Any thoughts on this...need some help!

[quicksilver]

I've been lurking around a while, then got caught up in moving, so I guess you could say this is my first REAL post. Unfortunately, it's a cry for help for the experts I've seen in action here (and everybody else as well) .

I've got a 72 Cheyenne LWB, 3 speed on the column, with a 307 that the guy I bought it from put in it, and it still has a points distributor as well.

I think my problem started back around November when I drove the truck home to Virginia for hunting season. It has just recently gotten noticeably worse, but that may be because I've started a 30 mile/day commute, and the truck is my daily driver. The only way I can describe it is similar to a big gust of wind hitting/slowing the truck down intermittently when I'm pulling a grade, and a little noticeable at higher RPMs before shifting (but not alot). It feels like it just kind of lags or cuts out. Not the engine, but more like maybe clutch or tranny. On level ground it doesn't do it at all except maybe a hint at the higher RPMs, but I try to shift way before that due to my feable attempts to save gas The engine doesn't break up when I'm in neutral and putting some RPMs to it. Which kind of made me think it wasn't fuel or spark. But I've never felt a clutch slip, or had one that was (my best guess) a little over 30 years old. I don't know if he put a new clutch in it, but I doubt it.

If anybody has any thoughts, please feel free to dump them on me. I wasn't sure where to put this thread, so I just thought I'd start it here. Moderators, fell free to move it as applicable. Thanks ahead of time for any help.
'Preciate it.

Doug

[crawdad]

Sounds to me like you've got a clutch slipping. RPM's go up, speed goes down. Did you say the engine sounds ok during all of this?

[mrein3]

Have you done a compression test? Maybe that 307 has lost just enough to poop out at higher rpms pulling a load. You wouldn't notice any difference standing in the driveway buzzing the throttle because there isn't any load on it.

[purple gas]

Might be an idea to see what a clutch is worth. I'm and automatic guy so I have no idea what the parts would cost, but if you could get some help it would likely be not too much to put one in yourself. If your gonna keep the truck with the 3 speed that is. Even if you bought the parts & pulled things apart and the old one looked good you could take the parts back if you didn't need them. My last standard was a VW beetle with a fairly warm motor and a new clutch was a good investment I thought even tho the old one wasn't totally gone. I'm not an expert tho.. Good luck & welcome from the great white north.

[lpaine]

Yeah, I vote for the worn-out 34 year old clutch too, does the engine feel like it's revving up on longer hills under a load,? (that would be the clutch slipping) The parts wouldn't probably cost more than a couple hundred bucks, and depending on your own mechanical skills you could probably do it yourself if you have access to a hoist, I don't think you would want to attempt a clutch change lying on your back in the driveway or shop,(you'll have to drop the tranny out) and you'll want to get the flywheel re-surfaced (ground) at a machine shop. Also that would be a good time to replace the rear oil seal if needed.Good Luck.

[quicksilver]

Hey guys. Thanks for the inputs. I notice no change in the RPMs, it pretty much stays the same. If anything it seems like it may drop off a little. I'm probably going to try the compression check. I need to change valve seals anyway, so between both jobs it'll give me a reason to pick up some tools.
I've priced a clutch setup, and it doesn't seem too awfully bad. Any ideas on what clutch dia. size/spline count I'd have? I can get plenty of assistance, so I could probably do it myself.
I was worried that the truck might start showing some signs of old age when I started this commute. It might be just about time to pull the cover off the Z and do a little work on the truck.
Any more comments are welcome, and thanks again.

[Sonny]

When was the fuel filter changed? If the filter is clogged, your 34 year old fuel pump may not be producing enough pressure/volume to overcome the resistance of a clogged filter and the carb bowl runs out of fuel. It is realy noticeable when you try and see how far you push to find where "E" is on your fuel guage.

