hi i am a new poster here so this is my first question. I have 79 bronco with a 351m, auto, stock converter, 3.50 gears, and 36inch super swampers. It also has a Edelbrock performer intake and a 600 performer carb with a 1inch divided carb spacer. I just installed a comp cams xe262h cam which is 218/224@.050 and .513/.519. I also installed matching valve springs and melling stock replacment timing set. I have lost most of my bottom end power and it makes ok power above 2500 rpm. My question is does any one now if that melling stock replacment timing set is 4* retarded like a factory timing set. I know i need at least 4.10 gears but i would think it should run better than it does. Do you guys think it is the cam or the timing set. Thanks

 

Welcome to FTE.

Assuming the rest of your engine is in decent shape, the most likely causes of your problem are: a) timing set, and b) axle ratio.

No matter what the engine can do, running 36" tires with 3.5:1 axle gears will bog it down.

The "stock replacement" timing set probably has the factory retarded cam timing built in. You need a performance double-roller chain timing set with a multi-position crank sprocket. The multi-position crank sprocket will allow you to set the cam timing correctly (0 degrees). Retarded cam timing hurts low-rpm torque, and in your case, it aggravates the bogging problem your gears cause.

What about your exhaust system? You really need a good high-flow exhaust system to make the cam and induction changes worthwhile.

 

Thanks. I have a 2.5inch duals with magnaflow mufflers

 

My 400, C6, 3:55 gear combo works great! Thats with a stock 2V manifold and a 500cfm Holley, comp cams 268, ertl flat tops for 9-1 comp, and Heddman headers with turbo mufflers. I think the extra 50 cubes and straight up timing helps alot with the low end. I have no problem barking my 15.5/35/15 TSL SX's with this combo and these are some heavy tires. I would think you could turn those 36's with ease.
Just my 2cents

 

Yeah, I can spin my 35" x-terrains with my 400 and I have 3.5 gears. I can, however feel the difference between 35" tires and the 33" tires I had before, definitely less low end pull. I have a Edelbrock performer and 600 cfm carb. I just stuck in a Truck Avenger cam (260/260 with .507 lift) truck has slightly more lope sound than before, but still idles well at 500 rpm, pulls a little better on the top end, and barks the tires more often when I take off. My old timing chain had a ton of slack, so I put on a new double row adjustable one, but the cam comes advanced 4 degrees stock.

Incidentally, I have read somewhere that the 4 degree retard only applied to car engines, and 400 truck engines did not recieve the retarded cam timing (my 78 F-50 w/ a 400 has a big sticker stating that it is non-emissions, and the fuel filler is not small (well it wasn't; I stuck a small one on when I swapped beds because it was taking forever to fill my fuel tank with the regular filler) so they wouldn't have had to retard it for emissions reasons.

Just a side note to Kopfenjager: I exploded my third member (both bearing caps busting in half) last year at Tellico when I got crossed up in the rocks, so be prepared. I still managed to drive out on the front axle, and the ring gear scraping the housing in the back.)

 

The 4 degree retard applied to truck engines also. My 78 F250 had some emissions controls, it was non-cat and ran on leaded gas. My 400 had a retarded timing set from the factory.

 

Make sure you've got enough ignition lead. You can experiment with increasing the static timing. If you don't have enough compression to match the cam it will help.

 

Unless you have a lot of weight in the bed, spinning the rear tires on a pickup is a lot easier than it is on a Bronco.

Apparently, the only post-'73 M-block engines without retarded cam timing were 351Ms in 1978 Broncos and 1979 HD pickups (F250/350).

The only emissions control devices that HD engines were exempt from were catalytic converters and Thermactor AIR (smog pump).

Even HD engines had retarded cam timing (usually), retarded ignition timing, and EGR. By '79 or '80, Ford started putting Thermactor AIR on HD engines also.

 

thanks for all the imput. I i now plan on putting in the nice timing set. Plus now im planning on putting 4.56 gears and building a nice 9.0to1 400. I need all the help i can get with my 5200lb truck. hope to have all this done in the next couple monthes

 

yes...spinning tires is a vicious thing on a bronco. The 104 inch wheelbase lends itself to really good weight transfer. Either there is wheelhop during a spin and ive even heard that one can pop a wheelie if launched correctly. I'm guessing its a rumour but has anyone heard about that?

 

So my '79 F150 w/ 351M is more than likely stocked with a retarded camshaft?

So, if I get a new camshaft I will need a new timing gear set and chain, right?