There is nothing wrong with a 351M/400 in a light car. Build it up to 408ci or go with a TMI 434ci stroker kit. Run a manual tranny or a wide ratio AOD and then don't over gear the rear. In a car under 3000 lbs and big block torque levels, you don't need 3.91 or 4.11 rear gears. You can run 3.27 or even 3.08 gears and then let the tranny and your motors flat torque curve do the work. The big plus with a light car and lots of torque, you don't need to spin the heck out of the motor to get good stop-light to stop-light times and you have a decent 1/8 mile car to boot.

 

My truck is about 4000 lbs. I have a 3.25:1 rear ratio. My EFI 434 peaks at about 5200 RPM with 800 to 900 CFM of air intake. To get more RPM, I need to increase the intake air, but with 500 ft-lbs average torque over the entire range from 2000 to 5000 RPM, it will pull hard through a full 1/4 mile. My biggest problem is getting the tires to stick.

A smaller motor has to rev higher to pull 900 CFM, so it needs a higher gear ratio. If you put a big carb on a small motor, it will run poorly at low RPM. A dual quad setup is needed to get that much air into a small motor and still have drivability.

A 351C with a tunnel ram intake and dual quads with 456 gears in a light vehicle is a potent combo, but so is a larger displacement motor with less gearing.

The true disadvantage of a 351M/400/434 is the lack of a good intake manifold. You need to adapt a 351C manifold to get a good dual quad setup that will deliver 900 CFM or more and still be driveable.

 

Nice, if I go with the 408 and 10:1 compression ratio on my mustang what cam should I use on the big side?

 

In one of these recent threads, someone was using a Crane H-272-2 cam. This has an Intake Valve Closing angle of 67 degrees ABDC. The DCR will be about 7.8:1 with this cam and 10:1 static CR.
This cam should work fine in your motor. It will produce over 400 ft-lbs torque from 2000 RPM through 5000 RPM, with peak torque of 448 ft-lbs at 3500 RPM. The peak HP is 381 @ 5000 RPM.

I wouldn't use a cam with an IVC less than 60 degrees ABDC in a 408 with 10.0:1 static CR.

 

hmmm that was my old camshaft, It had good results, Im now using hit-282-2-nc 282 int and 290 ext but its a bit worn out due to bad oil preasure, so Im thinking on a 278 - 290, or maybe a comp cam in the 270 range

 

I ran the Crane H278-2 with my old 4V Cleveland heads on my 400. That had about 10.2:1 CR. It ran on 91 Octane without pinging, unless the motor got hot.

Even a 275DEH from Comp Cams might give you more dynamic compression than you want. Check the IVC on that cam.
I'll check it later, when I am on my desktop.

 

well low-mid range rpms was always what was in sight, its not like im building a ***** to the wall 10 second truck, just a better than average 400, something with alittle giddyup to it, i wouldent think about building a high rpm 400, ever.

 

Comp Cams XE256 or 255DEH are good cams for low to midrange power, but the compression ratio must be kept close to 9.0:1 or less.

 

Im a little confused with comp cams and crane cams, both advertise difrent degrees with diferent rpm ranges and uses, It seams less duration for a comp cam is more rpm friendly than to a cran cam, wich one is more acurate or better for a 400 ?

 

Which cams are you talking about?

What are the specs that you have for these cams?

 

fwiw, my 400 is going into an 87 TC. I'm planning a mild build, AOD or C6, and 3.08 gears. Motor mounts and exhaust clearance are going to be an issue. I'm currently waiting (10 days now) for the parts store to get 79 Tbird mounts to try. I figure the lower half will be custom. Now, I don't know which Mustang you're putting yours in, but if it's a Fox body, well....

I should note my rpm will remain low, and will let the 3.08 gears and low range torque pull me along.

 

havi

I have a pic of the mounts I used on my photobucket site, do a search for my "xafalcongs" handle and you will find it. My motor mounts are for a truck and use 2 bolts to attach to the engine block and then 1 captured bolt that runs down through the frame mount and is secured by 1 nut and washer from underneath (much like the Fox body motor mounts). I tried the larger 3 bolt motor mounts (for a T-bird) that used a long through bolt that runs parallel to the engine and through both the engine mount and the frame mount. The problem with the 3 bolt mounts is the drivers side header primary pipe will rub on the metal portion of the mount. The 2 bolt mounts are much lighter also....both mounts weigh about the same as one of the 3 bolt mounts. I have to make my own frame mounts but it wasn't that hard.

Headers for a 351C in a Fox will work but you may need to make some minor mods to the floor pan because the 400 will move the collectors outboard by about 1/2" - 3/4" per side and will move them closer to the floor pan by about 3/8"-1/2".

For tranny, if you can swing it, try to build your own and swap in a wide ratio AOD. You will need one of the conversion kits to mate it to the big bellhousing bolt pattern but with 3.08:1 gears, I think you will be much happier with the results of a good 1-2 ratio (2.84 vs 2.48 first gear) plus the OD. With a 25-26" tall tire, you should see 2000-2100 rpm at 70mph. That means one kick down and you are in the sweet spot of your torque curve, about 2800-3200 rpm.

 

the thing with a 400 in a light car is that you can gear it with 308 or 275 and with the low end torque you don't need to get past 4500rpm. youd have close to 400hp if not more and 450+ ft lbs. I''' be building a '75 stangII for scca fun and would love to drop in a 400 special...aussie heads...pretty much the engine i'm working on now....it would be a monster in the short courses.

Then I'd consider adding the over/underdrive and 325 gears....final drive of 2.2 for doing the billion mph on the interstate and lower gears for whatever comes up short range 6 gears- built c-4 with shift kit- index 'slap' shifter- bring it on

and when the 400 takes 1-4 in jegs engine masters this year there will be parts readily available to make the 6k rpm or more...intakes, crank, rods, etc.

 

joe,

I picked up on the fact that you say your cam is worn due to low oil pressure. If oil pressure were low enough to wear a cam, the rest of the engine would be toast.

What oil or oil additives are you using? If you are not using an oil with ZPPD or an additive to give you ZPPD, this is what is wearing out your cam and lifters.

Not long ago, the oil companies started making the assumption that modern engines have roller cam followers so there is no longer a need for ZPPD additive since it is only needed for flat tappet cams. This is ALL brands of standard oil INCLUDING synthetics.

To make a flat tappet cam live, you currently have three choices; oil for diesel engines (such as Shell Rotella T, Chevron Delo or Mobil Delvac,) Racing Oil such as Pennzoil Racing Oil, or Engine Oil Supplement(EOS) from the Chevy house added at every oil change.

The diesel engine oil will soon be reformulated such that the ZPPD will be removed from it, so I don't know how long this will be a viable option.

I think that it is terrible that the oil companies have done this without really telling anyone about it, but if we will all pass the word, then us guys with old engines can keep them running.

 

This is very intresting, since it happend to me, not only the cam got trashed, but the cilinder, bearing etc too, I had to disassemble the whole thing again, so how do I know which oil brings the ZPPD ?

Danlee I am comparing the comp cam XE274H and the crane cam H-278-2 since its the range Im aiming for, I was going to use the crane H-288 but I found it extremly agresive, since I milled my heads "0.02" and I am going to buy tmeyer pistons Im gonna have a 10:1 ratio, will I be able to use pump fuel with any of the first 2 cams ?