350 TBI tows 5000/6000lbs

General engine tech -- Drag Racing to Circle Track

Moderator: Team

donforeman
New Member
New Member
Posts: 28
Joined: Mon Feb 02, 2015 11:04 pm

350 TBI tows 5000/6000lbs

Post by donforeman » Fri Jun 01, 2018 12:55 pm

I purchased a clean low mileage 95 G30 van a while back. I looked and looked for something to tow with that was reasonable priced and was not beat up with fairly low miles. So when this one popped up I bought it without much thought. Turns out in 1995 Chevy made a G30 with all 3/4 ton running gear and that's what I bought not a true 1 ton van.

So the 4l60e started acting up a little and I rebuilt that a year ago using better parts and advise off a few forums. For towing 5000 lbs though the 350 tbi struggles on the hills here Oregon. Flat towing is pretty normal. I find myself in 2nd gear and 40mph at times on hills. I did swap the 3.26 gears for 4.11 in the rear and that helped. I also changed a few shift points on the chip using tunerpro and that helped too.

So the big question is, Should I bother with trying to improve the 350 tbi a little or just use it as it and start saving for another tow vehicle? The engine is in great shape at only 107k and doesn't use oil or anything. Gas mileage is not horrible. I would consider doing a cam swap or head/cam swap if it would make a big enough difference for the money. not looking to race the thing, 2000-4000 is the rpm range I care about. Diesels that are not worn out and newer trucks are mostly out of my budget at the moment. So far the engine is bone stock except for an open air cleaner and a 20% under drive pulley from summit. I do have a mobile chassis dyno, and I stuck it on there a few months ago just for laughs. The bump on the graph is the torque converter locking.

Image
Image

HDBD
Expert
Expert
Posts: 500
Joined: Sun Jun 01, 2008 4:32 pm
Location: Northwest

Re: 350 TBI tows 5000/6000lbs

Post by HDBD » Fri Jun 01, 2018 1:19 pm

So a question to a question
What are your smog laws and what mods will they allow?

donforeman
New Member
New Member
Posts: 28
Joined: Mon Feb 02, 2015 11:04 pm

Re: 350 TBI tows 5000/6000lbs

Post by donforeman » Fri Jun 01, 2018 1:29 pm

In my county there is no smog for vehicles over 21 years, but there some minimal requirements in other Oregon counties up north. I would like to leave the basics (erg and cat) in place as I may be moving north soon. This van has no air pump. No requirement for an exception number to swap parts like California does. The cat on the van is a 3" replacement, done before I got the van.

HDBD
Expert
Expert
Posts: 500
Joined: Sun Jun 01, 2008 4:32 pm
Location: Northwest

Re: 350 TBI tows 5000/6000lbs

Post by HDBD » Fri Jun 01, 2018 1:36 pm

The TBI fuel system will support a carb. I would get rid of the TBI and put a performer intake and a rebuilt quadrajet or if bucks are scarce even a stock dual plane mid 70s early 80s manifold with the same carb. Change the cam to an RV torque grind, yours is hydraulic roller right? If not a flat tappet will work. Play with the initial timing and let the stock TBI computer control the spark. These changes will have a strong influence on midrange torque which is what you need.

travis
Pro
Pro
Posts: 459
Joined: Sun Mar 15, 2009 5:31 am

Re: 350 TBI tows 5000/6000lbs

Post by travis » Fri Jun 01, 2018 3:17 pm

http://tbichips.com/?page_id=73

Lots and lots of good info here.

The cam in these things is so tiny that they really don’t seem to respond much to anything until you put a little cam and valve springs in them.

Nice van btw...I was looking for something like that before I bought my suburban, but around here the painters and lawn care guys snatch them up fast

PRH
Member
Member
Posts: 120
Joined: Fri Sep 08, 2017 4:16 pm
Location: S. Burlington, Vt.

Re: 350 TBI tows 5000/6000lbs

Post by PRH » Fri Jun 01, 2018 4:09 pm

If that engine has the high swirl heads..... “if it were me”, they would be gone.
A few of my friends had c2500’s with tbi 350’s that used those heads and they were horrible tow vehicles. Just flat past about 3200rpm. No real passing power or any kind of upper rpm(4000-4500) power for getting up to speed or pulling hills at decent speeds in lower gears.

