So I just put on a new head on my 210. (Finally, after like 7 or 8 tries with coolant leaking everywhere....but that's another story). Anyway, so this new head's combustion chambers are shaped differently. Other than that, they are the same. I got the thing all bolted back up and went to start it, and it was running really rough. It was also backfiring a ton. I tried driving it, and it didn't even have enough power to make it out of my driveway (up hill). It has fuel (obviously, if it's running). It also has spark. I checked all 4 plugs.
I pulled the fuel line off and cranked it over and it cranks over REALLY easy on all 4 cylinders. Is it possible that the different shaped combustion chambers are causing lower compression *that* bad to the point the car barely runs? I figured it might lower them a little, but realistically, how bad? Stock compression is 9.0:1.
It's the A15 motor, '81 model year. Any help is appreciated! I haven't done a compression check yet, but I'm going to borrow my friend's gauge and do that tonight.
No Compression!! Need help!
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EZcheese15
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EZcheese15
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DAEDALUS wrote:When you say that the combustion chambers are shaped differently, you mean that the volume above the piston at TDC is different?
Yes.
Also, I don't know how the timing could be off. It is a pushrod motor, so I didn't mess with the cam at all. And I adjusted the valves when putting it back together.
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EZcheese15
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Ok, here's a little update:
Plugged in the compression gauge. Got compression in all 4. Spec is 192psi, I got about 210 in all 4. Guess the head I put on actually has a little higher compression.
Anyway, still runs like crap....and I've got two theories:
1st one is that with the higher compression head, I need to make some adjustments. I gapped the plugs closer, but that didn't seem to make a noticeable difference. Tomorrow I will try to retard the timing a bit and also adjust the fuel mixture on the carb.
2nd one is that I got some vacuum lines mixed up. My friend looked over the car and found a vacuum nipple I was missing a hose on. Only problem is, I don't have a vacuum hose to put on it. I'm going to look at the vaccum diagrams and try to figure out if I have a vacuum leak.
I'm leaning towards #1, but #2 maybe a culprit too.
Reverend...like I said, it's a pushrod so I couldn't have screwed up the cam timing. And the valves were adjusted when I put the rockers back on. I'm pretty sure it's fuel related (waaaaaaaaay too rich) because I've got spark on all 4's, yet I can pull plug wire #2 or #3 off and it doesn't make a difference in the way the car is running. I think maybe the fuel is flooding the cylinders.
Also, I just thought of this....the above statement makes even more sense since it's #2 and #3 that make no difference. #1 and #4 kill it. They are also the farthest away from the carb. So that means they are running leaner than #2 and #3. And if it's really really rich, and #1 and #4 are running lean, they are really running normal. Which would explain why the car dies if those plugs are pulled! Haha! Maybe I just thought of the answer to the problems.
Any more insight is much appreciated though!!
Plugged in the compression gauge. Got compression in all 4. Spec is 192psi, I got about 210 in all 4. Guess the head I put on actually has a little higher compression.
Anyway, still runs like crap....and I've got two theories:
1st one is that with the higher compression head, I need to make some adjustments. I gapped the plugs closer, but that didn't seem to make a noticeable difference. Tomorrow I will try to retard the timing a bit and also adjust the fuel mixture on the carb.
2nd one is that I got some vacuum lines mixed up. My friend looked over the car and found a vacuum nipple I was missing a hose on. Only problem is, I don't have a vacuum hose to put on it. I'm going to look at the vaccum diagrams and try to figure out if I have a vacuum leak.
I'm leaning towards #1, but #2 maybe a culprit too.
Reverend...like I said, it's a pushrod so I couldn't have screwed up the cam timing. And the valves were adjusted when I put the rockers back on. I'm pretty sure it's fuel related (waaaaaaaaay too rich) because I've got spark on all 4's, yet I can pull plug wire #2 or #3 off and it doesn't make a difference in the way the car is running. I think maybe the fuel is flooding the cylinders.
Also, I just thought of this....the above statement makes even more sense since it's #2 and #3 that make no difference. #1 and #4 kill it. They are also the farthest away from the carb. So that means they are running leaner than #2 and #3. And if it's really really rich, and #1 and #4 are running lean, they are really running normal. Which would explain why the car dies if those plugs are pulled! Haha! Maybe I just thought of the answer to the problems.
Any more insight is much appreciated though!!