[szpilafam]

My Son Has A 351w With A Stage2 Summit Intake He Currently Has A 600cfm Edelbrock Carb 1406 Model, He Wants To Get A 750 Cfm Carb, Is That To Much? It's On A Full Sized Bronco And No Intentions Of Street Racing, But It Lacks Any Real Umpf When He Gets On It In The Mud

[cobalt327]

If this is an otherwise stock engine, the 600 will work OK, but the 1406 is calibrated for economy, not power.

The ignition timing curve will need help, and if the timing set is stock (depending on the year), it could have the cam excessively retarded for emissions compliance. If so, a new timing set will help.

Headers, dual exhaust will also help power, w/o hurting drivability or mileage. Lower rear gears might help depending on what it now has, but drivability and economy WILL be affected.

A mild cam could help if the engine is otherwise in good shape.

[302 Z28]

No he does not need a 750cfm carb, the 600cfm carb is closer to what the engine needs for the purposes stated.

Vince

[eloc431962]

Originally Posted by szpilafam

My Son Has A 351w With A Stage2 Summit Intake He Currently Has A 600cfm Edelbrock Carb 1406 Model, He Wants To Get A 750 Cfm Carb, Is That To Much? It's On A Full Sized Bronco And No Intentions Of Street Racing, But It Lacks Any Real Umpf When He Gets On It In The Mud

Carb size will depend on the modification of the engine JMO. But if it's a stock engine then the 600 should do a fine job. You can go bigger but if not careful it will be over kill . IMHO I have ran a Holley 3310 vac sec on a basically stock windsor and it performed really well.



Cole

[Irelands child]

Depending on the year and casting number of the heads, almost anything you do carb and intake wise might not help much. Dinky valve sizes after about '75 and the EGR hump in the exhaust will 'kill' any external mods.

[szpilafam]

thanks for the replies, he has put some money in it but just the intake and a carb spacer???? all the emmisions crap has been removed except for the exhaust he has ordered new headers. there is a vacuum timing advance it's hooked up but let me throw this at u, when he stomps it it just kinda goes, nothing crazy, and i'm thinking u got a 351 wheres the power? no burn outs or anything, i know it's a big truck but i used to have a f150 with the same engine and it would squawk 'em. i ve had to turn bothe the adjusting screws almost all the way in or it runs like straight doodoo. he's not looking to race 'em but we live in the country and like to mud, i wanna see him throw some mud so i'd like to see more power he's 17 so he would also

oh yeah it's a 86 eddie bauer with 2 in lift other than that and the intake it's stock
also have a 81 with a 302 that will be modified pretty much like his when his is done.

[eloc431962]

Originally Posted by Irelands child

Depending on the year and casting number of the heads, almost anything you do carb and intake wise might not help much. Dinky valve sizes after about '75 and the EGR hump in the exhaust will 'kill' any external mods.

This is all true, I ran the 3310 on my 69 model windsor with the stock heads.
Still have that engine .



Cole

[NOlowrider]

What size tires? Over sized tires will kill the gear ratio, plus adding more rotating mass. Did the carb spacer add anything to the performance? Sometimes they can do the opposite of what you want. Make sure you put the correct one on. They are different types for different applications. Just my 2 cents.

[PancakesandSausage]

Originally Posted by szpilafam

thanks for the replies, he has put some money in it but just the intake and a carb spacer???? all the emmisions crap has been removed except for the exhaust he has ordered new headers. there is a vacuum timing advance it's hooked up but let me throw this at u, when he stomps it it just kinda goes, nothing crazy, and i'm thinking u got a 351 wheres the power? no burn outs or anything, i know it's a big truck but i used to have a f150 with the same engine and it would squawk 'em. i ve had to turn bothe the adjusting screws almost all the way in or it runs like straight doodoo. he's not looking to race 'em but we live in the country and like to mud, i wanna see him throw some mud so i'd like to see more power he's 17 so he would also

oh yeah it's a 86 eddie bauer with 2 in lift other than that and the intake it's stock
also have a 81 with a 302 that will be modified pretty much like his when his is done.

