Aluminum rods hitting cam

[Strange Magic]

Your gonna have to make that call yourself. It is your engine and you have to sleep well at night feeling comfortable with what you did, or are going to do. Building a 700 plus inch engine via the net, is not really recommended. It is up to you to sift through what you feel is reality and what is not. It can be a very tough task to do.

[demented]

Your gonna have to make that call yourself. It is your engine and you have to sleep well at night feeling comfortable with what you did, or are going to do. Building a 700 plus inch engine via the net, is not really recommended. It is up to you to sift through what you feel is reality and what is not. It can be a very tough task to do.

Got that right!!! I have been at this thing for over a year and its been actually a pleasure figuring out things like this and making sure everything is right. I'm in no hurry, just want to make sure its right. In the end I know I built this thing myself. Thats more than some guys can say.

[ingram]

Coming at this from a different perspective...I do not recommend small base circle lobes. One of the advantages of the 55mm camshaft journals is that the cam profile can be designed for a larger base circle diameter. A better profile with more area can be designed using the larger base circle. A larger roller wheel diameter also allows for a cam profile with more area. If the cam profiles on your camshaft were indeed designed for the larger base circle diameter, then making the lobes smaller to clear the rods will defeat the whole purpose.

[demented]

Just for the hell of it, I decided to call Woody at GRP today and ask him his opinion and could they cam cut the rods. After a few quick questions he told me yes they could do it and the cost was minimal at $120.00. I asked him how much material they would take off the rod and he told me that they would take off what GRP feels is a safe amount for those rods, That was .070. I was surprised he told me that but it gives me a target to shoot for and knowing that GRP feels its safe to take that amount out, should be fine for my app.

[Strange Magic]

Coming at this from a different perspective...I do not recommend small base circle lobes. One of the advantages of the 55mm camshaft journals is that the cam profile can be designed for a larger base circle diameter. A better profile with more area can be designed using the larger base circle. A larger roller wheel diameter also allows for a cam profile with more area. If the cam profiles on your camshaft were indeed designed for the larger base circle diameter, then making the lobes smaller to clear the rods will defeat the whole purpose.

This is a great point and a great topic of discussion. There are only a few cam companys that know there limitation on base circle without destroying a lifter. Some others will just randomly get into an area that allows for the wheel to get pretty pissed off from the inability to ride on that lobe. I see this quite often, and pictures of beaten camshafts as well that surface up on internet forums. As the quest continues for bigger heads, there is just as much of a quest for larger camshafts, yet with still the same limitations of what the bearing journal size will offer. Many have overstepped their boundarys in this area and have experienced camshaft or lifter failure. I'll take a reduction of lift any day, to keep that wheel on the lobe. In my personal opinion, lift sits at about a 9 on a scale of 1-10 for importance. I'm sure others will have different opinions. Many will venture to say that area, which is more lift per given crankshaft degrees is a way, a vehicle, a means, to fill the cylinder, and that might be true, but you sacrafice velocity from volume, and when you sacrafice velocity for more volume, you lose your ability to broaden that torque curve.

It's the average that gets you from A to B, and not the single one highest HP figure. I use lower lifts in larger heads and larger lifts in smaller heads, but thats just me.

[Strange Magic]

I decided to call Woody at GRP today and ask him his opinion and could they cam cut the rods. After a few quick questions he told me yes they could do it and the cost was minimal at $120.00. I asked him how much material they would take off the rod and he told me that they would take off what GRP feels is a safe amount for those rods, That was .070.

Thats cool. I am glad that they are back offering the cam cut.

I was surprised he told me that but it gives me a target to shoot for

A little confused at this statement. You mention "a target for you to shoot for". Are they going to cut them or are you going to cut them?

[demented]

No I figured I would cut them myself. The reason for the call to grp was more for piece of mind. The way I figure it is that I can machine only what I need to while grp would make a "blind cut" without anyway to check against my assembly. I can keep going back to the block and rotating assembly to make sure I have a good fit.

