1970 Jeep P/U w/ SBB 350 low end performance questions

I really could use some informed opinions here.

I bought a 1970 full sized Jeep pickup I’m doing a ground up on for working around a piece of property. It came with what I think is the best engine Jeep ever put in their vehicles, a Buick 350.

Here are the problems:
1- It’s a Buick 350, so parts and info about performance building them is limited.
2- The Hi-perf. parts and info there is, is basically geared towards the street strip guys.

If I were to do a Hi-perf rebuild aimed at low to mid range performance what can I expect from it in the way of HP and torque in its useable range? Say 1,200 to 3,200 RPM. This engine will probably never see anything over 5,200 RPM

Here are the mods I’m planning:
1- Q-jet rebuild kit and tweaks aimed at low end perf.
2- Stock intake with cleaned up passages and port matched
3- Heads will have mild port work/port matched and 1.92/1.55 valves
4- A good RV/towing cam. I’m currently really eyeing the one from Lunati
5- Adjustable timing gears and chain for tweaking advance.
6- The appropriate timing and timing curve work to the distributor advance
7- 0.030 overbore and compression kept to around 9.5 to 1
8- Either buy a header kit from Headers by Ed or buy the individual pieces to make a low/mid range performance header

I don’t have the budget for forced induction so please keep comments aimed at NA.

99% of the time this truck is going to be used for hauling materials, pulling stumps, and towing a utility trailer. Things well within its abilities, and I wouldn’t even be asking for opinions. It’s the other 1% of the time that concerns me. A couple times a year I want to tow a 5<SUP>th</SUP> wheel.

To optimize low speed work I’ve geared the truck so that it will be running at 2800 RPM at 70 MPH.

Keeping out all the other variables that come into play and keeping comments to just the engine itself, with the mods I plan, what kind of HP and torque can I expect this engine to put out in its usable range? All work is aimed at having peak torque around 2800 RPM or lower(preferable).

Thanks in advance. Resbum

 

How many miles do you expect to put on it in a year? I ask because you could get a gear vendors overdrive unit, but they are not cheap at $2500...

 

Hi Dan, for the plans I have for this truck it's not worth the $$$. The majority of its life is going to be spent working low and slow.

Here's what one of the Jeep specialty sites lists about the 1970 Jeep Buick 350 specs

The "Dauntless" Buick 350 V8 uses a cast iron block and cylinder heads with overhead valves and hydraulic lifters.
The Buick 350 was used from 1969 until 1970 in J-series pickups and Wagoneers.
<TABLE border=1 width=400><TBODY><TR><TH colSpan=2 align=middle>Dauntless Buick 350 V8</TH></TR><TR><TD>Bore x Stroke</TD><TD>3.80" x 3.85"</TD></TR><TR><TD>Displacement</TD><TD>350(5.73L)</TD></TR><TR><TD>Compression Ratio</TD><TD>9.0:1</TD></TR><TR><TD>Horsepower (gross)</TD><TD>230@4400</TD></TR><TR><TD>Torque (gross)</TD><TD>350@2400</TD></TR><TR><TD>Main Bearings</TD><TD>5</TD></TR><TR><TD>Valve Configuration</TD><TD>OHV</TD></TR><TR><TD>Fuel</TD><TD>2bbl</TD></TR></TBODY></TABLE>


These numbers were posted with a 2 barrel. I've already found a 1970 q-jet and intake off of another engine for it.

I forgot to mention that I'll also be running a cold air intake through an unused headlight panel behind the grill.

What has me kinda stumped is that I know in the early 70's they changed the way hp and torque are measured.

With the mods I listed in my first post is it unrealistic to hope I can get this engine well into the 400's in torque in the 2600 to 2800 RPM range?

Any opinions?

 

Welcome to V8Buick!!!!

I like all your ideas, looks like you are on the right track! You should be able to get about 300 hp and 400 ft of tq without any issue.

The only concern I have would be that you would most likely get more torque from the engine from 2000-3500 rpms with a 2bb carb. Above 3500 rpms the Q jet would be much better though as i am sure you know. As you know it is a trade off, the 2bb would be better in low rpms and the q jet better in higher rpms. You say you want max torque at low rpms so this is what I would do:

Have the heads ported by a pro and have them focus on the low and mid lift numbers. Shoot for 10.5:1 compression ratio to help get the cylinder pressure up then run premium fuel. I would use a TA RV212 cam.

