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| Cam selection https://www.slantsix.org/forum/viewtopic.php?t=62138 |
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| Author: | lgu32 [ Mon Mar 26, 2018 1:25 am ] |
| Post subject: | Cam selection |
I am looking parts for new engine. From my current 225 I can fix the head with manifolds. Bottom end is probably gone as I had the timing gear damage (few topics ago). Typical use is in streets and couple days in a summer at track. I already have 4.10 gears, Sure Grip and modified 904 with a torque converter which has "slightly modified". This converter stall at 2200-2300. I am ready for custom built converter with higher stall. Comparison between cams is bit difficult. A Comp Cams 264H is advertised 220 degrees @0.05. Sound racy but the rest of text says "smooth idle", "good for towing". Not for me thank you. Hughes racing cam at similar 0.05 degrees is full race cam. I have also seen discussion of Oregon grind cams. I think my choice will be "strong at the oil pump gear" so regrinded cams are not my 1st options. I will keep the powerline - except torque converter - then choose a cam - and then the rest of parts. The parts I am going to reuse for new engine is the ported and big valve head - Cllifford injected intake and Dutra duals. Pistons, con rods can be replaced. The peak power could be at 5000 and redline 6000 |
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| Author: | Rick Covalt [ Mon Mar 26, 2018 3:24 am ] |
| Post subject: | Re: Cam selection |
Quote: I think my choice will be "strong at the oil pump gear" so
Avoiding oil pump gear failures is one of the reasons people use regrind cams.
regrinded cams are not my 1st options. |
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| Author: | Dart270 [ Mon Mar 26, 2018 5:40 am ] |
| Post subject: | Re: Cam selection |
Yes, using a regrind is exactly for the reason of having a strong oil pump gear. Many new cam blanks do not have properly made/treated gears on them. What static compression ratio are you going to use, and what fuel type or octane? Lou |
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| Author: | lgu32 [ Mon Mar 26, 2018 6:36 am ] |
| Post subject: | Re: Cam selection |
Quote: Yes, using a regrind is exactly for the reason of having a strong oil pump gear. Many new cam blanks do not have properly made/treated gears on them.
Ok, I didnt think about that. I was thinking regrinds are all with half worn gear.What static compression ratio are you going to use, and what fuel type or octane? Lou Let's assume my damaged engine still has block, rods, crank, pistons in condition I can use them. The block is 0.060" OS and it is milled 2,25mm. The head was "blueprinted". As I have used E85 only the 10:1 static compression was not problem. I had Mopar P4286679 cam in it but it is now gone. With that cam compression tester made 200PSI (!) readings. Was ok with 26/30 degree ignition timing. I could think a step hotter cam. |
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| Author: | DusterIdiot [ Mon Mar 26, 2018 5:15 pm ] |
| Post subject: | Re: Cam selection |
Quote: I had Mopar P4286679 cam in it but it is now gone.
Mopar purple shaft cams made in the 2000's tended to have gear problems.That cam was 268-ish in duration... if looking for more duration to support the revs, I'd look for something in the 280 adv duration 230 @ .050 min... If you ported the head pretty well the Erson AM cam would have been one to look at... also make sure to check your valve guides, the 280+ cams tend to approach .500 lift and if the guides weren't cut down to clear that lift, at high rpms you will hammer the guide and knock it loose out of the head (been there did that to 3 guides...)... |
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| Author: | lgu32 [ Tue Mar 27, 2018 2:58 am ] |
| Post subject: | Re: Cam selection |
Sure I have check quides as I need 4 valves too because pistons did the hammering after timing gear damage. Are Erson cams good in the oil pump area? How are Hughes cams in quality? I have seen Doug's article about the cam failure. There was instructions for additional oil jet. Does it fix the problem enough? |
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| Author: | Dart270 [ Tue Mar 27, 2018 5:14 am ] |
| Post subject: | Re: Cam selection |
If I were running E85 all the time, I would shoot for 11:1 static compression. The Oregon 346 grind would be a small step up from that MP cam, and there are many others larger than that from Oregon that would work. Lobe 34 intake and lobe 1628 exhaust with a 106 lobe sep angle would work well without doing much (or any?) work to the valve guides and would get you 6k RPM easy. Install at 100-102 deg centreline. Lou |
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