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Does this make any sense? ? ?

Please follow this one for a bit:

Again... working on a newly acquired chopped down Beetle Dune Buggy. Not a pro job... obviously some guys in a backyard did it.

It's a 70 chassis with a 69 Solex 30 PICT 2 carb on a 1600 74 motor.

I previously posted that it runs a little sluggish and then the throttle picks up unexpectedly and idles up and down with no pattern. We might see it speed up twice a lap or we may go 10 laps without it, but suddenly it's like a governor kicks in or the throttle was punched for an instant.

I replaced the vacuum line, disconnected the throttle positioner completely while plugging it's line and securing it's linkage. Pinned the choke open. I tried running it with the advance disconnected and plugged... and saw the same throttle phenomenon.

Now the head scratcher:

Decided to pull and change plugs and commented to the son about how carbon built the Left ones were (assuming the Driver side is still Left when the motor is in backarsewards ;-). I then pulled the Right (passenger) ones and saw they looked nearly new and were soaking wet with gas even though we didn't run it for a couple of days. I put a screwdriver in each wire and could see spark, but I don't know how viscous it should be. We fired it up and I smelled each pipe and the Right side smelled gassy... then ran it a bit and noticed the right was barely hot and the left was very hot. We then beat the tar out of it around and around the field for a good half hour and I could touch the Right manifold with the back of my hand (it was barely warm) while the left was too hot to risk getting skin near it. One time that thing kicked in and ran so hard just as I made a bend up hill downshifting to first that it tried to spin the rear end clean around and then didn't have enough uuuumph the next moment to sustain second.

I'm guessing that something is making the Right side start running for an instant here and there and at most other times it seems to be no more than a weak air compressor over there. I could see if a valve stayed open or something how this could happen with one cylinder, but what could possibly make both cylinders on one side behave in this off/on manner at once?????

Thanks so much for the replies I've gotten so far and for any that anybody might be able to add now.

Reply to
rdoc
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A '74 1600cc. With DP manifold? Rubber bootie leaking or head-to-manifold end casting gasket not sealing (very common).

Or...crack in manifold

Here is how I have tracked down difficult leaks that don't respond to the spray WD-40 tricks:

Make an adapter to fit on top of manifold (in place of carb). Pressurize this with a few psi air. Remove both rocker arm shafts so that all the valves are closed.

You can hear air escaping and also test with soapy water solution.

Speedy Jim

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Reply to
Speedy Jim

Thanks, Jim... I don't know what the manifold type is. It has a number string that starts with, IIRC, 113. I did, after your post however, loosen it to retighten it and it seems to not fit properly. I also did not notice a gasket in there.

Can a 69 manifold work alright on the 74 1600? It still has the old carb.

Not sure what you mean by 'rubber bootie leaking' either.

Thanks again.

Reply to
rdoc

'74 1600 had this manifold:

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It connects to the heads with this:
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The alum casting seals to the heads with this gasket:
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And the center section connects to the alum end castings with these Booties:
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'66 thru '69 ('70 similar) used this manifold:
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one piece. The one piece manifold seals to the heads with copper rings:
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It sounds like your '74 engine may be a "mishmash" of parts or isn't really a '74.

Speedy Jim

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Reply to
Speedy Jim

I would not be surprised one bit that many parts are mish-mashed. The number under the generator is AH-348899... my understanding is that is a 48HP 74

1600... one of the inlaws says he understands it may have come out of a bus while another says that was not the case.

At any rate... I thought the two pipes on the manifold were two separate items on top of each other and the one that matches up to the exhaust manifolds do not come close to matching or sealing. Are these ported to each other somehow? If they are then there would be a problem. As I mentioned before it is a 30 PICT 2 carb and it has a single round port on it's mount to the head. I didn't notice a gasket and may try to snag a new one even if there is one... just to make sure. Just went out and looked at the manifold number... 113-129-701-M the VW logo and a 2.

Also... someone else has said that there is one pushrod for each side of the motor that controls all of the exhaust valves for both heads, if I understood right, and that it might be loose. If that is the way it is (and again... it's been 30 years and I don't remember), how do I go about knowing which rod it is and checking or tightening it?

Like I said... this is a home-built Billy-Buggy for blowing around the farm here and will not need to sustain 60MPH on the hiways. It's just for the kid to have some fun and for him to get a little bit of feel for driving something around besides a big, slow tractor. I don't enjoy blowing across the fields and down to the barn at the top end of second gear at all, bouncing and spinning and sliding and eating mud and only yell wahooooo to impress the boy, mind ya ;-))))))) I only take those extra rounds again and again for diagnostic sake.

Reply to
rdoc

Yes, AH would be '74.

The small pipe underneath carries hot exhaust gas to make a "hot spot" in the manifold above. The upper and lower pipes are not connected as far as any flow is concerned.

As I mentioned

And that means the '74 heads were swapped for earlier ones.

I didn't notice a gasket and may try to snag a new one even if

There is one *cam lobe* for each pair of valves (left and right). And that's true for Intakes as well as Exhausts. So there are 4 cam lobes. There are 8 pushrods though.

if I

LOL

Jim

Reply to
Speedy Jim

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