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New motor,or lower gears,or both

B

BigBK5

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I towed my boat to the lake this weekend up hills and lots of turns.It was very slow going. My 74 blazer has stock 350 with a new eddy performer intake,holley 600 carb,th350,203 tc,35in toyo mt,373 gears.I know my gears are probably not low enough,but was wondering if a peppier motor would compensate. Im sure the motor is original and probably worn.Im ok with doing a gear swap and a motor upgrade,but would rather do one or the other. Opinions? Concerns? Insults? Don't really plan on wheeling this pig,just want to tow my boat topless this summer.

Brian
 
How big of a boat?


That is the real question.

My 79 with 3.42's and BFG 35's (33.6's) was fine. Plenty of power.

Swapped in 4.10's in a different pair of axles and some Nitto 38's (37's) and a 700r4 and now she is gutless at highway speeds.

Point I'm trying to make is your gears, with the 3 speed, should be ok with 35's, if you had overdrive I'd say gears for sure...

So how big is your boat?
 
18.5 foot reinell w/v6. Don't know the weight.My 04 tundra pulls it just fine.
 
7ac.jpg



Yeah, that boat with trailer is probably 4000 lbs. Or more.

You need powwa
 
Your 04 tundra spanks the k5 in a race huh?
 
Your original motor from ‘74 had about 150 hp so I’m sure it’s less than that now. My vote is a new engine since it’s probably overdue and take it from there.
 
A big block would compensate for the high gearing & big tires,but the transmission will suffer from the extra strain and may fail prematurely..
It will also empty your wallet at the gas station much faster too..

Smaller tires would lower the gearing and weigh less,that would probably help a lot without doing much else,unless the engine is just plain tired..
 
I'm not sure my setup is quite dialed in for towing yet, but with the L31 long block and TPI (should be over 250HP and well over 350ft lbs), even towing ~2500lbs on steep hills (3.42's/33's/SM465) I could not maintain freeway speeds. Those are pretty steep hills, but if the L31/TPI combo can't handle it with probably 2000lbs less, I don't know as there is much likelihood for success with any 350CID engine that isn't forced induction. Or, dropping it into second and spinning the engine at 5000RPM.

OP and I are running nearly the same RPMs, so I think it's a pretty valid comparison, except I don't have a torque converter. That much additional weight, I doubt anything but additional displacement is going to help. Maybe 4.56's and hope for the best, but if I was going 4.56's and not towing all the time, I'd be looking for an OD trans, and the costs just start piling on from there. I'd agree with skunked's recipe. Except maybe an NV4500 because I hate automatics. :)
 
an NV4500 would work too. Since he has an auto now I would look for an L29/4L80E (or the 4L85E) combo out of a truck or burb. Put a cam and a tune on it and it will yank his boat all over town and down the highway like a boss.
 
Problem I have seen with both my own and my Dad's rig when he had a squarebody (both 350 and 454, 465 with and w/out gear vendors overdrive, 4.10's, and 32's) is that if the axle gearing isn't just right, your choice is lugging at 1:1 trans ratio, or engine screaming at ~2:1, and/or slowing the heck down. OD with some pretty steep rear gears is the answer IMO. Something that puts the 1:1 ratio somewhere around 3-35000RPM seems to be a pretty good spot. 35's/4.88/1:1 trans gets you almost to 3000RPM. OD would tame the RPM's when not hill climbing or unloaded.

Heck, if one was going with a manual trans, you could do the NV4500 swap and gears, then decide later if the BBC is a necessity. If going 4L80E, I would do it all at once.
 
3.73 gears and 35's isn't that bad of a combination on the highway. You will start screaming the engine with no overdrive in the transmission if you go much lower. Keep in mind the the OP mentioned maintaining speed on hills while driving on the highway and not fourwheeling or taking off from a stop. Also, 3.73 gears in a 1:1 drive trans (no OD) is even lower geared than if you had 5.13 gears with a 700r4 (5.13 x 0.70 = 3.59). The upside to having a 700r4, or other OD trans, is you do have another gear to choose from which gets you lower but then you still have the ability to shift to OD to calm down the RPM a little.

My opinion would be to concentrate on the engine because if you go to low enough axle gears to notice a difference than you will also deal with screaming the engine when you get over 50 mph. An '04 Tundra V-8 was rated around 245 HP so likely a lot more than what the '74 350 is putting out.
 
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