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Hesitation upon acceleration when cold, poor gas mileage
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awhitehouse51
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PostPosted: Sat May 08, 2021 1:39 pm    Post subject: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

Hey all, I rebuilt my motor about 2500 miles ago and am having a few small issues with it. pertinent information first: was a stock 1600, I put oversized valve heads on, changed my 009 distributor for a SVDA petronix flamethrower with electronic igntion (no points) and the coil to match the distributor. Everything else is stock. After the rebuild, I was getting about 13-15 mpg (17 on a good day). keep in mind this is mostly city driving. When I double checked my timing the other day, saw that at 3300 rpm with the vacuum line disconnected and plugged, I was running about 24* full advance. Advanced it a little bit so its now sitting at 28* full advance. my gas mileage ended up getting worse, im 1 tank since the adjustment and now at 12 mpg. I've read that for the SVDA distributor the correct timing is 28*-33* full advance. Someone double check me on this? Previous to the rebuild, my stock motor with 009 distributor was running about 20-22 mpg. If this is just my gas mileage with oversized valve heads, then it is what it is.

The other issue I'm having is a really bad hesitation upon acceleration from a stop. This only happens when the engine is cold. If I run it on the highway or around the city for a bit and its warmed up it goes away and accelerates no issue. I didn't have this issue before I rebuilt the motor. There are no vacuum leaks. I have NOT adjusted the carb, because as I said previous I didn't have an issue with this before I rebuilt the motor. I suppose it could be a carb issue, but I dont understand how swapping the stock heads out for ones with oversized valves would cause this issue. And of course, photo for tax and attention.
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bsairhead
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PostPosted: Sat May 08, 2021 2:32 pm    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

28-30 degrees with lines off at full mechanical advance is correct. Do a cold engine valve adjustment, set timing adjust carb.
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Wildthings
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PostPosted: Sat May 08, 2021 3:26 pm    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

How about the numbers off the sides of your carb and distributor. Are you sure you are using the correct mark on the pulley when timing your engine? You need to be using the "U" mark when timing at full mechanical advance.

What is your elevation? As you go up in elevation you can safely add additional timing advance.
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awhitehouse51
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PostPosted: Sat May 08, 2021 10:17 pm    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

Wildthings wrote:
How about the numbers off the sides of your carb and distributor. Are you sure you are using the correct mark on the pulley when timing your engine? You need to be using the "U" mark when timing at full mechanical advance.

What is your elevation? As you go up in elevation you can safely add additional timing advance.


Carb is the stock Solex 34-pict3. this is the distributor purchased: https://www.busdepot.com/186504 . my pulley only has 1 mark, a v cut out on the engine side of the pulley, marking TDC. when timing to full advance i set my timing gun to 28* advance and adjust so that mark lines up with the split in the case. I’m in salt lake city, so maybe i’ll try going to the upper end of the limit and see where that takes me.
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Wildthings
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PostPosted: Sat May 08, 2021 11:45 pm    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

I make no claims to be all knowledgeable on the marks on a Type 1 pulley. Maybe try verifying that your mark is TDC by using a pencil or some kind of piston stop inserted through the #1 or #3 spark plug hole.

At 4000' upping your timing to 32-34° BTDC @ 3800 rpm hose(s) off and plugged should work well. Do be wary of knock on a hot day though.
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PostPosted: Sun May 09, 2021 3:43 am    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

awhitehouse51 wrote:
Wildthings wrote:
How about the numbers off the sides of your carb and distributor. Are you sure you are using the correct mark on the pulley when timing your engine? You need to be using the "U" mark when timing at full mechanical advance.

What is your elevation? As you go up in elevation you can safely add additional timing advance.


Carb is the stock Solex 34-pict3. this is the distributor purchased: https://www.busdepot.com/186504 . my pulley only has 1 mark, a v cut out on the engine side of the pulley, marking TDC. when timing to full advance i set my timing gun to 28* advance and adjust so that mark lines up with the split in the case. I’m in salt lake city, so maybe i’ll try going to the upper end of the limit and see where that takes me.


I don’t think that is right. Many pulleys had one mark which is NOT TDC.

Confirm TDC with the wooden dowel in cylinder method
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PostPosted: Sun May 09, 2021 8:24 am    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

https://www.thesamba.com/vw/forum/viewtopic.php?t=251672&highlight=stock+pulley+marks
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Starbucket
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PostPosted: Sun May 09, 2021 11:24 am    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

Poor running when cold I would feel the heat riser pipe under the carb after it is started cold, it should get too hot to touch after a few min.s or it's clogged. You could put the 009 back in and see if your problems go away. Did you put in new push rods to go with your new heads?
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awhitehouse51
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PostPosted: Sun May 09, 2021 4:04 pm    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

Starbucket wrote:
Poor running when cold I would feel the heat riser pipe under the carb after it is started cold, it should get too hot to touch after a few min.s or it's clogged. You could put the 009 back in and see if your problems go away. Did you put in new push rods to go with your new heads?


