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Opinions on swapping in a 454.

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william_7900

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I have a 350 in my 71' Blazer but it has absolutely no guts... It doesn't smoke but just doesn't turn the tires very well. I am running 4.11 gears with 35" tires (even with 33's it doesn't have much umph....).

I don't want to change the gears because i don't want to be running a 3000 RPM's at 65 or 70...

I swapped in an NV4500 5 speed tranny a few years ago. Also it has a new carb.

What are the negatives of doing this swap and what must I change? (added weight, things that will twist up behind a 454 that wouldn't with the 350, differences in torque etc...)

I'm mostly interested in just making the thing fun to drive again...

I swapped a 360 into one of my Jeeps back when i was a Jeep guy and it made a huge difference in just general drivability - I'm hoping for the same if i swap in a 454...

Thanks for the feedback and help.

William
 
theres not much to look out for really,should be a really simple swap. what axles and t case do u have?
 
hmm...well a stock BBC shouldnt hurt them (on road) if its built a little and u do go offroad u might have some issues. u might want to swap in some 1 ton axles if u plan on going offroad with 1/2tons and a big block, or be easy on it.
 
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My buddy dropped a 454 into a "cab on blazer frame" with a flatbed and that thing was "fun to drive" He was running 36" TSLs w/ 1/2 ton axles and he faired ok but all he drove in was mud!
 
Build a 380hp 450lb/ft torque 383. Have the power of a BB and weight of your stock motor. I did this with 4.56 gears, locker, and 35's in my 81. That thing was a beast. Ah hell go with a 500 lb torque 454 and throw some 1 ton running gear under it and kick ass with some 40" boggers!!
 
It's a pretty straight forward swap but there are a few problems with big blocks in first gens.

The biggest problem is firewall clearance. The solutions are move the engine forward 2 inches, 2-3 inch body lift, or cut the firewall for clearance or combination of all three. Be careful if you decide to move the engine foreward because you can run out of fan clearance in a big hurry especially if you're using a long water pump.

The second problem is oil pan clearance. Make sure you use a single step oil pan (pan is straight and drops down to sump) not a double step oil pan because it will not clear the crossmember.

Headers can be a pain, I really haven't found any headers that fit and don't get in the way of the front driveline, the shackles and everything else. I've found it helpful to install 1/2" spacers between the motor mounts and the crossmember so the header tubes don't hit the crossmember.
 
trailblazr81 said:
Build a 380hp 450lb/ft torque 383. Have the power of a BB and weight of your stock motor. I did this with 4.56 gears, locker, and 35's in my 81. That thing was a beast. Ah hell go with a 500 lb torque 454 and throw some 1 ton running gear under it and kick ass with some 40" boggers!!
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Those are similar to the numbers that my 383 makes and my 1/2 ton drivetrain did not fair well with it on the street.

Within 6 months of building the motor I blew up a driveshaft u-joint, broke a t-case yoke and sheared the bearing journal off of a 12 bolt detroit :eek1: (luckily that one was warrantied and I got my money back and applied it to 1 ton stuff). All of this was on the street, but I can't say I was easy on it (you know, 18 year olds with 400 hp :rolleyes:)
 
Methinks you just need to beef up the 350.

Unless you are moving a LOT more than 5000lbs, a 350 should have pretty good get up and go. I know mine does, and I wouldn't trade it for a BBC unless I needed to tow some crazy weight.
 
dyeager535 said:
Methinks you just need to beef up the 350.

Unless you are moving a LOT more than 5000lbs, a 350 should have pretty good get up and go. I know mine does, and I wouldn't trade it for a BBC unless I needed to tow some crazy weight.
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When you say "beef up the 350" - what do you have in mind specifically?

thanks for the feedback.

William
 
Hes talking about roller rockers, air gap intake, bolt on stuff. screw it go with the big block there both gonna get crappy mileage! lol half ton axles are strong as long as you dont turn! lol save up for your 1 tons then you will be set. 454 and 1ton axles = good times!
 
