TheSamba.com :: View topic - 1968 Bug. Runs like a pig when hot. -Engine is shot

Tue Nov 18, 2008 4:26 pm

Ok, It starts out fine and runs normal until the engine heats up then it runs like a pig (have to damn near floor it to take off) and does not hold a steady idle speed. My guess would be it is sucking in hot air but I have seen many others with the same setup and they have not complained.

Dual Brosol/Solex 40mm (a bit big for a 1600DP but the P.O did not know that)

Tue Nov 18, 2008 5:49 pm

Have you checked your valves?

Tue Nov 18, 2008 7:37 pm

blarneyman wrote: Have you checked your valves?

Checked when the engine was out and twice after it was back in. Set to .004 and .006

Tue Nov 18, 2008 9:50 pm

Sounds like timing to me. Do points first, then timing.

Wed Nov 19, 2008 8:01 am

Sean Stibi wrote: blarneyman wrote: Have you checked your valves?

Checked when the engine was out and twice after it was back in. Set to .004 and .006

THere ya go.. unless it is an early s/p motor from like...pre 67...
.006 is the norm for both valves.
Coil getting hot??
fuel pump dying...
I see from the second photo that the dist. is 180 out.

Wed Nov 19, 2008 2:55 pm

kevin11 wrote: Sean Stibi wrote: blarneyman wrote: Have you checked your valves?

Checked when the engine was out and twice after it was back in. Set to .004 and .006

THere ya go.. unless it is an early s/p motor from like...pre 67...
.006 is the norm for both valves.
Coil getting hot??
fuel pump dying...
I see from the second photo that the dist. is 180 out.

Engine Photo that I have up is from BEFORE it was running correctly(well, somewhat anyway) so the distributor is now facing the correct way.
Tried another Fuel pump, No difference. (was a good idea)
Coil stays cooler than the '71 bug that I have been working with.
It is a Dual Port 1600 (possibly bigger). Valve adjustment is good where it is, I got annoyed so I checked while the engine was hot one day and they still had enough of a gap so the valves would not be held open at all.

I think I will check the timing again. It is 30 degrees maximum advance right? 009 Distributor. Points are adjusted.

Wed Nov 19, 2008 3:42 pm

Sean Stibi wrote: I think I will check the timing again. It is 30 degrees maximum advance right? 009 Distributor. Points are adjusted.

30 may be too much. Back it off to 28 @ 3500rpm and see if it helps.

How do your plugs look?

I just saw your pictures... get rid of that chrome shroud and chrome cylinder tin! Those shrouds suck, and don't direct the air where it needs to go, plus, chrome is an insulator. If you have chrome valve covers, I suggest you put the stock ones back on too.

I also see that you have no vent holes on your decklid, and you have a 1600 in there. You have no lower tin, and all that heat from your header is going straight up and into the shroud. You're suffocating that engine.

Wed Nov 19, 2008 5:46 pm

One other thing with the fan shroud. In the pics, it looks like the heat exchanger hose openings are open (unplugged). Those need to be plugged if you're not running heat exchangers. You are loosing a lot of air flow over your cylinders.

Wed Nov 19, 2008 6:06 pm

SkrapMetal wrote:

30 may be too much. Back it off to 28 @ 3500rpm and see if it helps.

How do your plugs look?

I just saw your pictures... get rid of that chrome shroud and chrome cylinder tin! Those shrouds suck, and don't direct the air where it needs to go, plus, chrome is an insulator. If you have chrome valve covers, I suggest you put the stock ones back on too.

I also see that you have no vent holes on your decklid, and you have a 1600 in there. You have no lower tin, and all that heat from your header is going straight up and into the shroud. You're suffocating that engine.

Pulled the plugs before coming to look here. They are a bit darker than I would like but most would say that it is fine where it is. I will lean it out a bit later.

About the engine tin... I think the previous owner was in love with chrome. Chrome rims, Chrome steering wheel (At least he used my favorite one), Chrome sleeve over the shifter, and Chrome engine tin (YES Valve Covers too). At least he did not have time to put the chrome emergency brake handle on it, That sucker would burn your hand if the sun was on it for a little while.

I don't know what to do about the engine lid. That IS an Issue that I have known about since I opened it one day and just about melted my face off. I tried driving around with it off and it did run better but still had the issue of if you stopped for about 20 seconds then tried to take off again it acts like a stubborn donkey, It does NOT want to move.