No, i reused the pushrods that were in there. nothing wrong with them so didn’t feel a need to replace. as for the old 009 distributor, it was no good which is why it got replaced. good call on the heat risers, i will have to check that.
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awhitehouse51
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PostPosted: Sun May 09, 2021 4:07 pm    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

Abscate wrote:
awhitehouse51 wrote:
Wildthings wrote:
How about the numbers off the sides of your carb and distributor. Are you sure you are using the correct mark on the pulley when timing your engine? You need to be using the "U" mark when timing at full mechanical advance.

What is your elevation? As you go up in elevation you can safely add additional timing advance.


Carb is the stock Solex 34-pict3. this is the distributor purchased: https://www.busdepot.com/186504 . my pulley only has 1 mark, a v cut out on the engine side of the pulley, marking TDC. when timing to full advance i set my timing gun to 28* advance and adjust so that mark lines up with the split in the case. I’m in salt lake city, so maybe i’ll try going to the upper end of the limit and see where that takes me.



I don’t think that is right. Many pulleys had one mark which is NOT TDC.

Confirm TDC with the wooden dowel in cylinder method


You’re right. i never saw the dimple in mine, just the one notch which i assumed was TDC. just went and looked, and it does have the dimple on the outer rim, and the notch is to the left, which denotes 5* ATDC. will reset everything using my new-found knowledge and see where that gets me!
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PostPosted: Mon May 10, 2021 8:04 am    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

My 71 westy sat for 4 mo.s and the gas mileage dropped, it turned out the rear brakes were dragging.
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PostPosted: Mon May 10, 2021 11:41 am    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

Set your timing using the dimple and at the advanced end of the normal range and you should see a significant increase in power and gas mileage.
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PostPosted: Mon May 10, 2021 3:46 pm    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

Case parting line not that dot someone put on the case.
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awhitehouse51
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PostPosted: Mon May 10, 2021 8:57 pm    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

Wildthings wrote:
Set your timing using the dimple and at the advanced end of the normal range and you should see a significant increase in power and gas mileage.


spent the better part of tonight going thru everything. reset valves at .006, adjusted timing to 30* @ full advance (with vacuum line disconnected and plugged,) and adjusted my carb up according to rob & daves aircooled page (http://www.vw-resource.com/34pict3.html). the engine was warmed up after i was done so haven’t experienced anything cold yet, but driving home i really didn’t feel any difference. still struggled to get it up to 70mph on the highway, any sort of incline brought me right down to 55-60. head temps seem to be okay, measuring at the exposed part of the head that the exhaust port bolts up to, i’ve measured between 280-290 on cyl 4. there’s still a big hesitation if i step on the gas too quick, but i think that’s just a carburetor thing. will keep y’all updated on how it performs when cold and see if my gas mileage has changed at all.
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60vwnewengland
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PostPosted: Tue May 11, 2021 2:12 am    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

awhitehouse51 wrote:
still struggled to get it up to 70mph on the highway, any sort of incline brought me right down to 55-60


70 is really pushing it. You drive your motor balls to the wall at 70 for hours that seems like a recipe for a burnt up motor. 55-60 up inclines also seems normal to me.
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PostPosted: Fri May 14, 2021 12:01 am    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

Quote:
still struggled to get it up to 70mph on the highway, any sort of incline brought me right down to 55-60


Quote:
Previous to the rebuild, my stock motor with 009 distributor was running about 20-22 mpg.


Sounds like you were running way too lean/advanced before, were enjoying the extra power from such, and mileage, cooked your heads/engine, and then got a nice rebuild out of it

Educate yourself further before cooking another engine

Ask me how I know...
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PostPosted: Fri May 14, 2021 7:24 am    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

70 in our 69 Westfalia with a dual port 1600 is almost screaming. 55-60 is really comfortable.
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PostPosted: Fri May 14, 2021 8:06 am    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

OB Bus wrote:
70 in our 69 Westfalia with a dual port 1600 is almost screaming. 55-60 is really comfortable.
Running at that RPM (70mph) for sustained periods concerns me, but I’ve seen no real negative consequences from it. Famous last words eh? Laughing
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awhitehouse51
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PostPosted: Wed May 19, 2021 9:01 am    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

so it’s been about a week since a tune up, let me tell you all how it’s been. i’ve dropped my speed down to 60-65 on the highway and it seems to really enjoy that. i’m currently on a big trip, ~800 miles round trip. the first gas station i refueled at after ONLY highway driving was interesting. my odometer read ~120 miles, but actual mileage was closer to 135. forgot to compensate for larger tires. averaged about 21 mpg, which i am ecstatic about! when the engine is warmed up, it drives like a dream. no stumbling no hesitation. took route 12 from Zion all the way up to Torrey UT, going up some incredible inclines that sent me down to 15-20 mph but the bus handled like a champ. my first morning on the road however, i couldn’t drive for about 15 minutes at first. my bus started right up, but as soon as i’d go to press on the gas, doesn’t matter if i pumped it or barely moved the gas pedal, it would try to die out. had to wait for the motor to warm up, then was on my way. unfortunately leaving Zion my speedo cable broke so no more tracking gas mileage
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PostPosted: Wed May 19, 2021 2:06 pm    Post subject: Re: Hesitation upon acceleration when cold, poor gas mileage Reply with quote

awhitehouse51 wrote:
unfortunately leaving Zion my speedo cable broke so no more tracking gas mileage


Load one of those free speedometer apps on your phone. You will be able to calculate mileage and know your speed.
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