I put a 454 in my 72. I will never run an SBC again. 454 = Fun to Drive
Lots of lowend power too without the need for higher RPMs.
I vote BBC all the way! :D
 
Why dont you just add a Edelbrock Performance Package (Heads, Cam, intake and carb) to the 350. Supposed to give you about 400 HP. That should be enough to move your Blazer pretty good. ;)
 
william_7900 said:
When you say "beef up the 350" - what do you have in mind specifically?

thanks for the feedback.

William
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Heads, exhaust, rebuild if the engine is worn out. Heads and exhaust themselves can be upwards of +80HP if done right, and thats based on many independent dyno results.

Absolutely no reason on the planet to deal with the mileage of a big block, nor the added weight or expense (oh, lets see, bracketry, exhaust, acquisition cost, new fan shroud, radiator, and what else?), if you have no intention of ever needing the power it will provide.

I don't know about everyone elses trucks, but 13/16MPG with no overdrive beats the hell out of any old BBC comparably setup I've ever seen by a large percentage. At least a 10% increase in economy, minimum.
 
All I know is the E tec 220 rpm edlebrock kit I had for my 350 made great mid to top power but still suppossedly 400+ hp but but between the carb and lack of low end it had to go! I think sometimes I should have went stock vortec fo-fiddy-fo....
 
dude i wouldent do it.... i did do it and im still in the middle of the swap. going from a 350 to a 454. everything is diffrent man, motor mounts, trany, t-case. you cant use any of ur old stuff, youll need a new distributer, headers, alternator, radiator, most lilkley drivelines if you dont keep the same t-case... ah its a nightmare. just put in a newer, stronger 350. thats the easy way to go. i got one out of an 87 with 85k in it. motor trany and t-case
 
Burt4x4 said:
I put a 454 in my 72. I will never run an SBC again. 454 = Fun to Drive
Lots of lowend power too without the need for higher RPMs.
I vote BBC all the way! :D
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x2! Finished my swap about a month ago. Fried the rings in the 350 then found a low milage 454. Put in a comp cam with new lifters, timing chain, HV oil pump flowtech headers, holley 770 street avenger,and weiand intake and have been tickled pink since. Sold all my sbc junk.
 
73redblaze said:
dude i wouldent do it.... i did do it and im still in the middle of the swap. going from a 350 to a 454. everything is diffrent man, motor mounts, trany, t-case. you cant use any of ur old stuff, youll need a new distributer, headers, alternator, radiator, most lilkley drivelines if you dont keep the same t-case... ah its a nightmare. just put in a newer, stronger 350. thats the easy way to go. i got one out of an 87 with 85k in it. motor trany and t-case
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Wuh chu talkin bout? EVERYTHING bolted up in my swap. Besides the obvious like the dizzy and headers. And its really recomended to upgrade the radiator. I used the factory 454 mounts that came with the motor.
 
I vote 454. Even a "mild" 454 will be better than a new 350.

73redblaze said:
dude i wouldent do it.... i did do it and im still in the middle of the swap. going from a 350 to a 454. everything is diffrent man, motor mounts, trany, t-case. you cant use any of ur old stuff, youll need a new distributer, headers, alternator, radiator, most lilkley drivelines if you dont keep the same t-case... ah its a nightmare. just put in a newer, stronger 350. thats the easy way to go. i got one out of an 87 with 85k in it. motor trany and t-case
Click to expand...

Unless you had a BOP 350 in there to begin with. The 350 to 454 swap should be pretty easy. Motor mounts are the same, bellhousing is the same bolt pattern. Distributor is the same, the 350's alternator will work if you get the correct brackets, same thing with the power steering pump. The starter is even the same. The only thing you really need is headers/manifolds, and possibly a bigger radiator.
 
well i dont know that much but i do know i had to change my motor mounts, headers, radiator, ext. the alt was just old. but yea you will most likly have a th350 if its a half ton so you will need to get a th400 with a 32 spline t-case. atleast that was what i had to do. i just would swap in a 350 if i could start over.
 
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