taday' Before any machining of the piston proper is done one must always establish a register or a reference point. because of how my fixture holds pistons I use the head of the piston and machine a register on the balance pads in side the skirt. EVEN (pay attention this is important!) if the piston is already machined there (these were not) it is rarely accurate or parralel with the head. So always do that first. I use this deal I made some (Yikes!) 20 years ago to hold my pistons for machining. It can deal with pin offsets , tapered skirts and so with a bit of care I can centre any piston and clamp it tight enuf for machining. I am very gentle by the way. Just a wisker each time so nothing moves. here is the finished deal. Taper matches the original valve relief for angle and since the cylinder head casting fills much of the combustion space I need so much removed I may as well just do it this way. Using averages this piston dome will give the same result as if the whole piston was plus .070 out of the hole. Stock piston was traditionally .003 out with one particular 4 barrel engine being 012 out so gain is substantial. by the time I give the heads a haircut and use my NOS steel gaskets all will be well. I am caculating a minimum of 11 to 1 for cam selection and figuring. The relationship between comp ratio and cam duration is a BIG deal in making and engine perform. Don P1525 is the engine tech piston part number.
Don, I like your approach concerning Mopars in general, and the Poly 318 engines, in particular. You are providing a great service with the right info on rebuilding on what is a great, but way over-looked Mopar V-8. Learning a lot here!
I agree...very interesting and fun build thread....I have been saving a stock 1959 325 poly for a future build....this is very helpful, thanks
Impressive work! I'd love to see a parts cost break down on this engine. Just curious I know 360 heads will fit on a LA motor will they fit on a poly? .
No , LA heads will NOT fit any POLY head engine. However, the timing chain, cover and dizzy will directly bolt on. Also the oil pump and pan.
Sorry to burst your bubble, but LA heads can be installed...NOT a direct bolt on, but doable, same as putting Poly heads on an LA. Short response: http://www.1962to1965mopar.ornocar.com/poly318.html
RE LA. I have built many many LA engines and was one of the first, if not the first to develop the 380 inch deal using reworked OEM stuff. Yes they are a great engine. So is the hemi which am also very familiar wth both the RB version and the old A series However this is about the 318 poly. Why Because it interests me. I started with this engine some 47 years ago. As I near the point in my life where I probably should start thinking about not driving a racecar anymore this is an area I would like to return to and explore. Not as I did as a young 15 year old building my first motor and racing it a year later but as an old dude with a lot more knowledge and expeince then I had then. While i have done a few hi $$$ engines for customers I find that boring. The budget hand built stuff is what i really enjoy. Going to the shop each day and doing an hour or so on the project. Making steady but slow progress. Cost of the build? I am not even going to keep track. I will tell you though that it will be around $1500. Why ? Because I look for deals and have a lot of unused favours after 40 + years as a Mech and automotive machinst. Many of my old colleges just say "Take it" and will accept no $$. I paid $125 for the engine and 727 transmission. $50 for the four barrel intake and nothing for the 360 rods. (much stronger then the old 318.) Pistons were a donation from a nearby shop I had done a few favours for over the last many years. He didnt have them in stock but I send many of my old customers there now. I believe wholesale cost was about $126 as I had priced them out before he volunteered. He would accept nothing for boring the block even though it is a 2 stage bore. Bearing and rings will cost around $200 and another $75 for an oil pump. Cam lifters and springs will probably set me back around $300 and these engines need pushrods as the originals are like cheeze. Manton has made them for me in the past. I have also made many of my own. I havent decided yet which way to go. So add another $500 for other stuff if you want. Still not very expensive engine. If you are screaming that "you cant build that much HP for that" , I can . Tis what i do. And it will be reliable too. How did I get here? I saw pics and Video of McTims 312 Ford based FED. I made the comment to him that it was so cool that I wished I had a early 318 poly for my next rail. He replied "Why dont you?" There was no real good answer why not. In fact the idea intriqued me. So here I is. So I am not looking for the better combo or the best engine, I am seeing what I can do with this one. And that BTW is the secret to making this hobby affordable for those of us born without the siver spoon. Pick and motor you like and do your best within your budget to see what you can get out of it. My Buddy has a blown SBC in a RED (aka a go kart). He would go through probably $15000 to $20000 per year to keep it running. Most of his input although not all revolves around signing a cheque to someone who does the work for him. One day when he was being particularily rude ("I dont do that . I just pick up the phone and call ####### andsay send me one of these") I said to him. "I dont know why you guys even bother having a car built , buying a mega $ engine and trans and putting in the fuel and comng here when it is all about how much you can spend. Why not just phone the Trophy shop and order a nice "I Am The Winner" big trophy. Then you would always be the winner and us normal folks would have more time to race here." (and it would also be a lot quieter in the pits ;>) Don
I'm loving this thread, what your doing here is way up in my book of what a REAL hot rodder is all about. I think the same thing when I read the stuff mctim does with the y-blocks. I wish I had the experiance to be doing the same, I'm a metal fab guy more then a wrench but then I have a few years left I hope, maybe I'll start learnin!
