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Owner of a broken cart
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Discussion Starter · #1 ·
I finally got my tractor done, and corn in the ground. Now time to build the old worn out motor. (86' sbc 305)

This may not be feasible, or there may be better/easier options. But i figure i'll ask the experts anyways.

I want to build this 305 focusing on LOW end torque and fuel efficiency.

Off the top of my head, im leaning towards edel dual plane, and a quadrajet.

My question is what cam and pistons/compression ratio and heads might be best for this.

Or a Turbo?
Resized_20210425_141306.jpeg
 

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Owner of a broken cart
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Discussion Starter · #3 · (Edited)
So far this 305 does amazing. I literally just plant at idle with the planter buried about 3" in the ground. Maybe one notch above idle planting up an incline.
Just want to improve it further.
:edit: Idles at about 850-950 (Needs carb work, will gradually drop idle and die.)
 

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super heavy flywheel. Intake could be an Offy dual port. F.I. or small edelbrock style carb. C.R. around 9:1.
with fuel injection throttle control/governor is a better system.Intake cam timing of around 190º keep exhaust the same. .420 lift with 305 vortec heads. 1 1/2 '' diameter long tube headers with 2' collector extensions, mufflers to taste
 

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More for Less Racer
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Stock rebuild on the short block, do some bowl blending and valve back-cuts on the heads to boost the low lift flow, basic aluminum dual plane intake. You've already got the headers.

The two main items....a custom ground cam....and add one of those self learning TBI EFI kits. FI Tech, Atomic, Sniper, whatever.

That's if you really want to chase the low rpm power and mileage.

Glad to see you got the old tractor conversion together!! Too Cool, can't believe you also actually use it to pull ground implements LOL 🆒 (y)
 

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billpac thats way too much cam for a low rpm 305. The engine might run as high as 2200 rpm while working and maybe 3500 while traveling, The camshaft you propose will take a 305 to 6k rpm, useless range and tough on fuel.
 

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You're probably right, Moose. I saw that cam recommended for a 305 in a March '99 article in Car Craft Magazine, and it's what I'm running in my 350 with Vortec heads, which pulls strong at anything over 1500 RPM. And, I know, it's apples and oranges betwen his tractor and my T-bucket. I'll bet the folks at Comp can come up with a recommendation given the parameters of his 305 buildup. :)
 

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Okay, okay . . . no need to get all stinky. I found them helpful when I was choosing my cam, and they must have some credibility, or why would Ken Duttweiler use them in the LSR engines he builds for George Poteet?
 

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Cars, Trucks, Boats, Motorcycl
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I want to build this 305 focusing on LOW end torque and fuel efficiency.
I'd just do a stock rebuild... I'm sure you already have vastly more torque than you can ever use...
Maybe add smallest SBC cam that you can find for more low RPMs efficiency... like a 1950's low RPMs truck cam or one of those 125 HP California emissions cams... the swirl port torque heads we hotrodders throw away... maybe deeper dish pistons to prevent spark knock on regular gas with a tiny cam and to prevent overheating, I think '86 car 305's got shallower dish pistons for a bump up in compression ratio/HP... Q-Jet carb. should be great... one for a 305, not a larger engine...
 

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L03, 305 heads or LO5, 350 head. Both are swirl port head’s from 1987 through 1995. For the L05 head you want the casting ending in 193 which is the 64cc chamber version of these 350 heads. The Swirl Port head’s were specifically made for grunt motors at low RPMs that deliver good fuel specific numbers.

You don’t need a really big carb probably not even a four barrel, but that said, a tractor is going to work the cylinders with a lot of open throttle so even though the revs my be conservative the throttles will be mostly open compared to cruising around on the street, this is more like running in a good size boat. With that thought something like an Edelbrock 500 to 600 CFM set a little rich to keep the upper cylinder temps down would be perfect. A diesel is more perfect as it always takes a full breath so it always makes maximum cylinder pressure against its compression ratio, this is not so with a throttled petrol engine.

The other problem you’re up against is the 305 is not available with a 4 bolt bottom end where the 350 is. Given the high loading on the crank that a tractor demands the extra bottom end stability of 4 bolt mains is highly desirable.

