What needs to be changed in the bottom end to safely spin 7000 rpms?
10-27-2004, 12:35 PM
#1
What needs to be changed in the bottom end to safely spin 7000 rpms? I'm planning on swapping over to one of the bigger cams which is going to require higher rpms, and I was wanting to know what all needs to be changed to safely spin 7000+ rpms. More than likely I'll be shifting the car around 6900-7000 rpms with a 7300-7400 rev limiter. I know some people have had luck with their completely stock bottom end holding together, but I wanna be sure. Thanks.
10-27-2004, 12:49 PM
#2
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if you want to be sure, build the bottom end
i wouldnt run the stock bottom end over 6700/6800
i know people have, but they are playing with a timebomb
arp rod bolts will help with higher RPMS
i wouldnt run the stock bottom end over 6700/6800
i know people have, but they are playing with a timebomb
arp rod bolts will help with higher RPMS
10-27-2004, 03:35 PM
#4
Hard Jonny: I really wanna keep the bottom end stock so that I can run for the cam only list. Plus I dont have the funds to build the bottom end, but you can change the rod bolts and still be considered cam only. I currently have 6500 shift points now with a 6700 rev limiter and havent run into any problems, but going any higher than that scares me. I'd really like to just change the rod bolts so that I can still be considered cam only, but I was wanting to know if rod bolts will safely let me spin 6900 rpms with a 7200-7300 rev limiter?
10-27-2004, 04:24 PM
#7
Originally Posted by BlackBeaSSt
CANNIBAL: What do you mean by this:
I have checked the housing bore on the rods before and after the rod bolt install (ARP Pro-series bolts). There is some definite deformation after the new bolts are installed. Every motor we build with stock rods has the housing bore re-sized .002" larger than stock to accept a new, oversized bearing from Clevite for this very reason.
I can't remember off the top of my head exactly how much out-of-round the rods went after the new bolts
That's why I said, ideally. This would ensure a proper setup.
Lots of people get away with simply installing the bolts only, no bore re-sizing.
I'm one of those people that sleeps better knowing proper protocol was followed.
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10-27-2004, 05:42 PM
#9
So there may be a risk of changing out the rod bolts alone? Some may not run into any problems, but then some do? Youre suggesting that I have the housing bore resized? What exactly does that mean? I just wanted to replace the bolts alone and keep the motor in the car. Having the housing bore resized sounds like something that would need to be done with the motor out...thats just what it sounds like. Im the type who likes the peace of mind that everything is done right too, but I really dont wanna change up too much in the bottom end because when Im ready to do that and get the money to build the bottom end, Im going to do it all and not just a few parts here and there. Again, I wanna still be considered cam only so that I can run for the list.
11-04-2004, 12:17 PM
#10
So there may be a risk of changing out the rod bolts alone?
Yes, explained above and in the link provided.
Some may not run into any problems, but then some do?
Yes, explained above and in the link provided.
Youre suggesting that I have the housing bore resized?
If it were my car, yes.
What exactly does that mean?
The rod ends are bored out to a larger size and the use of larger oversized bearings are used to prevent this distortion that causes the rod ends to potentially and measurably be taken out of round.
Having the housing bore resized sounds like something that would need to be done with the motor out
Yes, motor has to come completely out.
Yes, explained above and in the link provided.
Some may not run into any problems, but then some do?
Yes, explained above and in the link provided.
Youre suggesting that I have the housing bore resized?
If it were my car, yes.
What exactly does that mean?
The rod ends are bored out to a larger size and the use of larger oversized bearings are used to prevent this distortion that causes the rod ends to potentially and measurably be taken out of round.
Having the housing bore resized sounds like something that would need to be done with the motor out
Yes, motor has to come completely out.
11-04-2004, 03:07 PM
#11
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Originally Posted by CANNIBAL
So there may be a risk of changing out the rod bolts alone?
Yes, explained above and in the link provided.
Some may not run into any problems, but then some do?
Yes, explained above and in the link provided.
Youre suggesting that I have the housing bore resized?
If it were my car, yes.
What exactly does that mean?
The rod ends are bored out to a larger size and the use of larger oversized bearings are used to prevent this distortion that causes the rod ends to potentially and measurably be taken out of round.
Having the housing bore resized sounds like something that would need to be done with the motor out
Yes, motor has to come completely out.
