hello i have a 79 ford f-150 and i am currently building a 400 it is bored 30 over it has and edelbrock performer intake and a edelbrock 600cfm carb it is going to have a fresh set of rebuilt heads on it my question is this i just bought a cam it is from comp cams it is the 268h the specs on it are adv.dur 268\268 dur at .050 is 218\218 lift is .494\.494 lobe is 110 i was wondering if anyone has ran this cam with my simular setup and how well did it work thankyou

 

I suggest posting this thread in the 351m/400 forum.

 

Moved to proper forum.

 

I'm running that exact cam, but with a 70's ltd 2v intake and a warmed over 2150 carb, hedman headers to a y-pipe and a flowmaster 40. I'm currently in the process of switching gears to 4.86's, but with the stock 3.55's I couldn't not stop spinning tires 30" and smaller. With my 35/15.5/15 tsl/sx swampers I can sqawl em in the first two gears of my c-6. This is with gears way to tall for the tires, and a stock torque converter. This cam produces plenty of torque for me, some people are different. If I keep my foot out of it I can avg 12-15 mpg, with the 3.55's. This is in a shortened 77 F-150. Different truck, different gears, trany and a 4v intake and carb will all change the attitude of a cam. But for a single pattern cam, these engines favor a dual pattern, I've been impressed with comps 268/218 by .494lift cam.
happy motoring.

 

Always use a dual pattern cam on a Ford engine.

 

Many years ago I built a 400 for my Torino. 750 vac. secondary Holley, Edelbrock Performer manifold, mildly ported 2-v heads, Comp Cams 268 HE cam, tons more stuff and machine work. The end result- bottom end was not great, made tremendous power in the 2500 to 5000 range, ran out of breath at 6000 rpm (yeah, I really did peg 6000 a few times). If I had to do it again I would certainly go with a dual pattern cam as most Ford heads need help on the exhaust side. I wouldn't use a 750 cfm carb either, 600 is plenty for the street. Gas mileage? HA! About 12 on the highway, 9 in the city, 2.75:1 rear, C6 tranny. That was back in the 80's and gas was cheaper then and it still hurt to fill it up.

 

I like what I'm reading here, I'm just finishing the assembly on my 400, 268h cam, bored 030, Holley Truck Avenger, Weiand Action+, 410 gears, 33" tires, going to pull my travel trailer for a while!!!

 

with that cam did you have any problems with the lift so you wont slap a valve, do you know how much lift you can run on a stock set of heads that are rebuilt with comp cam springs

 

If you are talking about valve to piston clearance, there is a ton on these engines. That said I would never build an engine without checking it anyway, but it won't be a problem.

Do you know how to check it?

Hope this helps,
Doc

 

The most reliable way to check clearance is to put some modelling clay on the tops of the pistons, install the heads, pushrods, etc., then hand crank the crank shaft, remove the heads and you can measure the clearance in the impressions left in the clay. Practically speaking from my experience with a 400 and the Comp Cams 268HE grind, with pistons with valve reliefs (stock or TRW) you can easily get away with 0.500" lift. I even had my heads and deck milled to increase compression and still had no interference problems with this cam using 1.73:1 ration roller rocker arms. I tell ya, I sank so much money in that engine, but it was fast and 400's were almost as popular as the plague back in the 1980's.

 

I can honestly say I have never heard the 400 as being "as popular as the plague" before. I always thought of the 400 as the performance underdog of great Torque motors.

 

after i put the clay on top the pistons and bolt down the heads and all of the other stuff and hand crank the engin how much clearance should i have between the valve and the piston i was wanting to deck them so how much clearance should i have between them

 

I believe about .060-.080 inch is good for a mild street engine. (movement at the needle) I heard of people running it tighter, but I don't have any personal exp.

P.S. Quench (needs closed chamber heads) you run about .038-.043 inch with a steel rod, and .050-.065 inch with ally-um-anum(aluminum).*piston to valve clearance*














piston to head clearance.