IMO,
Sonny

[screamin_c102]

with Sonny. This doesn't sound like a clutch at all. I would also check to see if you are getting good vac at the advance of your distributor. I have seen vac line suck down and pinch off when under a load (high vac) this would cause timing issues under load making the engine lose power. A clutch would be a waste of time and money. If the engine was recently changed the clutch was probably yarded out as well.

Just my $.02

[Longhorn Man]

You tried a tune up?

I agree that your clutch is most likely fine.

[quicksilver]

Thanks again fellas. I've got a 3 dayer next weekend, so I plan to do a little wrenchin. I may even go snag a fuel filter tomorrow and try it. I haven't changed it in my 2 years of owning the truck. I had actually thought about it before, but figured I'd be able to see it more often than just under a load. But hey, a complete tune up sounds doable.

[1-PU70]

I vote on thr gas filter.

[dregs454]

My truck had similar problems, fuel filter fixed the problem. Before I bought it, the truck sat for 2 year. I changed the filter right when I bought it, and then didn't think about it as I drove it for a few months. Well, all the dirt that accumulated in the 2 years came out in the first few months I drove it. The fuel filter was totally clogged. Fuel filters are cheap, and easy to change, so if it hasn't been done in 2 years, definately try it.

[franko72]

I would change the plugs and points if it has points, Maybe cap and button. I vote for a tune up like longhorn man suggested before I did anything else

[chucks70]

Check the sock in your gas tank too, mine was clogged and cause a similar problem.

[shifty]

If this also happens when you stomp on the gas (like...when you're passing someone), I'd also say it was a gas filter. Cheap part, too. World of difference between a clogged one and clean one.

[quicksilver]

Yeh guys, I changed the filter (gas and air), fuel and vacuum hoses today. It does run better , but it still has the lag. I'm planning on plugs and points next weekend, or if I can get them done this week, then the weekend is for valve seals and compression check.
Again, the motor doesn't actually sputter or break up. I'm just trying to eliminate any other possibilities before I tackle the clutch.
Thanks for the comments/suggestions.
This place is a great source of info

[cableguy0]

forget them points. throw in an hei especially driving 60 miles minimum a day those points will be way more trouble than they are worth. you should be able to get a used hei for around 35 or 40 bucks put on a new cap and rotor and run a new power wire and you will be good to go. also need new ignition wires for the swap as well as plugs but thats all normal tune up stuff anyways.

[Gary Lee]

Originally Posted by cableguy0

forget them points. throw in an hei especially driving 60 miles minimum a day those points will be way more trouble than they are worth. you should be able to get a used hei for around 35 or 40 bucks put on a new cap and rotor and run a new power wire and you will be good to go. also need new ignition wires for the swap as well as plugs but thats all normal tune up stuff anyways.

I agree... if you want a good idea, just pull a plug wire and set it on the valve cover and have someone turn it over... Is it a good blue spark?But more juice is always a good thing, and I for one like not messing with points and condensors....

If the clutch was bad, your rpms would climb as it spins and you go nowhere... or it finally heats up enough to catch.... I would hazard to guess as it could be so many lil things... But I wish yu luck

Gary

[quicksilver]

So check this out. I may have been a little premature last night in making that post. I took it out for a little while last night, and it seemed like to me it was still doing the same thing. But I get up this morning and drive in to work and then back home this afternoon, and nothing like before, even pulling hills. Nothing at all. So I might be fixed, but I still plan to mess with it.
I had thought about the HEI as well. Especially after reading about those points, blah.
Thanks fellas.

[busterwivell]

Cableguy is sssssssssooooooooooooo right. Get an HEI in that thing. It can't be a clutch problem, or the RPM's would go up while speed goes down. HEI, wires, cap, rotor, plugs and you'll be good to go for a LLLOOOOONNNNNGGGG time again.

[quicksilver]

Thanks busterrrrrrrrrrrrrr I've been looking around on here and EBay for an HEI. We'll see what happens.

[cableguy0]

i have a stock unit that worked when it was pulled a couple years ago it would probably need a cap and rotor otherwise good if u would wanna come get it i will let ya have it for 30 bucks