Cam Question
Posting Guru
Joined: Jul 2002
Posts: 1,785
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From: Paola, KS
Cam Question
Is the detonation at part throttle or wide open? What is the advertised compression with those pistons? What is the centerline of the cam and lift off it?
BTW what tranny are you using? Is it from the diesel?
BTW what tranny are you using? Is it from the diesel?
Laughing Gas
Joined: Aug 2003
Posts: 919
Likes: 4
From: Newberg Oregon
Cam Question
thx brian ,yes im using the diesel trans, pistons 8.9 cr i believe, valve lift int .490, ex .516, 107, 117 centerline. it mostly detonates the second the secondaries open but sometimes under load on pri. I should have zero decked the block im toldbut i didnt know there were 3 block heights. should have read that book first
. i have been a mechanic for 23 yrs but this one has me stumped, course its my own
thanks for any help
russ
. i have been a mechanic for 23 yrs but this one has me stumped, course its my own thanks for any helpruss
Posting Guru
Joined: Jul 2002
Posts: 1,785
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From: Paola, KS
Cam Question
Have you checked for vacuum leaks. I am running 10.3:1 comp and my only detonates when it is real hot outside or I have it under a heavy load. What kind of gas are you using? I would say your carb is jetted to lean. Is it a manual or electric choke?
So your 5-speed had the holes for the starter? My '91 also started life as a 7.3/5-speed and the trans was not drilled for the starter.
I have run both a Edelbrock 600cfm carb and the 750 with the 750 I never saw any difference in milage and it did not affect the throttle response, however there was much more power in the top end.
So your 5-speed had the holes for the starter? My '91 also started life as a 7.3/5-speed and the trans was not drilled for the starter.
I have run both a Edelbrock 600cfm carb and the 750 with the 750 I never saw any difference in milage and it did not affect the throttle response, however there was much more power in the top end.
Posting Guru
Joined: Apr 2000
Posts: 1,249
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From: Pryor
Cam Question
Sounds like it is leaning out when the secondaries open up. You should check that first. It could also be your vacuum advance advancing the ignition too much too quick. They make adjustable ones. The first thing I would check though is fuel.
JJ
JJ
Junior User
Joined: May 2003
Posts: 79
Likes: 0
From: Rockwood TN
Cam Question
Food for thought. Did you check the damper to make sure it was still "tight". Mine was spinning on the shaft when I got it. took me a few minutes to figure out why it ran so much worse after I timed it.
Thread Starter
|
Junior User
Joined: Aug 2003
Posts: 62
Likes: 2
Cam Question
I am still here. Just watching over the responces. The reason I was asking about the "A460", is that my brother in-law has been a Marine mechanic for 25 years and has a new one from a "reverse rotation" conversion. And I am tring to "freshen" this thing up as cheap as possible. Still standard bore with out any visable cylinder wear and the ring lands look great in the stock pistons, so it is just getting a good "torque plate" hone, polished crank and valve job.
I was hoping that with this cam, free flowing exhaust, and tuned stock carb to get 260-275HP and 400+ft/lb of torque. The specs are 216-220 @0.050" .493/.502" with 114 lobe sep.
I was hoping that with this cam, free flowing exhaust, and tuned stock carb to get 260-275HP and 400+ft/lb of torque. The specs are 216-220 @0.050" .493/.502" with 114 lobe sep.
Last edited by 7K42S; Aug 28, 2003 at 06:34 PM.
Posting Guru
Joined: Apr 2000
Posts: 1,249
Likes: 2
From: Pryor
Cam Question
Brian,
Thanks. The old truck runs really good. Obviously the L will run mid 13's. The old truck has a tougher time launching, probably due to the long bed, springs, and especially the tires. The old truck does have a better passing gear though. From anywhere around 30-90 it is almost scary. A lot of times it will posi out when it shifts from first to second. That's at about 55 mph. I haven't had it to the track, but i would suspect that it would turn no less than 14's. With good traction and maybe some taller gears, you'd be talking 13's.
JJ
Thanks. The old truck runs really good. Obviously the L will run mid 13's. The old truck has a tougher time launching, probably due to the long bed, springs, and especially the tires. The old truck does have a better passing gear though. From anywhere around 30-90 it is almost scary. A lot of times it will posi out when it shifts from first to second. That's at about 55 mph. I haven't had it to the track, but i would suspect that it would turn no less than 14's. With good traction and maybe some taller gears, you'd be talking 13's.
