FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: aj on April 19, 2018, 07:51:25 AM
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Going in a 70 gt500, 3:50 with mild converter. Looking for good balance between decent idle/street manners and some good midrange ooomph.
Motor is 465CJ, 10.7:1, with mildly ported CJ heads with 2.15 intakes and stock CJ exhaust manifolds. Looking for a hydraulic roller since I already have set of Morel hyd roller lifters.
My machinist mentioned comp xr-282hr as an off the shelf option. But I know cam designs have evolved quite bit since I fiddled around with motors 25 years ago so there’s likely better options.
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http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1569&sb=0
Didn't see a 282 but did see a 280hr in the catalog, imagine this is what he was suggesting?
I think in general it's the right "size" as dictated by the duration, 230/236 is about right for a likely 3800lb/auto/manifolds/3.50 gear deal at 465ci. Rollers don't automatically mean more lift is run than a similar flat tappet, but one of their main advantage is allowing a more aggressive lobe so I'd shoot for .550-.560 lift which is still mild.
Also, the stock manifolds will mean a custom cam will help quite a bit, likely with more duration split than that cam employs. The stock CJ manifolds will back up the exhaust stroke so a bit more time to blowdown the exhaust would help, and maybe spread the centers a bit to keep the intake stroke clean
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The Xtreme Energy series from Comp sounds like a sewing machine. They're noisy because of the lobe shape.
Do you have power brakes? What's the stall speed on the converter?
You're gonna need quite a bit of advertised duration to get away from that 10.7:1 that you have going on, and even then you may experience some issues with pump gas.
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Do you know what the quench distance is? or deck height?
0.060"+ quench distance will not make things better.
Iron heads with 10.7:1 is really pushing it.
Custom cam for sure - by someone who knows these engines (Brent as an example).
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Car has power brakes. Jay at Broader Transmission built the converter and described it as just a bit looser than stock. Car has 3:50 gears.
I regret to say deck height is .020 below. Wish it was tighter but thats what I’ll be forced to work with.
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It's 10.7 with the pistons .020" in the hole and a .040" gasket?
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You're gonna need quite a bit of advertised duration to get away from that 10.7:1 that you have going on, and even then you may experience some issues with pump gas.
Speaking from experience with a 10.5+ 351C with iron heads - this. and the quench won't help, as noted. Be well worth it to have someone like Brent spec the thing in and have it delivered to you. That way all factors can be reviewed.
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Just reran compression calculator:
Bore: 4.162
Stroke: 4.250
Rods: 6.7
Gasket dia 4.400 (felpro 1020)
Gasket thick .041
Deck height 10.155
Top Ring down .330
Head CC 76cc
Pistons 7cc (flat top with valve relief)
Piston to Deck .020
Cubic inch 462
Compression 10.57
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Numbers jive. You'd be at 10.7 without factoring in crevice volume. So, your 10.6 estimate is probably correct if all of those numbers and measurements are correct.
Not happy with the .060" quench distance, it's more of a detriment than higher compression.
If you don't have flow numbers on the heads, I can probably estimate it. A "mildly" ported CJ head will probably be somewhere around 260-270 cfm.
I'm assuming that you're using a factory CJ intake.
Taking into account the torque converter, vacuum requirements, and your personal requirements, I'd be at:
283/291 advertised, 227/235 @ .050", 113 LSA on a 109 ICL, .565"/.588" lift.
It would be a billet steel camshaft and would require a steel distributor gear. Valve spring pressures would need to be at 130-140 seat, 350 open. Overlap would be at 61°, which would work your power brake booster just fine.
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Springs: The Isky 8005s I recently purchased appear to have right pressures. Also have POP shafts ,end stands and HS rockers waiting on the cam.
Approx Head flow: You’d know better than me. FWIW heads were just fitted with larger valves 2.15/166 Ferrea
Will be using stock CJ intake and exhaust manifold.
What is lead time on custom cam ?
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They run about a week to week and a half.
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Brent, thanks for info. Just sent you an email.
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I have this one for sale. Custom Straub grind for my 390 with mildly worked iron heads. New cam, never installed. Decided to get a little more aggressive.
221 / 230 @ .05
.340 / .320 lobe lift
.588 / .554
109 LSA
Opn-cls 4.5 36.5 / 47 3
277 / 286 @ .006
ICL 108
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Something else to keep in mind - not sure about the fuel quality where "you" are, but here the max is 91 (a couple of 93s sometimes) and everything is 10% ethanol. It's pretty bad. The trucks, hybrid, mower, yard stuff, generator do well on 87 - no problems, they don't seem to care. Used to run the 10.5:1 351C with a 238/248 108 CL solid Crane on 91 pump fuel but that was mid 2000s. Have a bigger hydro roller in it now and it will not run well on anything less than 2 parts 110 leaded and 3 parts pump 91. I'm also having issues keeping intake gaskets intact. On the 302, I just installed FelPro 1250S3 which have a stainless steel inside and should resist alcohol additives. The basic Mr. Gasket parts were not holding up. At this time, I don't see anything like that for the 351C so I just keep a lot of gaskets hanging on the wall.
