I'm building a 334 stroker, got my crank and pistons, now I'm getting ready to buy rods. The crank is a stroker crank already set up to go in a 350 and the pistons are .030 over Speed Pro Hyper's. My question is will 5.7" rods be too long for the 3.75" stroke. If they are should I go the short stroke and get 5.565" rods for a 400? If I use the 400 rods what do I have to do to get them to fit the crank? Since the crank is already to go in the 350 do I still have to cut the main journals down to 305 mains? Lotso questions, maybe better if it was broken down a bit...if you guys could give me a hand here, I'd appreciate it.

 

305 and 350 mains are the same. You will probably have clearance probs with the cam and the rod bolt heads, it will depend on how big the cam lift is.

Put pistons in the holes for cyls 1 and 6 with the cam installed and see what clearance you have. You should be able to get a .050 feeler gauge in between the rod bolt head and the cam lobe when the rod is at the highest point (the farthest away from the crank centerline) during the rotation cycle.

 

ok you say 334, that's a 305 block with a 400 Crank, if that's the case the 400 crank journals must be ground to the 305 size, and i would use the 5.65" rods so you dont have clearance problems, you will have with the 5.7 rods.

 

will the 5.565" rods fit on the crank if its already been machined for a 350?

 

there is no size difference for connecting rod journals from 1968 on.

 

If you already have your pistons, it's too late to be fishing around for what rod length to use. With a given piston and stroke, you can only use exactly one rod length and have it come out right. There is no clearance issue with the different length rods.

What pistons do you have, exactly? Part number would be the best thing.

The sum of 4 numbers must equal 9.025" in a stock (un-decked) block, ± .010". Those numbers are:

• ½ of the stroke. You already have the crank, so you know what that one is; since it's a 400 crank, it's half of 3.75", which is 1.875"
• the rod length (what we're solving for)
• the piston pin height. Since you already have pistons, that number is what it is, and all you can do now is look it up. In a stock 305, 350, or 400, it's 1.56"; so if you have stock 305 pistons, that's what they are
• the deck clearance (distance below the deck that the piston reaches at TDC), which is .025" from the factory

Do the math, it will tell you what rods to use.

Like jcb said, the 305, 350, and 400 rod journals are the same diameter (before re-grinding of course). The thing about the crank that has to be changed to make the 400 one fit into a 305 or 350 block is the main journals, which are the same. Remember, the crankshaft is the same casting in a 305 and a 350, usually 442. So a "383" crank and a "334" crank are actually the same thing dimensionally, just like the 305 and 350 cranks; they may be balanced slightly differently, but they'll physically measure the same.

Please keep a running total of how much you have in all these special parts, and in machine work; and post it when you're through. I'm sure alot of people on this BBS would like to see what the cost is, to compare with other possible mods.

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"So many Mustangs, so little time..."
ICON Motorsports

 

The pistons are .030 over Speed Pro hyper pistons, specs below:

Bore: 3.766 in.
Stroke: 3.480 in.
Rod length: See notes below
Compression height: 1.560 in.
Compression ratio: See notes below
Head type: Flattop with 4 reliefs
Oversize: .030 in.
Ring size: (2) 5/64 in., (1) 3/16 in.
Weight: 487 grams

* 305
Stroke: 3.480 in.
Rod length: 5.700 in.
Compression ratio: 9.29:1 (58cc heads), 9.02:1 (60.5cc heads), 8.68:1 (64cc heads), 8.33:1 (68cc heads), 8.01:1 (72cc heads), 7.71:1 (76 cc heads)

* 305 stroker engine with 400 crank and rods
Stroke: 3.750 in.
Rod length: 5.565 in.
Compression ratio: 9.93:1 (58cc heads), 9.65:1 (60.5cc heads), 9.28:1 (64cc heads), 8.90:1 (68cc heads), 8.55:1 (72cc heads), 8.23:1 (76c heads)

The crank is a one piece rear 383 stroker crank which will go into a 88 roller block.

So far I've only spent $453($175 for the longblock, $169 for the crank and $109 on the pistons).

As mentioned above, the pistons will work for the stroker combo and I've got a crank that will fit in the block. I've found a set of 5.565" rods for $115, gonna go with those now that I've got a few things cleared up. So far the bill isn't too bad, IMO.

Sorry for the long post, if any of you guys have any suggestions, let me know.