I tried putting the timing down to 30 and it did not like it. It ran smooth above about 3500 (I would guess 3500 but I have no tach) but below that it hates. I think that is because of the Header and carbs that would work really well on a engine that is WAY bigger.

Edit: Yeah, Those pictures are a bit out dated. I was reading a thread here about a month ago about how someone had those heat exchanger holes open and they were told to plug them so I plugged mine too.

Between you guys and me, we have covered most things twice and others were great ideas but it STILL runs like a pig or a donkey. Anyone got another idea? I just rebuilt a 1600 (well a little above 1600, it has 86mm cylinders instead of 85.5) and that one runs good and I KNOW it is not right yet.

Wed Nov 19, 2008 7:43 pm

If you cap off the holes for the heat exchangers, you need to drill a 1/2" hole in the cap for some air to pass through.. you shouldn't block them completely.

Jake Raby wrote: the 1.5 hole had the same volume losses as the stock heaterbox in the "off position".. The system was designed to continually have a volume loss, as the heaterboxes have a release flap at the top that bleeds air when the heater is off.

Personally, I'd replace that shroud with a doghouse type shroud instead of trying to make that one better.

You should really take care of the heat issues I listed, and see if that by itself doesn't improve your situation.

Wed Nov 19, 2008 7:59 pm

I was planning on buying the tin I am missing and replacing the chrome cylinder tin (because they are horrible in more than 2 ways). It already has the doghouse type shroud, it just happens to be chrome and a new one is somewhat expensive.

Wed Nov 19, 2008 9:27 pm

Sean Stibi wrote: I was planning on buying the tin I am missing and replacing the chrome cylinder tin (because they are horrible in more than 2 ways). It already has the doghouse type shroud, it just happens to be chrome and a new one is somewhat expensive.

Well it's not so much as the chrome being a problem as the inside of it is. The chrome ones are not designed internally the same way a stock shroud is designed. It doesn't direct the air where it's needed the most (the hot spots), and it doesn't hold the same amount of air as a stock shroud. If you check the classifieds, used ones aren't that expensive. There's some on there now from $7.00 on up. I'd rather clean up a used beat up shroud than buy any of the newer stuff that's out, but that's just me.

And about the engine lid... it needs to breathe for the time being. Get a set of stand-offs, or prop the lid open at the bottom with a tennis ball.

Thu Nov 20, 2008 8:09 am

I had the same doghouse fan shroud on mine a couple months back. Ran really hot. It even had the vanes inside. I changed it out for the stock doghouse shroud and now it runs really cool. Maybe too cool!

Sun Nov 23, 2008 6:31 pm

Ok... I got really annoyed yesterday so I started to pull the engine out and today it was out completely. I took the head off cyl 1 and 2 and found that the spark plug had been cross threaded by the PO and was not going in but half way, I never noticed because I could not see and I don't force things. I was annoyed at that but I knew I could fix it easily. I figured that was one of my main problems for it running so bad.

I went ahead and cleaned the head before I did the valve job. Well, I cleaned it and found something that I REALLY did not want to. I found a crack between the valves in cylinder 2 along with the spark plug thing, dents in the combustion chamber, and a nice scratch in the cylinder wall. Cylinders are worn out as well.

you guys think I found my problems yet? Do I dare take off the 3 and 4 head? lol...

Sun Nov 23, 2008 9:35 pm

Well, I'd say it's time for a tear down. No sense in stopping now.

Mon Nov 24, 2008 1:19 pm

Well, took the other head off and I found a piston that looks like the surface of the moon in places. So now I have 2 bad cylinders, a cracked head, and a ruined piston (rod is probably not too happy either)... Now I have to decide on what I want to build.

Mon Nov 24, 2008 2:32 pm

I'd tear the case apart next, you might find more.

Mon Nov 24, 2008 2:46 pm

Well, It is coming apart and getting rebuilt. Just have to decide what I want to build because more than one cylinder is shot and cylinder head #2 is bad looking too. If just the top end is this bad, the rest can't be good looking.
Here are a couple pictures. This is not something I wanted to find yet.

I think it is time to collect from when I rebuilt my sisters engine...

Tue Nov 25, 2008 1:06 am

i just saw the pic of ur engine b4 u took it out

WOW, the PO should be facing the firing sqaud
ive never seen so many faults in one engine bay