So im building a healthy 400 replacement motor for my dying 351m thats in my 78 F150 4x4. It's lifted and rides on 35's and its my daily driver, and on the weekends ill take it to "The End of the world" for some mud slingin fun with my buddies on the weekends. The 351m already has a performer 400 intake on it, and some hedman headers and a holley 4bbl. I'm going to swap those onto the 400 after i clean them up. But my issue is i want to get a cam for it, i LOVE the loping idle sound, but i dont have alot of money as im 16 and dont have a job (yes im applying as we speak) and i want to use a cam with a lope but try to have as high as lift and long as duration possible while using as much of the stock valvetrain as possible. Any idea's?

 

Well cam replacement also well depend havily if you are going to upgrade your heads as well as your exhaust. do you plan on getting a small valve job to replace the seats or maybe get larger valves and also are you going to want to run headers instead of the stock manifolds? Don't forget about your intake either a big lift means nothing if your intake restricts the flow of air giving you only minimal returns. Now don't get me wrong you will still see an increase in horse power and torque with a new properly selected cam but a little more information is needed. Now something simple you can do is called port matching. The idea is that the intake runners and the intake on your heads might or may not be equal in size but the size of the gasket ports is where the money is at. If the intake gasket opening are way larger than you runners or heads then it may be a good idea to port match.

This is something that you can do yourself and see big returns for no cost if you already have the tools. what you need is a die grinder preferably air powered but not required carbide burs with long shank. A felt tip marker or mechanics dye and patients.

Using the stock manifold you may or may not be able to do anything to your intake as the walls can sometimes be too thin to work with however using a cheap edelbrok intake you can gain lots.

FIrst off mark the area you are going to work with the marker or dye. Now what you would want there is to place your intake gasktet and place it in it's little glory postion and using a scratch awl or I just use a grinded screw driver scribe the line the actual port size on the runners or heads depending on which you are doing. This will give you your guidlines to work with.

Now this I should mention also entails some risk to the parts if you get going to fast and remove too much material you can ruin heads and intakes so go slow and take your time. what you want to do is make the runner transtion smoothly all the way through the port decreasing resistance and increasing flow.

Using the dieginder you remove material up to your guidelines and smooth out the runner or intake port. working slowly you shjould be able to see the difference in the stock casting to your new bigger ports. THis is a picture from a chevy intake but it works well for demonstration. You can see the difference in the size of the ports is huge there is a lot of air choked up there waiting to feed your engine. Now here is a different picture showing the difference between a port that is almost finished compraed to stock (I am having to steal all these pictures please fogive me didn't have an of my own on hand.)

Getting the air to your engine is what you are trying to get out of that bigger lift and with a simple port matching job you can help free up that horse power for your new cam.

I would recomend goin on a junkyard crawl if you are going to use the stock manifold this will give you a practice manifold to use. Then when all said and done you can use whichever one you prefer or think you did a better job.

I can't stress enough on patients though take your time and go slow porting an any form takes hours to do it properly and get a good finish don't worry if it isn't shiny like polished alimunum or plateing the bigger port is the sexy part.

Now for your cam don't forget since your on a bidget a monster cam could be expensive another way to get there is a new rocker ratio but that is a bit more in depth and I would recomend some more research into the subject all the way around before you decide what you are going to do.

For more help with your cam is it a hydrualic or solid? This is important because of the lobe design hydlic parts don't agree with flat tappet and visa-versa. feel free to shoot me an email with more information and I will see what I can find for yoy.

although either way the cam specs for what I found for you are as follows.
Gross Lobe lift.
0.340 intake 0.340 exhaust

rocker ratio 1.5

centerline angle
114 intake 99.5 exhaust

TIMING
IVO 22 (at seat) -6 (at .050)
IVC 70 (at seat) 26 (at .050)
EVO 58 (at seat) 35.5 (at .050)
EVC 39 (at seat) -9.5 (at .050)

Hope this helps please shoot me an email or message me if you have more quetions.
spudmuffin1@gmail.com

 

Well dont mean to sound rude, but if you read carefully, i explain that i have a Edelbrock performer 400 intake for my 400, as well as a set of hedman headers. I do also plan on port matching my heads. I will also get a 3 angle valve job on them!

 

Also, i plan on keeping most of the stock valvetrain, and 351m/400's are Hydraulic flat tappet motors.

 

Alright sounds good sorry I don't know how I missed that information. D'oh Well I will see what I can dig up for you cam wise.

