Help on 318 rebuild

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stumblinhorse

stumblinhorse

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Grand County, CO
Hello, new to the forum and don't have a a-body but have a 69 d100. But there seems to be a lot of good info on here and a bunch of knowledgeable small block people. So I hope you don't mind a few question(and comments) from time to time. I have begun taking my truck through the process of turning it back to great from being pretty good. I have maintained the engine in the past and finally was tired of hard hot starts and different idling at every stop etc. So I am going in!

Pertinent information for the truck/engine is that it is a 318-2 casting, build numbers on the block say 01239 which I assume means Jan-23-1969. Stock it was a 2-bbl Stromberg. It has a Np435 hooked up to it and an open 741 3.55. Current mileage is 105k and everything is pretty much original, except for my welded on new sheet metal.

I have put on a dual exhaust on stock manifolds, Weiand Stealth and a Eddie Perf 600 8% lean jetted for my 7000ft altitude. I put in electronic ignition with the "blue" Box and billet dizzy. And new shiny valve covers because my wife liked them and the old ones looked bad and leaked.

Truck is a driver.

So to my questions. The next upgrade I am planning is to ditch the stock exhaust manifold for 1 5/8" tube full headers and tie into my current 2.25" dual exhaust. Is that worth the cost and time. Or should I look elsewhere. I will probably pull the motor to take to a machine shop in the area for a bore, new pistons, valve job etc next winter. I need to save up for all that work. And the shops are already really backed up right now. So this winter is out for the getting it in.

Thanks for any advice.
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VERY nice truck!!! As for the 318 - you don't need the headers right now - they won't add enough to really notice (well, you'll be noisier)... now if you do the "big" rebuild, they would be a worth while investment. A lot of folks will likely "ding" you for boring a 318 (as in why would you spend the $$) - I say, if that's what you want - do it! Just keep your expectations realistic - when all is said and done, it is still just a warmed up 318. Mopar on! :thumbsup:
 
1st, Welcome! 2nd, beautiful truck!
Now, I would recommend doing a compression test. I've seen a lot of 'em with valves that aren't sealing, especially if it doesn't have hardened seats. This leads to loss of power, poor gas mileage, and can lead to hard starts. Heads are so important to the way the vehicle performs.

Very well could be a good valve job (or different set of heads), and timing chain, and you'd be set for a long time.
Pulling the motor for a full rebuild is always a good thing too.
 
Welcome aboard!

IF you use headers, I myself would do a 2-1/2 exhaust pipe with use of a cross over H pipe. At this size pipe, there isn’t an upgrade I can’t handle. Unless it’s a super charger or N02 of copious amounts

As said above there isn’t much of a seat of the pants gain with the headers. Efficiency of the engine should go up. What you should find is more mileage and power, the power felt will be a low amount.

If you add a case him to the engine builder, make it a mild one. This will be the most effective power return on a daily driver.
 
I'd say the header swap is worth it. I did it on my last gas pickup and it made a difference and sounded great.
 
Brings back memories.... we had a '70 Dodge truck, real light yellow, and we took it to Colo to see family. Love the factory "work benches" the fenders provide when you open the hood :) .
 
Throttle shaft wear on the carb can cause erratic idle RPM's and carb condition can also cause hard starts.
It'd be a shame to rebuild it and find out it was just the carb all along.

The compression test, oil consumption and timing chain slop would be some good things to take into account before just tearing into it and spending money it might not need.
 
Thanks for all the positive comments! I appreciate it. The 2 things mentioned are right where my "head" is at. Should I pull the heads and have them done or spend on the headers? Since it is a leaded gas era truck that was used as a truck, hauling, trailer, slide in camper etc. My valves are probably hammered in.
 
stumblinhorse said:
Thanks for all the positive comments! I appreciate it. The 2 things mentioned are right where my "head" is at. Should I pull the heads and have them done or spend on the headers? Since it is a leaded gas era truck that was used as a truck, hauling, trailer, slide in camper etc. My valves are probably hammered in.
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Dont know if there would be telltale signs,perhaps heads may have been done at some point. I guess pulling them will tell all.
Nice truck!
Enjoy your stay here at FABO!
 
stumblinhorse said:
Thanks for all the positive comments! I appreciate it. The 2 things mentioned are right where my "head" is at. Should I pull the heads and have them done or spend on the headers? Since it is a leaded gas era truck that was used as a truck, hauling, trailer, slide in camper etc. My valves are probably hammered in.
Click to expand...
20 minutes for a compression test would tell you a lot.
 
hard hot starts and different idling - my guess is you need to isolate the carb from engine heat. and what else do u want? 2.25" exhaust is plenty for a 318 with a 600 carb and a street truck up to 6000 rpm. if the truck has been worked hard some valves may be sunk, and do a compression test-but with hydraulic lifters plunger travel helps. how much oil does it burn?
 
Make sure compression test is done with carb at work.
As mentioned I would do some diagnostics before committing to a full rebuild. It may just need top end stuff...save you a lot of $$. If you replace pistons, be sure to check weights. A large difference in weights can lead to a lot of $$.
Have fun and enjoy! Welcome and beautiful truck!
 
Marcohotrod said:
hard hot starts and different idling - my guess is you need to isolate the carb from engine heat. and what else do u want? 2.25" exhaust is plenty for a 318 with a 600 carb and a street truck up to 6000 rpm. if the truck has been worked hard some valves may be sunk, and do a compression test-but with hydraulic lifters plunger travel helps. how much oil does it burn?
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So the differing idle speed problem went away with the new manifold and carb. That was the start of my upgrade in the last month. Sorry I wasn't clear. I was tired of the rebuilding the almost 50 year carb and still having to fiddling with the idle mixture with a vacuum gauge. So I decided to upgrade.

But I would say it leaks more oil than it burns! I have chased down a couple of leaks recently and replacing the valve covers using new rubber gaskets has helped. I am going to pick up a compression test tool and test it.
 
4spdragtop said:
Make sure compression test is done with carb at work.
As mentioned I would do some diagnostics before committing to a full rebuild. It may just need top end stuff...save you a lot of $$. If you replace pistons, be sure to check weights. A large difference in weights can lead to a lot of $$.
Have fun and enjoy! Welcome and beautiful truck!
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Thanks!

Not sure what "carb at work" means. I am familiar with just shutting off fuel and fire and cranking for a compression test. Can you please explain?
 
engine warm, good battery, throttle open, all plugs removed, crank each cylinder over 4 or 5 revs. turn OFF autocorrect on phone
 
A compression test will tell the tale. If a cylinder is low do a leak down check.

I had a 69 d-100 as the first truck I ever bought, 318 4-speed, 3.91 gear, beat the living hell out of that truck, the rear end finally gave out.

Put the engine in my wife's duster, beat on it alot more, built a bigger engine for the duster, pulled it out and put it the barn.

A guy bought the engine because it would match the other engine in his boat, the damn thing would not die.

And cheap headers fit with no issues, I think I even had an old set off a car in my truck.
 
sireland67 said:
A compression test will tell the tale. If a cylinder is low do a leak down check.

I had a 69 d-100 as the first truck I ever bought, 318 4-speed, 3.91 gear, beat the living hell out of that truck, the rear end finally gave out.

Put the engine in my wife's duster, beat on it alot more, built a bigger engine for the duster, pulled it out and put it the barn.

A guy bought the engine because it would match the other engine in his boat, the damn thing would not die.

And cheap headers fit with no issues, I think I even had an old set off a car in my truck.
Click to expand...

Thanks!

Lots of room for headers in there! I can stand in there with my feet on the ground on either side of the motor.
 
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