[Jason Pettis]

We have had to cut several sets of GRP's for long stroke/big cam journal big blocks (and small blocks too) and have not had any issues after doing so. The typical big block rod we have to cut ends up .680-.700 thick measured from the bearing bore to the cut part. Not sure how thick you will end up at but you can use this as a guideline if you like.

[demented]

Ok guys,
I took the time today and cut the four rods that needed to be clearanced. Dumbass that I am I forgot my cam card at home so I didn't have a chance to degree the cam so I just checked it a few different ways with the cam advanced a full amount and retarded a full amount. I have a cloyes hex ajust timing chain so it is easy for to adjust for checking purposes. I intended to degree the cam tomorrow for an actual measurement. SO with the cam at full advance on the adjustment, I had .042 clearance and at half adjustment I had .060 clearance. Like I said I will get an actual clearance tomorrow when I degree the cam. On the big end of the rod, I took off up to the .070 that GRP recommended and I ended up with .698 thickness from the bearing bore to the machined surface I did. I'm hoping it will be enough clearance once I degree in the cam. SO do you guys think that with this little bit of info I gave you guys, will this sound like it will have enough clearence or should I look at having the cam slightly reground to get more clearance.

[Strange Magic]

Dumbass that I am I forgot my cam card at home so I didn't have a chance to degree the cam so I just checked it a few different ways with the cam advanced a full amount and retarded a full amount. I have a cloyes hex ajust timing chain so it is easy for to adjust for checking purposes.

It might be easy to adjust and user friendly, but you should never just assume or trust anything when it comes to degreeing a camshaft in. Haste makes waste. Get the camshaft degreed in first and foremost, then start the checking proceedure. This should have been done already before the topic hit the board. Just say'n.

I would be willing to answer the remainder of the questions you have, only after you validate the information. Validated information only comes from after the process has been done on camshaft degreeing. Please don't get me wrong, but I don't want you to waste your time and more so, I don't want to waste my time investing answers towards a non-validated situation.

"No spin zone" "Get the facts".

P.S. In your statement somewhere in here, you mentioned that nobody can afford a set of 1200 dollar rods if a mistake has been made. You also mentioned that you've been on this project for over 1 year. My question to you is, why the rush all of a sudden to get this paticular area behind you so fast, whereas your cutting on these non-replaceable rods, non affordable rods without taking the proper steps? I'm just trying to get an understanding to get a clear picture, or an acceptable reasoning why the cart went before the horse on this proceedure.

[demented]

OK I will answer you the best possible way I can.

It might be easy to adjust and user friendly, but you should never just assume or trust anything when it comes to degreeing a camshaft in. Haste makes waste. Get the camshaft degreed in first and foremost, then start the checking proceedure. This should have been done already before the topic hit the board. Just say'n.

I would be willing to answer the remainder of the questions you have, only after you validate the information. Validated information only comes from after the process has been done on camshaft degreeing. Please don't get me wrong, but I don't want you to waste your time and more so, I don't want to waste my time investing answers towards a non-validated situation.

"No spin zone" "Get the facts".

I guess the best way to start is like this. I build one or two motors from scratch every couple of years for myself or friends. The last motor for myself was a 632 about 8 years ago and a 604 bbc for a friend three years ago. I'm a heavy equipment mechanic by trade. I don't build race motors often so I ask alot of questions and make many mistakes along the way. I'm learning. After I hurt my 632bbc I decided that i would build bigger but I knew at that time I would be taking chances along the way becasue its a totally different science once you get over a 4.750 stroke. I have been asking alot of questions of the pros and doing alot of reasearch as well to make sure that I don't make major blunders. I have had a few glitches along the way but at every step I have taken the time to measure and remeasure things many times over. And if I can't or don't have the capacity to measure something I bring it to someone who can.
This motor has been a clearancing nightmare but I have been patient in taking care of the issues. It may not sound it on the the forum like that but I assure you that I make sure that the decision I make has been thought over very carefully. Internet sucks as far as knowing many details about what is really going on.
Before I started clearancing the rotating assembly I did it in steps. First was just fitting the parts in and getting them to spin freely without having any hangups. Second part was to gain proper clearance around the rotating assembly, and third was cam to rod clearance. I left the cam to rod clearance last because of one thing and that was some research I was doing with Steve Lowe SR of LSM cams. He had taken my info of what I was doing at the time I was ordering a cam and ran it by his R and D team to see if what HE wanted to do would work with my assembly. He originally wanted to install a 60 mm cam in my motor but found that the rods would hit the cam the way he wanted to do it. But he did advise me that a 55 mm would have plenty of clearance. Unfortunately He never got back to me and I ended up getting a cam from Danny at Predator cams ( which I believe is very comparable to an LSM cam) Danny too told me the cam would fit without any problems. GRP also told me that the rods would fit as well. I took all that info for granted I guess.

