I installed the cam and the rods are hitting the cam. They are new scat rods. After I pulled the cam out I looked down the cam bore and saw rod portruding in the path. The cam is a summit #1105. Is this as simple as needing a smaller base circle cam or do I need to grind on the rod. It is more than just the bolt that shows. Anyone with this experience care to elaborate?

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First I need the stroke of your crank. I have built a 383 with a 3.75 stroke. Are you using a 350 or a 400 block? The proper way to make a stroker engine is to first mock up the engine. On a 350 the rods will hit the side of the block around the oil pan rail and possibly on the bottom of the cylinder walls. All of this will need to be clearenced to .050 in. I recommend having an experienced eninge builder do this because you risk junking your block. Next you will need the rods clearenced to the cam. You will have to grind down the rods and rod botlts to get it to fit. Again a job for an experienced engine builder or go very slowly. As soon as you get .050 in clearence stop and go on to the next one. After that you need the entire rotating assembly balanced. If it is externally balanced supply the harmonic balancer and flywheel/flexplate to the machine shop. Building a stroker at home is can be done just take your time and go very carefully and make sure everything has .050 clearence. So go ahead and have fun or shell at some money at a shop and hope they do not screw it up.

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84 Z28 383
Stripped w/Cage back halved w/ladder bars and coil overs and 9 inch
700R-4 3.73

 

Chronos, The block is a 400sbc like the topic says. The stroke is 3.75. The crank, rods and pistons all spin freely assembled together. I know that it is just the cam conflicting with rod bolts. The rod bolts are arp wavlocs the head on those bolts are already tapered alot I don't if could grind down anymore on those. Does anyone have experience with those rod bolts?

 

You should really take the rods to your local machine shop and have them clearanced. Most shops have experience building 383 5.7 strokers now days and they can normally clearance a set of rods for about 40bucks.
I would get all eight done. Keeps the motor balance closer.

Depending on which cam you are running, reduced base circles are timeconsuming to setup. I had to get a .2 smaller basecircle to get my scat 4340 capscrew rods to clear without machine work.


Just say fun with 400s

[This message has been edited by jcb999 (edited August 07, 2001).]

 

Sounds like basically you just have the wrong rods... stock 400 rods fit in a stock 400, no problems (duh) so correctly selected 5.7s should as well. Stock 350 rods may not, which sounds like what you've got. Several of the rod makers sell rods specifically designed for stroker motors which are already set up correctly like stock 400 ones are.

It is normal for the rods in a 400, even a stock one, to swing through the "cylinder" of volume occupied by the cam; however the lobes are turned in such a way at the time the crank passes through there that everything clears. The ones on the right bank come closer than the ones on the left because of relationship of the cam lobes to the crank with the cylinders tilted in that direction.

Basically you have 2 options: either clearance the rods, or get a reduced base circle cam. If you do the cam change thing, get an adjustable push rod when you buy the cam, you'll be needing it. To be honest with you, you ought to change the cam anyway, that's not a very good cam for what you're doing; look at a Comp XE268 for a comparison. It has the same .050" duration, similar lift, and far less "advertised" duration; so it will idle better, get better gas mileage, and produce more power. Plus, I believe Comp will make you up one of that series on a small core for $25.

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