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Post by Johnny L on Jul 7, 2012 10:08:11 GMT -5
Purely my own opinion from my own experiences but I have had great results using stock 318s with stock 904 trannys and a 4:56 gear. I've also had great results using a stock 318 with a manual tranny and 3:55 gear, but I did end up blowing that motor up after 3 hard runs behind the manual (and running with no water for most of the last run). I know a few guys who have stock bottom end 318s with a mild cam (close to a 340 grind) swirl port heads with nothing more than a basic valve job and good ignition/carb that will run alongside the big money engines all day long and never get too hot. Seems that these chevy guys that are building high compression, 400+ hp engines don't realize that higher compression = more heat = short run. I'm trying a built engine for the first time after running nothing but stockers my entire derby life. Stock bottom end 318 ('86 block), rebuilt '94 Magnum heads (fresh valve job, new springs/seals, mild port job), mild bullet roller cam, 1.6:1 rockers, eddy air gap intake, hei, holley 600 4bbl. The engine is right at 9:1 compression and definitely less than 300hp but super torquey and pulls hard at lower rpms. I plan on mating it with a rebuilt 904 and a 3:90-4:11 gear.
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Post by mkvien on Jul 7, 2012 11:09:11 GMT -5
I have never rebuilt a bottom end on a mopar engine, have done valve jobs, swapped intakes and cams, carbs, etc. A stock bottom end on a 318 or 360 is pretty tough, and when they do finally give up, I'll just find another. That being said, only thing rebuilding the bottom end would do is give me more compression, and that is not a good recipe for a derby engine in my opinion.
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Post by twisted66 on Jul 7, 2012 13:15:33 GMT -5
What about just replacing the valve springs on a 360? I have an engine that runs pretty strong as is right now but starts to float the valves in the higher rmp's I honestly have no idea at what rpm it starts floating at. So I guess my question is does anybody know of a good set of springs I can put on it? I just don't have the time or funds available to have the heads done right now. Or should I just pull an intake and exhaust spring off run them to the engine builder to see if he can find me an adequate match?
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Black333
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Post by Black333 on Jul 7, 2012 13:21:32 GMT -5
What about just replacing the valve springs on a 360? I have an engine that runs pretty strong as is right now but starts to float the valves in the higher rmp's I honestly have no idea at what rpm it starts floating at. So I guess my question is does anybody know of a good set of springs I can put on it? I just don't have the time or funds available to have the heads done right now. Or should I just pull an intake and exhaust spring off run them to the engine builder to see if he can find me an adequate match? if its your everyday run of the mill 360. just go to the parts store and get valve springs for a 340.
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Post by twisted66 on Jul 7, 2012 13:28:57 GMT -5
What about just replacing the valve springs on a 360? I have an engine that runs pretty strong as is right now but starts to float the valves in the higher rmp's I honestly have no idea at what rpm it starts floating at. So I guess my question is does anybody know of a good set of springs I can put on it? I just don't have the time or funds available to have the heads done right now. Or should I just pull an intake and exhaust spring off run them to the engine builder to see if he can find me an adequate match? if its your everyday run of the mill 360. just go to the parts store and get valve springs for a 340. It's totally stock to my knowledge. But it is out of a motorhome 1973 model year so I don't know if that would make any difference
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Black333
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Post by Black333 on Jul 7, 2012 13:39:55 GMT -5
if its your everyday run of the mill 360. just go to the parts store and get valve springs for a 340. It's totally stock to my knowledge. But it is out of a motorhome 1973 model year so I don't know if that would make any difference yep. swap in the 340 springs and see how it likes it. you might be runnin out of cam also. dont know till you change the springs. are you sure its valve float?
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Post by twisted66 on Jul 7, 2012 13:49:30 GMT -5
It's totally stock to my knowledge. But it is out of a motorhome 1973 model year so I don't know if that would make any difference yep. swap in the 340 springs and see how it likes it. you might be runnin out of cam also. dont know till you change the springs. are you sure its valve float? Hmm I guess I'm not sure it's valve float. But a local engine builder who I once worked for but no longer do and will not support him. But it is on no terms of his lack of engine build skill told me it was floating when he listened to the engine run at a show last august. I guess I could try to post a short video clip so everyone could listen. It just sounds like it starts popping out the headers in the higher rmp
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Black333
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Post by Black333 on Jul 7, 2012 14:06:31 GMT -5
yep. swap in the 340 springs and see how it likes it. you might be runnin out of cam also. dont know till you change the springs. are you sure its valve float? Hmm I guess I'm not sure it's valve float. But a local engine builder who I once worked for but no longer do and will not support him. But it is on no terms of his lack of engine build skill told me it was floating when he listened to the engine run at a show last august. I guess I could try to post a short video clip so everyone could listen. It just sounds like it starts popping out the headers in the higher rmp (popping) usually meens its leen, but not all the time. how high of rpm do you think its hitting before it starts popping could be a broken valve spring could be a ignition problem could be lean pull a plug out and have a look. if its snow white. its lean keep us posted
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Post by twisted66 on Jul 7, 2012 14:15:24 GMT -5
Hmm I guess I'm not sure it's valve float. But a local engine builder who I once worked for but no longer do and will not support him. But it is on no terms of his lack of engine build skill told me it was floating when he listened to the engine run at a show last august. I guess I could try to post a short video clip so everyone could listen. It just sounds like it starts popping out the headers in the higher rmp (popping) usually meens its leen, but not all the time. how high of rpm do you think its hitting before it starts popping could be a broken valve spring could be a ignition problem could be lean pull a plug out and have a look. if its snow white. its lean keep us posted I'll go pull all the plugs and have a look. I'm running it with 4.56's and about a 26" tall ag tire so it revs fairly quick but I have no idea at what rpm it develops I'd say it's pretty close to the engines max sustainable rmp anyways. And I will keep it posted. Thank you for the help.
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Post by carson29 on Jul 8, 2012 11:15:46 GMT -5
Spark plug? What do you guys run on a 318? I would like the shortest ones possible. I will be running a Buick hei. I know on the old site it was posted but never thought to save it.
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Post by Johnny L on Jul 8, 2012 15:27:41 GMT -5
I've always run champion RJ14YC (i think thats the correct part #) Plugs
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dm440c
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Post by dm440c on Jul 9, 2012 9:59:48 GMT -5
I usually use the Comp valve springs and allow the point float to be my rev limiter. No need to spin the engine any faster than that IMO unless you think spending money is cool.
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Post by JoJo Davis on Jul 9, 2012 12:49:49 GMT -5
My most recent experience with a mopar motor, it popped alot until I fixed the ground wire. Once I got a good gauge ground wire on the block it quit popping...
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Post by derbydriver666 on Jul 9, 2012 17:59:46 GMT -5
didnt ever get to look but what did you have in that Shocker for motor/ gears My most recent experience with a mopar motor, it popped alot until I fixed the ground wire. Once I got a good gauge ground wire on the block it quit popping...
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Post by JoJo Davis on Jul 10, 2012 7:05:28 GMT -5
400/727 4.30 gears...would have been awesome if I had not drew heat 1...lol puked all the fluid out trying to move around out there...lol
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