JJ
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Posting Guru
Joined: Jul 2002
Posts: 1,785
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From: Paola, KS
Cam Question
1-2 at 55mph? I am guessing you have like a 3.00 gear then?
Does your cruise work? My dad has a 76 with factory cruise, but the wheel is all messed up and does not work. I see you used like an early 80's wheel.
Does your cruise work? My dad has a 76 with factory cruise, but the wheel is all messed up and does not work. I see you used like an early 80's wheel.
Posting Guru
Joined: Apr 2000
Posts: 1,249
Likes: 2
From: Pryor
Cam Question
3.25 gears, tire height is something like 28 inches (I can't remember off the top of my head), and shifting at around 5300-5400 RPM's.
Yes my cruise does work. I had the old big wheel and changed it out. I still have my old wheel. It has a few cracks but works fine. I still have the little silver switches, too. As a matter of fact, my dad has a set of NOS cruise switches for the old big steering wheel (pre-78).
JJ
Yes my cruise does work. I had the old big wheel and changed it out. I still have my old wheel. It has a few cracks but works fine. I still have the little silver switches, too. As a matter of fact, my dad has a set of NOS cruise switches for the old big steering wheel (pre-78).
JJ
Laughing Gas
Joined: Aug 2003
Posts: 919
Likes: 4
From: Newberg Oregon
Cam Question
thanks all i have no vac leaks and an adjustable vac advance. the trans was not drilled for anything but the two top bolts lined up and i centered a big slug of aluminum on the input shaft and used the tin spacer to machine all the holes with homemade drill guides out of half inch flatbar. a blunted 7/16ths bit works awesome, a trick a machinist told me for reaming hardened steel. i am going to go to basics and recheck actual timing and jetting and see what it does. more later
russ
russ
Laughing Gas
Joined: Aug 2003
Posts: 919
Likes: 4
From: Newberg Oregon
Cam Question
new question, had to pull out in traffic and stand on it and at 3500 to 4000 the oil pressure dropped down a lot, wondering if these whip up the oil with 91 style pan ,and yes its full of oil and i checkec it just after running to make sure the factory cooler is full. windage tray maybe??
russ
russ
Posting Guru
Joined: Apr 2000
Posts: 1,249
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From: Pryor
Cam Question
I've heard of people pumpin all the oil out of their pan and onto the top of their motor. Never seen it happen. Also heard that 460's are bad about windage. I've got a windage tray from MPG heads. Never had any problems with my oiling (none that I know of!!!).
JJ
JJ
New User
Joined: Sep 2003
Posts: 5
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Cam Question
Looking for a good cam myself, rebuilding a 460 out of an '81 van for my '77 F150 4x4, replacing a 351M w/ a cracked block. I'd like to keep good throttle response and down low torque, but have power for occasional towing on the open road. Running 33" tires, not sure on the axle ratio, have all the numbers off the axle but haven't checked them in the manual, pretty sure it's 3.73 or higher. Keeping 8.1 stock comp. r. for now, looking at the Comp Cam 260H High Energy.
JT77
'77 F150 4x4, 460/C6 shortbed
'56 C600, 292, 4/2, 16' flat
JT77
'77 F150 4x4, 460/C6 shortbed
'56 C600, 292, 4/2, 16' flat
New User
Joined: May 2003
Posts: 6
Likes: 0
Cam Question
JT77,
I just rebuilt my '84 460 about 1,000 miles ago and used the Comp Cams 260H High Energy cam that you are considering. I really like this cam. My needs are similar to those you described so I doubt you will be dissatisfied. I ground out the smog bumps, gasket matched the intake/heads, very mild bowl and SS-radius work (myself), a good 3-angle valve job, and bored .030". Other than that nothing. Oh yeah, straight-up timing set. Stock exhaust manifolds running out a 3" single exhaust. Stock intake and carb. The response and torque is great, but it really eats the gas above 65 mph.
Doug
I just rebuilt my '84 460 about 1,000 miles ago and used the Comp Cams 260H High Energy cam that you are considering. I really like this cam. My needs are similar to those you described so I doubt you will be dissatisfied. I ground out the smog bumps, gasket matched the intake/heads, very mild bowl and SS-radius work (myself), a good 3-angle valve job, and bored .030". Other than that nothing. Oh yeah, straight-up timing set. Stock exhaust manifolds running out a 3" single exhaust. Stock intake and carb. The response and torque is great, but it really eats the gas above 65 mph.
Doug