Am going to rebuild a 351M into a 400 and installing a different cam, roller rockers, headers, etc.
I see in the forums that people either run Holley or Edelbrock carbs. What is wrong with the stock Motorcraft carb that is currently on my 351 after it undergoes a rebuild also? I'm only going to run on the street and no off-road stuff. Not planning on turning the motor more than 3500-4000 RPM's.

Also, I want to install different cam. Am lookin at Comp Cams part #'s 32-219-3 (260H) and 32-221-3 (268H). Want a little more HP, torque, MPG than stock cam and want a little more "throatier" exhaust sound with somewhat smooth idle (can have a little lope but not much) Which one of these two cams would be recommended? Positives/Negatives of each. Am planning on headers and dual exhaust.

Am interested in Comp Cams cheaper roller rockers (stamped steel rocker w/ roller on push rod end). Are these better than stock or would I be wasting my money. Probably need new rockers anyway as stock ones have 145,000+ miles on them.


Thanks for any and all information!!
Eric




1978 Ford F250 Crew cab, short box, 4x4 undergoing frame-up resto.

 

The 260H is going to have a much smoother idle and will probably give better economy than the 268. The 268 has the potential to make way more power. The 260 also works at a slightly lower RPM range. Your choice.

 

The 268 makes plenty of low end torque in my 460. It has a slight lope when warm.
Jimmy

 

The stock carb, even if it is a 4BBL, isn't really a performance carb. Specifically, it runs too lean. If it's a 2BBL, it's too small to get more than 4000rpm out of that engine, and it will struggle to get that. A friend of mine has a 400 with an Edelbrock performer intake, and a Holley 650 double pumper. That truck can really move with this setup, and he has gotten better than 14mpg on the highway with it.

 

Get a dual pattern cam for that engine.

 

The main advantage of a better-than-stock cam is to allow the engine to "breathe" better, which means more airflow.

The stock Motorcraft 2V carb can be tweaked to allow more airflow, but the maximum practical airflow is probably about 400-425 cfm. A 4V carb will allow much more airflow, which will support higher rpm power.

I wouldn't recommend either of the cams you mentioned for the 400. Dual-pattern cams are better suited to optimize breathing with the 2V Cleveland-style heads.

I like the Comp 265DEH (32-207-3) or the XE262H (32-242-4). Either of those cams will give you more power than the 268H in a 400.

Don't waster your money on semi-roller rockers. Go full roller for the maximum benefit.

 

Called Comp Cams to ask their opinion on what cam to use: either 260H or 265DEH (dual pattern) and he said to go with 260H since I want a towing rig running auto slush box, stock converter, 4:10 gears, 33" tires, 2bbl stock carb, etc. Why do you guys say to go with dual pattern cam when cam manuf. say otherwise?

Thanks!

eric

 

Eric, I can e-mail you a short 5 second clip of my 268H in my 460 idling if you want to hear it.
Jimmy

 

Experience.

I have seen several dyno runs (not computer simulations) where shorter duration, lower lift dual-pattern cams blew away longer duration, higher lift single-pattern cams in Ford 400 engines.

I have never (yet) seen a single-pattern cam live up to its "potential" in a Ford 400 engine, and I've seen even milder dual-pattern cams than I suggested nearly double the stock torque and hp numbers in a Ford 400.

The best I've seen from the 268H in a Ford 400 was barely 300 hp (and just over 400 ft lb torque). I've seen the 265DEH hit almost 400 hp and almost 500 ft lb torque.

Look at the factory cams used in 351C 2V and 351M/400 engines. They're all dual-pattern cams.

The only 335-series engines that used single-pattern cams from the factory were the highest performance 351C 4V engines (the Boss and HO only). Breathing characteristics of the 4V heads are completely different than the 2V heads.

Don't get me wrong, I like Comp Cams products, but I'd bet the guy you talked to on the phone has never built a Ford 400, and likely not even a 351C. At best, he was probably going by a chart that somebody else wrote up, perhaps based entirely on "theoretical" guesstimates.

 

http://www.iskycams.com/techinfo_index.html

read Isky'ds tech tip on dual pattern cams. they feel that dual pattern cams give up low to mid-range torque to gain high RPM horsepower. If that is the case then as soon as you said "towing" you eliminated the dual pattern cam. Is this true? Only the dyno will tell, but it is food for thought.