I towed a 3450lb 68 Plymouth on a 1500lb open trailer with a short bed 2wd 1993 Dakota with a 3.9 Magnum(180hp)and a 5 speed....... and they couldn’t keep up with me on the hills here in New England.
That Dakota chassis dynoed at about 150rwhp on a dyno jet😎

I’d probably get some Vortec heads, performer eps vortec intake, 650 avs carb and swap the cam to something like the Lunati 701 Voodoo.

My Dad had a 1977 Dodge B200 conversion van and put a warmed over 360 in it.
STD performer, 600 Holley, headers, stock 1.88 heads with a mild bowl job, Comp 268h cam...... and that combo towed pretty well.
It had 3.23’s and 27” fires.
Somewhat handy with a die grinder.

ZIGGY
Guru
Guru
Posts: 1269
Joined: Mon Mar 05, 2007 3:15 am
Location: Dallas, Texas

Re: 350 TBI tows 5000/6000lbs

Post by ZIGGY » Fri Jun 01, 2018 4:29 pm

Took a quick look at tbichips. From personal observation and (IIRC) Speedtalk posts, the tbi intake
manifolds on these are terribly restrictive and choke any other mods. My scan of tbichips info may have
missed it, but I saw nothing about intake manifolds (except a negative reference for Edelbrock w/Holley inj.),
just everything else from air cleaner to heads. Anybody here get more good grunt while using the stock or
aftermarket tbi intake? I think the plenum spacers are a cheap small boost but that's it.

Truckedup
Guru
Guru
Posts: 1790
Joined: Mon Jan 21, 2013 2:41 pm

Re: 350 TBI tows 5000/6000lbs

Post by Truckedup » Fri Jun 01, 2018 5:13 pm

PRH wrote:
Fri Jun 01, 2018 4:09 pm
I towed a 3450lb 68 Plymouth on a 1500lb open trailer with a short bed 2wd 1993 Dakota with a 3.9 Magnum(180hp)and a 5 speed....... and they couldn’t keep up with me on the hills here in New England.
That Dakota chassis dynoed at about 150rwhp on a dyno jet😎

What type vehicles were they driving?
Motorcycle land speed racing... wearing animal hides and clinging to vibrating oily machines propelled by fire

travis
Pro
Pro
Posts: 459
Joined: Sun Mar 15, 2009 5:31 am

Re: 350 TBI tows 5000/6000lbs

Post by travis » Fri Jun 01, 2018 5:28 pm

Truckedup wrote:
Fri Jun 01, 2018 5:13 pm
PRH wrote:
Fri Jun 01, 2018 4:09 pm
I towed a 3450lb 68 Plymouth on a 1500lb open trailer with a short bed 2wd 1993 Dakota with a 3.9 Magnum(180hp)and a 5 speed....... and they couldn’t keep up with me on the hills here in New England.
That Dakota chassis dynoed at about 150rwhp on a dyno jet😎

What type vehicles were they driving?
I towed a 3800 pound late ‘80’s Cadillac on a tow dolly from NY to OK behind a ‘85 K10 4x4 with a stock 305/700r4. In the hills of TN, nobody could keep up with me...at least on the long downhills :lol: 90mph downhill to be crawling by the top of the next hill...I called it the inertia technique :lol:

PRH
Member
Member
Posts: 120
Joined: Fri Sep 08, 2017 4:16 pm
Location: S. Burlington, Vt.

Re: 350 TBI tows 5000/6000lbs

Post by PRH » Fri Jun 01, 2018 5:48 pm

Truckedup wrote:
Fri Jun 01, 2018 5:13 pm
PRH wrote:
Fri Jun 01, 2018 4:09 pm
I towed a 3450lb 68 Plymouth on a 1500lb open trailer with a short bed 2wd 1993 Dakota with a 3.9 Magnum(180hp)and a 5 speed....... and they couldn’t keep up with me on the hills here in New England.
That Dakota chassis dynoed at about 150rwhp on a dyno jet😎

What type vehicles were they driving?
The afore mentioned c2500’s powered by 350’s with swirl port heads and TBI.
Somewhat handy with a die grinder.

dfarr67
Pro
Pro
Posts: 272
Joined: Sat Jul 27, 2013 7:14 pm

Re: 350 TBI tows 5000/6000lbs

Post by dfarr67 » Fri Jun 01, 2018 6:22 pm

LT1 cam, need good vacume
vortec heads, with conversion intake
easy to bump fuel pressure on these
3:73 might have been a better gear choice

maybe DynamicEFI standalone- cheap plug in for 7747.