A thought struck me as I was headed out the door. How are the seats going to be cut by stone or by cutting die. If it is by cutting make sure you ask your machine shop about bowl blending. Some machine shops charge extra to blend in the bowl. Now if you are only getting a minor increase in valve size you might be able to get away without it but a larger valve will have a lot of shrouding after being cut.

Here you can see a before and after bowl blend the bowl on the left has already been done and the one on the right is right after the seat cut. You can see the ledge left by the cutter this will disrupt air flow negating the benefits from your new valve job. Something to keep in mind.

Out of curiosity what angles are you using?

 

I dont know yet about angles, but im having my auto teacher re-grind my valves for me and im going to sandblast my valves clean and lap the valves to the seats. I dont think i'll go up to bigger valves though, im gonna try to port and polish them though.

 

Alright sounds good just make sure to measure everything when all said and done remember when polishing to a new seat and re-grinding valves the seat gets bigger and the valve smaller so you could pull the valve through the seat if you take too much off. If using a shallower angle on the valve however that shouldn't happen but it is a possibility.

After work today I will be able to call the cam companies to get you a pert number on that grind I found for you.

 

With the pathetic stock comp ratio it would not be a good idea to put a big cam in with a "loping idle" in your truck. All of the speed components have to be matched to get a good, strong engine. With the low compression, crappy stock heads and the stock highway gears you would have a motor with no bottom end power.

 

get a performer cam and lifter set that was made for the performer intake and new springs

 

It shouldn't be to bad unless I was mistaken the 400m runs right around 8.4 with that he could get around 265hp at the wheels not a big number torque that great either like 370ft/lbs the curve I am looking at isn't great but I could live with it if it was my first build. But without building it up theres isn't much he could do.

Now say using some entry level heads he had them ported and had some larger valves put in say 1.900 and 1.5000. Using a higher compression ratio around 10:1 still very pump gas friendly and a different cam than suggested he could raise it to 375hp at the wheels and 422ft/lbs.

 

How much would i have to mill off the heads (without bouncing valves off the piston) to get 10:1 comp ratio?

 

I like your idea cj06, i wanna do that and here are the specs on the performer cam i would like to use to match it with the intake, Could i use it on its own besides a new set of springs?
(Edelbrock Performer Plus Camshaft)

ENGINE: FORD 351M 400 V8
RPM RANGE: Idle-5500

Duration at 0.006" Lift: Intake: 282° Exhaust: 292°
Duration at 0.050" Lift: Intake: 204° Exhaust: 214°
Lift at Cam: Intake: 0.280" Exhaust: 0.295"
Lift at Valve: Intake: 0.484" Exhaust: 0.510"
Timing at 0.050" lift: Open Close
Intake: 5° ATDC 29° ABDC
Exhaust: 44° BBDC 10° BTDC
Centerlines: Lobe Separation - 112° Intake Centerline - 107°

 

new springs have a higher spring rate than stock and they also are designed for the lift of the cam , stock springs have thicker diameter coils and could easily bottom out causing bent pushrods . plus they are seldom replaced at the machine shop and just shimmed for there height , they do get fatigued .
i always believed that the cam is the heart of the system and for it to run right like what you are expecting it to do all parts should be a equal match to each other !

i dont think you can machine enough of to get your 10-1 ratio with out running into other problems like will the intake now bolt up with out work to make it seat properly !

you may need the proper pistons to get the 10-1 ratio you want

 

Compcams has a free download which allows you to input different combinations of engine components and see the results on a mock dyno chart.

http://www.compcams.com/Pages/409/camquest-6.aspx

Be carefull getting too radical a cam as it will not perform very well at low RPM and you may need to change your torque converter to a higher stall.

the stock valve spring will not work with anything other than a stock cam so your looking at about $450.00 for a cam, lifters, timing chain with sprokets (critically important as the stock one is 4 degrees retarded).

what are you planning for pistons? the m351's dont work with the 400 crank.

here is a link to a build like you are planning.

Ford 400 and 351M Performance Upgrades and Parts - FordMuscle

another link on a 400 build with dyno results on different set ups.

TMeyer, Inc. Precision Automotive Machining

have fun!!
X

 

Comp 268, 1500-5500rpms, nice lope to it, still retains some of the gas mileage, the recomended springs, p&p the heads, a good double roller timing chain and bump up the compression to at least 9.5:1, and that combo should put a smile on your face with the intake and the headers.

Its more about picking parts that compliment each other, it don't sound like your going to be racing your truck, so anything over 5500rpms is silly to have and affects drivability. The combo I descibed would be a real tourquie combo, perfect for muddin and street driving.
Just my .02