Mileage cams and intakes
 

Wondering if anyone here has had good results using mileage cams? I am building a low-med rpm 455 for towing using an overdrive and mild gearing, headers, etc.
Cruising rpm will be in the 1,200-1,700 range.

Also want to try my dual port intake. Has anyone used this before?

Years ago I had a 71 lemans sport vert that came with a 455. It had a real small aftermarket cam like the summit 2800. It WAS all done by 4000 rpm but with the .308 gear it got 19 on the highway.

Just a WAG but if I were to try to do what your doing I would use the 2800 cam, a performer or sp2p and a set of cleaned up small valve 4x heads. just my WAG.

I will look into your com idea. did look at Crowers mileage cam specs.

Also now looking at vintage Pontiac cams, 2bbl, etc. The 067 and 066 cams are also being considered.

I think the SP2P is anther thing to play with. Going to start looking for one.

If I was really going for mileage I would use part # 518111 (A). If you are going to do some towing your going to have to compromise just a bit so I would use the #537441(E) or the 9777254 (U). I would use the stock iron Q jet intake or a performer with a Q-jet . I would use iron RA111 exhaust manifolds so I wouldn't have to richen up the carburetor jets like you will have to do if you used headers. I would recurve a HEI-mechanical all in at 2,000 and make the distributor advance run off manifold vacuum. Try to get a adjustable vacuum advance and give it as much as it will take before detonation. No EGR, but use the thermostatically controlled air cleaner, the kind that has a snorkel to the inside of the fender for cold air--the other earlier type when fully open will just get hot air from the radiator so use the newer type (1970+). If this is a automatic I would use the tightest converter I could find ( most likely that would be stock ). With a non overdrive and a 2.56 rear end you should expect 22-24 mpg in a 4500lb+ clam shell Catalina wagon @ 55-60mph.

D.

That kind of mileage would be a fantasy for me. the cam numbers you mentioned..... there is no reference to whos part number they are...?

Steve, they are Pontiac grind cams and part #'s----most of them done by Mac Mckellar or McKeller had a hand in doing them. Melling most likely uses the same part # and they might have supplied the cams to Pontiac in the first place. If you have Pete McCarthy's book those cams are listed. A word of shock when reading about the lift on the intake side. The lift seems a bit low .374 but I can assure you would never know it as most of the breathing is done on the low end side anyway--that's why Pontiac intakes are ground at 30 degrees. I hope you have some 0-5% ethanol stations around, anything more than that and the m.p.g. numbers start to fall off.
Steve, you didn't mention what heads and compression your using... Open chamber heads are more efficient.
I mentioned the 2.56 rear end because with a 455 the darn thing has enough torque with that axle ratio, so you don't need a overdrive and the extra weight of it to go along.
D.

mileage cam
 

Years ago I used a Crower Baja Torque Master cam in a 350 Pontiac. It was a 2bbl engine originally but I swapped in a cast intake, Rochester and duals. It was a '69 Firebird convertible. The dizzy received lighter advance springs. Once I got 24 on a trip; usually on any long drive it would get over 20. The Crower had .435" lift and 205/205 duration IIRC. It had good power past 4500 rpm. I did 125 in it once and had more left. I'm sure the rear axle was something taller than 3.08, probably 2.78. I recall Hot Rod magazine testing a SP2P on a Trans Am and saying it pulled past 4000 but somehow I'm doubtful. I have one I got off ebay; the runners are really narrow. If you're interested, PM me. They come up on ebay frequently, no one ever advises they're a mpg intake. I recall reading Edelbrock advised against using them with mileage cams as they would cause detonation.

Just a note , EGR improves MPG by displacing air/fuel mixture with exhaust.
It makes the engine "appear" smaller at cruise and light throttle.
Also has no effect on wot , as it closes without vacuum.
Run one. Late TA manifolds come to mind.
Look at smalerl cam from a Comp XE series. Quick ramp will help low lift flow , faster closing will raise dynamic compression.

Just a note , EGR improves MPG by displacing air/fuel mixture with exhaust.
It makes the engine "appear" smaller at cruise and light throttle.
Also has no effect on wot , as it closes without vacuum.
Run one. Late TA manifolds come to mind.
Look at smalerl cam from a Comp XE series. Quick ramp will help low lift flow , faster closing will raise dynamic compression.