I would for sure go to an electric fan to free up some HP and tq and let it rev quicker. Another place to gain more power is by using lighter forged pistons or if budget does not allow then get some nice light piston wrist pins to save rotating weight even with stock type pistons. My forged rods and pistons are about 200 grams lighter per hole vs stock, that is a huge savings although it is costly...

Here is a mild 350 with the head porting, mild cam ect.

http://www.v8buick.com/showthread.php?t=153248

 

Sean, I like the idea about the 2BBL carb. The main reason I say this would be because the QJet would only make more power at higher rpm at lower vacuum when the secondaries would start to open up but that pretty much means full throttle. The primaries are very small on the QJet and there will probably be times when towing that you'd have to push it hard to get them to open because of the vacuum pulloff holding the secondaries closed. Now, the the regular 2BBL is much bigger than the primaries only of the QJet so you could make more power smoothly in the range you need without the secondaries popping in and out.

This would be one of the times I'd recommend a Holley 600 cfm vacuum secondary or maybe an Edelbrock 600. Either type will transisition over to the secondaries much more smoothly at part throttle than the QJet and they both have bigger primaries than the QJet which possibly would mean less tipping into the secondaries period. You would need an adapter to install them on the stock intake. I would see if you can find a 4-hole standard to 4 hole spreadbore/QJet adapter. This would aid in low end power compared to an open type. I'd have one made if I had to.

Keep the cam small as suggested. I'm not sure which Lunati you're talking about but the RV12 would be great. The small cams will rev to 5000 rpm no problem but the 2BBL would be a restriction to power at that rpm. Torque output won't change much but HP will from 2BBL to 4BBL.

Sean one place I disagree is with the compression. Don't go anywhere near 10:1 for towing unless you can get 100 octane. Towing is probably the worst case story for octane need. Running hot, uphill, pulling a load. With the mild cam and high compression the cylinder pressure would be skyhigh. I'd think 9:1 would be fine running premium and a good timing curve in the distributer. Overall if you have to run a less than optimum timing curve because of compression/gas issues then you were better off running less compression. I'd consider forged pistons for strength if you can get them reasonable. Use stock pistons with only cleanup cuts on the deck and heads to keep compression increase to a minimum.

Whatever headwork you can have done , have done but all out heads aren't necessary. Portwork and port matching is a waste of time unless you have head ports intruding into the intake ports causing reversion. Your ports are plenty big. Worry about opening up the bowls under the valves. Bigger valves probably won't help either.

Instead of building your headers yourself why not try these and modify as needed. The smaller tubes will help low end.

http://www.taperformance.com/proddetail.asp?prod=TA_2010CH

The rpm range you've chosen to tow/drive at would be good. If you go lower it will lug when loaded. That is why alot of the trucks used for towing use O.D. lockouts to keep the trans from always kicking down to get the revs up.

Overall going by the stock spec with some mild headwork, cam upgrade, headers, and 4BBl install power should get close to where you want to be.

 

Good points about the compression...

I like your idea for a square bore carb, I did not think of that...

 

Thanks Sean and Mike,

I looked at the links you both provided. I also appreciate the advice on the 4bbl carb. I'll have to go back and rethink that option. The q-jet has a good reputation amongst the offroaders if you put in the effort to set them up right, and that's what I was basing my decision on. I take your point that towing is a totally different animal, with different needs.

Also, the Lunati cam I'm considering is the voodoo #67000.
See specs below. It's comparable to the RV212

"Hydraulic. The best torque cam for 350 applications. Expect strong low to mid range horsepower and torque gains. Excellent for RV type vehicles, pleasure boats or towing applications. Good idle!

• Advertised Duration (Int/Exh): 250/256
• Duration @ .050 (Int/Exh): 207/213
• Gross Valve Lift (Int/Exh): .451/.470
• LSA/ICL: 112/108
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: 1000-5200
• Includes: Cam Only

Part Number: 67000"


The electric fan was in the plans. Also, it came with no AC, so no power robbing there.

The compression was another area I was trying to find compromise. I like your input about 9 to 1 and playing with the timing more.

As long as I know my plans will get me in the neighborhood of 400ft/lbs, at an RPM I need it, I'll feel OK about towing that big 5th wheel a couple times a year.

I'll just have to go whatever speed the engine likes to hunker down and grunt along.