Look for fast355, he has done some amazing things with TBI.

77cruiser
Guru
Guru
Posts: 1118
Joined: Fri Dec 29, 2006 10:32 pm
Location: I Falls MN
Contact:

Re: 350 TBI tows 5000/6000lbs

Post by 77cruiser » Fri Jun 01, 2018 6:39 pm

What size are the tires, thinking about the gears? My 1/2 TBI had 3.42 & 29 inch tires & I thought 3.9 gears would've helped it out a bit.
Still not much there with those TBI's tried pulling a 26 ft camper into the wind 65 mph ended up getting 6.2 mpg.
Jim

MTENGINES
Expert
Expert
Posts: 549
Joined: Wed May 23, 2012 1:52 am
Location: MN

Re: 350 TBI tows 5000/6000lbs

Post by MTENGINES » Fri Jun 01, 2018 8:19 pm

Guys he does not need new heads. simply bolting vortec heads on will do nothing. The swirlport heads are not as bad as people think. they flow enough air and have a generous amount of cross section. These heads work well in leancruise because you dont need to add 40 degrees of timing.

here are a few different builds i have done over the years for myself and customers.

208/216@.050 .460 lift 112 lsa made 240hp @4900rpm 360lbft@3500rpm stock intake. custom tune and headers. Then we swapped to performer intake with adapter. engine made 270hp@5100 340lbft@4000. this was just our shop truck.

218/218@.050 .465 lift 112lsa made 295@5200 350lb ft 4000 9.5:1 .030 basic valve job bowl blend. edelbrock performer headers and tune.

224/234@.050 .465/.485 112 made 310@5400 360lb ft 4000 9.5:1 .030 similar as above

all these engine were for guys that wanted nothing but improved power for towing. the best thing you can do is change your rear gears put a 2500 stall lock up in in and a big trans cooler. it will drive completely different.

As far as throwing a carb on it. DO NOT! I have tuned probably 50 of these engines using tunerpro and eblflash, also burning my own chips.

My advice is just stick a cam and springs in it, put in an external adjustable fuel pressure regulator and a different fuel pump. i used a bosche replacement for a grand national. Next would be torque converter. dont worry about people saying 2500 is too much on the street. thats bs you have lock up.

donforeman
New Member
New Member
Posts: 28
Joined: Mon Feb 02, 2015 11:04 pm

Re: 350 TBI tows 5000/6000lbs

Post by donforeman » Fri Jun 01, 2018 8:30 pm

77cruiser wrote:
Fri Jun 01, 2018 6:39 pm
What size are the tires, thinking about the gears? My 1/2 TBI had 3.42 & 29 inch tires & I thought 3.9 gears would've helped it out a bit.
Still not much there with those TBI's tried pulling a 26 ft camper into the wind 65 mph ended up getting 6.2 mpg.
I am very happy with my switch to 4.11s even with the stock engine. I used a VSSB from a Suburban with 245/75/16 tires as that is the same size as the van, so my speedo is back to normal.

donforeman
New Member
New Member
Posts: 28
Joined: Mon Feb 02, 2015 11:04 pm

Re: 350 TBI tows 5000/6000lbs

Post by donforeman » Fri Jun 01, 2018 8:57 pm

Thanks for all the advice, everyone's post was helpful. I did run a pressure sensor on the chassis dyno. At least with the stock engine there was not an excessive amount of vacuum in the manifold at 4000 rpm and lower with the TBI as is. I have been burning chips for a few months, mostly just messing with transmission shift points up to this stage. So from the posts it looks like everybody thinks a mild cam and springs would be helpful. I will try that next, and try a few changes to the chip, timing and fuel wise.

Post Reply