 

Darn, Sounds like you just need to install a 460.
No substitue for cubic inches I guess.
Jimmy

 

Alright guys, you've really gotten me confused!!!

Bubba - I would like to see some dyno results (numbers, graphs, etc if you have them) of a 351M/400 running a dual pattern cam as well as all the particulars about the engine/intake/exhaust setup like 2bbl or 4 bbl., intake, headers or manifold, dual or single pipes, mufflers or not and what brand if any. There are sooooo many variables in producing HP and torque. Your comments go against the Isky cam link that was posted as well as the person from Comp Cams that I talked too.

Are you running dual pattern in your truck?

If the stock cam is already dual pattern, what type of cam do we use to gain more HP and torque?

Here is what I am planning on doing: converting my 351M to a 400 ci. motor (not a problem), using stock intake manifold, stock Motorcraft 2bbl carb, roller tip rocker arms, headers (maybe Hedman or any other suggestions?), dual pipes (~2.5" to 3" diam), dual Flowmaster mufflers, C6 tranny on 4x4 pickup, stock converter, 33" tires, 4:10 gears and wanting good hp and torque in the 1000-3500 RPM range for possibly towing a camper trailer (or just to feel the "get up and go" potential of the engine. I am not planning on turning the motor faster than 4000 ever (if I can help it!)

I'm not doubting your experience, just want to make sure I've done my homework before jumping into a cam purchase and then realize I could have had better performance from a different cam setup.

Thanks for everyone's comments and suggestions!!! If anybody has dyno results (numbers, charts, etc) from 260H or 265DEH in a 400 Ford, sound clips from running motors, etc, feel free to email them to me.


Eric

 

You guys should read the Isky article a little closer.
That article is about racing engines, not street engines.
If your upper rpm objective is 4000, there is almost nothing relevant to your situation in that article.

I'm running a dual-pattern stock 351M cam in my truck.

To gain more torque and hp, you should use a dual-pattern cam with more duration and lift than the stock cam.

If you're going to keep the stock carb, you'll be limited to 350-400 cfm, which will be barely adequate at 4K rpm. I'd recommend using a 600 cfm 4V carb.

If you're going with headers, look for equal-length tubes and the smallest primary tubes you can get; 1.5" is ideal, 1.75" is too much. I'd recommend a 3" Y-pipe and 3" single exhaust. Take your pick on decent quality performance mufflers (Borla, Dynomax, Flowmaster, Gibson, whatever).

Since you're most concerned about power in the 1K-3.5K rpm range, I'd suggest the 255DEH dual-pattern cam.

Give me a couple of days to dig up more detailed numbers/graphs on some cam dyno tests.

 

No question about dual pattern cams making more power on Ford heads with their typically screwed up exhaust ports, but for towing, he's concerned with what happens at 1500-2000 RPM. Low to mid RPM torque is the primary consideration and whatever happens at 3500-4000 must take a back seat. Isky's contention is that single pattern cams make more torque, dual pattern cams breathe better at higher RPMs and therefore make more power.

I don't know if this is true or not, but it is a possible explanation for CompCams recommendation.

 

I would tend to believe that CompCAms knows what the hE*^ they are talking about. They have been building valvetrains for many years.
If you told them what you were building and what you wanted the engine to do, then I'm sure that they recommended the best camshaft for your explanation.
For better high rpm horsepower and breathing, a split pattern cam will work better to help compensate for the poor flowing stock exhaust ports.
For more lowend usable torque, a single pattern cam will be fine. Some restriction on the exhaust will create more back pressure and increase low end torque and throttle responce.
I know that back pressure makes a difference because 364 days a year when my 5.0 LX is driven, it has an offroad exhaust on it. It loses some low end punch, but pulls better from 3000 to 6000 rpm.
The other 1 day a year, when it goes for emmisions testing, I reinstall the stock converters and it has more tiresmoking low end grunt, but falls off about 5000rpm instead of 6000.
I would use what the cam manufaturer told you because it is designed to do what you want it to do.
They wouldn't stay in business very long if they were to go around selling the wrong cams to everybody.
Jimmy