Resbum

 

Two more points:

1. If you care about MPG then go with the Q jet, and another option for more low rpm power is a 800 cfm version of the Q jet (look for a 72-74 Buick 455 carb). I have used these 800 cfm carbs on my 350s and they have better low rpm performance since the extra cfm gain is on the primaries. I find much better performance with the 800 cfm carbs and they are cfm on demand style so they do not over carb no matter what. These carbs do require some mods to work well on your 350 and a little time with jetting changes could make a vast improvement!

2. If you do go with a square bore carb then consider the Alum TA intake since it is made for either spread or square bore carbs. The weight savings is also nice however remember that it has no provision for divorced choke...

 

Resbum....I commend you for doing this. I have often thought that the 350 Buick is an excellent engine of towing. If I would have had more spare time, I would have already had one in a 1980's GMC 1/2 ton pickup in 2004. I have often considered and thought of this build up over the past 15 years on what exactly I would do.

I feel that some of the remarks made here are not consistent with a towing application, not to disagree with Sean as he is the resident 350 patriot....but his thoughts are more focused on "performance" of the 350 Buick and not really the efforts involved with towing.

I'll lay out the facts that I am aware of first before offering any advice.
1. The factory 350 Buick is designed with towing in mind even thought is was never intended in such.

- The engine pulled around 6000 lb barges during the 70's and 80's without an issue. Some of these land barges were then attached to trailers to pull campers, race cars and boats on a fairly regular basis during their life spans in the aforementioned barges. The bore to stroke ratio is perfect for low end grunt along with the intake manifolds tall narrow long runners that maintained high port velocity at low RPM. These factors assisted in development of low and mid range torque a plenty. Matter of fact in a Car Craft article in the 1999 Engine Builders guide David Freiberger stated that the 350 Buick has Big Block Torque in a small block package that no other OE manufacturer has rivaled since it's inception.

- The factory camshaft has in no way has the ability to be used in a racing application as all of the power is delivered below the factory 5200 RPM redline. Utilizing your factory camshaft as delivered would not hinder the 350's ability to ever pull anything, all torque is delivered at a meager 3200 RPM and that's Big Block 410 ft/lbs in some cases of the engine.

- Compression dictates torque development, the more cylinder pressure, the more torque. The issue with the Buick 350 is that long stroke also creates opportunity of detonation, which kills towing ability. In your case I feel that ample torque of 400 ft/lbs can be achieved with 8.5 - 9.5:1 compression. That would allow for the use of regular 87 octane fuel when using a stock or RV camshaft that focuses on maintaining cylinder pressure vice bleeding it off like a drag racing camshaft with ample overlap of valves.

- The 2 barrel carb is way more effective in torque development than the 4 barrel, that is mostly due to the intake volume vice the number of barrels of the carb. Intake port velocity decreases when all the barrels are opened fully until engine speed overcomes this low velocity point. A factory 4 barrel intake manifold would work best in any situation when concerned with low end torque.

- The 350 Buick has heavy rods and pistons like Sean has stated. These are beneficial when towing. This rotational mass assists in getting heavy loads moving with the energy stored within the rotating mass....also known as inertia. The operating RPM of the engine supports the use of the heavy factory internals. There are thousands of 350 Buicks still on the roads that have millions of miles between them using these same internals.

With these facts... my personal opinion would look at internal friction and increasing the torque development of the engine using a completely factory engine with the following exceptions:

JE pistons make a V6 forged low compression Buick piston that is virtually a stock replacement for the low compression turbo 231. The compression height is exactly the same as the 350 Buick. This allows you the ability to create 8:1 compression and have thinner current technology piston rings. These would decrease the internal friction of the engine drastically while providing great quality forged pistons for the abuse of towing.

TA thin head gaskets, increase compression to 8.5 or 9:1 depending on any head milling machine work.

A single or double roller timing set......life time insurance and very robust.

TA Oil Pump pressure booster or high volume kit, for lubrication insurance. I never build a Buick Small Block without it.

Factory exhaust manifolds. There are some out there with a 2 1/2 " opening, (your Jeep may have them already) if they cannot be found the 2 1/4 is easy to come by and for towing, headers would not be the answer. Too much heat that would destroy the flanges, gaskets and tubing itself without costly coatings. Then the gaskets would be a PITA to change all the time. I doubt they would last long under those conditions.

