Ok, I am going to be building a 1978 400 with about 10:1 compression and all the goodies - headers, intake, carb, ported and polished heads, etc. I am wondering what kind of cam figures I should look for. I am looking for around 500hp/500ft# and the low end is pretty important to me. I really don't want to put a stall converter in my auto and I want to know what the hell the deal is with the stupid converter thing. My brother put a 292 in his manual and that was no problem for it so what is the deal with auto tranny's. Thanx for the help.

 

One more thing to add. I have been looking at a couple of cams and the ones that I like are all from Comp. However, they are single pattern (same dur for int & exh). I have heard that you want your exhaust to be more. True? If so, can you have them custom make a cam and how much would that cost? Thanx for all the help.

 

I personally like the selection from Lunati. I don't remember the specs. but they have one that I have been eyeing. I am currently running the 260H Comp cam and the numbers for the Lunati are far more impressive.

 

>Ok, I am going to be building a 1978 400 with about 10:1
>compression and all the goodies - headers, intake, carb,
>ported and polished heads, etc.

which headers, intake, carb?
which heads? ported? different valves?

>I am wondering what kind of
>cam figures I should look for. I am looking for around
>500hp/500ft# and the low end is pretty important to me. I
>really don't want to put a stall converter in my auto and I
>want to know what the hell the deal is with the stupid
>converter thing. My brother put a 292 in his manual and that
>was no problem for it so what is the deal with auto
>tranny's. Thanx for the help.

i'm no expert on this, but my guess is that you'll have to give up some low-end to get 1.25 HP per inch, and you'll need a high-stall converter and lower gears too. you could probably get 300HP with enough low-end torque to give you whiplash, and probably "decent" low-end torque (no high-stall needed) up to 350 or 400HP, but somewhere in there you have to decide between one or the other.

the deal with a 292 deg. cam with a manual is that you can rev it higher before you let out the clutch. a high-stall converter basically does the same for an auto. if you need one and don't have it, the car will be VERY slow off the line, up until you hit the speed where the engine starts to make it's power, then it will start pulling like a ****... with high stall, it pulls like a **** from the get-go!

the guys who ARE experts here will need to know about the parts i asked about above, plus what it's going in and what you want it to do. if you haven't bought any parts yet, then just what is the motor going in (weight, tire size), and what do you want to do (pull a bulldozer on a trailer, drag race, muddin'... give that kind of info and they can pretty much recommend everything you need.

 

I would agree with Brad. I think that 500hp is wishful thinking on a 10:1 compression. Unless you running a supercharger or nitrous.

What are you going to use the truck for? That will help in cam selection. Keep in mind the bigger the cam the higher stall you are going to need on the convertor, which is goin to lead to more heat in the tranny.


Brian

 

Ok guys I have finally made my decision. I want this truck to snap my neck in two when I step on the gas. I want low end coming out of my ears and I would like some decent midrange, too! But the low end is the key. I mean, under 35 MPH, I want to be able to goose it and any passengers will hit their heads on the back window. Now what kind of duration figures do you recommend. I am thinking that all I will have to run to get that is 9.5:1, sound about right? Thanx for all the help.

 

i would recommend a cam with a dual patern in the 204 to 214 range. just a little better than stock. and should work fairly well with 9.5:1 c.r. BTW, you ever considered a stroker. if you did check out some of the other posts.

later.......:P

 

[updated:LAST EDITED ON 26-Jul-02 AT 06:55 PM (EST)]congratulations - your decision is going to save you a LOT of gas money, and quite a bit of cost on the rebuild too!

i don't know what your budget is like, but if you know how to rebuild a holley (or want to learn) then you can get your carb & intake on ebay for about $150 total. i don't know 400's well enough to pick what you need, but there is always a good selection of used vacuum secondary holleys with ford A/T kickdown and electric choke. some even have some "trick" parts on them already. you can do a search in this forum for "400 intake" and find some advice that applies to your build. same for headers. there are all sorts of weird intakes on ebay (not all at once), but the performer and the weiand that's similar are pretty common. headers seem to be less common than intakes and carbs (i think because they eventually rust and die) but you can find them too. i'd get new ones though - some real long ones with 1-5/8" primaries, that are "ceramic" or "jet hot" coated. i think heddman and blackjack make some that should be right. hookers usually have bigger tubes. 335-series pistons are NOT real popular on ebay, but there are some from time to time. timing sets, oil pumps, $10 chrome valve covers, and gasket sets are plentiful.

a roller cam should allow you a little more mid/high rpm power, while still keeping the low-end torque. it's a little more trouble to convert, but maybe worth looking into.

and the number one rule: LOWER GEARS! even without a high-rpm type motor, lower gears kick ***! don't fear the gear...
(unless you want gas mileage & high top speed)

 

I think that you have established an arbitrary HP figure and boxed yourself in without really understanding all the tradeoff's necessary to achieve your goal!!!!to achieve 500 hp you'll probably have to have about an 850 cfm carb that will get about 3 mpg-----is money NOT a consideration??What about building an engine with longeivity---you can run the Hell out of it and maybe it will last a year or so then you can spend another 6,000 to rebuild it all over...........You can achieve 400 hp fairly easily and install 4:10 gears and pop all the necks and ***** that you can squeeze into the cab!!!!!Most folks want good accelleration but they also want a truck that is dependable and gets somewhat decent(8 to 10) fuel milage-----If money is no object(dollars that don't make sense)that you can achieve whatever you heart desires.........keep us informed , fd :-X11

 

an 850 will be entirely too big. the formula for finding carb size is C.I.D. X MAX. RPM / 3456 = CFM @100% VOLUMETRIC EFFIENCY. very few street motors reach 100% volumetric effiency. most are around 85%. plus too big of a carb will outright kill low end try a 600 cfm or a 650 cfm carb that should be motr than sufficient for your needs

 

well there are a few points to talk about. 500/500 is very doable with a 400, but a 10:1cr makes it rough. First off what type of heads, 4V or aussie 2V? Headers, I would go with 1 3/4 for 2V and 2" for 4V. A 750 cfm (650 for a 2V) carb is plenty, there is not much hp gain going with a 850, but wow the fuel consumpton is huge. Flat top pistons will help make a lot of power for you. Also go with a single plane intake and the wieand spacers. Last is cams, well I like the Crower 390 series, I picked a 227/233 dur @ .050 with a .550/.547 lift, a good lift high duration cam will make the power. Now for that no low end, dont believe it, cause its not always true.

For those that want to play with numbers, here is my build

400C 4V

400 block
351 4V closed chambered heads ported and polished, 5 angle grind
2.25 intake / 1.73 exhaust valves
cr 11.76 - flat tops and mill work
.030 over
wieand excellerator (stealth) intake
deamon 750 carb
227/233 .550/.547 cam
rhoads lifters

run the numbers tell me what you get, I get 504hp / 497#

this same build with a 10:1 my guess is 450-475hp