Hey guys, we have a problem that I'm hoping isn't anything major.
Basically our 1641 engine likes to run on 2 cylinders most, if not all, the time. We have tried a number of things though we haven't had much time to work on it lately.
Anyway, one day, for whatever reason, I noticed that the intake casting for the 3rd and 4th cylinder was loose was leaking quite a bit of air in. I figured this could be part of the reason for how weak the engine had been running, so I tightened it down...while the engine was running. It then proceeded to immediately rev up to 3-4000 rpms and then quit completely.
The engine will not stay running with the intake tight unless you keep pumping the accelerator to keep gas squirting in, and even then, it revs way up.
If I loosen the intake on the one side, it will start up and run with seemingly no problems (besides the fact that it's only running on 2 cylinders).
My initial thoughts are that as soon as I tightened the intake, the air/fuel mixture became too lean, and thus, the revving up and death.
So the first thing I did was change out the carb with another carb that had been set up and run with an engine that ran on all four cylinders.
This had absolutely no effect.
Any ideas on things that I should check?
Sorry about the length of this, but it's extremely hard to explain this in words and I'm sure I left some stuff out.
Thanks a lot guys,
Pat

_________________
Get me that hammer, pronto!

It would seem that by tightening the manifold bolts you would have less of an air leak and that would richen up the mixture, however with the reving up that usally indicates a leaner condition. Is it possiable that tightening the manifold pulled on the carb linkage and opened the carb butterfly more? I would start with replacing the intakes to carb manifold rubber couplings, both intake and the carb gaskets. With the air leak I would also check compression. Lean mixtures like that promote extensive wear on the engine componets.

_________________
Water cooled Dry Sumped Subaru Powered Turbo Charged Fuel Injected 2500CC Tank. Oh Rah! He who dies with the most Toys not only wins, He also wears them out!

Hah, yes, you are right, there is a gigantic, huge gaping hole in my theory that makes it contradictory...hmmm.
No, it didn't move, plus the throttle cable isn't even hooked up at the moment.
But, I'm not even worried about it running "good" yet, I just want it to fire on all four cylinders. Then I can work out the bugs...no pun intended.
Thanks for the quick response.

_________________
Get me that hammer, pronto!

Hey I'm not sure but check the firing order 1432. Also check your rocker arms, if they are not opening/moving then that will make it run bad. I just worked on a buggy for a guy that had a lash cap fall off and the push rod slide past the arm and the engine ran BAD. Back fired out the carb and wrecked the filter. Also check the spark at the plug end, just something to try. Thanks Dave T

Firing order's good, need to check the rockers ( though we just adjusted valve clearance a couple months ago), and all the spark plugs are sparking strong.
Any other things we should try as well?
I'd like to be able to drive this thing around a bit before summer's over.
Thanks a lot,
Pat

_________________
Get me that hammer, pronto!

Have you sprayed starting fluid around the intake gaskets after you tightened them up (and or replaced them) to check for leaks? Is your timing correct and the advance working?

_________________
Water cooled Dry Sumped Subaru Powered Turbo Charged Fuel Injected 2500CC Tank. Oh Rah! He who dies with the most Toys not only wins, He also wears them out!

Well, no, but the engine has to be running for that to work doesn't it? I can't keep the engine running, and when it does, it's only running on cylinders 1 & 2.
The only other thing is timing, which I have the distributor loose as it sits now, just so I can fool with it a little while I'm trying to start it, so I'm pretty sure it's not timing, but I could be wrong.
Thanks Odyknuck

_________________
Get me that hammer, pronto!

Well now we may be getting somewere. Static time the distributer to its required spec (depending on motor and distributer) an leave it there until you can adjust it with a timing light. Have you checked to make sure the rotor ligns up with No.1 Cylinder when its on the compression stroke.
In your earlyer post you mentioned about trying another carb off a running moter. All motors are not the same and one carb does not fit all motoer, meaning different jetting, idel and mix adjustment is usally required. The starting fluid test will also work when only 2 cyclinders are firing. If the ones that are not firing fire when sprayed you will know that there is an issue with an intake leak. Are you sure you are getting fuel to all cylinders.

_________________
Water cooled Dry Sumped Subaru Powered Turbo Charged Fuel Injected 2500CC Tank. Oh Rah! He who dies with the most Toys not only wins, He also wears them out!

Ok, I will static time the distributor. Plug wires are in the correct order and cyl 1 fires on the compression stroke.
Once again, the engine will run on cylinders 1 & 2 if I loosen the intake casting bolts on 3 & 4, but when they are tight, it absolutely does not want to run unless you keep pumping the accelerator.
And yes, all cylinders seem to be getting fuel as evidence of the spark plugs being wet on the non-firing cylinders.
As for the carb, that is true, but it doesn't seem that it should make much of a difference in this case. I'll probably put the old one back on though.

_________________
Get me that hammer, pronto!

Hmm! It sounds like when you lossen the bolts on 3 & 4 and then 1 &2 fire its allowing more intake suction on 1 & 2 and less on 3 & 4 allowing 1 & 2 more fuel. Is the compression with in 10% on all 4 cylinders? Have you checked the 2 rubber intake couplings yet?

