I have a bunch of questions and hope that you folks may have some answers.

First the engine / vehicle background.

1972 D1VE 429 bored .030 over
1972 D2VEAA heads.
stock cam....as far as I know.
stock 4bbl cast iron intake non egr.
New Edelbrock 600cfm 4bbl
New reman Duraspark distributor..autolite plugs ...autolite wires.
Doug Thorley Tri-Y headers
2 1/2 duals with flowmasters.

The vehicle:
1977 F-250 Highboy
4.11 gear ratio with limited slip
c-6 transmission and divorced transfer case.

Here are the questions.

1) Are the heads on this engine going to cause poor mileage or simply contribute to lesser power potential?

2) In light of what I am using for parts, what would an estimate of optimal timing be? Where would you start?

3) What should I consider to be acceptable for mileage? I don't soft pedal it all the time... Occasionally plant the pedal to the floor to blow the spiders out. I checked my mileage on the last tank full....8mpg. Too low or normal?


4) With the 4.11 gear ratio and the 33x12.50 tires I am running, what would you expect to see for engine rpm at 60 mph? I don't have a tach but it sounds fast. I assume that with 4.11's I will never see over 10 mpg...right?

5) given the option would you change the cooling fan? This one is of the early type...(non flex fan) the ridgid one with steel fixed blades. Do these eat power / mileage? If so is it worth swapping for a flex fan?

6) the idle speed seems slow. With the c-6, what should the idle be before dropping it into drive? It seems a tad lopy at idle but not like a performance cam lope. More like the timing is off type lope. A stock 429 should idle pretty smooth...yes? I know some engines aren't all that slick at idle...but as I recall from my younger years...the bigger stock Fords were pretty stable at idle...no? Mine wants to idle so low that the dash lights dim and it is close to dying. If it was a hot rod with a lightened flywheel I would expect to have to "goose it" to keep it alive...but this one is stock.

7) it seems like it makes a bunch of power when I have the pedal down. It will get up to full snort pretty quick. I have always heard that the heads I have aren't good for much other than door stops. What would anyone suspect this engine makes for Hp/torque. Is all this seat of the pants feeling making me think it has more poop than it does?

Sorry for the blast of questions. I drive semi on night shift and have way too much time to think... I take notes and save up the questions till I can get to a computer to dump them here.

Thanks in advance for any help you can give.
Bill

 

Well Bill, Firstly Welcome to FTE! My disclaimer is that I am building my first 460 and all the research I have done so far indicate that you should replace those heads. Ford used them one year and while they work, they are prone to detonation and that is really dangerous for your engine. Next up is the timing chain. Cloyes makes a very good roller chain for the pre71 engines that restores camshaft timing to "straight up" verses the 4 degree retard Ford used after 71. I like engine idle around 650. Best fan is a 5 or 6 blade Ford fan with thermostatic clutch and shroud. The gear ratio is for 4x4 use and would cost way more to change than you would ever see returned in fuel savings. Timing (personal preference) 8 degrees initial all in at 3000 RPM and total advance of around 34-36 degrees. I am building a driver engine and these ideas and recommendations are what I will use. I think you should do a compression test. Poor or uneven compression can account for the lopey idle you are experiencing. As for fuel mileage 8 to 10 is about right for your truck.

 

first off what is the idle speed? it may actually be low and causing a "lope". Next yes the 72 open chamber heads will hurt performance due to the issues with the detonation problems usually associated with them, personally I would look to a set of D3VE heads these are a closed chamber design which will reduce the proprencity to detonate allowing the use of more timing and lower grades of fuel but will not raise compression like the earlier heads are known for thus needing higher octane fuel.

 

1. Yes

2. Start at about 8 deg initial and work your way up until you begin to hear some pre-ignition (detonation or "ping") then back the timing up about 2 degrees and lock it. Not the most scientific method, but for a generic truck doing daily duty it will get you close enough.

3. MIleage is depended on your vehicle setup and what you do with it. It's a carb'd near-stock 460 in a 4wd truck with a pretty steep gear, not a Civic. Estimate accordingly. If I were you and I ever managed to get 10-12 on the highway, I'd be thrilled.

4. With 33" tires I would expect to see about 2550-2600 on the tach at 60 mph. You can figure it yourself. Take the tire diameter and multiply by 3.15 (pi) to get the roll-out (distance to turn one revolution). Take the speed in mph, multiply by 5280 to convert to feet, and multiply by 12 to convert to inches (or just multiply by 63360 to save a step). This gives you inches per hour. Divide by 60 to get inches per minute. Divide by the roll-out you calculated before to get tire revolutions per minute. Multipy by the differential ratio to get driveshaft revolutions per minute. Throw in 50-100 RPM to account for torque converter slop and you should have a decent estimate of engine speed, presuming your tranny has a 1:1 top gear ratio (which your C6 does).

... or you can go here and just plug the numbers in for a quicky RPM calc - http://www.speedworldmotorplex.com/calc.htm

5. Yes, fans take power to turn. If you don't need all the cooling of the rigid fan, then swap it. If you pull trailers or drive in an extremely hot environment, don't change it.

6. Low idle can cause a little lope, but so can a vacuum leak, a bad plug or wire, poor compression in one cylinder.... the list is long. You need to do some diagnosis to determine if the bobble is isolated to one particular cylinder.

7. Absulutely no clue about power, but with a stock cam and untouched D2 heads it ain't much. If you were getting over 250 I'd be surprised. Most of your off-the-line "get up and go" is the result of the cubic inches, the good first gear in a C6, and a 4.11 geared diff.

Brad

 

You should be able to get better feul mileage. When I swapped my 400 for a 429, I went from 8 MPG to 12 MPG. And, I have a Larger Carb (750), larger tire (35's), worse gears (4:56) and stock exaust manifolds, than you. I'm not sure of the #'s on my heads, they are 72 cc's and rebuilt. I would look into your carberation and timing, and when the monies right, replace the heads.

 

Pistons and CR are adjustable since you will bore the engine. I am planning on using KB 138s on this engine whether I am forced to bore it or not. I have had good luck with the KB pistons in many FE motors I have built over the years and while they are a bit spendy, heavy and getting that top ring gap right can be tricky I still like them. The KB138s should produce an 8.4 or so CR with run of the mill D3 heads. The chamber on these heads seems to vary from 92-98cc's. I had a spec sheet from Ford that listed D3's at 88 cc's so I guess the only way to know for sure is to measure them. After my D3s are gone through I'll have the machinist cc them. The KB 138 pistons tend to squeeze up closer to zero deck without actually decking the block. If I wind up 0.10 or so down the hole I don’t care. This is good for me because I do not want to get in the position of milling the intake or cutting the heads. I will have the head and block surfaced but only enough to make everything flat so the gaskets seal properly. I am shooting for a pretty much out of the box build in a 3800 pound pickup that will not do any work. I plan on just showing off on Saturday night at the local cruise in and running around to a truck show once in a while. Many of the people on this site race these engines. There knowledge and experience is valuable and will ensure I build an engine that will last a long time. I am building for reliability, dependability, some reasonable economy, and the ability to “light em up” once in a while. When you do this yourself on a limited budget you must get it right the first time. One error is one too many.