Today after working some more on the /6 tunnel ram I switched to the poly and with the piston at TDC and no head gasket I popped the head on. Nothing hits! So far so good. (everyday a little progress) Just for inspriation after I fired up the other rail and let it warm up to full temp. Nothing like the sound of a big cam and open headers to inspire one. Too hot here (already past 90F)to get into anything too strenous. I think I will drive down and see how Mike is coming on his T440 Hemi powered build. Don
Here is the paper deal I made a couple of days ago from the circumference of a slightly modified 318 poly intake port. Here it is sitting in a 340 360 gasket. This gives a good visual of how careful one must be with the poly.While the poly ports are a great design and while there is great potential for improvement there are still some definate limits . The solution ? Keep the engine cubes low and do as good a job as you can on the porting. Then the head will be able to feed the smaller cube engine 100% plus and you will realize what a great design it was . The fact that it s not huge does not mean it isnt a great design. It simply means these castings were cast for a 318 (not a 418 for example.) The stroker temptations in this case is the automotive equivalent of shooting yourself in the foot. Or as my late Mother-In-Law, Ruth Peck, would have said, "Dont do it! Taint fer it!" Don
From what I've seen on an Aussie mopar Forum, going one way(forgot witch!) is a lot easier than the other.
This is a really neat project. I love it. I just wish you would build a 300 inch 318 is a and run it on the salt. Or a 3 liter slant six. It's good running a three mile drag.
There ya go Don! the challenge has been laid down, come join us on the salt, you'll never be the same.
McTim has tempted me to come before. I checked with a official at the timing assc to see if the car (/6 car)would pass tech. Turns out I accidently built it from the right size tubng. , He offered to go over the other areas with me online with photos if nec to make sure I would come prepared. He was very helpful. But them he warned me all open wheeled cars must wear a Hans device. By this point I had already asked my wife if she would be up to trucking the car down there. She said "sure." But that was more then I could handle . The hans deice and to be truthful I am starting to find the car hard to get in and out of. Also you must be able to exit the car in 30 sec or something. Takes me now about 5 minutes on a good day. The new car is tighter and lower so X that. However two thigs. One instead of going to Europe next year for our major holiday we are going to Bonneville during Speed Week. She already has the maps out and places she wants to stop along the way set out. And that is NEXT year. She is a good planner to say the least . She has already driven on the salt. In fact I thought she was going to get lost when we were there. See photo. I was nervous out there. Secondly there is nothing stopping one of you lads from doing one. I would be up for any info you would like although I am sure that wouldnt be necessary. Don
Quite correct George. There is little or no advantage to installing LA heads on a Poly block...you would just end up with a slightly different LA engine. But, a big inch Poly is another story as Gary P has demonstrated so very well. Gary
"Or a 3 liter slant six" Here is one I was involved with in the 1970s. It is a 3 litre approx (170 cubes) and had a corvair turbo. I supplied all power plants for this car. Like my current rail it could be carried in the back of a 1/2 ton. With a long box Chevy or GMC you could even close the tail gate. Your comment jogged my memory and I dug out some old photos. Sorry to reminise. This car was very very successful. Stu Denyes owned it a drove it and I partnered at first by supplying power . Eventually he took over full reins but I still did his motors. Even back then Stu won $1000s with this car. In the money virtually every weekend for several years. Usually won. Main track, Old Mohawk and also Cayuga as it is here on its maiden voyage. About 1975 or 76. . Body is still around. Don
If you want to see the car run, I'm sure you can find a driver that can get out in 30 sec. I'll volunteer.
Then I would have to worry about you! I did however roll it through my mind after I posted this about extending my career with a designated driver. When I raced doorslammers I always had a "shoe" in the car on raceday although I made at least one checkout pass. This car is not real popular with the local "professional racers" so I never asked any to drive it although my nemisis with the 454 FED has driven it and did a real fine job of it too. In fact here he is carrying the wheels last year when he drove it. Anyway that is thought for another day. Today I dug out the new pistons . I have 8 or a whole set. The one you have all seen earlier is only my "trysee." I always mess around with a spare first, just in case. Since I am happy with the plan I set all these up in the lathe and machined the register on all of them. Perhaps tomorrow if I have time I willl do the taper on the piston crown. Seems to be going very quickly this project. Pin fit then balancing and it is ready for rings and bearings. Don
2 pistons machined, 6 to go. Machining reduces weight by 19 grams. Set up takes less time then I had antticipated. Don
Piston crown machining is done. Pin fit and balance next. Now to remember were I put the new pins. Don
351M my pistons are Enginetech 1525P(hastings) Silvolite number is 1167. Pin size is I believe .009" under mopar size (.9842 mopar, .9752 ford). pain in the butt but doable. I may ream them close then finish them on my pals sunnen . I would prefer to hone them all the way myself but he may not like that idea. I am using 360 Mopar rods which are probably double the strength of the old polys. They are also heavier. A 340 steel crank would make the balance easier but it is what it is. These pins will be pressfit. I could bush the 360 rods and keep the Ford pin but then I would have to set up and cut pin lock grooves. I would also have to bore the rods for the bushing depending on what I could get size wise as .009 is not enuf room just to bush. All my stuff for that went with the machine shop equipment when I sold it all and it is not a real fun job anyway. Enlarging the piston for the mopar pin is easier.I have a lot of experience with pressfits in race engnes and am very comfortable with it now. .001" clearance per inch dia is the secret. I am fanatical about that. Too tight or "they will wear in" is an invitation for disaster. A couple of minutes extra work insures absolutley no trouble. Don
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