Also - Pulling an intake shows the intake passages and the back of the valves to be covered in a very sticky maple syrup coating. If you stuff the ports with paper towels, you'll not get all the paper out. Bottom line for the fun cars is that I will be buying a drum of Sunoco 110 and a drum of Methanol. If I run straight 110 in a car, no glue in the ports and fairly clean piston tops. Because of the cost - $420/drum for 110, it's likely that we will consolidate the two door cars and run the one door car eventually on methanol along with the dragster. A street/strip car on methanol seems a bit much but the fuel cost is less than half, even though you pump almost twice the fuel. And no gunk if you manage it right.
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Something else to keep in mind - not sure about the fuel quality where "you" are, but here the max is 91 (a couple of 93s sometimes) and everything is 10% ethanol. It's pretty bad. The trucks, hybrid, mower, yard stuff, generator do well on 87 - no problems, they don't seem to care. Used to run the 10.5:1 351C with a 238/248 108 CL solid Crane on 91 pump fuel but that was mid 2000s. Have a bigger hydro roller in it now and it will not run well on anything less than 2 parts 110 leaded and 3 parts pump 91. I'm also having issues keeping intake gaskets intact. On the 302, I just installed FelPro 1250S3 which have a stainless steel inside and should resist alcohol additives. The basic Mr. Gasket parts were not holding up. At this time, I don't see anything like that for the 351C so I just keep a lot of gaskets hanging on the wall.
Also - Pulling an intake shows the intake passages and the back of the valves to be covered in a very sticky maple syrup coating. If you stuff the ports with paper towels, you'll not get all the paper out. Bottom line for the fun cars is that I will be buying a drum of Sunoco 110 and a drum of Methanol. If I run straight 110 in a car, no glue in the ports and fairly clean piston tops. Because of the cost - $420/drum for 110, it's likely that we will consolidate the two door cars and run the one door car eventually on methanol along with the dragster. A street/strip car on methanol seems a bit much but the fuel cost is less than half, even though you pump almost twice the fuel. And no gunk if you manage it right.
Be sure you use good methanol like M1. Don't buy the recycled industrial stuff. You will regret it.
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I like Brent's choice based on what I infer is the end use, mostly because the gear choice and lack of headers
You will be leaving a lot on the table with those exhaust manifolds, and even more if it has a resto exhaust, but regardless, it should be a very very healthy driver.
For a street toy, be sure to have the distributor recurved, doesn't make much of a difference on the dyno, but part throttle and stoplight fun, it's night and day compared to a stock Ford curve or as-delivered aftermarket
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Mystang. I’m a proud member of the: “I put headers on a big block 69 Mustang in my driveway” club.
Yep. 30 years ago I did a little drag racing with the car in near stock form. Well when I put Hooker headers with 24” collector extentions, it picked up a whopping 4/10s in the quarter.
Back then I was a semi-broke kid obsessing over ET slips. Glad I didn’t throw those CJ manifolds in the trash. After fighting headed install for 3 straight nights, I was tempted.
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They are easy, you just need to do it all at once :) 20 minutes from engine on the floor to car back off jacks, headers done....didn't even go under it, so didn't even set it on jackstands
(http://s20.postimg.cc/xl6mrm1ot/Noway.jpg)
(http://s20.postimg.cc/lxckx2cjx/Noway2.jpg)
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Ross, I tried that stunt show last summer after stalking this forum and seeing your pictures. But I got the motor/tranny hung up and wedged as it was about halfway out. My 16-yr old son and I found ourselves in such an odd predicament...with the motor half in/half out..and pointed at the garage ceiling, we had a really good laugh. In fact we unhooked the hoist and took a few pictures of the calamity for my gearhead buddies and laughed at ourselves another hour. Finally I threw in the towel and unbolted one header. But through it all...I kept showing my son your picture...saying “...it’s gotta be possible , this picture’s proof”
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Ross, I tried that stunt show last summer after stalking this forum and seeing your pictures. But I got the motor/tranny hung up and wedged as it was about halfway out. My 16-yr old son and I found ourselves in such an odd predicament...with the motor half in/half out..and pointed at the garage ceiling, we had a really good laugh. In fact we unhooked the hoist and took a few pictures of the calamity for my gearhead buddies and laughed at ourselves another hour. Finally I threw in the towel and unbolted one header. But through it all...I kept showing my son your picture...saying “...it’s gotta be possible , this picture’s proof”
That's a riot, although it must have been a challenge to laugh and not swear LOL