305 upgrades?

[turbosix]

First thing I would check would be my timing. Timing that is retarded will kill power.
Also, as noted earlier. A 2004R should be an easy swap due to it being the same length as the 350 (you can use the same drive shaft), but if you got a 700R4 from a square, just get all parts needed.

[69chevytrucker]

Originally Posted by Gmc-76

I think I'm going to find a 700r4 and swap it in and do a rear end re-gear later on. That and a dual plane intake should be just fine for now. Will a 700r4 out of a 4x4 work with my 2wd? Is there any way I can just remove the transfer case and it will be a direct swap?

nope that wont work at all tail shaft will be diff

[Gmc-76]

What would I find a 200r4 in? S10/blazer? And I found a lead on a 305 mated up to a 700r4 out of a 87 Monte Carlo. would the tranny from the Monte Carlo be a direct swap into my 85 c10? Sorry for so many questions, I'm not much of a transmission guy

[gchemist]

Yes, the car 700R4 will fit. You have to move the trans crossmember back about 1". The holes are drilled already too. You'll have to find a drive shaft thats fits from a truck or have yours cut and balanced.
A 200R4 is basically found in cars.

[Gmc-76]

Some what sad news....my dad wont let me do a 700r4 swap until EVERYTHING else on the truck is fixed...I found a 90'k5 that ran and drove and I could even test drive for $500(body was literally shot)I hate bieng 16 sometimes so now I have to play the waiting game...

[TwoFiftyShifter]

Get to work!

Seriously. If you show that you have the gumption to repair the truck, pops may just let you swap some parts.

I'd recommend a 3.42 gear swap myself. Keep your transmission.

[Gmc-76]

TwoFiftyShifter... Believe me, I work! Its just hard for me to stop after I start haha. Ive parted out 2 squares and a 89 k1500 so far, and managed to make money on each one

[50seven]

Under the hood check for vacuum leaks. Biggest power robber of any old sbc. Block off the EGR another big vacuum leak IMO.

Change out the rear diff. Find a diff from a 1/2 ton 4x4 they are usually 3.42 or 3.73. The axles should be interchangeable so you can slide your 5 bolt axles right in. Usually the gear ratios can be found on the option list in the glove box. GT4 = 3.73 gears GT5 = 4.10 gears G80 = posi diff. Do some research. If you have a 10 bolt replace with a 10 bolt so all your parts will work easy breezy

[Gmc-76]

50seven, I haven't checked for vacuum leaks but that's a good idea, thanks. In the glove box it says 2.73 rear...this truck still has the original owners manual and everything from the factory!(I'm the 2nd owner) and I'm going to try to find a 3.42. I need to get that 700r4 action going now

[gchemist]

What size tires are you running? 3.08 gears are better suited for 255/60R15 tires. It's what I run on my truck. Over all drive ratio makes a difference.

Check for a rebuilt carb: http://www.nationalcarburetors.com/

A tuned Q-jet wil blow away most carbs. Using vacuum and RPM gauges to tune make a huge difference. You can learn. It just takes a little learning and time.

[Gmc-76]

gchemist-Im running the same size tire as you. What do you think a 3.08 rear and 700r4 would get me? I have a tach, just have to install it this weekend. I might try to rebuild the quadrate myself..it would be a good learning experience.

[gchemist]

With a tonneau cover, my ZZ4 ~355 HP/405 ft/lbs can manage 18.5 MPG with the right conditions. In the city, I average ~13 MPG due to a 2500 stall converter. It locks in 3rd or OD. I usually drive around in 3rd, unless speeds exceed 45 MPH. The old stock 305 managed about the same MPG. Maybe a little higher on the highway up to 65 MPH. Click on my videos. The 3.08 gears can work. The first 700R4 gear is deep. I can light up the peg leg tire for more than a block if I keep my foot to the floor.

[Gmc-76]

Awesome. So a 700r4 and a 3.08 rear, with a dual plane aluminum intake and a carb rebuild/tune is the way im going. Hopefully with that setup, I can make a few rice burners see my taillights.

[bdiamond]

The trouble with a 3.08 and a 700r4 is that cruising rpm are so low the engine isn't stays out of the "sweet spot". Mileage will suffer and the trans will tend to lock and unlock all the time.... Well, unless you cruise at 85+, then carry on...

[Gmc-76]

bdiamond- I cant imagine what my old 86 was then, it had a 700r4 and a 2.73 rear...i had it doign 85mph no problem one time

[gchemist]

bdiamond is correct about SB having a sweet spot. Gmc-76 will drive the same combo I have now. My ZZ4 turns 1950 RPMs at 70 MPH. It's in its power band above 1500 RPMs. The torque is relatively flat. Add more RPMs and the truck flies!! TX 45 with a speed limit of 80 is fun to drive on. The engine turns more RPMs, higher torque band, and flying like you wouldn't believe. His 305 will be at the bottom of its torque band. Stock engines like 2000-2300 RPMs for cruise speeds. The 700r will put 70-75 MPH right in the gap. He'll need to really tune it and work on it. If compression, timing, exhaust, and intake work good, I think he'll be happy. I was ok with the old stock 305. Now, I'm crazy happy with my ZZ4.

[Rich84]

When I installed my 700r I had 2:56 gears with 30" tires..It felt like a dog off the line. 1800ish RPM's at 70mph. 3:73 gears really woke it up and put it in the "sweet spot"

[Gmc-76]

Im thinking stock exhaust manifolds, true duals (2.1/4'' pipe) with flow master 40's and either 90's behind the rear tires or 45's dumped tucked up as much as possible. These old trucks don't have to be slow. I want mine to be able to cruise highway speeds (65-75mph) and I will be satisfied

[Gmc-76]

Been doing lots of little work to the truck lately. Does anybody think I should make a build thread???

[Rich84]

The Flowmaster 40's are going to drive you crazy on the highway. They drone like crazy.

[motornut]

Originally Posted by Gmc-76

Im thinking stock exhaust manifolds, true duals (2.1/4'' pipe) with flow master 40's and either 90's behind the rear tires or 45's dumped tucked up as much as possible. These old trucks don't have to be slow. I want mine to be able to cruise highway speeds (65-75mph) and I will be satisfied

sounds about what my Jimmys are running,just love em
I grind out my manifolds,get rid of those bumps.
next I'm pulling the old stock,2B for a new QuadJet...
Older performer intake,gona paint blue to look stock for 79.

[Tom]

Originally Posted by cable666guy

, plus the od would let it run faster at a given rpm compared to the th 350.

You've got that backwards.

OP- why would you think stock manifolds when you are looking for power? Nothing gives more power for the dollar spent then headers when it comes to easy mods.

[Gmc-76]

At some point I plan on getting a set of headers. I think what cable666guy was trying to say at a given rpm(ex:1500rpm) that my stock truck with the th350 in the final gear could only go around 55mph(if only given 1500rpm). If my stock motor with a 700r4 behind it was in the final gear @1500rpm it could go around 70mph(if only given that 1500rpm). cable666guy, correct me if I'm wrong

[Gmc-76]

Originally Posted by motornut

sounds about what my Jimmys are running,just love em
I grind out my manifolds,get rid of those bumps.
next I'm pulling the old stock,2B for a new QuadJet...
Older performer intake,gona paint blue to look stock for 79.

motornut, out of curiosity, are you running true duals? What size pipe? Also does your jimmy have the emissions junk on it?

[motornut]

Originally Posted by Gmc-76

motornut, out of curiosity, are you running true duals? What size pipe? Also does your jimmy have the emissions junk on it?

yup both trucks are true duals,but (79-305) has an H pipe,both @2.25,no Ejunk really