After a long space I got caught up in the shop with Sr dragster stuff and set back working on the engine development for my 318 poly dragster. If you have never been through this dont let the rust and dust bother you. Right now is more planning and checking. Rest assured all will be brain surgery clean when assembled. Block has been bored to 4 inch yielding 333 cubes. This is my "trysee" piston hung on one of the old rods for test fitting. As you can see for an off the shelf piston from another brand it fits remarkably close and minor machining will bring it into spec. This is the type of stuff I really enjoy. Going fast with nothing. Anyway trial fit was very encouraging. The goal for those who want to know is 500+ HP. This will require a bunch of RPM and some careful head work. More as we progress. Don
love to see people squeezing hp out of engines that never really did. Its more fun if its challenging. good luck although more than 500 hp is quite reachable
I have long had a theory about the 340. The theory is when they went to develop the 340 they just used the old thick Poly 318 block cores and bored the hell out of the block. 4.04 - 3.91 = .130 in other words the 340 bore is a hair over 1/8 or .125 which was max overbore on most fifties engines. So why not use 340 pistons suitably modified with valve notches for the poly valves? Or is that a 360 piston in the picture? O wait never mind.
Be patient my friends. This is a long long long way from my first rodeo. 360 piston (bin there done that already ) would not come high enuf in the bore with the 3.31 crank. 340s is pushing the envelope a bit much (no safety and would require just so much more work then these and after final machining would be getting near critical thin in a couple of areas. These already have a notch in the right place which means of course they also have support in the casting underneath for that notch and need only minor work . The deck height is wonderful. On the plus side. They fit the pins with a couple of minutes work on the pin hone and I have decided to use them. Yes they are dished but even the dish is still .070" out of the hole or above deck. Yes over 500 hp is possible but I aways error on the low side. Better always to be pleasantly surprised then sorrily disappointed. 500hp I think is realistic and achievable. What are these pistons from? I might say someday but not today. Don
Here is a poly that belongs to a close friend. I made 2 sets of Valve covers for him. His cast aluminum ones he has would not fit the updated the valve train. His is now a 362. Not quite sure HP's but it is really good. Keep us informed, also have some sweet period correct dual carb intake and valve covers that might be for sale.
Ever since you mentioned this build some months back I've been awaiting this. I always enjoy your builds, more noggin than wallet goes into them. So when the time comes, more of your long posts explaining both the what & the why will be happily read. Thanks.
Some shots of Larry Ferguson's 318 dragster from the late '60s and early '70s. It raced both in Australia and New Zealand. Last shot is of the motor moved to altered chassis.
This gives me some hope. My buddy has a 318 he said I could have because "they were dogs". A free engine I could give a 'lil pep to would be great. Subscribed.
My departed pal Terry Roche had an early 318 poly in one of the first Scotty Fenn dragsters . It was also run in Denny Williams duece roadster. Ran pretty well for the times and it was dependable. Ran mostly at Henderson, Nv. Good luck with the build.
My guess, a 351C? Your mighty close! Same sock factory different area. Wow those are all great photos. The cross ram is nice. The rocker exotic. The injection on the cars from Down under most impressive. BTW these engines are not Dogs. The came in 230 HP 260 HP and 290 Hp from the factory.I have read where one of the Barris brothers said he had a 283 HP 283 Chevy in 57 and hs brother a 290HP 318 fury and the fury would spank him regularily. I also have somewhere in my old Magazines a picture of AG Foyt sitting or driving a sprint car with a 318 Poly. Anyway this will be the Budget version because that is what I enjoy. Nothing but nothing brings me more joy then trailering rich kids. I will tell you this tail for example . For a friend and for fun I built a 426 from a 400 mopar. I had the crank stroked to 3.54. And with a mild overbore hand machined a set of 440 Mopar forged replacments to use with domes and deep valve reliefs. Although he didnt use the cam i wanted the one he got was not real bad and I put it together using an old set of Stg 6 Aluminum mopar heads I had ported and ran years ago after i refreshed them for him. (about 311 CFm on the flow bench) He one weekend took the car to Esta in New York and was pitted beside a 65 Dodge SS clone running a new 528 Indy stroker. They raced all day and while I dont remeber who had the final best tally no runs were more then a few hundreds apart. Car weights would be within 100 lbs, maybe closer. Total cost to my friend for his engine was around $2500. When he returned he showed me the time tickets and told me the story. He went on excitedly how cool the big 528 was. Billet this , anodized that polished etc etc (YAWN for me)After about ten minutes I asked him. "Does it bother you to be able to beat or run with a $25,000 engines set up with a $2500 one?" It got real quiet. For me though that is what gives me pleasure. (And no I never built him another. Figured you want shiny and expensive go for it!) The enjoyment of working away quietly in the shop figuring making trying fitting and planning is very relaxing and enjoyable. That is how I expect this one to be as well. Besides I started my drag racing career with one (Poly engine). Here it is. About July 1966. Don Which is BTW the First Engine I ever built.
