Aluminum rods hitting cam

[Bad Hombre]

Do not cut the rods. I would look into a different set of rods.

If i'm not mistaken, your the same guy that wrote this below, and I find it very ironic that you obviously do not build engines and have some poor mis-leading advice as well on the subject.

I built all of my engines in the past and for others but not as a high volume. I had this problem a long time ago when i ran a BB. I swapped out a set of C&A rods for a set of GRP`s.

[Strange Magic]

I had this problem a long time ago when i ran a BB.

Just out of curiosity, what size was that big block chevrolet that you built?

[demented]

Thanksfort posting the pics guys.
I don't use a belt drive on thos motor. I have a cloyes hexadjust that was made for the .400 raised cam. I mud race and the thought of the belt getting mud or rocks in it and breaking keeps me from running a belt. Bad enough I rhave to run one for the oil pum and fuel. I'm down at me shop lookingh at my mill and accessories to see if I have what I will need to do this. I also am going to run some tests on scrap to see if I can get a nice finish.

[Strange Magic]

You go back and forth between the mill and the engine until you get some clearance. It's very tough to evalauate really anything until you get rid of that interference.

P.S. I assume your in a 4.840 block. Who's crankshaft is that? Crower, Bryant?

[demented]

I had this problem a long time ago when i ran a BB.

Just out of curiosity, what size was that big block chevrolet that you built?

722 ci alky injected with two stages of nitrous

Callies crank

[Strange Magic]

That question you highlighted was directed at bad hombre. I am just curious to what big block chevrolet he has built that required a modification such as what we are discussing.

Demented, I know your not going to want to hear this, but a stroke of 5.375 and a GRP 5500 series rod, should have been done in the .600 raised as shown here. http://www.dartheads.com/products/race- ... locks.html

It's not really the stroke thats the issue, it's the intended Hp and the "must use and needed of the 2.200 and 5500 pro material rod".

Hopefully in the worst case senerio, you did not tell the camshaft manufacture to make the base circle as tight as feesably possible, this will allow you additional room if they make you another stick that is of a tight base circle. Assuming if you have to remove to much material whereas the rod is in jepordy.

[Bad Hombre]

I had this problem a long time ago when i ran a BB.

Just out of curiosity, what size was that big block chevrolet that you built?

Whats the difference what size the engine was. Does`nt matter if it a Ford, Chevy, Pontiac, etc etc etc. The problem is the rod interfering with the cam. Maybe you can answer for me since you know everything.

[Dan Timberlake]

What is the minimum clearance you want ot see between the cam and rods? How much difference for steel and aluminum?

I don't deal with engines this serious, but would want at least 1/16 "

[demented]

The reason why i chose the crank, rod, piston pin height, and cam size was becasue I knew it could be done. As a matter of fact Sonny Leonard did a bunch of these same size motors years back with the same merlin block I have in iron and aluminum block version. Now I can say that at that time the 5500 series GRP rods were not available, however, the crank size, aluminum rods and 55mm cams were available at that time. Its been done so its not a new combo by anymeans. The idea of changing blocks is not going to happen, To expensive since all the machine work is done with this one I have. The idea of changing rods is also not going to happen. Any aluminum rod set is going to cost over $1100.00 and last I knew there are not many people racing that can piss away that kind of money. Not bashing anyone so don't take it the wrong way .
After spending a few hours looking and thinking about this in front of my mill, I started by running some test passes on some aluminum plate I had and wanted to see if I could duplicate the finish of the rods. Yup, I could. So I have found a nice way to secure and locate the rods with the ways you guys have suggested and I am confident that I can take care of this issue myself. I just have to pick up some dyken blue layout paint and set the rods in place and make some marks. The only thing I am rethinking is the idea that Bill Jones had about the 6" cutter. I think thats a nice radius for cam relief but I have to see if I can locate a cutter like that. Wouldn't be a bad idea to own a cutter like that anyways. But today I was making my test cuts with a two flute 3/4" end mill with good results.
OK a couple other questions,
I have been setting up rotating clearances at .080 to .090 on this motor due to crank flex with this big arm. So should I have that same clearance at the cam as well? I am thinking the answer is yes.
Another question, IS the lobe closest to the rod when the cam is advanced or retarded? I can't remember but i am thinking when I go to measure I should set the cam for some lee-way.
Also shoudl I just mill the four rods that hit or do all eight to keep the weight the same and then have them balanced? I have not had the rotating assembly balanced yet so balancing the rods is an option for me. The balancing is going to be my next step after I straighten this glitch out.

[Dave Koehler]

Since you have a modified and an unmodified rod on each journal you can survive. Each bobweight is made up of 100% rotating weight (your 2 rods).
As long as your balance shop understands what you are doing it should be a no brainer.

[Strange Magic]

2 or 4 flute is all you need. It's a very simple process. DRO's on your bridgeport will cme in handy as well.

I only do what is necessary, and if it's 4 rods, then 4 rods get done. Your going to come to find out that the weight difference is minimal enough that it's not worth talking about.

It is understood that what your doing has been done, you are not the first, nor will you be the last. On a Callies, you most likely are going to have to push in an ample amount of mallory/heavy metal. I suspect your pistons to be in the nieghbor hood of around 650 or maybe even more grams. Your pins to be 165 or greater grams, your rod total to be 675 or so grams and your ring package north of 50 grams w/ring groove spacer. These Callies usually need ample heavy metal.

Someone mentioned something about the belt stretching 8 degrees. I'm not saying that this is not true, but I find this statement very hard to believe and I don't think jesel would agree with it. Just an opinion. Yes, I do understand that this application is timing chain.

Any aluminum rod set is going to cost over $1100.00 and last I knew there are not many people racing that can piss away that kind of money.

When you doing an engine that is 700 plus cubic inches, 1100 bucks is a tiny drop in the bucket compared to the total cost of the engine, when done correctly. A mistake can cost you significant more dollars than a mear 1100 bucks. 700 plus cubic inch engines on multiple stages of spray, done correctly is north of 35K.

[bill jones]

-here's some notes from 4-3/4" stroke engine I worked on maybe 10 years ago.
------------------------------------------------------------------------------------------------
note #1:
-install cam shaft into short block, degree it in and check for cam lobe to rod interference.

-Found that this particular cam can NOT be advanced to more than 102INT c/l where
rods #2-4-6 & 8 all hit at that point.

-Intake centerline can be retarded as far as the Jesel will allow.
---------------------------------------------
Note #2:
-assemble the short block with the heads.

-Includes degree the cam at 111° Intake c/l raceready at the valve, which is the absolute maximum advance this cam can be before the cam lobes hit the rods.

-The Jesel sprocket is now painted RED where interference occurs.
-----------------------------------------------
-I don't know for sure but chances are the firing order was 18436572----and since #2-4-6 & 8 were the 4 rods that were the problem and each rod is on a different journal---I personally see no reason to machine the other four rods just for balance reasons.

[demented]

Sounds good guys but I'm still unsure about how much clearance I should actually have. I have seen many guys recommend .050 as a minimum. But I am wondering due to the bigger crank and the tendency for it to flex more, should I use more clearance?

[wyrmrider]

better to check with cam advanced in case you change to a bigger cam later or have to advance your cam
.050 or 1/16 should be ok If you flex that much you have other problems

[demented]

The only reason I bring up crank flex is because I have read many articles that point out the fact that long stroke crank shafts that do not have a good journal overlap tend to flex more than shorter stroke cranks. Its a typical issue that many big cube engine builders have found. They recomend adding .010 to .020 more clearance to all your measurements over the norm for the reason I just mentioned. This is all new to me but I am listening and asking questions so I know.