Yes, explained above and in the link provided.
Some may not run into any problems, but then some do?
Yes, explained above and in the link provided.
Youre suggesting that I have the housing bore resized?
If it were my car, yes.
What exactly does that mean?
The rod ends are bored out to a larger size and the use of larger oversized bearings are used to prevent this distortion that causes the rod ends to potentially and measurably be taken out of round.
Having the housing bore resized sounds like something that would need to be done with the motor out
Yes, motor has to come completely out.
I am not trying to hate Jeremy, but READ! all your answers are there bro!
FWIW if it were me and I had the motor apart, Id go with forged pistons and rods with a stock crank....
11-04-2004, 04:10 PM
#12
Are you saying that when I do my 383 stroker that I will need to resize the new forged rods if I use ARP bolts? Are the rods sized when the engine is being built at GM With OEM bolts? Do the shops that sell short blocks for $2000 on this forum resize the rodson those rebuilds? I'm 58 years old and have built a few SBC's over the years and all I ever used was some plastigauge. I hate to say it but I must be really behind the times.
11-04-2004, 04:39 PM
#13
Originally Posted by BlackBeaSSt
Hard Jonny: I really wanna keep the bottom end stock so that I can run for the cam only list. Plus I dont have the funds to build the bottom end, but you can change the rod bolts and still be considered cam only.
Not sure how to be PC on this... if one can't find the funds to upgrade the bottom end to live with the high rpm, will one be able to find the cash to replace the orginal short block if something breaks with the 7,000+ high rpm eventually?
just my .02 coming from someone that has his H&C car peak at 5,900 rpm and shifts at 6,200 to 6,300 to keep the rpm down so the combo lives for a nice long while...
11-04-2004, 05:04 PM
#14
Are you saying that when I do my 383 stroker that I will need to resize the new forged rods if I use ARP bolts?
It depends on what the bores measure on pre-assembly. You should install the rod caps onto the rod in a rod vise or the like. Install the rod bolts and torque to their spec/stretch, measure the rod end bores, if the bores are out of round with the rod bolts to spec then you'll need to have the ends re-sized appropriately.
Are the rods sized when the engine is being built at GM With OEM bolts?
No, the LS1 uses a cracked rod design that eliminates the need for re-sizing the rod bores when doing an OEM rebuild.
Do the shops that sell short blocks for $2000 on this forum resize the rodson those rebuilds?
One would hope and assume so, however, my motto is to never assume. The only way to know for sure is to call the shops themselves and ask.
It depends on what the bores measure on pre-assembly. You should install the rod caps onto the rod in a rod vise or the like. Install the rod bolts and torque to their spec/stretch, measure the rod end bores, if the bores are out of round with the rod bolts to spec then you'll need to have the ends re-sized appropriately.
Are the rods sized when the engine is being built at GM With OEM bolts?
No, the LS1 uses a cracked rod design that eliminates the need for re-sizing the rod bores when doing an OEM rebuild.
Do the shops that sell short blocks for $2000 on this forum resize the rodson those rebuilds?
One would hope and assume so, however, my motto is to never assume. The only way to know for sure is to call the shops themselves and ask.
11-04-2004, 05:05 PM
#15
Originally Posted by 99 Black Bird T/A
Not sure how to be PC on this... if one can't find the funds to upgrade the bottom end to live with the high rpm, will one be able to find the cash to replace the orginal short block if something breaks with the 7,000+ high rpm eventually?
11-04-2004, 06:55 PM
#16
Im not going to have the motor out. I just want to replace the rod bolts because I have a 2000 model car and I have more of a chance of blowing the bottom end than 01-02 models. I dont wanna take the motor out and I dont plan to. The only reason for me wanting to upgrade the rod bolts is so that I can shift the car a little higher to get the full effect of the T-Rex cam. Honestly, I wanna take the chance of just replacing the rod bolts because I dont wanna pull the motor. A lot of gotten away with it, hopefully I will too.
11-06-2004, 12:26 AM
#19
I dont plan on building my bottom end unless it goes. The only reason for me wanting to upgrade the rod bolts is so that I can spin the motor to 7000 to get the most of out of the cam Im swapping to. (T-Rex) Im crossing my fingers that I'll be ok to just replace the rod bolts.