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-   -   1989 350 Small Block Needs Help to Tow (http://www.airforums.com/forums/f463/1989-350-small-block-needs-help-to-tow-68660.html)

Richard B. 08-26-2010 06:19 AM

1989 350 Small Block Needs Help to Tow
 
I have a real nice 1989 3/4 ton 4x4 Suburban that has 350 TBI.
It tows a 22' 4000 lb. Safari and is great unless it faces a grade.
I am asking for suggestions that will cost less than the truck is worth ($8000?).
Changing the rear gear ratio means changing the front too remember.
I do not want a 454 as I want to maintain the same block so fit will not be an issue.
I have been given advice that a "RV Cam(shaft)" is what I want; it puts the horsepower down in the lower revs where a TV needs it, not up above 4000 rpm. Any opinions or experience with a "RV Cam"?
Thanks.

DryHeat56 08-26-2010 07:52 AM

Richard,

I used to have a 87 Sub, 350 TBI, 3.73 rear and the 4R100 trans. Four years ago I bought a creampuff 95 Sub 3/4 ton K2500, 350 TBI, 4.10 rear and 4L80E trans. I have continued pulling the same trailer (19ft. Komfort) with both vehicles. My observations: the 4.10 rear is a big improvement when pulling grades, the 4L80E trans is a pulling beast compaed to the 4R100. Now, that being said, since they are both small block engines, they must be kept "wound up" when pulling grades to keep them in their powerbands. My current Sub has 215, 000 miles and runs like a clock. Maybe another option for you would be to upgrade to a 94 or 95 Sub with a 350 TBI and the 4.10 rear? I got into my truck four years ago for $4,000. I am sorry I do not have any experience with RV cams. Good luck!

Tim

SteveH 08-26-2010 07:52 AM

An RV cam will help, but only a small amount...you'd probably not be satisfied with the improvement vs money spent, IMHO.

The two things I would consider if in your position, would be first, the gear change. This would give you the most improvement for the buck, and yes, it would cost about 1500-$2000, if you find a reasonable independent shop.

Don't know the condition or mileage of your existing 350, but the biggest thing you could do would be to rebuild the engine into a 383 cu in engine. Obviously more expensive than the the gear change, but again if you found a reasonable independent shop, should be able to be done for about $3000-$4000. The 383 is a stroked 350 engine (uses the same block), and will easily produce the torque figures of a big block.

rangebowdrie 08-26-2010 08:00 AM

One suggestion would be to replace the 350 with a 383 stroker engine.
Most engine rebuilders offer this package, or for more money, you can get one as a crate engine from Chevy.
Generally, a 383 will have around 320 hp, and 430 lbs ft torque. This exceeds the hp, and comes close to the torque ratings that the 454 had in its last years of production. Runs on 87 octane gas too.

r carl 08-27-2010 05:55 PM

Small-Block Chevy Stroker Kit - Budget 383 Cube Build - Super Chevy Magazine

lsmith 08-27-2010 08:51 PM

350 replacment
 
can't beat this ZZ4 turnkey engine, includes everything except oil. Just put one in my 4200 1948 Cadillac street rod and great performance

lsmith 08-27-2010 08:55 PM

sorry forgot the link

can't beat this ZZ4 turnkey engine, includes everything except oil. Just put one in my 4200 1948 Cadillac street rod and great performance

GM Performance 19201330 - GM Performance ZZ4 350 C.I.D. 350 HP Turn Key Crate Engines - Overview - SummitRacing.com

RankAm 08-28-2010 12:41 PM

I have a 99 Suburban 1500 4WD 255HP Vortec 5700. Is that the 350 small block?

How can I tell which transmission I have? My original sticker states that I have "H.D. transmission cooler," the heavy duty trailering equipment, and the 3.73 rear axle ratio.

Thanks

rangebowdrie 08-28-2010 03:38 PM

Yes, the 5700 Vortec is a 5.7,aka a 350 small block. The 1500 series sub, of that year uses a 4L60E trans.

The ZZ4 engine, mentioned a post or two ago, is a high performance engine designed for lighter weight vehicles. Its HP, and torque figures come-in at much higher RPMs than the HT383. It is not an engine designed for towing/low rpm torque, it is a "street rod" engine.

AlbertF 08-28-2010 05:23 PM

Your gross combined weight shouldn't be more than about 11,000 lbs. What's happening on the grades? What gear, what engine speed, what vehicle speed? And how steep? Your area is quite flat, and grades above 4% are quite rare in most of Ontario.

It may simply be a matter of expectations.

Richard B. 09-01-2010 11:37 AM

Thanks for all the responses.....
 
Thanks for all your replies; unfortunately I am still unsure of what to do.
A freind of mine who absolutely knows engines and GMs in particular said the 383 route is not what I want; the rpms have to be over 4000 to get into its horsepower range and my TBI would have to go in favour of a carb to get the most out of it. He recommended the RV CAm, but admits he has no first hand experience with them.
The Vortec late 90's "small block" is another idea; will it fit into my bay with no major mods???
As far as how flat Ontario is; we do ski here you know! And it is not the only place I want to venture.
My truck/trailer are under 10,000 lbs, more like 9000 total; remember the 4x4 3/4 ton drive ratios are already high....I'' kave to spin the shaft and count tire rotations to find out what it really is.

Richard B. 09-01-2010 11:40 AM

It may simply be a matter of expectations is the key to your reply.
I don't want to be passing on long uphills, but I am not even holding my own.
This is at 90 km/hr, drops to 2nd gear (it's a 3 speed tranny; TH400). I am unsure of engine rpm; no tach.

SteveH 09-01-2010 11:47 AM

Quote:

Originally Posted by Richard B. (Post 889778)
Thanks for all your replies; unfortunately I am still unsure of what to do.
A freind of mine who absolutely knows engines and GMs in particular said the 383 route is not what I want; the rpms have to be over 4000 to get into its horsepower range and my TBI would have to go in favour of a carb to get the most out of it.

I'm sorry to have to say this, but your friend is wrong. I've built two 383's, and if they are cam'ed for towing, they do not have to turn lots of RPM's to make power. They are basically the same bore as a 350, with a stroke of 3.75" vs 3.48" of a 350. This gives them better low RPM torque, all other things being equal. And, there is no reason at all the TBI won't work on a 383.

Do what you want, but a 383 small block is a torque monster.

r carl 09-01-2010 11:53 AM

Quote:

Originally Posted by Richard B. (Post 889778)
Thanks for all your replies; unfortunately I am still unsure of what to do.
A freind of mine who absolutely knows engines and GMs in particular said the 383 route is not what I want; the rpms have to be over 4000 to get into its horsepower range and my TBI would have to go in favour of a carb to get the most out of it. He recommended the RV CAm, but admits he has no first hand experience with them.
The Vortec late 90's "small block" is another idea; will it fit into my bay with no major mods???
As far as how flat Ontario is; we do ski here you know! And it is not the only place I want to venture.
My truck/trailer are under 10,000 lbs, more like 9000 total; remember the 4x4 3/4 ton drive ratios are already high....I'' kave to spin the shaft and count tire rotations to find out what it really is.

Your mechanic should be looking at the torque curve not the horsepower curve. Your stock 350 torque peaks out around 2200rpm. Your highway rpm should be around that in 3rd gear. You dont want to tow in overdrive in your year of suburban.


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