Engine Build Opinions*ON THE ROAD*

[Explorer]

Down to rebuilding my 200ci. Keep in mind this is for a 66 Bronco with 4:10 gears. Total street build. I need to retain my vacuum for adding PB, and low to mid range torque. Thinking about an Isky #321256 256/256 cam, .450 lift, 202 duration, 112 lobe. I have a bare CI head and intake, 289 springs, double roller timing set, Duraspark 2, and Holley 350 cfm. It will be bored .030 over, zero decked. I need to make a decision to go with Keith Black flat top pistons or stock dished and how much to shave the head. I would like wind up with about 9.5 compression. With the .450 lift should I keep the 1.5 rockers or go to 1.6? Any suggestions along with expected HP/Torque numbers and power band would really help. I would like to take my parts to my builder next week. I really need to make a decision on this.

 

[Lazy JW]

... I need to make a decision to go with Keith Black flat top pistons or stock dished and how much to shave the head. I would like wind up with about 9.5 compression.....

Not really a very tough decision, it's simply time to do some math. You already stated that it will be zero-decked and you want about 9.5 compression, now it's just a matter of comparing the combustion chamber volume to the swept volume; this will make your decision for you.

Sounds like a nice build you have planned.
Have fun,
Joe

 

[Explorer]

I've worked the math a hundred times, but just don't know enough to figure out the right torque curve. I think I'm right with my cam choice for highway cruise speeds vs torque as I can adjust my tire size between 28" and 31", but I have no experience with a I6 period. For this money I really need to get it right. Running a 3 speed vs automatic helps with my gearing/shift points.

 

[JackFish]

You know you can use stock 2.3l HSC Tempo/Topaz flat-top pistons too, eh?

The only difference is the 2.3 HSC pistons have a .090 pin offset, and the 200 pistons have a .060 offset. However, they still work fine, and are available oversize up to .080 from Speed Pro.

 

[Explorer]

Yea, I have the Falcon Performance Hand book. There are just so many variables with cams, dynamic compression, head flow, rocker ratio that I need expert advise as to if all this will come together correctly. Pro's and con's of flat top or dished piston's in shaving this head as it only get's done once. Quence and knowing actual torque curve are still stuff I can't get a grasp on. I ought to spend the money for a desktop dyno program. Then I could punch in diff numbers and see the results. I've found a couple for compression ratio's and HP but not anything to punch in the numbers and graph to see what it's doing at diff rpm's. I'm a fast learner, but I'm starting from being totally ignorant on engine builds. If anyone know's of an affordable dyno program please let me know.

 

[WerbyFord]

Ok here is what my computer, the Gonkulator, says:
Your build [assuming 1.5 x 36 headers which was a total guess - I don't know Bronco header dimensions...] :
computes to (gross horsepower not net or rear wheel)
Torq 182 at 2000
Torq 217 at 3800
Powr 188 at 5000
Slightly better than a stock 200 at 2000 for low end, and from there it just gets better.

The 1.60 rockers added about 4hp but took off 3ftlb down at 2000.
I'd skip em since you mentioned keeping torq if you have 1.50s free already.
The cam computed best at 108i and 116e centers, ie 4 advanced which may be as ground.

What about a 4v? With a 390 Holley your build came out to
Torq 190 at 2000
Torq 220 at 3900
Powr 197 at 5200
Gains across the board since you get small venturis down low but big cfm up high.


I don't know how good these computed numbers are - if they were v8 I'd trust them a lot more since I can compare to so much more data. Then again, we are starting to get some dyno data on the small six, so I compare to what I can before predicting like this.
Nice build, good luck.

 

[Explorer]

Now thats something I can understand. The headers will be Clifford dual short tube into 2 1/4" dual pipes and mufflers. The small cfm 4v carb would suit me better, I was just afraid it was too much carb. I really appreciate the info.

 

[Lazy JW]

I've worked the math a hundred times, but just don't know enough to figure out the right torque curve.....

Ummmmm....... you've already stated your choice of head, cam, and compression ratio. Unless you decide to change one of those, there really is nothing left but to do the math and build it.

I still say you have a nice build planned. I would be VERY reluctant to shave any more off that expensive head than absolutely necessary. Make a mistake and it cannot be put back on. I would be more inclined to risk making a mistake on the pistons as they are MUCH cheaper.
Joe

 

[Broncitis]

The clifford shorty headers are the only way to go, I ran an Xpipe right behind them, CI at this point does not have a good bronco header are else I would have bought it there, the cam you have chosen is an extremely mild cam that I am certain was targeted to the log head, I believe a good in between cam with the one you are looking at and the CI 264/110 is the comp cams 260/110, I had a custom cam ground by bullet cams 260/110 at .496 lift at 1.6 which I never used when I decided to go supercharged, with the new head I believe some of these older profiles can be bumped up a bit with the new AL head, I ran a supercharger profile cam on my 200 in my bronco with 29'" tires N/A to break it in and it ran great with 4.11 rearend gears. I know also believe if you never go above 31" tires with the 4.11's you will also be happy with the 264/110 especially if you are mosly going down the highway.