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Actually the EGR was primarily designed to function in the cruise mode with the type of distributor advance that would cause detonation without it. If you change the curve, but more importantly switch to manifold vacuum to the distributor instead of ported vacuum you will see a change. The change is in the cruise mode mpg. The draw back is higher NOX emissions which is why EGR was created in the first place. BTW this intake charge dilution was the reason some manufacturers (the one I worked for included) to start increasing displacement to make up for lost hp and drive-ability.... unfortunately this decreased mileage and engine efficiency. Thank goodness for three way cats as we were able to return some of the performance/efficiency with the use of a limited/restricted amount of EGR.

D.

Hey Steve,
I keep thinking of this thread. You might be asking a question about doing something that's seldom been done... :)
The ideas presented sound good.

Jim Hand says the port volume of most 68-up "D" intake ports is close to the same. I'm guessing a set of 6X-8's might be the ticket for this potential build?, knocking off the sharp edges in the ports, keeping the port volume as small as possible for port velocity, comp. ratio of a little over 9:1. zero decking the block for utmost combustion effeciency.

I used a Sealed Power CS641 (duration @ .050 198 degrees, intake, 208 degrees exh, LSA 111 degrees) cam in the 350 that currently resides in my 77 T/A. Sealed Power lists it as a replacement for the 066 and 067. It gets fair MPG, but I've never spent enough time on it to try improvements. I bought a SP2P to try on the 350, and have a regular performer I plan to try also

My T/A got excellent MPG when stock (stock as in COMPLETELY stock, I removed the cat converter,only). 21 MPG was not uncommon, Got 22 MPG several times. All this WITH the EGR functioning...I like the idea of using a larger torque engine (couldn't think of a much better one than a Pontiac!!!), and lugging it out on the highway getting the RPMS low enough to hopefully get some decent MPG #'s...
THe stock cam in my T/A was a teenie weenie cam (which developed a flat cam lobe @ around 60-70,000 miles) Sealed Power has a replacement cam for the small cam, also, it's a CS690, .364" gross lift. My car ran very well with this cam, I think it's the same cam (spec wise) you have in the 265.

I sold 3 Comp Cams 260H cams, (these are NOT the XE cams) in the good old days when I sold auto parts. The cams I sold went in 77-78 T/A 400's. Everyone liked how their cars ran after the switch. I wonder... about that cam for a 455

I'm curious what others say, especially concerning cam selection, comp ratio. With the ability to tune a Q-Jet so finely (thanks to Cliff!!!) I think some good results are around the corner.

I want to try a MPG oriented 400 in my T/A. MY car currently has the 2.41 gear in ti w/ the 350 engine. I have a TH350 lockup from a 81 turbo T/A, it would knock the RPM's down another 300-350, putting in in the range of your setup. I'm loosening my strangle hold of not caring for O.D. tranmissions after reading Cliff's book on them...(may never own one, but...)

I wonder about the use of stock exh manifolds. A 455 has a pretty fair amount of air flowing through it. Don't want to choke it, but the volumetric effeciency is at a low RPM, stock exh manifolds might be the ticket...

Steve, I pray for a great 2012 for you, lookng forward to seeing this build!!!
Jeff

The problem with 6X heads is chamber volume and MOST importantly large valves. What is needed is a 1.96 / 1.66 and even better is the 1.88 / 1.60. The problem with 1.88 / 160 is the bathtub/valve shrouding chamber design, so the 1.96 /1.66 open chamber head is the best bet.
Large valves are fine in a performance application, but if you are going for mileage you need port velocity at low engine speed and the small valve small port diameter does the job better. That is also why I recommended the performer small port intake manifold. That is also the reason Cadillac engineers designed the 472" and 500" engine with small valves to be able to keep the torque and have decent mileage for a 5,000lb. + car.

D.

I've got a sp2p I'd let go cheap. Just pm me

This 455 engine project for my '61 Safari is definately evolving. Last week it was going to be a 6X 068 1.5 rocker deal. Now am leaning toward a set of small valve heads and trying a tiny cam like the 066 or even the '59-'63 2bbl cam.
Of course, these things can all be changed if I am not happy with it.
On the early heads being closed chamber- true. However, I can modify them to an open chamber design and get a more attractive chamber size too for my displacement. I opened and cc'd chambers on 670 heads in the mid 80s and also opened the Super Chiefs on my Fueler.
A few days back , I brought in a pair of #15s. They tore them down and one head had a 30 intake seat, the other had a 45 seat! uh.
Now going to look around my yard tomorrow for a pair of small valve heads. Will pull them off and get them into the machine shop. I'd prefer not to have to buy a new set of valves for the little buggers. We'll see.