One thing you didn't mention was tire size. It all depends what size tire he is running right now, especially if he is mudding. Large tires with high axle gear ratios will KILL responsiveness. If the engine is running fine otherwise, I would leave the 600 on there and get a steeper gear set. He WILL feel a difference. If he is running 35s, 4.56 gears will be perfect, but be forewarned, he'll also feel it at the gas pump. Most folks don't realize how important a proper gearset is for the "feel" of a vehicle.

[PancakesandSausage]

I forgot to mention--a 750 will probably be overkill for the engine. Too much carb can be worse than too little. The 1406 is a great all around carb for mild builds. I am willing to bet the sluggishness is due to the gears.

[eloc431962]

You do need to take everything into consideration. I use to run mud trucks several years ago and yo need to factor it all in tire size rear gears.What trans you will be running all the mods to the engine.JMO



Cole

[szpilafam]

stock gears, he does have 33's wants 35's specially since we just lifted it but man they r like super xspensive!!!!!! craigslist must have been created by the good Lord himself cuz i've found a couple great deals locally, looking tough isn't the problem, out here you either have a fast car or a fast 4 wheel drive, his has the potential and his only bills are insurance and gas so all the money he makes goes into the truck, i used to work on diesel engines in the army but carb engines...eh, not so good at. i want to give him enough to show off a little but not to much to get him in trouble!!!! i also have a bronco an 81 with the old 4 speed granny 302 in it, and i can burn em off if i want to but, prefer to play in the mud. he wants to go muddin with the boys and old dad gets to tag along but i want him to get some more juice without sacrificing lift/ tires/ etc.

[spinn]

The 600 should be fine.

If the carb is vacuum secondary , always over carb. Take the benefit of a stiffer spring in the secondaries to limit cfm. The primary velocity can be much stronger resulting in a power gain.

Some non performance 3.8 v6 factory engines came with 750 cfm Qjets.

[PancakesandSausage]

Originally Posted by szpilafam

stock gears, he does have 33's wants 35's specially since we just lifted it but man they r like super xspensive!!!!!! craigslist must have been created by the good Lord himself cuz i've found a couple great deals locally, looking tough isn't the problem, out here you either have a fast car or a fast 4 wheel drive, his has the potential and his only bills are insurance and gas so all the money he makes goes into the truck, i used to work on diesel engines in the army but carb engines...eh, not so good at. i want to give him enough to show off a little but not to much to get him in trouble!!!! i also have a bronco an 81 with the old 4 speed granny 302 in it, and i can burn em off if i want to but, prefer to play in the mud. he wants to go muddin with the boys and old dad gets to tag along but i want him to get some more juice without sacrificing lift/ tires/ etc.

I had a '79 K5 Blazer with a mildly built engine, 1406 Edelbrock, Performer intake, headers, etc. It had 33's and then I jumped to 36" Swampers. I never changed the original gears and it ran like a dog (very slow) but I didn't care because it was a pavement pounder. I noticed a difference when I put in a 14 bolt rear with 4.10s. If his plans are for 35s in the future, you DEFINITELY want the steeper gears. I would say 4.56 at the very least to put him in the correct power band. I think your tranny has overdrive(?) so he will get better mileage than w/out OD. Again, I wouldn't invest in the engine if it is running fine, especially if he uses it on the street alot. Big trucks with big tires can perform very well with the right gear/tire combo and a stock engine. Same principle when Jeeps with 4 cylinder engines with big tires do a decent job--they have the right differential gears.

If I ever wanted to stomp on it, I would just put the tranny in 2 low. It had a 350TH in the Blazer.

[JeffB]

Maybe check out Howard Cams for one of their Torque grinds also Crower Cams has the Baja Beast series of cams,then get the distributor curve upgraded to match.