cc305 to cc306, worth it?
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Joined: Jul 1998
Posts: 197
From: Los Angeles, CA
cc305 to cc306, worth it?
I'm kinda tired of the 305, but is changing to a 306 or something similar really worth the effort or is it better to just wait and eventually rebuild the whole thing?
I may have to change a lifter and possibly the opti soon, that's why I was thinking about doing a cam swap as well
I may have to change a lifter and possibly the opti soon, that's why I was thinking about doing a cam swap as well
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Joined: Oct 2002
Posts: 2,277
From: Orange Kounty, Kalifornia
If you go that big of cam, then up your compression to raise your DCR. Otherwise you will loose DCR by just swapping the cam. Keep in mind the 306 has 70+ degrees of overlap compared to the 50+ on the 305.
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Joined: Mar 2002
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From: Baton Rouge, LA, USA
You would pick up 15 - 20 hp with that cam upgrade.
However, I'd upgrade to an Extreme cam. The ramps are much quicker than the ole' 305/306.
You can also play with the Lobe Centers to get the DCR up so you won't lose low-end. A 306 can be ground on a 109 LSA, 6 degrees advanced (or a 107 LSA, 4 degrees advanced) for the same DCR as a 305. It would idle like @ss, though.
A 230/236 Extreme on a 112 LSA, 5 degrees advanced (or a 111 LSA, 4 degrees advanced for the same effect) would net you the same DCR as you have with the 305 cam also. So, you'd have the same low-end power as current, just more top-end and a choppier idle.
Make sure you have 140 lb seat pressure if you use an Extreme cam, though.
Mike
However, I'd upgrade to an Extreme cam. The ramps are much quicker than the ole' 305/306.
You can also play with the Lobe Centers to get the DCR up so you won't lose low-end. A 306 can be ground on a 109 LSA, 6 degrees advanced (or a 107 LSA, 4 degrees advanced) for the same DCR as a 305. It would idle like @ss, though.
A 230/236 Extreme on a 112 LSA, 5 degrees advanced (or a 111 LSA, 4 degrees advanced for the same effect) would net you the same DCR as you have with the 305 cam also. So, you'd have the same low-end power as current, just more top-end and a choppier idle.
Make sure you have 140 lb seat pressure if you use an Extreme cam, though.
Mike
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Joined: Oct 2002
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From: Orange Kounty, Kalifornia
EngineerMike - I remember that AFR has a device to prevent valve float... can't remember what it was called. What if you had "normal" spring pressures but had AFRs valve float device which presses on the lifters.
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From: Los Angeles, CA
I'm still trying to figure out what I want to do with the car. I use it for commuting, but it's mostly highway. I don't care too much about the mileage if still reasonnable, nor the quality of the idle as long as I don't have to idle above 1200 or so.
I have about 140k miles on the engine, so I need to figure out if it is even worth doing anything but a straight rebuild. It shows no signs it needs it though, so it's a tough decision...
Do you guys think it is worth doing another cam swap or will the difference be so little that I should get some better head work (I've a port and polish job on them) and then pick a cam?
I have about 140k miles on the engine, so I need to figure out if it is even worth doing anything but a straight rebuild. It shows no signs it needs it though, so it's a tough decision...
Do you guys think it is worth doing another cam swap or will the difference be so little that I should get some better head work (I've a port and polish job on them) and then pick a cam?
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Joined: Oct 2002
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From: Orange Kounty, Kalifornia
Since you're still in the planning stages, I'd get a DCR calculator. You can figure out your Dynamic Compression Ratio very easily and plan your heads/cam combo. Let me know if you need any help.
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Joined: Oct 2002
Posts: 2,277
From: Orange Kounty, Kalifornia
This is a quick and dirty without knowing your details.
Running the CC305 in a stock set up with .049 GM head gaskets will get you 8.14 DCR... a bit low.
Again, the assumption is that your heads are at 58cc
Running a Felpro .039 head Gasket brings it up to 8.33 DCR
Running a Impala head gasket at .029 will get you a 8.56 DCR which is a bit on the high side, but with aluminum heads and a 160 Thermostat you should be ok. That also gives you a static 11.02:1 Static Compression Ratio which would really wake up your current cam and head work.
Port matching the intake should help a bit.
It's really your call, both the head and cam should be done at the same time to really match. A lot of guys are on the CC306 but I personally don't want that much overlap.
CMotorsports has a 227/233 that looks very tempting... and it is offered in a 111, 112, and 114 LSA.
Running the CC305 in a stock set up with .049 GM head gaskets will get you 8.14 DCR... a bit low.
Again, the assumption is that your heads are at 58cc
Running a Felpro .039 head Gasket brings it up to 8.33 DCR
Running a Impala head gasket at .029 will get you a 8.56 DCR which is a bit on the high side, but with aluminum heads and a 160 Thermostat you should be ok. That also gives you a static 11.02:1 Static Compression Ratio which would really wake up your current cam and head work.
Port matching the intake should help a bit.
It's really your call, both the head and cam should be done at the same time to really match. A lot of guys are on the CC306 but I personally don't want that much overlap.
CMotorsports has a 227/233 that looks very tempting... and it is offered in a 111, 112, and 114 LSA.
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Joined: Mar 2002
Posts: 2,743
From: Baton Rouge, LA, USA
Originally posted by Wild1
EngineerMike - I remember that AFR has a device to prevent valve float... can't remember what it was called. What if you had "normal" spring pressures but had AFRs valve float device which presses on the lifters.
EngineerMike - I remember that AFR has a device to prevent valve float... can't remember what it was called. What if you had "normal" spring pressures but had AFRs valve float device which presses on the lifters.
Besides, why spend $230 on a rev kit when proper valvesprings can be had for $100?
There is nothing wrong with using 140 lb seat pressure.
Mike
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From: Oklahoma where trees are made of wood.
The problem I have with 140 # seat pressures is that usually puts the open pressures over 400 #s , bad for poor rockers. But if youre upgrading to a strong or already have a good stron rocker 140#s will be welcome, keeps that bounce at a minimum.
I would look elsewhere than the cc306, there are faster cams out there that will make broader powerbands and be less peaky. I would recomend the XE 230/236 on a slightly narrower LC. ask a good shop what they think you should have it ground on. I of course narrowed mine down to 110 with the 230/236 but I have a 5.7 rod 383.
I would look elsewhere than the cc306, there are faster cams out there that will make broader powerbands and be less peaky. I would recomend the XE 230/236 on a slightly narrower LC. ask a good shop what they think you should have it ground on. I of course narrowed mine down to 110 with the 230/236 but I have a 5.7 rod 383.
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Joined: Mar 2002
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From: Baton Rouge, LA, USA
I agree about the rockers. My open pressure is ~420lb, which would eventually break the stock rockers or even good aluminum rockers. The Pro Magnums (like mine) would last forever, though.
Mike
Mike
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Joined: Dec 1999
Posts: 1,697
From: Petersham, MA
Originally posted by engineermike
There is nothing wrong with using 140 lb seat pressure.
Mike
There is nothing wrong with using 140 lb seat pressure.
Mike
I think the Comp R lifters can handle a little more seat pressure than the stockers if I'm not mistaken.