Oooh, try again. See Don's post above^^^. Plus, there were quite a bit of speed parts available for these, and they were no slouch out of the box stock, either! A LOT of parts from the later "LA" series fit the Poly 318. There is a dual-quad factory intake available that ran WCFB carbs, along with a couple of dual-quad aluminum intakes that are still available. If you have a '61 - '67 Dodge Sweptline truck with the 318 Poly, you can get outstanding performance headers that are precision built and FIT from Norm in California (check Bing for his webpage Norm 318 Sweptline header). The Poly 318 is waaaaaay underrated. Which is fine, since you can get a running engine for free, in most cases, since very few know about the Poly 318.
There was nothing wrong with the Poly engine. It was overshadowed in its time by the big brother Hemi and later by the big block wedge, 383 413 426 and 440. The big block would fit anywhere the Poly would, they were both practically the same overall size and weight. The only reason Chev emphasized their small block so long was that their big engine was a dog. Their first big block, the 1958 348, was actually slower than a 283 in stock form. Later on they got the 409 which was better but still wouldn't run with a 426 wedge never mind the hemi. As for the Ford Y block, as a performance engine, the less said the better. All Ford's "Total Performance" models were based on the big FE engine and the new 289 small block. In the fifties the Plymouth poly was the engine to beat in the low priced field. In stock form, as delivered from the showroom, the 56 and 57 Plymouth Fury was the fastest car in its class. Where Chev had the edge was in offering hop up equipment from the factory like the Duntov cam. Take another look at the head in Don's photo. Looks a lot like a Hemi doesn't it? In fact it is basically a hemi with the exhaust valve moved away to the side. This was done so they could work both valves using rockers on a common shaft, which made it simpler and cheaper than the Hemi which had 2 rocker shafts. It also made the head narrower and lighter. In 1954 - 57 you could buy a Chrysler with either a hemi or poly engine, both engines were identical except for the heads. The poly would run with the hemi right up to 80MPH in stock form. In modified form the hemi had even more of an advantage but the point is, the poly had the advantage in performance over the common wedge head, being a half way point between the wedge and hemi. Chev finally got wise to this in 1966 when they brought out their big block 396 and 427 series. It had the modified hemi, canted valve design the same as the poly but with stamped tin, ball stud rocker arms. This was just about the time Chrysler abandoned the idea in favor of wedge heads for the street and hemi heads for racing. What all this means is the poly engine was never developed as a performance engine after 1957 even though it had a lot more potential than some of its rivals.
"Take another look at the head in Don's photo. Looks a lot like a Hemi doesn't it? In fact it is basically a hemi with the exhaust valve moved away to the side." Not really. Actually.....not at all.
