Hey guys, I know what I6 performance has been adressed alot here, bu, i am kind of at a loss. I have done a pretty decent amount of work to my I6, and I am still somewhat dissapointed. The engine had some pretty bad rod knock awhile ago, so I figured it was time for a rebuild. Had the block and heads hot tanked, had a balve job done, crank journals re-ground, everything was done right as far as machining, no problems. As the engine sits now, its got the 300:
-bored .30 over
-Crane truck cam
-Offie Intake
-Holley 4bbl
-Duraspark ignition swap
-Open exhaust, no cats and just a glass pack
The only mod I havent bolted up yet is a set of headers, but, as it sits it seems to me that the engine should be pretty hot right now, but I am disspointed, it seems somewhat sluggish, lacking power, and has nothing on the highway. Its in an '84 F-150 4x4, with a 4spd tranny with a granny gear, and 33" tired. Does anyone have any idea where i should go from here? I dont see the headers making THAT much of a differance with what I have. I woudl appreciate any insight that you guys have. Thanks!
Eric

 

-Offie Intake
-Holley 4bbl

which intake? DP or C-Series

what size holley and how is it bolted the the intake?

 

Not sure of what series the intake is, but...there are no planes inside, like...no dividers inside the phlenum. And, as I should...I dont know the cfm of the carb, I want to say around 600cfm, its vacuum secondarys, i do know that i came off of a chevy 305 and ran great, and seeing as how the I-6 is now a 305 after being bored over, it shouldnt be that big of a problem. I will head outside and check the numbers on it and post again.
Eric

 

i have the same setup but my I6 is rebuilt stock with a cam ...... i have mega power.... more than my friends 77 351M

 

You got this thing tuned right?

 

Carb is a 4160 600cfm, sounds about right for this engine...I suppose the carb could not be tuned right, I hope that that is the culprit. What jet sizes and power valves are you guys running? But, next a 351, night and day, 351 hands down...and thats not cool.
Eric

 

lol im runny a stock 1 bbl

 

Problem is simple: you have all this potential power and nowhere for it to go. Throw on a header. Believe me. I have a header into a 3" SI/DO exiting right under the middle of the rear bumper (no, it's the FRONT BUMPER, duh! ), welded a Y-collector together, no cat, Clifford single-plane, 525 Road Demon Jr., DSII/HEI module/TFI coil (did the HEI module last weekend, didn't make much of a difference over the DS II module except it starts a little easier and is cheaper to replace...). And there's a world of difference over the stock, feedback carbed motor *everywhere*. Low-end too. And part-throttle. It will break the right rear tire loose easily at 30-40 MPH in third in the rain, and before I fine-tuned it, it laid 100+' of 31" Bridgestone on hot, dry pavement with a 3.08 rear. It wouldn't even squeak the tire in stock form, or spin 'em wet.

And the Crane cam will be here tomorrow morning, and I have a hand-ported EFI head to throw on, and that's where things get interesting...

Biggest obstacle to proper performance with a lot of Ford heads is a restrictive exhaust port. The I6 is by no means an exception. If you're using the stock carbed log exhaust, it's making more EGR than power. And the EFI manifolds will run out of breathing room fast with a cam and massaged head. A header is the only real way to go when extracting top performance out of any engine. Actually, it's my first priority. After all, everything else you do has to go *somewhere*...

 

4 speed granny gear with a set of 33's? Im betting that you have 3.08 gears in it, which would explain why its so gutless. Buy some bigger gears.

-Matt

 

3.08's? That stock? Because I beleive that it has stock gears. But, my complaint is on both ends of the spectrum, i have thought about re-gearing it to get more *** on the bottom end, but, it sucks on the highway too, in 4th gear I can cruise at 60-65mph but the engine is screaming (not sure of rpm's, dont have a tach)
Eric

 

I second the gears, you need to upgrade or go to a small tire take your pick.

 

I agree, that will help me out alot low end, but, thats going to make a bad situation worse when it comes to the highway, wont it?
Eric

 

The stock 240Six and 300Six intake and exhaust manifolds are no different from the old 53 F-100's manifolds in construction. Edelbrock used to offer an intake for the 300Six--its part number was 5557--but I understand they have discontinued it now. Heat from the exhaust runners kills the A/F mix trying to enter the heads. It really heats up the mix. If you add that condition to the typically poor and restrictive exhaust ports on most Ford heads, you have a real problem.
50_BUCK_WORK_TRUCK's modifications seem to me to be really well thought out. I really would take his parts combination and advice in deep consideration.
At any rate, an engine is, basically, a gasoline-driven air pump. All the power accessories money can't buy won't let the motor run as well as it could if the exhaust is restrictive. If the engine breathes in well and is constipated going out, it is still inefficient and is clogged. If that is the case, it is still slower than what it should be or could be.
PLEASE, keep in mind, this is my PERSONAL OPINION, therefore, it may not be of any value. Still, I confess I do think it to be valid. The BEST intake manifolds ever cast for anybody's inline Sixes are available from Clifford. I have installed them, tuned them, and used them on 250Sixes in two cars, 240Six in one truck, and two 300Sixes; I have also helped install them on two GM..gasp!...250's and an AMC 258. It really does make a world of difference. One of the 300's I built had a Clifford manifold and Cyclone header. It really did have a lot of torque and horsepower. Granted, the Offenhauser intake is better than the stock Ford piece; however, I do truly feel a Clifford unit would help you out a LOT.

But, as you asked in your post, tuning what you have is crucial as well. And, unless your 4160 Holley has an anti-backfire valve, DON'T LET IT BACKFIRE THROUGH THE CARB!!

 

If it is still on the unit, you can look at the tag on your differential and it will give you the gear ratio. It will give you the ratio, the build date, and the factory which built it. It will also give you the ring gear diameter.

Nevertheless, if it is screaming like that in 4th, I figure you have a lower gear than a 3.08. (The higher the number, of course, the lower the gear.)

 

Not with the right choice in gears. Your choices are sort of limited with the 4 speed. Believe me, I had one too. Id go for maybe 3.73's with your 33's. I think that would be the ticket for a good balance between power, and a good measure of highway cruising.

-Matt