Also would like to try a sp2p as well.

This wagon will use a 2.56 rear gear with a 700r4 and headers. It is the same combo I have my GTO and I really like it. I do not use the lock up. Engine runs between 1,200 and 1,800 rpm most of the time and has decent vacumn. 455, 6X heads, 068, 1.5 rockers, 3 tube headers.
I use headers on almost everything. I like them.

[QUOTE=Steve Barcak;4507477]This 455 engine project for my '61 Safari is definately evolving. Last week it was going to be a 6X 068 1.5 rocker deal. Now am leaning toward a set of small valve heads and trying a tiny cam like the 066 or even the '59-'63 2bbl cam.
Of course, these things can all be changed if I am not happy with it.
On the early heads being closed chamber- true. However, I can modify them to an open chamber design and get a more attractive chamber size too for my displacement. I opened and cc'd chambers on 670 heads in the mid 80s and also opened the Super Chiefs on my Fueler.
A few days back , I brought in a pair of #15s. They tore them down and one head had a 30 intake seat, the other had a 45 seat! uh.
Now going to look around my yard tomorrow for a pair of small valve heads. Will pull them off and get them into the machine shop. I'd prefer not to have to buy a new set of valves for the little buggers. We'll see.

Also would like to try a sp2p as well.
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Steve, the #529472 (D) cam which is the 59's 2bbl. 10.0 comp.280HP automatic, 60-64 283 hp 10.5 comp.automatic is exactly the same grind as the 97779066 (N). I would still suggest the smaller (U) cam and it works with high velocity small valve heads. I had a set of 15's on my 455 for a while, but I needed 5gals. of aviation fuel to 15gals of 92 premium to keep the 10.0 compression from detonating although you could use dished pistons.
D.

Steve- why not use the lockup? I like having the lockup in the Suburban (only functions in 3rd & 4th of the 700R4).

Years ago I put a Fairbanks low-stall converter in a slightly-modified 289 Ranchero and saw about a one-MPG improvement in the long term. Anybody offer a low-stall lockup converter?

Build a big motor and turn it slow...
 

Steve,
As we have discussed before, limiting the 455's rpm @ the mph that you want to cruise at is the best single way to push the mpg into the high teens or low 20s hen used in a 4-5,000 # vehicle. Keeping the cruise rpm south of 2500 works well for my heavy Pontiacs. My 500fhp 4100 TA with 2:73 gears has delivered 17mpg @ 75mph turning around 2300rpm. My 2:93 geared 4600# GP delivers 15 mpg @ 2500/75 mph and my 3:08 geared o/drive equipped 11 second 3960 # GTO delivers 16.5 mpg @ 80 mph/2300 rpm.

Jack, the 700 in my GTO is setup to only lock up in high gear. I did have the lock up working earlier this year with the little 265 but, the little engine could barely handle the 2.56 with OD without the lock up.
I have not tried it with the 455. Maybe I should. It's just when I see the tach at 1,200-1,400 I am not thinking of dropping 200 more rpm.
good point though, with a 455 with little heads and cam, the lock up may help wihen not towing

It is cool when you engage the lock up. it is , effectively , a 5th gear rpm wise.

Agreed Les. I would love to get the kind of mileage you get on some of my combos. It is just a matter of fine tuning. Am already using the right parts.
I've been a fan of 2 series gears since the early 90s. Have no desire to use anything else at this time.
I could just imagine running 80mph in an 11 second GTO and pulling 16.5 mpg. You obviously have your cars set up better than I do.

Steve - don't know how much you are towing.

I was able to achieve better mileage and torque results in a heavy vehicle (28 foot motorhome) towing my van (total weight motorhome and van 26000 pounds) using a squarebore Carter AFB that I customized. Mileage was better both towing and with the motorhome alone by about 8 percent over an 800 CFM Q-Jet. I used an Offenhauser intake and a 750 CFM AFB.

Steady-state cruise vacuum reading with the Q-Jet of about 14 inches improved to about 16 inches with the larger primary AFB.

Jon.