FAST EZ EFI kit. All the benefits for off road use, better throttle response, increased low end torque, FUEL ECONOMY. Square bore throttle body that has all the benefits of the previous discussion without the insane headaches of a Q-Jet for a towing application. I really think the Q-Jet is not towing friendly cause the secondary's would be open all the time or not open when needed since it is regulated by vacuum signal. In towing applications vacuum is generally high all the time cause power is applied gradually, not all at once. It would just be very difficult to get that Q-Jet right for towing.

Multi-Spark ignition system. Not to say MSD as there are many other companies. I have always had luck with the Accel 300+

H-Pipe for increases in mid range torque and exhaust scavenging.

As you can see, I did not say an RV camshaft, because I feel it is not needed. The stock camshaft is almost the same, costs nothing and provides decent fuel economy.

:Brow:

 

Great info!

 

Yes, that is great info. Everything everyone has contributed to the thread is all I was hoping for.

Different opinions of how to get low to mid range power out of the Buick 350.
:beer Cheers to all of you.

The EFI is probably not going to happen. I agree with everything said about EFI, but the whole reason I chose a 1970 Jeep was to have a simple, reliable, tough truck to take into my retirement years. When it won't start I check for fuel and spark, then back track to where the problem is and fix it with simple tools, laying on the ground. No sensors, no computer, no extra wiring, etc. The one exception to this will probably be electronic ignition in the distributor, but even that is in question. There is something to be said for the simplicity of good old fashion points.

Anybody who thinks they have good info to share, please contribute your thoughts. I am currently finishing up the brakes and steering on the Jeep and I'm at least one month away from starting the engine work. Until I order parts and tear the engine apart it's not too late to change my mind.

Thanks again, Resbum.

 

After reading all of what has been posted before I have three thoughts. First, how much does the 5th wheel weigh? Second, how much mileage would you be putting on the truck while towing? Third, what are the towing specifics of your truck(i.e. GVW, GCVW,etc.)

As a FSJ owner I have towed a lot with my rigs. The ones that I had from the late 60's and early 70's all had drum brakes all the way around. IMHO, I could be concerned about the amount of braking power the truck will have when towing.

 

Hi N360LL,

Thanks for jumping in on the conversation. Since you have firsthand knowledge I would graciously accept whatever you’ve learned from towing with FSJ’s!!! Although your questions aren’t engine related, they are very important questions to ask. I’ll answer them so that everyone understands I’m building a complete package in this truck.
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com<o></o>
To keep this thread on topic, could we keep our discussions here to the engine? I’ll drop you a PM with my email so that you can share off topic info with me there. I hope you understand.
<o></o>
The 5<SUP>th</SUP> wheel is a 40 foot triple axle toyhauler.
Dry weight from the factory 12470lbs
Tongue weight 2760lbs
GVW loaded 18,000lbs
THAT’S why I was concerned about the 1% of the time I want to tow with the truck.
<o></o>
Whoever ordered this truck in ‘70 ordered it as heavy-duty as Jeep would make it. Basically, it’s a 1970 Jeep dually, minus the dually. Literally.
<o></o>
The truck:
1970 Jeep Gladiator, Custom Cab, Camper Special, Model 3408Z, with extra gas tank
GVW- 8,000lbs, It’s a heavy ton
It came with the rare factory 8 lug Dana 60 full-floating axles in the rear, Dana 44 up front
Dana 20 transfer case
TH400 transmission
Four corner drum brakes and closed knuckle steering
The factory installed extra plates welded to the frame, running between the front and rear axles. From what I’ve learned this was extremely rare in the civilian models and was almost only ever done on the military versions.
<o></o>
My mods to the drive train, steering, suspension, and brakes:
I’ve been rebuilding the truck from the ground up, right down to the nuts, bolts, and washers.
<o></o>
TH400- TCI RV/towing torque converter, shift kit, various other heavy-duty parts, lower first and second gear kit, and an additional cooler for the fluid
<o></o>
Dana 20 transfer case- I found a ‘68 Bronco Dana 20 and robbed its lower 2.48:1 gears out of it and bought a Dana 18 front output gear to do the low gear conversion into my Jeep Dana 20 housing
<o></o>
With the tires and gearing I plan the math says the TCI torque converter will be fully engaged at 1800rpm and 4 1/2mph, when in low range. I’m extremely pleased with the spread I got between the low end performance and the 2,800 rpm 70mph cruising speed.
<o></o>
New driveshafts with the Dana Splicer heavy-duty U-joints
<o></o>
Dana 60 rear end- Total rebuild with all new Dana Splicer parts, Detroit TrueTrac differential, 4.10:1 gearing, Dutchman chromoly axles
<o></o>
Dana 44 front end- I bought a front end out of a 1978 FSJ. Converted to under frame mount, spring over axle for about 4”of lift. It came with the disc brakes and open knuckle steering. Bought 8 lug disc brake hubs and the proper brake caliper brackets. Same total rebuild as the Dana 60 rear end, TrueTrac differential, gears, and Dutchman chromoly axles.
<o></o>
For steering I did a steering over kit with all new Moog components, and the under frame spring mount will help keep the tighter turning radius the Dana 44 open knuckle has
<o></o>
For suspension I’ve done an under frame spring mount conversion front and rear, with all new bushings, etc. I’m currently working on one ton airbags install that can be easily installed and removed when I need it for the 5<SUP>th</SUP> wheel. Bilstein shocks on all four corners, and I’m still debating whether to install four in the rear.

