Dale Davies
Well-Known Member
Gosh, you are picking knits there. Get yourself a copy of High-Performance Cams and Valvetrains, written by Billy Godbold and read it front to back two or three times before going off the deep end again!
Looking for more pep off the line
- Thread starter Alecb
- Start date
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PRH
Well-Known Member
The OP looks like he’s leaning towards the XE268.
Seems like a solid choice for the combo to me.
Seems like a solid choice for the combo to me.
Alecb
Well-Known Member
PRH
Well-Known Member
There’s more to camming for street use than which one makes the best looking number on the dyno.
Unfortunately these are things only you can answer, everyone's levels of compromise are different. Will you be happy with a xe268h more than likely would you like a similar cam on a 105-108 lsa possibly.
Dale Davies
Well-Known Member
Definately a good street cam. Comp Cams description and specs:
XE268H - 10
For 273 to 360 LA engines. That is a fairly wide CID spread. In a 273 it should be fairly lumpy while in a 360 it should be fairly smooth. That sentence is my comment.
At 0.050 tappet lift; I 224°, E 230°.
Adv'd ; I 268, E 280°
LSA ; 110°
Valve lift ; I 0.477, E 0.480
Largest recommended for a stock converter. In 273-318 it is best with a 2,000 stall.
This is Comp Cams information.
Again I recommend looking up and watching David Vizard's Powertec 10 videos on camshaft selection. One directly discusses the 128 formula.
Another good source of information is High-Performance Cams and Valvetrains by Billy Godbold, ex head cam designer for Comp Cams.
Both gentlemen are highly knowledgable in engines and camshafts. Billy comes at the selection process from an engineering perspective of getting relevant information regarding the engine and intended use. From there he picks the EVO then the IVC and finally the IVO and EVC points. David comes at it from the other direction and simplifies the decision making process for those of us less technically "in the know".
I do not dispute that the XE268H is a good cam. At Summit you can find it listed as XE268H-12 also. This is protecting them from the more is better think. A 112° LSA may allow an engine to pass an emissions test that a tighter LSA would fail.
After watching DV's videos more than once on cam selection and reading Billy Godbold's book, along with DV's book, How to Build Power, I feel considering a new cam will be purchased and ordering it with the LSA you want, costs no more, I recommend 106° LSA or 107° LSA as a sesecond choice. 105° would be good if a lopey idle is acceptable. This would work well with 10.5:1 CR and probably 11:1 CR. With distilled water injection with 2% water soluble oil as used in machine shops, there would be no problem burning 87 fuel. Chose a large enough water jet to control detonation by using a pressure switch to turn the pump on. At high vacuum.which is low manifold pressure, detonation is not an issue. As the throttle opens manifold pressure increases along with the tendency for detonation. Water cools and slows the combustion process, so a couple more degrees of advance can be dialed in. Water adds no emission components and reduces NOX.
Watch DV's octane video for a more in depth explanation
Nope! Not yet. But if you want, this is your call now, I can follow you around and rip up your posts exposing how much of a stupid *** you are. Hypocrite!
1: Didn’t go off the deep end. Not even a toe in the water.
2: I have it and read it.
3: I exposed your hypocrisy and you’re just sore about it.
So what is your ******* beef with me?
Certainly seems like your starting with me.
Dale Davies
Well-Known Member
Not at all. You started it.
No sir! You must have taken something the wrong way.
I have ZERO issues with you but you came at me.
To that end, ball in your court. I stand by what I said and I’ll say it over and over on every one of your posts. I caught you and you’re upset. Get over it. If you can’t take criticism…….
As far as I’m concerned, I’m just having a conversation with everyone here. Untwist your panties.
If I need to break out the crayons and draw you a basic map, I’ll do so.
TXOval
340 stroked to 416
Just for a data point, my 340 (in a 66 Barracuda) used the Comp 268 cam, iron 2.02 heads, stock manifold, TTI stepped headers, and a 3.23 rear end.
It had a 2000 stall (904) and was “slow” out of the hole. Could I burn both tires, yes, but I was never happy.
Switch converter to a 3000 and 3.73 gears and it will react much different
It had a 2000 stall (904) and was “slow” out of the hole. Could I burn both tires, yes, but I was never happy.
Switch converter to a 3000 and 3.73 gears and it will react much different
Oh hell yea that’s waking up the puppy.
Alecb
Well-Known Member
It’s been a while since an update, I pulled the engine out of the car to inspect the engine after my failure in LA. Turns out a bolt fell into the intake and was holding the #7 intake valve open. The valve and seat was chewed up, so I got a used set of J heads and swapped the bad head out. While I had the engine out I installed headers and a 3000-3500 stall converter. Holy cow did it wake up! It peels tires without hesitation now and accelerates hard! It also sounds way better with headers over the manifolds.
Ouch! But now you know, fixed the problem and you’re off and running. Happily down the road you GO!
