
Packages arrived today, if I can't find a shop locally to do the work on the head I will look into finding one in Seattle. If anyone knows of a good shop that does good performance head work in Seattle please let me know.
What you want to do is change out the exhaust valve and valve stem that is a stock 7mm stem to a 6mm stem. And a five angle valve seat grind. That's pretty much the only way to improve exhaust flow on a turbo head due to the ceramic ports. Seams your intake flows already.
What you want to do is change out the exhaust valve and valve stem that is a stock 7mm stem to a 6mm stem. And a five angle valve seat grind. That's pretty much the only way to improve exhaust flow on a turbo head due to the ceramic ports. Seams your intake flows already.
Nope there 8.9mm. I think the 16v heads are 7mm. Let me check. Yep it's the 16v head that has the 7mm exhaust valve stem. Anyways you can take the 8.9mm exhaust valve stem down to an 8mm diameter(with new valves, guides, retainers, springs and seals). Valve's and the material they are made with today are superior to 30 year old valves and the way they were made.
Nope there 8.9mm. I think the 16v heads are 7mm. Let me check. Yep it's the 16v head that has the 7mm exhaust valve stem. Anyways you can take the 8.9mm exhaust valve stem down to an 8mm diameter(with new valves, guides, retainers, springs and seals). Valve's and the material they are made with today are superior to 30 year old valves and the way they were made.
Thanks, I have heard that the valve stem on the exhaust is basically all you can do to improve exhaust valve flow at the head. But I have also heard that the exhaust valves weren't really the limiting factor and that increased exhaust size,etc. reduced back preassure and allowed the head to exhaust to it's full potential. This was supposed to apply to only medium modified engines and heavily modified engines exceeded the exhaust side. But hey, I have no practical experience just read a lot of Internet and you never know if a poster is actually knowledgeable. So I don't know.
However I just plan to have it checked out and if a valve job is necessary have that done and there are some water passages that were welded close for the 3.2 liter build that need to be drilled and ground out. and then the head mating surface milled if needed. The o-ring grooves are another slight delima. Enough on that, just need to find a good head shop and go from there. I assume a good head and valve job were done on the heaeds when it was built and I was told the head was used for only two racing seasons.
Thanks for mentioning the exhaust valves, but my pockets aren't deep so I just hope to get it all flat and true and valves seating and not leaking.
The slippery slope I have started down continues to possibly nip me in the butt! Oooohhhh the highs and the lows of this game we play pursuing horse power!
I met with the machinist and looked at the new head and I had the other head I had purchased still there so we were able to compare, etc. Here are the items we noticed that we know the answer to.
One intake valve showed a little fluid visible around it but it did not leak, just looked like a layer may have formed so that can be cleaned up easy enough. Cam housing side of head straight and true and level. Head to block seems to be slightly low between cylinder 2&3 so we would lightly surface head, not a problem there.
The water passage I was told that was filled in and just needed to be drilled out ends up being a passage that protrudes from the head (see the attached markup) and they ground around it as well so that there is no area for the threaded bolt holes that are typically there. I was worried about this and thought it might be a deal breaker but John Vitesse said I could insert/weld in a water jacket neck to solve that, so at least that isn’t the end of the world. Thanks for the advice John! Looking at the images it looks like the new head has water passages added over combustion chambers 1 and 4, yikes! News just doesn't seem to be getting better.
Here is the item that I am really pondering and worried that it makes the head un-useable for me on the 2.5 liter. The valve quench area/ combustion chamber has been heavily massaged and is larger than stock (around 4 and 100/1000" so it seems like around 104mm?) to match the cylinders on the 3.2 liter block it was on, so that a standard head gasket protrudes into/over the depression/quench area. Basically if you look at the radius of the o-ring and the combustion chamber top and bottom and then look at the radius of the combustion chamber on the sides, you can see the sides have a smaller radius to them but pushed out a bit. Larger cylinder head gasket isn’t the problem, but the gap/shelf of the 2.5 liter cylinder as it relates to the larger combustion chamber in this modified head is my worry, will this create strange turbulence and thus inefficient head performance? So I am not certain if it is larger than the stock 2.5 liter combustion chamber will work on my car and thus I have to give up the dream of this larger valved and ported to match intake head on my car. The springs and retainers are substantially larger than what is on the other head, it looks like it was done well, but not certain if that does me any good, anyone have experience with this.
So basically that item may be a deal breakers and not certain if I should rebuild the previous head that needs a new valve job and valve springs (has some broken inner springs) but was highly ported and have it ported to the new intake manifold I got with this new head, or if it is OK to use this new head and combustion chamber.
Really bummed to say the least! I can get my money out of it I am sure, but I was really excited about a larger valved and ported head that matched a performance intake. Planned on using my stock cam shaft since there is no information on this one, thought I would take it out and see if there are any markings on it that might shed some light.
Really hoping someone tells me some good news regarding he head, but I have to think that ledge of smaller cylinder wall inside the enlarged combustion chamber might cause some strange turbulence and inefficiencies. ;( I could build a 3+ Liter turbo, I am sure putting a whole engine in with the new turbo and other parts is probably easier than installing them in the car, right? Kidding, just kidding!
03-22-2018, 12:29 PM
It wasn't Lindsey Racing it was a shop I had never spoken with before that came up somewhere as specializing in building Porsche Heads (including 944), they seemed knowledgeable, but I think I contacted them because the performance head springs and retainers pictured on their site looked like the ones on the last head I bought and if nothing else I was looking for a way to source matching parts if needed. I do appreciate your comments because the other individual had said that pressing the guides in was the part that required caution.