<o></o>
Now, the part that’s just as important as the power to get it all moving: The braking system to stop it all. As I mentioned above, I already did the disc brake conversion up front. I’m currently waiting for the components for the rear disc brake conversion, and also the one ton hydroboost with larger master cylinder conversion. While I have the bed off and gas tank out I've been replumbing all new hard lines for the brakes and fuel. I'll also be adding stainless steel soft lines to all four corners of the brakes. This will be finished off with some really sweet ceramic pads I found for it. I’m still debating an adjustable proportioning valve.

<o></o>
Tires and rims- Rims will be US Wheel 8 lug steel rims rated at 3,000lbs and tires will be Dunlap Rover M/T Maxx Traction On/Off-Road Commercial Traction light truck tires rated at 3860lbs

 

N360LL, I tried to drop you a PM, but your box is full. Is there some other way for me to get you my email address?

Thanks

 

left click on his name and go to the "email" option... The note you send will go to his e-mail.

 

post up some pics and keep us updated! There is a Buick Powered jeep section if you did not notice... I say post the pics of the Jeep here as well...

 

Thanks Sean, I wasn't thinking.

Here's some pics from the day I bought it last spring. It hadn't been on the road in two years. Not bad for a $300 40 year old truck.







I have more pics on a memory card somewhere.

 

Cool truck!!! Is it a 3/4 ton?

 

A J4000 has the capability to do a lot more than a J-10. That was my concern. The J4000 shares a long list of componants with the M-series trucks that the military used for so long. And being a long wheelbase truck will help with the 5th wheel installation and the way it pulls the trailer.

And since you have done a full blown mechanical resto-mod in order to make the truck what you want I am relatively certain that your engine upgrade plan will work for you. It appears that you are very prudent and methodical. Can I assume that you know and understand the principles of towing and proper trailer pulling? I think yes is the answer. Have you considered a switch-pitch torque converter as part of the mods?

The one place I would be concerned is in the engine cooling area at high altitude, high temp and large load or any combination there of.

And remember, if the 350 doesn't do what you want simply put a 455 in the engine compartment and the torque and horsepower problem is solved.

 

Thanks N360LL. It sounds like you know the older Jeeps and with your first hand towing experience your opinion that this will work is very reassuring to me.

I am pretty knowledge about towing. Through my dad I've been around trucks my whole life and in the early 90's I hauled max-cube doubles around the western 11 states for a year. My hat goes off to people that live out of a truck for their whole career.

I did briefly look at the switch-pitch torque converts. This is only the second automatic I've ever owned, and the first one I did mods on. My course is locked in on the way I went, but if it ever gives me problems I'll most definitely give a switch-pitch torque convert a hard look.

I am going to address engine cooling thoroughly. Both water and oil. I have some good ideas planned, but haven't committed to them yet.

When I bought the 5th wheel my very first consideration was to swap out for a 455. But for the limited amount of time the truck will be towing I really didn't want to give up economy for the remaining 99% of the time. Had this been any other OE 350 I probably would have done a BB swap immediately. I knew the SBB 350 was close to being able to reliably meet my needs, but wasn't quiet sure. Hence, the reason for starting this thread. Besides, I've always loved one off bastard child vehicle projects. Most other people would have probably set out to find an early 70's F-250 to do this project with. Also, I think there is a cool factor in telling people I tow my "home on wheels" with a gas powered small block. :shock:

Here's a pic of the engine. There's a story behind why it looks like it does. This is how I got it and why the truck hadn't been on the road in 2 years.