340 Purple camshaft help
I checked the Summit site and found the following Mopar Performance Purple cam & lifter kits for small blocks. Here are the part numbers and the lift specifications:
1) P4452757 -->Lift .410/.425
2) P4452782 -->Lift .429/.444
3) P4452759 -->Lift .430/.450
4) P4452761 -->Lift .450/.455
5) P4452992 -->Lift .474/.474
6) P4120231 -->Lift .484/.484
7) P4120233 -->Lift .508/.508
8) P5007696 -->Lift .508/.508
Since the 318/340/360 share so many similarities, I checked my 1968 Plymouth shop manual for guidance. (The 360 did not yet exist in that model year so we will "wing it" a bit.) There were two different sets of camshaft specifications for the 340 engine, depending upon the type of transmission mated to the engine. I can only estimate that there may be similarities with the 360 camshafts. Here is what I got:
Automatic --> Lift .430/.445 (very close to #2 above)
Manual --> Lift .445/.455 (similar to #4 above)
If someone has a shop manual with 360 valve lift specifications, it would be even more helpful but I thought I would throw this out for you anyway. If nothing else, perhaps it will prompt someone to correct me and find the answer that you are ultimately searching for.
Do you know if the transmission originally intended for the rebuild was automatic or manual? If so, you may already have your answer. If not, please read on but beware that the following is not "by the book", although nothing is being put at risk.
A suggestion that I might have for you is to take some measurements with a good micrometer caliper, if you have access to one. This method is only an educated guess and I am more than willing to accept that FABO veterans may suggest that this idea is full of B.S.
1) Get access to a good micrometer caliper, preferably a digital one (ie: 3 digit resolution)
2) Measure the diameter of one complete intake lobe across the widest point. Note this number.
3) Measure the diameter of the same lobe across the narrowest point (should be one quarter turn from the previous measurement. Note this number.
4) Subtract the smaller number from the larger one and note this result. If I am correct, it should determine how much of a lump there is out of round from a perfect circle.
5) Multiply the difference by 1.5 to reflect the valve lift, presuming that the rocker arm ratio is 1.5.
5) Repeat steps 2-5 with measurements on an exhaust lobe.
Essentially, I am suggesting that the two measurements on any given lobe of the shaft will help to determine how much a given cam lobe deviates from a perfect circle in order to generate the lift. The multiplying factor of 1.5 for the rocker arm translates the lobe lift into valve lift.
For more consistent measurement accuracy, perform the measurements for every intake lobe and every exhaust lobe and then perform an average of the final calculations for each type (but do NOT mix the two lobe types up if there is a difference between intake and exhaust). If you have something that matches up with any of the sets of camshaft specifications I provided from Summit, you are in business.
Good luck!
While you have the micrometer caliper in hand, measure the exact length of the pushrods. They may or may not be stock length and it would help you with pricing if you knew the length. (I might be interested in the pushrods.)
I just tore down a 360 to build a 408 stroker motor. This 360 had a brand new build but was never fired. I pulled the rolling assembly out and am going to list for sale but it is stock. But the big thing is there was a brand spanking new 340 purple cam in it but I do not know anything about it. The only numbers I can find is 1136. I would love to get the specs on it so I could sell it along with the lifters and pushrods. Any help would be greatly appreciated be it help with ID or sterring me to where I could find the info. Thanks much!