For a cam probably something like the L03/L05 mild factory cam is as good as it gets as you aren’t going to work the engine high in its rev range so you need to play the cam into where your going to operate. Really this is a case where a 400 with a 2 barrel is perfect as torque is a measure of how much mass flow going through the engine in a given period of time. There are two common ways to increase mass flow : first is for a given RPM make the displacement bigger; second is spin the displacements you got faster. Either works but one doesn’t fit your RPM constraint. The third way is to increase the feed pressure into the cylinder, using some form of supercharge that adds let’s say 7 pounds of boost over atmospheric of 14 pounds this increases mass flow which causes the engine to act like it’s bigger than it is.

Bogie
 

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Cars, Trucks, Boats, Motorcycl
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You don’t need a really big carb probably not even a four barrel, but that said, a tractor is going to work the cylinders with a lot of open throttle so even though the revs my be conservative the throttles will be mostly open compared to cruising around on the street -Bogie
Actually, the engine that came in that tractor was about 20 HP and 25 lb.-ft. of torque so a SBC 305" with it's 200 HP and 300 lb.-Ft. of torque is MONSTROUS compared to the original engine! I only suggested the Q-Jet 4 bbl. because of its small, highly efficient primaries... the back of the carb. should be blocked off so fuel never gets into the rear and goes bad. I assumed this engine came with a Q-Jet. Or maybe it came with the efficient 1/2 Q-Jet 2 bbl... In any event, 1/8 throttle opening is prolly the most you would ever need for farming... maybe more if you want to skid/'drift' the tractor around in circles for fun...
Why bother with solid lifters? Here's a 184/194 durations truck cam/lifters. You want this durations or less: Summit Racing SUM-K1100 Summit Racing® Classic Cam and Lifter Kits | Summit Racing
Jegs might have a lower price, but they don't seem to go this small in durations... it would be a
#200-100K if they had it... or may find it for less online... ebay, Competition Products, Northern Auto Parts, etc... a custom grind for something even smaller would cost 2 - 4 times as much...
 

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Okay, okay . . . no need to get all stinky. I found them helpful when I was choosing my cam, and they must have some credibility, or why would Ken Duttweiler use them in the LSR engines he builds for George Poteet?
Follow the Benjamin's. !
 

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More for Less Racer
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Okay, okay . . . no need to get all stinky. I found them helpful when I was choosing my cam, and they must have some credibility, or why would Ken Duttweiler use them in the LSR engines he builds for George Poteet?
The person on the tech line that Joe Average talks to is not the same engineer Ken Duttweiler would be consulting with.....Joe Average talks to the $10/hour phone jockey who is just working the computer selection program in front of him.
Comp Cams has the average public snowballed with years of advertising blitz....they've got a great marketing department.
 

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I'm having trouble understanding what you are trying to accomplish. I can understand wanting to freshen up the motor, but if its already doing the job well, I don't understand the need for more torque. Remember that the transmission may not be strong enough to deal with more torque. Since you are actually "working" the tractor and its doing well, I would just concentrate on making it reliable and depenable.
 

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Stock 305 cam, heavy flywheel, swirl port 193 heads (leave the ramp intact), a nice intake and a well tuned 4bbl (style points for a Kendig carb though - kidding!). The recently mentioned graphite/stainless .026 gasket, and a very good distributor tuneup with a multi spark box....she'd be SOLID. If you're not going to use a heat crossover, then definitely get a cool carb (brand) carb shield. We used to install lots of em on SBC speedboats that towed skiers and toobers. Full engine load, skier falls off; throttle goes to zero, swing aound and turn engines off to pick up skier...now boat wont start. Especially with Edelbrocks. If you cant afford the TBI deal EricNova mentioned...I seriously suggest a 600-ish CFM Edelbrock "AVS-2". The annular boosters will pay dividends.
I did an alternator conversion on an unstyled JD 'B' tractor. Guy used a 1 wire alternator and the battery was always dead. He wasnt pulling enough Revs to 'excite' the alternator and charge the battery. if so; just bump the revs up or use an AC compensator type arrangement, till it starts charging. Might not effect you but it bears mentioning.
 

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Owner of a broken cart
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Discussion Starter · #20 ·
I'm having trouble understanding what you are trying to accomplish. I can understand wanting to freshen up the motor, but if its already doing the job well, I don't understand the need for more torque. Remember that the transmission may not be strong enough to deal with more torque. Since you are actually "working" the tractor and its doing well, I would just concentrate on making it reliable and depenable.
To do MORE work with less rpm
 
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