_________________
Water cooled Dry Sumped Subaru Powered Turbo Charged Fuel Injected 2500CC Tank. Oh Rah! He who dies with the most Toys not only wins, He also wears them out!

Now I think we're on the same page.
Yeah, the compression is something that I've wondered about and need to check.
Am I checking the couplings for leakage, I guess?

Also, just to a another tidbit of information, when everything's tight and I get it running (solely off of the gas from the accelerator pump), it's still only running on the two cylinders (1 & 2).
Thanks a lot for sticking with me on this one, hah.

_________________
Get me that hammer, pronto!

So I gather it never really runs on 3 & 4? Yes check couplings for leaks or just replace them they are cheap. Definatly check the compression and valve s.

_________________
Water cooled Dry Sumped Subaru Powered Turbo Charged Fuel Injected 2500CC Tank. Oh Rah! He who dies with the most Toys not only wins, He also wears them out!

Pretty much. Couplings should be fine as we bought them not too long ago, but I'll make it a point to check.
What should I look for in regards to the valves? Am I looking for something major?

_________________
Get me that hammer, pronto!

You want to make sure they (Rocker arms) are not adjusted too tight meaning you may a valve open when it should be closed when the cam is on the base circle of its lobe.

_________________
Water cooled Dry Sumped Subaru Powered Turbo Charged Fuel Injected 2500CC Tank. Oh Rah! He who dies with the most Toys not only wins, He also wears them out!

Railhomie, PM me and I'll give you my number. If you got a trailer bring it out to the house next week, and I'll look at it for you.

Larry

Larry,
Now thats the best solution to his problem to date lol. Its very diffucult to diagnose engine problems sight unseen. Its usally the littlest thing that gets overlooked. Been there done that.

_________________
Water cooled Dry Sumped Subaru Powered Turbo Charged Fuel Injected 2500CC Tank. Oh Rah! He who dies with the most Toys not only wins, He also wears them out!

Very true, very true. I was just looking for ideas and you helped a lot with that. Thanks man. Maybe I'll get to meet you someday.

_________________
Get me that hammer, pronto!

Hopefully you guys can get it worked out. Sooner or later I will be going to D&K or some where south to go riding. Or you can allways come up tp Wellsville in October. Maybe then we will meet and tear up the trails.

_________________
Water cooled Dry Sumped Subaru Powered Turbo Charged Fuel Injected 2500CC Tank. Oh Rah! He who dies with the most Toys not only wins, He also wears them out!

That sounds good to me. I want to check that place out, bad!!! A couple ridin buddies have been kickin it around to try and make a trip up there this fall. Long ride, but I hear its well worth it. Maybe the October ride they are trying to pick a date for in that other thread.

Larry

i have a 1915 with weber two barrell that had the same problem reving really high then dying just as quick but mine did run onall fours what i did was spray starting fluid around the intake and there was air sucking in extreamily bad if you have metal intake gaskets i hnever had luck with those yet what i did was get intake gasket which comes in a roll and cut a gasket out to match the intake gasket and got a high temp gasket maker and put it on the quark gasket and let it dry 24 hours without pumping the throttle at all finger tighten the bolts for the intake and after 24 hours snug them down to spec. as for the running on two cylinders from the high reving my motor also at the time had cracked intake or exhaust valve springs i had to really look because its hard to see if you just take a quick look in there but check for a broken valve spring on those cylinders im not even sure if that is your problem just trying to help you I also have a 1641 which had the same problem in may 07 only mine was lacking #2 cylinder from the broken valve spring just give that a look look at the far back of the spring closest to head see if it is cracked it can be cracked and still intact and not laying in pieces inside the head

Roy J.

I still haven't gotten a chance to look at it, but thanks, that'll definitely be going on the list of things to check.

_________________
Get me that hammer, pronto!

You didn't mention whether the motor had previously ran or if it is one that the history is unknown. If it's unknown I would check to see if the distributor is 180 deg out. also that positive and neg are wired correctly on the coil. The engine will run with both of these done incorrectly but very poor.

Yes, it was running before, probably not up to par, but we rode the buggy for quite a while before I noticed that one of the cylinders was dead (now two are).
If I understand correctly, there are two places that the notch can be pointing (009) on the distributor with respect to the case. Which way do you guys normally have it?
I'm pretty sure the coil's wired right, but another thing worth checking I suppose.
Thanks a lot.

_________________
Get me that hammer, pronto!

Where abouts in louisvlle do you live, I'm in the Valley area If you wanna bring it by one day I will be glad to give you a hand with it.

Tony

_________________
A bad day Buggying is better then a good day of most anything else.

Thanks a lot for the offer Tony. I know two go-to people in Louisville now. We haven't had any time at all to even look at it since I started this thread, but once we do and we get stumped we know what our next step can be.
Thanks a lot everyone. I wish I could be working on it so that I could be giving some real-time feedback, but I don't know when that's going to happen.

_________________
Get me that hammer, pronto!