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Stock 360 output |
Post Reply | Page <1 1011121314 18> |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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Looks like I'm in the process of swapping the cam, any final votes on cam choice:
XE262H 262/270 adv, 218/224 @ 050, 493/500 lift 110 LSA 270H 270/270 adv, 224/224 @ 050, 480/480 lift 110 LSA 280H 280/280 adv, 230/230 @ 050, 490/490 lift 110 LSA Others???? Maybe a small solid flat tappet. Leaning towards the XE262H, just because I already have it, so it's the cheapest option, it has been reground, so probably slightly different specs now since they didn't have that exact grind in their system. Been a couple of votes for the 280H, which was my initial thought until I found I didn't have much compression to play with, cam card calls for 9:1 minimum. Turns out I have 993 heads, which supports lower compression observed previously. At the moment I'm playing with about 1400 stall, but may change that in due course and the 4.10 rear gears. I do have a mixed set of 1.6 and 1.7 rockers, that I will probably use as is, so could use the 1.7 on the intake with the XE262H to give it a bit of a boost. Otherwise I have to pull some lifters out of my Javelin if I want a matched set of either 1.6 or 1.7, maybe have 1.7 all round if that's the case and I don't run out of clearance somewhere. Also found that the existing lifter on #7 exhaust port is pretty heavily dished, so giving up a bit there, the rest of them look fine. Will try to do some measurements to see what cam is in there now before I pull it out. I'm going to be away for a week or so, which gives me a good opportunity to get some parts shipped down under. |
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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That converter will kill you with a bigger cam.
This is race only right? Use the cam you have, the 218 degree because it is the least mismatched with the converter. But it's still pretty big for that converter, the thing will be a dog off the line. Save your money and get a better cam later. Don't worry a lot about compression. Any of those will work fine with the compression you have. I've seen a completely stock short block run with a big solid and work fine. Yes, more compression would have been better, but the thing still made the jam and ran the number. But that is with a good converter. When you have a race converter go with the appropriate solid. A guideline I recommend is 230 degrees max with a hydraulic. Once you go above that you are looking for higher rpm power (hydraulic lifters start to be a problem), and at that point add 10 degrees duration (to accommodate the difference the take up ramp makes) and go to a solid - it makes more sense. You will still need good springs and valvetrain regardless, so change to a solid. Someone will list they have used one of those big magnum hydraulics successfully, but in my opinion a solid would work better. The only reason to use hydraulics that big is when the rules require it. |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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Converter change might have to be a winter project, then I can pull the crank out of the bottom and swap in one that has the TF flange on it to make life easier.
Headers look like they will also have to wait until American Racing does their small car version since the Hooker Super Comps have been discontinued. |
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70amcpwr
AMC Addicted Joined: Feb/16/2011 Location: Moultonboro NH Status: Offline Points: 1485 |
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Good try Ken, We're all trying. They drive from and on the other side down under for a reason
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70amcpwr You just can't fix stupid.
SOLD 1970 BBO Javelin, wifes 73 AMX 360 4spd. Next project 1969 AMX |
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69 SCRambler
AMC Apprentice Joined: Mar/06/2013 Location: NJ Status: Offline Points: 29 |
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Check the points. I had a similar issue a while back. Went back thru all the easy check list items. Found the points gapped incorrectly and bit pitted.
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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Now to throw a spanner in the works, I've just finished pulling the old cam out of the engine and it's got Crane HMV 272-2-NC stamped on the end of it:
From their catalogue: H-272-2 272/284 adv, 216/228 @ 050, 484/512 lift 112 LSA 1800-5400 RPM Probably explains why I could turn it to 5500 RPM, which did seem a bit much for a stock cam. Now comparing it to the planned XE262H: XE262H 262/270 adv, 218/224 @ 050, 493/500 lift 110 LSA 1800-5800 RPM Doesn't look like there will be much to gain there. The old cam did have one seriously wiped exhaust lobe (all others looked fine), so obviously that wouldn't have been helping. Not sure what to think now. |
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70amcpwr
AMC Addicted Joined: Feb/16/2011 Location: Moultonboro NH Status: Offline Points: 1485 |
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Same lobe as the bad valve? If not that's two weaknesses.
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70amcpwr You just can't fix stupid.
SOLD 1970 BBO Javelin, wifes 73 AMX 360 4spd. Next project 1969 AMX |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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For reference, compression test
1: 130 2: 130 3: 130 4: 130 5: 125 6: 120 7: 125 8: 130 Exhaust lobe on #7 was bad. |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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Bit more of an update:
Cam looks like this: Lifter looks like this: Looks like it has lost 0.073" off the lifter and 0.105" off the lobe, so is making about 0.229" lift at the valve compared to 0.512" from the cam spec. The real question is how much HP has one dud exhaust lobe been costing me and will I see a significant benefit from just fixing the problem or do I need to rethink my cam plans? |
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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Just put the other cam in because you have it. There will be very little performance difference between the 2. You are not losing much performance yet, but the problem would have continued to get worse as the lobe is through the surface hardening and will go completely flat, at which point other stuff will go wrong as the exhaust can't get out.
That also explains some of the less than ideal 60' cause of the 216 degree cam with a stock converter. Change the cam to a decent solid when you get a race converter. |
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