 

[Broncitis]

Sorry missed one other thing, stock cast pistons handled by CI will work great dished or flat for your build as mild as its going to be for your C/R choices. There are very few failures of stock seal power pistons if you run your timing correctly.

 

[Explorer]

Thanks guy's! Sounds like it's a solid build. Off to the machine shop first of the week. Now back to finishing the chassis. Wish some elves would come in and do the body, three Bronco's back to back has me burnt out on body work.

 

[Explorer]

You guy's got me thinking again, which for me is dangerous. The suggestion was made for a 4v carb. I was reading in another post about the autolite 480 and the dyno run's. I never see Edelbrock mentioned, which I am more familiar with. The 1404 500 cfm has 1.18 primary's 1.28" secondaries with .086 primary jets and .095 secondaries. I'm sure there is a reason it's never mentioned, so figured I'd ask.

 

[Harte3]

Not many if any are running a 4v on the SB6 unless they have the CI head/intake. Quite a few run a 4v on a 300...aftermarket intakes readily available. Some run the Edelbrock, some run a Holley...a few even a QuadraJet. An old saying is "drive an Edelbrock, race an Holley." Just whatever your preference runs to. The Holley may take a bit more tinkering to get it tuned the way one wants. When I did my build (see signature) I originally was looking for an AFB 9400s 400 cfm...kinda of rare and usually a bit spendy when found so I ended up using Holleys. The custom built Autolite by Pony Carbs appears to be a fine unit but spendy.

 

[Explorer]

Engine back from builder! Wound up pretty much as planned. Keith Black flat tops, block not quite zero decked, left a little bit. Shaved head to 52cc and it should be about 9.6:1 comp. Planning on dropping it in tomorrow. Now to find the money for carb, accessories and exhaust. It'll still be spring before it gets fired, but at least the big money is over with.

 

['68falconohio]

purrrrrty!!!!!

It'll still be spring before it gets fired, but at least the big money is over with.

If you want to ship it out to me, I'll make sure she's nice and broke in by spring!

 

[WerbyFord]

Explorer,
Sweet looking engine!
If you are as anxious as I would be here is a suggestion:
Spend on the header and exhaust, then look here for a decent used Autolite 4100 carb:

http://www.network54.com/Forum/88781/

The Ford Carb forum is a great bunch and you can usually find a good Autolite 4100 there. Sometimes these are quoted as a "600cfm" carb but I think that must be a non-standard rating at 2" Hg. Bob Sprowl of the FE Ford site had some dry flow tested and the results are on his site at

http://www.fordfe.info/Autolite4100Test.htm

So I figure the common 1.12 Autolite 4100 is a 500cfm carb at the standard of 1.5" Hg. Still a bit big but useable, very well mannered, and it will get you going. Then you can keep it as a spare for when the Holley is in a bad mood, or you can always sell a factory Auto 4100 and get most of your money back.

I agree with the "drive and Edel (or Autolite), race a Holley" quote above so I keep both types handy. Every carb shootout I do on the Gtech, it is always a Holley that wins. But, they drink gas so for a long trip the Autolites (probably Edel's too) will leave you some money left over for the strip entry fee.


PS, do you know the weight and trans gear ratios in that Bronco?

 

[Explorer]

Empty weight is 2955lbs. Gears are 3.41 first/ 1.86 second/ 1:1 third with 4:10 diff's. Yea, I'd like to hear her run. I've got a 2bbl adapter if I could find a known good carb for the breakin, plus a Duraspark setup. This is a frame off so I need $500 wiring harness, front clip and radiator before it's going to happen. My builder said let him know when its ready and he'll come to the house for the first start and cam breakin. Not too many builders that will do that. I wish the Edelbrock 500cfm would work, those carbs I'm used to working on. They just don't have anything smaller.

 

[Explorer]

Thanks guy's! Got the exhaust done yesterday. Split Clifford header, 2" into dual in/ dual out Flowmaster and dual 2" straight out the back. Even with the brand new carb, she fired right up. My builder came by for the cam breakin and everything went perfect, even he was impressed. If it runs as good as it sounds, worth every penney. Crisp response and you can't tell by the sound it's a six. Can't believe how good it runs with no tuning what so ever. Only leak is a thermostat gasket that must have messed up mounting the power steering bracket. Now to finish the rest of my build so I can get it out on the highway and see if it performs as good as it sounds. Thanks again to all of you for your help and suggestions.
Richard

 

[Explorer]

Sound clip added, actually it sounds better with a low rumble to it. http://www.youtube.com/watch?v=QFCAJtLByXc

 

[Explorer]

Well, it's been a long year in the making, but she's on the road. Drove her about 30 miles today and had it inspected. Temp, oil pressure all fine. Exhaust is amazingly quiet. At cruise speed even with no doors, couldn't even hear it. But she will talk to you when opened up. Runs fantastic! 30mph in high gear no problem, ton's of torque, and still strong at 55mph with plenty left. Now for proper breakin, a little fine tuning and I'll see what she'll do. Thanks to all of you that have helped me make this come together. I couldn't be happier with how it turned out.