Dale Davies
Well-Known Member
Years ago a friend had a back yard mechanic do a carb kit and tuneup on his 62 Pontiac. Smoked like crazy when he picked it up. The guy would do nothing. I was still in high school but a gear head. Pulled the plugs and found one with oil on it. Removed the head and found the imprint of a carb mount nut in the piston. Cast piston crown had a crack in it letting oil into the cylinder. Pulled the oil pan and that piston/rod assembly. Got a new replacement piston installed and new rings for that cylinder. Got the engine machine shop to check the valve seal in that cylinder and it was good. Put it back together with a slight deglaze and he drove it gor years.
Alecb
Well-Known Member
I’m much happier with my car now. It behaves more like I was initially hoping for.
Alecb
Well-Known Member
I love cool stories like this.
Johnny Dart
Well-Known Member
6 pages of sword fighting, and it turns out to being a bolt in the intake. Ain't that a beyotch. 
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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So this is still with the 218 cam?
Alecb
Well-Known Member
Yes, I never swapped the cam. I probably will in the future
You mean You didn't have to re-engineer Your heads w/LS valves & grind them to whiskers away from blowing out w/the aid of an ultrasonic mic to get a cammed 360 A-body to run like scalded balls?!?!?!......oh HELL no!!!
Go out & enjoy young man!!
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,809
- Reaction score
- 13,117
I heard a couple of guys dis that cam, but IMO, that size of cam, like all cams, runs best with the cylinder pressure matched to it.
Just to compare;
I ran a 223/230/110 cam in my 367, for four summers, at Scrs from 11.3 down to 10.7, and that was/is my all time favorite cam. There is only one thing you need to know; she needs an overdrive, so you can run a decent rear gear, for a dynamite zero to 60 mph pull; and still cruise 65/70 mph at a decent low rpm.
I ran that 223/110 cam at pressures from 185 to almost 200psi, and with several different manual transmissions, several different rear ends, and ultimately with a GV-overdrive.
Man! that thing pulled hard.
When that cam dropped lobes, I replaced it with the next bigger cam, a 230/238/110 from the same manufacturer; and then spent the rest of the summer trying to get the bottom-end back. But it was gone. So I bought another set of gears for my trans with 16% more torque multiplication in First gear; badaboom!
To this day, I fondly remember that 223 cam.
The point I want to make is that EVERY time you replace a cam, with one that closes the intake valve later, with no other changes, your engine will lose cylinder pressure which manifests as a loss of low-rpm power. To get it back, the pressure has to be brought back up. Or, the workaround is; more stall and/or more rear gear.
On the street, increasing the stall, is not always the best answer, like if you already have one over 3000rpm.
On the street, increasing the rear gear much beyond 3.55s affects your touring ability.
If hiway touring is part of your life, then overdrive should be also.
But, with the cam you have, you shouldn't have to worry about any of this, any time soon.
Bang on! ^^^^^
My Dad had a similar experience, only it was he who dropped a machine screw down the carb of his 440. Not a big one, maybe half an inch long. Instead of pulling the carb and fishing it out, he ran the motor thinking the screw would blow out the exhaust. It didn't. I don't remember how we determined it was still in the motor or what side it was in, but I pulled one head and there it was, lightly embedded in a piston. Thank goodness he didn't run it long. Pulled out the screw, leaving an impression of a screw head and threads in the (stock cast) piston. Put it back together and drove it for several years like that.
He wasn't so lucky when he dropped an exhaust valve in his Hemi then drove it for five miles to get home. That did some real damage. (Hint: not a good idea to run 87 octane gas in a 12.5 to one Hemi.)
Dale Davies
Well-Known Member
Years ago I apprenticed at a Cat dealer. A 1160 V8 came in from a packer. These were medium duty engines with 1 compression ring and 1 oil ring. Different strokes to change displacement and different model numbers; 1145, 1150 and the 1160. This engine broke an intake valve head off. Bounced around the cylinder, back out the port and into another cylinder. The heads had a common intake and a crossover where the air came in from the filter. That piece of valve went over the crossover and into all the cylinders on the other bank. Heads were dented up. How it got past the other intakd valves and across the intake I still do not understand.
You could get the 1160 in Ford 8000 trucks. Worked good in gravel trucks, but of course as a tractor they were inexpensive. Guys would hook onto a 40' trailer and head to Texas with a load. The 1160 was rated at 225HP which was likely pretty close to what was required to run a load down the road. They would knock out #7 and #8 rod bearings. R. Angus figured out that if the power screw on the governor was backed out a bit to drop power to 215HP, they would run all day at that on the dyno.
Cat re engineered the engine saying what all they changed and gave it a new model designation, 3208 with the power rated at 215. They eventually turbocharged it and got power up to about 400.
You could get the 1160 in Ford 8000 trucks. Worked good in gravel trucks, but of course as a tractor they were inexpensive. Guys would hook onto a 40' trailer and head to Texas with a load. The 1160 was rated at 225HP which was likely pretty close to what was required to run a load down the road. They would knock out #7 and #8 rod bearings. R. Angus figured out that if the power screw on the governor was backed out a bit to drop power to 215HP, they would run all day at that on the dyno.
Cat re engineered the engine saying what all they changed and gave it a new model designation, 3208 with the power rated at 215. They eventually turbocharged it and got power up to about 400.
Damn!!
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