Biggest problem is the water jackets. While these heads are well designed for what they were intended for modifying them beynd is a bit of a challenge. IE:There is water near the intake valve so one has to get creative to avoid hitting it.The temptation is to pop in big valves EXCEPT the avaialble flow of even these has not been realized as is and secondly once 2 inch is reached the valve is shrouded. I have settled on 1.94 for these heads . By removing the heavy valve guide boss comletely and raising the port roof to a smooth gentle rounded curve substantial gain can be achieved. I also a going to a .312 stem size which gives added port area and has shown in other heads I have worked on as much as a 5% improvement in flow. By NOT stroking the engine i insure that the heads will be able to feed the engine efficiently at all RPMS. If I am able to reach 228 CFM at 25 in H2O flow it will feed the engine well past 7000+ RPM. This is I think reasonable. If I had stroked it to say 4 inch I would need 276 CFM to feed it which I dont believe is possible with the stock head castings no matter what i do to them. (An often overlooked thought by the punch-drunk stroker crowd. )MORE is more often then not actually LESS in the final tally. The secret to making big power economicaly is to make sure EVERYTHING is working together. Heads, cubes ,stroke, RPM range of cam (duration) , Cam lift matches head flow max lift , Carb can feed engine well (not to small not too big.) Headers are Long enuf for HP Peak of engine. (Almost always overlooked) And so on. When everyone is singing the same tune in an engine, good things always happen. It is not fun or sexy particularily and there is nothing to boast about over the camp fire but that is how to get extraordinary performance from ordinary stuff. Here we dont use "bigger better longer louder etc". We work hard to find "right." tis fun . Don
Hey, always wanted to know...and yes, i know the poly and LA are different, but...how hard is it to stick their 4" MP crank meant for the LA into the web journals of a poly? Please PM or post the answer here.
A popular mod in Oz is to cut the mains on a 360 crank to 318 & use the 3.58" stroke. @ .030 overbore they get 349, usefull where there was few 340s & no 360s made down under. How would that stroke figure?
Heres a pic of my cross rammed 318 Poly in 1975 using a pair of Offy adaptors on a stock cast iron 1957 twin 4 intake & 600 Holleys, its the bottom pic, the top pic is whats there now, a single 600 holley on a Weiand intake .........my 1940 Dodge liked it a lot, so much that I've got another cast iron intake and a pair of Edelbrocks as a present for it.......andyd.
I was going to say 351m-400 pistons. Give that man a cigar! Tis fitting to because he is the original fellow who inspired this project. Or as we would say if you were here Tim. "Tis all your fault!" The stroker crank would fit fine and have done the 360 to 318 (and to 340) deal a few times before but read back a couple of my posts. I already covered this subject a bit. Do not want a stroker for this project. Today I made a port paper. I do this sometimes just to get a visual idea of what the manifold port relationship is to valve size. Size of the port expressed as a circle is 1.8 inch diameter. Not much room to enlarge so it helps understand why the smaller valve works or is a practcal maximum. I do this often . make a linear cardboard strip pattern around the perimeter of the port then let it spring back to a natural circle shape and measure it. While not super scientific it does fit the "A picture is worth a thousand words" deal. Don
It's all your's Don, I don't get any credit. I like how you work, I too get real tired of the "bigger is always better" thinking. Carry on sir, you are doing fine work.
I happen to agree whole-hartedly with you Dolmetsch, Bigger is NOT always better, matched components singing the same tune is how it's done. I bracket race my '66 Coronet with a simple 11.1 CR .030 over 440, standard port head with under .600 lift camshaft. Race weight is 3650 - car goes 10.50's People ask me regularly..."is it a stroker?" When I tell 'em what it is sometimes I think they don't believe me...I'll take that any day. Good luck with your project - I always felt the Poly has loads of potential.
Buy is a dirty word here. Havent got any spare gold anyway I do have time. I find this fun. Great on the 440 Cornet. 440 is probably the least expensive most responsive engine to build I have ever worked with. Yes i have had the track whisperer spead the rumour too. "It is a big roller cammed stroker. " But it was siimply the build from my book , What is now know as the OR build. I remeber my cam grinder calling me and talking when we ran the Charger (4150 race weight) "Buddy." he said "You aint never gonna git a car that big to run 11s with that." When we ran 11.41 at 119 MPH someone told him way down there. Next phone call was. "Hi Buddy, I heard a rumour" Mind you he contributed to our success in NO SMALL WAY! (Racer Brown) Today after some work on the / 6 tunnel ram I am going to give the "trysee" piston some machining.
Have you compared the poly head to the wedge head? I know the old poly head had valves sized in between the wedge 318 and 340 head and the ports look better. I also know Chrysler had some clever designers so maybe the wedge head is not as bad as it looks. So I guess the question is, are you using the poly head because it has more potential power than the wedge or just for the hell of it?
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