C4 ca mswap
Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
C4 cam swap
OK, I've been sick for the past 3 weeks, but today I made good progress today, unfortunately I did not pick up a damper puller so that is where I stopped,
I did check the AC Condenser that I bought it it is @ 1.0" thick and the stock condenser is 1.75-2.0 thick, I plan on placing all of the ac components during this cam swap
Everything is stripped down except the damper and cover, I'll grab a puller and get the cam out on Thursday or Friday
The plan is to downsize the hyd-roller cam from 238/242 to a 228/232 w/.612 lift
I did check the AC Condenser that I bought it it is @ 1.0" thick and the stock condenser is 1.75-2.0 thick, I plan on placing all of the ac components during this cam swap
Everything is stripped down except the damper and cover, I'll grab a puller and get the cam out on Thursday or Friday
The plan is to downsize the hyd-roller cam from 238/242 to a 228/232 w/.612 lift
Last edited by LD85; Mar 9, 2013 at 10:51 PM. Reason: spelling
Le Mans Master
Joined: Nov 2006
Posts: 5,032
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From: Greenwood Indiana
2021 C4 of the Year - Modified Finalist
C4 of Year Finalist (appearance mods) 2019
Glad you're feeling better. Don't you ever stop changing major parts on that thing? (You must be a masochist.) 
I've got a damper-puller if you still need one.
Did you ever get a hold of that degree wheel you were looking for?
I've got a damper-puller if you still need one.
Did you ever get a hold of that degree wheel you were looking for?
Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Thanks JM!
Yes, I bought a degree wheel and I'll rent the puller from AZ in a day or two.
Once I down size the cam, I'm going to be done with it for good, gonna keep my eye on the look out for a C6
Yes, I bought a degree wheel and I'll rent the puller from AZ in a day or two.
Once I down size the cam, I'm going to be done with it for good, gonna keep my eye on the look out for a C6
Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
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From: Indianapolis IN
I expect to drive it a lot this summer, I'll have it on the road by mid April,,, but,, the engine is still basically new, probably less than 10k miles on it, w/new interior and new paint, so I plan on hitting Fun Fest and "maybe" even go to Carlisle PA
Hot Rod Power Tour is going South of us so we wont be doing it this year,
If we move to a new place with more space I will keep it., I need a bigger garage
Hot Rod Power Tour is going South of us so we wont be doing it this year,
If we move to a new place with more space I will keep it., I need a bigger garage
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Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Had a long talk with Bullet Cams yesterday, flat out great people! They will take the time to talk with you if you need.
Regarding the split ration rockers, they said yes, when using the AFR heads, the EXH ratio inefficiency is very good, so slowing down the rocker with the 1.5 will actually boost the TQ in stead of using a 1.6's on the EXH. This was exactly my thought, on accident of course, but I knew the AFR EXH flow efficiency is @ 85% based on my flow charts, so there was no need to leave it open as long, and by using a .612" lift on the Intake, this helps the top end but sacrifices some low end TQ. Since I have 210cc heads, I did not want to kill anymore of my HP than necessary.
This does not affect the timing events, only the speed of the open and close of the valve and the lift. So, I'll be using 1.52-Exh & 1.6-Intake on the new cam
Cam specs are;
228/234 @ .050
284/289 @ .006
114 CL
.3825 lobe x 1.60 = .612"
.3825 lobe x 1.52 = .581"
Overlap at .050 = 3*
Overlap at .006 = 58.50*
Always a good day when stuff comes
Regarding the split ration rockers, they said yes, when using the AFR heads, the EXH ratio inefficiency is very good, so slowing down the rocker with the 1.5 will actually boost the TQ in stead of using a 1.6's on the EXH. This was exactly my thought, on accident of course, but I knew the AFR EXH flow efficiency is @ 85% based on my flow charts, so there was no need to leave it open as long, and by using a .612" lift on the Intake, this helps the top end but sacrifices some low end TQ. Since I have 210cc heads, I did not want to kill anymore of my HP than necessary.
This does not affect the timing events, only the speed of the open and close of the valve and the lift. So, I'll be using 1.52-Exh & 1.6-Intake on the new cam
Cam specs are;
228/234 @ .050
284/289 @ .006
114 CL
.3825 lobe x 1.60 = .612"
.3825 lobe x 1.52 = .581"
Overlap at .050 = 3*
Overlap at .006 = 58.50*
Always a good day when stuff comes
Last edited by LD85; Mar 22, 2013 at 08:03 AM.
Race Director
Joined: Apr 2003
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From: moraga ca
I ran 1.5 exhaust and 1.6 rockers for years with my split pattern cam. I changed to 1.6 all around last year. As always I made other changes on the car/motor so I couldn't tell if it helped or hurt. Good luck with the cam change. That was a pretty radical cam for a street 350.
Safety Car
Joined: Sep 2001
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From: Glenbeulah Wi
I ran 1.5 exhaust and 1.6 rockers for years with my split pattern cam. I changed to 1.6 all around last year. As always I made other changes on the car/motor so I couldn't tell if it helped or hurt. Good luck with the cam change. That was a pretty radical cam for a street 350.
Le Mans Master
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From: Akron Ohio
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St. Jude Donor '09-'10-'11
Larry,
Did you have this cam laying around or have bullet grind you a new one? Im just curious, why use the split ratio rockers, when you could have gotten a different exhaust lobe with a slower ramp rate. If you already had some of the parts laying around then it makes sense to build the cam to that.
Did you have this cam laying around or have bullet grind you a new one? Im just curious, why use the split ratio rockers, when you could have gotten a different exhaust lobe with a slower ramp rate. If you already had some of the parts laying around then it makes sense to build the cam to that.
Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Larry,
Did you have this cam laying around or have bullet grind you a new one? Im just curious, why use the split ratio rockers, when you could have gotten a different exhaust lobe with a slower ramp rate. If you already had some of the parts laying around then it makes sense to build the cam to that.
Did you have this cam laying around or have bullet grind you a new one? Im just curious, why use the split ratio rockers, when you could have gotten a different exhaust lobe with a slower ramp rate. If you already had some of the parts laying around then it makes sense to build the cam to that.
Last edited by LD85; Mar 22, 2013 at 05:53 PM. Reason: .403 not .408
Le Mans Master
Joined: Oct 2007
Posts: 9,682
Likes: 3,432
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
They reground the cam and I had the parts, BUT, from what I have read, the ideal rocker is a slow rocker, so really a larger lobe is ideal with the slower rocker, but I don't think, not sure, that I could get a .403" lobe fora Hyd Roller on a Small Base Circle Cam, I could be wrong
Can't wait to hear the new combination.
Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
I had 428-RWHP & 458-rwtq on this last 238/242 cam, so I would like to keep what I can on TQ and this will help in that direction with the shorter duration as you pointed out
I could have had them grind the lobes to accommodate the different lifts, but this way, I can always go back to the 1.6 to get .612 lift if I don't like the results
Last edited by LD85; Mar 23, 2013 at 08:24 PM.
