Cam Swap in Truck W/AC

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legopnuematic

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So after my 76 got rear ended in my driveway and I picked up a front clip for my 79 in the last few miles home it started ticking like crazy, spent 9 hours fiddling with the rockers and preload as they were not adjusted correctly, got it all buttoned up, took for a drive at operating temp, went WOT, all was good. Today I drove up to the coin op car wash to wash the truck and the front clip I picked up, on the way back The ticking came back. It wasn't like when it first began, but still apparent. I have had the truck for over 2 years and it has always had a light ticking at idle, like a PCV rattling (not the PCV causing this). When I was setting the valve preload it looked to me that the intake on #8 pushrod sat lower than the rest of the other push rods that were on the base circle. To me that says a dished lifter and flat lobe. Pushrod itself was not bent or damaged. I will put an indicator on it to verify lift against other intake lobes. I know there is that possibility that the major cause of the ticking could be a cracked flex plate too, but I am pretty certain the cam has some flattened lobes too.
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With the backstory out of the way, onto the meat and potatoes. My 76 has A/C and it is charged, so how much of a pain in the ass is it to swap the cam with the engine still in the truck and condenser still connected. The actual process of swapping the cam/lifters itself I am not worried about as I did all of that on my 79 350 and it fired right up the first time and break-in went good.

Since I will be pulling the intake I think I will put an aluminum intake on it and will be keeping the Q-Jet. I was looking at the Eddy 2101. Anyone have any experience with them and anything I should know/need for using it with a TH350, Q-Jet w/factory air cleaner and hot air type choke, big A/C compressor?

Plan on using a Comp 2100 timing chain as I did in my 79 and with a Comp lock plate. In my 79 I used a Summit K-1102 hydraulic flat tappet cam and have no opposition to it but am open to suggestions for other cams. Truck is equipped with 3.07 gears, 235/75/15's, TH350, stock manifolds and Y-pipe, and stock converter. Not building a race truck, just something for a solid daily driver with good mid range power and off idle, don't care about (or really want) a lopey idle and don't want to put a stall converter in.

I plan on pulling the oil pan to do the timing cover and then also to re gasket the oil pan, check the bottom end out, and put a new rear main seal in it as either the rear pan gasket is leaking or the rear main is leaking. Also take that as an opportunity to clean the front of the engine up and paint it and also paint the oil pan.

Thanks for any input and suggestions.
 

idahovette

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Is this the one that got the great gas mileage before? If so I think I'd try to run the same cam in it you had if you know what it is. Seemed like it ran good and got some terrific fuel mileage. just my 2 cents.
 

bucket

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Personally, I'd pull the engine and get it on a stand. It's a few more steps to do it that way, but it's easier on your back and the finished product will be nicer too. It would also be good to check out some of the bearings in case too much grit has been cycled through.

Just watch out for the "might as wells" doing it that way.
 

Craig 85

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Does your '76 have this throttle kicker for the A/C? My '79 350 did. It bumps the idle when the A/C is on. IIRC it's tied into the A/C clutch wire. Here's a link to Quadrajet parts. They may be able to help.

https://quadrajetparts.com/idle-solenoid-1977-p-2133.html

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legopnuematic

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Personally, I'd pull the engine and get it on a stand. It's a few more steps to do it that way, but it's easier on your back and the finished product will be nicer too. It would also be good to check out some of the bearings in case too much grit has been cycled through.

Just watch out for the "might as wells" doing it that way.

At first I wasn't wanting to pull it but rethinking it I think it might be the easier way. Then I would just need to clear the one side to pull it in where my 79 cab is, pull it, roll it back in the driveway with hood back on, get it on my stand then put the 79 cab back where it was. That way I can clean it good and paint it nicely.

I know how the might as wells will try tohappen too. You know, might as well bump the compression with some flat tops, those heads are weak, might as well rebuild that 400 I got sitting....

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legopnuematic

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Does your '76 have this throttle kicker for the A/C? My '79 350 did. It bumps the idle when the A/C is on. IIRC it's tied into the A/C clutch wire. Here's a link to Quadrajet parts. They may be able to help.

https://quadrajetparts.com/idle-solenoid-1977-p-2133.html

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Mine does not and I don't believe it was ever equipped with one as I have not found any evidence of the wire or witness marks on the carb body itself. The Q-Jet I got for my 79 does have one but I plan on using it on it for an accessory driven air compressor I'm scheming up.

