3.875 stroke?
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Originally Posted by dwestsr
How much grinding is needed to put an 8.75 stroke in a 350 block. Also which rod works best 5.7 or 6.00 h beam? Thanks
Just messing with you over this typo error. I feel sure that there are some experienced people on here who will give you a better answer then mine. I believe one thing that determines how much grinding is needed is the type of rods used. But at any rate this is a bump to the top. And ill be 
as I am very interested in this as well. 
Burning Brakes
Joined: Aug 2000
Posts: 1,146
Likes: 2
From: Albuquerque NM
Originally Posted by dwestsr
How much grinding is needed to put an 8.75 stroke in a 350 block. Also which rod works best 5.7 or 6.00 h beam? Thanks
In any case the 3.875 stroke only needs an extra 1/16" of grinding. "Some" 383's require a small radius cam as well...mine didn't.
If you have the choice the 3.875" stroke "sings" a little more with good heads and port matched intake.
If you can find the pistons, a 6.0 or 5.85 rod will do nicely. But, the advances in aftermarket cylinder heads (little port BIG flow) can take advantage of the increase TQ in smaller rods at lower rpms.
Drifting
Joined: Apr 2003
Posts: 1,379
Likes: 4
From: rome ny
Originally Posted by ZD1
How much grinding really has to do with which rods you use. A set of rods where the bolt screws into the upper rod will save more room than rods bolts that need nuts. Secondly, most of the rods manufacturers will say that their I-bean rods will have more clearance that their H-bean rods.
In any case the 3.875 stroke only needs an extra 1/16" of grinding. "Some" 383's require a small radius cam as well...mine didn't.
If you have the choice the 3.875" stroke "sings" a little more with good heads and port matched intake.
If you can find the pistons, a 6.0 or 5.85 rod will do nicely. But, the advances in aftermarket cylinder heads (little port BIG flow) can take advantage of the increase TQ in smaller rods at lower rpms.
In any case the 3.875 stroke only needs an extra 1/16" of grinding. "Some" 383's require a small radius cam as well...mine didn't.
If you have the choice the 3.875" stroke "sings" a little more with good heads and port matched intake.
If you can find the pistons, a 6.0 or 5.85 rod will do nicely. But, the advances in aftermarket cylinder heads (little port BIG flow) can take advantage of the increase TQ in smaller rods at lower rpms.
well said...i am building a 396ci now. i am using brodix m2 215 heads. flow around 305 cfm at .650 lift.. solid roller cam, should spin to 7500 on problem.
clearancing was minimal but does require a .900 base circle cam with lunati 6.0 billet rods.
spr has a stocking pistons, -5 flattop for 6" rod 3.875 stroke or -15 dish for 5.85 rod.
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
I didn't have to do any rod clearancing on my pan rails, but had to clearance a couple cylinders for the crank counterweights. I used a .990 base circle cam and it cleared my 6" rods by a significant margin. My build was a 3.875 stroke using 6" SCAT I beam rods. There are several pics of the build and the parts I used in my photos to the left
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Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Originally Posted by bacardioil
iam using 5.850 rods on my new 383 build engine thats the best rod to use.
Rods should be chosen based on the manufacturer (cost effectiveness) and the individual circumstances in a particular build (available compression heights on shelf pistons for example), not by length. The amount of angle, dwell, side load, etc is negligible on a street car or even a frequent 1/4 mile car that sees street duty.
Drifting
Joined: Apr 2003
Posts: 1,379
Likes: 4
From: rome ny
cabo is right.
the rod are chosen based on what the piston you have chosen calls for and what the crank calls for. my crank could be used with a 5.7,5.85 or 6" rod but the pistons had to have a 6" rod..
the rod are chosen based on what the piston you have chosen calls for and what the crank calls for. my crank could be used with a 5.7,5.85 or 6" rod but the pistons had to have a 6" rod..
Burning Brakes
Joined: Sep 2005
Posts: 993
Likes: 3
From: Iowa
Choose your rod length and then calculate your pin height to see if you can get a piston to fit it on your budget. The longer the rod the shorter the height and the more expensive/durable the piston will generally be. The crank counterweights may have been machined for the 5.7s but if not then you may have to run the longer 6s. Take half of your stroke plus your rod length plus any clearance say 5 thou for Road Race and then subtract off your Deck height and that will give you your pin height. Then see what is available for your needs and pick your rod and piston at the same time if your crank will allow that. As for clearance mock it up and check, they all seem to be different but I would plan on doing some grinding since all the sprint car engines I have seen have had to have their 400 blocks machined for that stroke.