P.S. In your statement somewhere in here, you mentioned that nobody can afford a set of 1200 dollar rods if a mistake has been made. You also mentioned that you've been on this project for over 1 year. My question to you is, why the rush all of a sudden to get this paticular area behind you so fast, whereas your cutting on these non-replaceable rods, non affordable rods without taking the proper steps? I'm just trying to get an understanding to get a clear picture, or an acceptable reasoning why the cart went before the horse on this proceedure.

I did mention that

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.

and the reason for that comment was that someone had mentioned just to scrap the idea of using these rods and buy a new set. I cant see throwing away $1100.00 for a set of rods just to have another set made by another company without actually knowing if that would work either. "GRP'S don't fit so try MGP"

Yes I have been on this project for a long time gathering parts. What I mentioned here is just a tip of the iceberg of what I wanted or needed to do with this motor.Its been getting taken care of on many different fronts. New dry sump, New intake, bigger injection system, different nitrous system, better transmission and convertor, all these things I have been on top of so that each part compliments the other to make a nice system in the end. This is one of the biggest reasons for the long time to put this together. In addition I am making sure its right before I go to the next steps throughout this buildup. Once I nail down the rod to cam clearance I am sending the rotating assembly off to get balanced. Then next step will be the heads!!! New Ti valves and all the fixings plus some additional porting to accomadate the bigger cubes.

I would be willing to answer the remainder of the questions you have, only after you validate the information.

Now for the info!!
The cam required to be degreed in at 114, I set it up at 113 because I like to allow a degree adv. for timing chain stretch( actually I like two degrees advanced). At this point I took and was able to get acurrate measurements between the rods and cam with a set of feeler guages and had .057 clearance at every lobe that had previous interferance. My thinking in the matter would be that once the timing chain stretchs with the springs I need to use on this thing (940lbs open pressure) I will gain a touch more clearance. Later on I'll have questions of higher ratio rockers.
Hopefully I explained myself good enough.

[af2]

OK I will answer you the best possible way I can.

Hopefully I explained myself good enough.

You did to me and all I can say is good for you using your talent to fix a problem...
Some people need to realize there are very capable people on this site.

[demented]

I do want to mention one other thing. I don't think that there is a handful of guys out there that would even try to build a motor this big and run it on injected alky let alone two stages of nitrous in addition. I feel that I have aquired a good amount of knowledge in this and I did gain that by trial and error. We will all make mistakes but the guys that don't "venture outside the box" will never know or understand why they keep getting there ass handed to them.

[af2]

I do want to mention one other thing. I don't think that there is a handful of guys out there that would even try to build a motor this big and run it on injected alky let alone two stages of nitrous in addition. I feel that I have aquired a good amount of knowledge in this and I did gain that by trial and error. We will all make mistakes but the guys that don't "venture outside the box" will never know or understand why they keep getting there ass handed to them.

Same thing here.. How many guys build an engine around a 6-71 roots blower and go 6.50 with 450"..

Pretty dam cool seeing the 9500 rpm+ cars screaming through the traps.

[Strange Magic]

I would recommend that you degree the camshaft in first. I would also recommend that you spin that crankshaft with the correct bob weight. This will allow you to see what your up against, if any and how much mallory might have to be pushed into those counters.