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legopnuematic

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Is this the one that got the great gas mileage before? If so I think I'd try to run the same cam in it you had if you know what it is. Seemed like it ran good and got some terrific fuel mileage. just my 2 cents.

Yep it's the one that got 27mpg. That was under near ideal circumstances, around town and when not being able to cruise on the highway at a constant speed it gets a solid 10mpg. The engine was an AutoZone reman that was put in in 2007, only has like 30,000 miles on it, so I would guess it is whatever came in the rebuild kit. I think if I do put a different than oe replacement one in it would be close to the oe specs but maybe a more modern and optimized grind.

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I had to remove my conderser and the support bar in the core support to get my cam out, if you want the ac to stay intact pull the engine. As for the cam, that is an old grind and will work but you could be leaving alot on the table by not using newer grinds and cam technology.
 

legopnuematic

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I had to remove my conderser and the support bar in the core support to get my cam out, if you want the ac to stay intact pull the engine. As for the cam, that is an old grind and will work but you could be leaving alot on the table by not using newer grinds and cam technology.
I think I'll pull it as I really don't want to mess with discharging and recharging the a/c and moving the condenser. Do you have any suggestions for a cam that uses new grinds for a basically stock application?

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4WDKC

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Call cam manufactures or Chris Straub and tell them what you have for correct cam. From what I have read you're going to want something in the lower rpm range with quick ramp rates to increase cylinder filling and pressure. Alot of people seem to like and recommend cams like the high energy 254,256 or 258 cams for mostly stock. If you have any thoughts about switching to efi get a cam with 112+ lobe separation angle, you can tune engines with lower LSA its just harder.
 

legopnuematic

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225/6, 350 c.i., 350 c.i., 5.9l Cummins
Call cam manufactures or Chris Straub and tell them what you have for correct cam. From what I have read you're going to want something in the lower rpm range with quick ramp rates to increase cylinder filling and pressure. Alot of people seem to like and recommend cams like the high energy 254,256 or 258 cams for mostly stock. If you have any thoughts about switching to efi get a cam with 112+ lobe separation angle, you can tune engines with lower LSA its just harder.

I plan on sticking with the poor mans fuel injection: The Quadrajet.

I think I will go with the Howards Cam's CL112001-14 it seems to be right around what I think is best suited for the truck. I did send in the recommendation form to Howards Cams so I'll see what they recommend, but I think it would probably be the one above or very close to it.
 

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As soon as I read "paint the oil pan" I thought you should pull the engine.
Certainly doing all of the chores you listed are possible with the engine installed but really man, why bother? I believe THAT will only make your task(s) exponentionally more difficult and after you pull it, the end result(s) WILL BE way better and more aesthetically pleasing.

If you ONLY wanted to cam swap then maybe , but that list of jobs grew rather long by the end of that post! :)
 
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legopnuematic

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225/6, 350 c.i., 350 c.i., 5.9l Cummins
As soon as I read "paint the oil pan" I thought you should pull the engine.
Certainly doing all of the chores you listed are possible with the engine installed but really man, why bother? I believe THAT will only make your task(s) exponentionally more difficult and after you pull it, the end result(s) WILL BE way better and more aesthetically pleasing.

If you ONLY wanted to cam swap then maybe , but that list of jobs grew rather long by the end of that post! :)

100% agree, The engine is coming out since I don't want to touch the condenser since I know if I discharge the system it will most likely never get recharged again. And with the way my luck has been recently I rather be able to check the rod bearings to make sure there isn't one that is the real cause of the noise. I did put an indicator on #8 Intake and confirmed that it has 0.030 less lift than the other intake valves at the pushrod side of the rocker (0.045 at the valve), but better safe than sorry.
 

legopnuematic

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Moved the 79 to the other side of the garage in order to pull the 76 in to pluck its heart out and perform surgery on it, once removed it will be rolled back into the driveway, 79 moved back over and then the work will begin on the 76's engine.
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Made sure the engine crane is able to get high enough to get it out. Think it ought to work.
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