Engine swap - issues with power

Olds 98

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Jun 20, 2019
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North Dakota
Hi Everyone, I’ve had this car 19 years. It’s a 1981 Olds 98 Regency. It originally came with a 307 with crappy computer controls. About 8 years ago before I moved and put it into storage I installed what I was told was a rebuilt 1972 Olds 35O rocket. I’ve been starting it every so often and driving it around. But after this engine swap it has always had this issue of not being able to get over 55mph or so.

I havent really needed it so I never did anything with it, well now I need it because my truck is broke down. Lol.

The 350 has a new Holley carb, new fuel pump, the car has a new gas tank, new radiator. I checked timing tonight and I noticed that my plastic timing marker is different than what is displayed online. My marker starts at 0 degrees on the right and moves 4 8 12 16 20 degrees to the left (counter clockwise) did I reverse the timing marker when I swapped things over or is this how it supposed to be? Because with a digital timing light tonight, it had 28 degrees initial timing to bring the harmonic balancer groove back to the zero tick on the plastic indicator? Thats with the vac advance and engine vac pinched off.

Im so confused lol.
 

Olds 98

New member
Jun 20, 2019
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1
North Dakota
Hi Everyone, I’ve had this car 19 years. It’s a 1981 Olds 98 Regency. It originally came with a 307 with crappy computer controls. About 8 years ago before I moved and put it into storage I installed what I was told was a rebuilt 1972 Olds 35O rocket. I’ve been starting it every so often and driving it around. But after this engine swap it has always had this issue of not being able to get over 55mph or so.

I havent really needed it so I never did anything with it, well now I need it because my truck is broke down. Lol.

The 350 has a new Holley carb, new fuel pump, the car has a new gas tank, new radiator. I checked timing tonight and I noticed that my plastic timing marker is different than what is displayed online. My marker starts at 0 degrees on the right and moves 4 8 12 16 20 degrees to the left (counter clockwise) did I reverse the timing marker when I swapped things over or is this how it supposed to be? Because with a digital timing light tonight, it had 28 degrees initial timing to bring the harmonic balancer groove back to the zero tick on the plastic indicator? Thats with the vac advance and engine vac pinched off.

Im so confused lol.
I also should mention when I full depress the throttle on the carb with my finger the secondaries don't open up.
 

Olds 98

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Jun 20, 2019
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North Dakota
I also should mention when I full depress the throttle on the carb with my finger the secondaries don't open up.
I got to thinking. When I unpinched the vacuum advance while checking timing the timing then jumped the correct direction on the timing marks further counter clockwise.

The engine is smooth, my air to fuel ratio gauge is around 12, the engine screams when I floor it even at a max speed of 55mph. So I’m wondering if the TH350 transmission just isn’t transferring that power to the wheels. Maybe its slipping, or overdrive isnt kicking in?
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
Is it the stock trans? Is it a 3 spd or overdrive, it can't be both. It could have a lock up torque converter even if a 3 spd. If it was stuck on, it would be a dog off the line. If the speedometer is right, you should be able to easily floor the needle with stock tall gearing. First the 0 on the timing marker should point to the passenger side. You want to retard your timing 8 degrees at idle, stock is 20 but it depends on the curve in your HEI. Too much timing will limit the top end but 55 is pretty slow, it should do double that easily. Make sure the advance weights are moving freely in the distributor. Good luck.
 

Olds 98

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Jun 20, 2019
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North Dakota
Is it the stock trans? Is it a 3 spd or overdrive, it can't be both. It could have a lock up torque converter even if a 3 spd. If it was stuck on, it would be a dog off the line. If the speedometer is right, you should be able to easily floor the needle with stock tall gearing. First the 0 on the timing marker should point to the passenger side. You want to retard your timing 8 degrees at idle, stock is 20 but it depends on the curve in your HEI. Too much timing will limit the top end but 55 is pretty slow, it should do double that easily. Make sure the advance weights are moving freely in the distributor. Good luck.
Its not the stock tranny. Its just a 3spd.

What do you mean the zero timing mark should point to the passenger side? The timing marker itself is mounted on the drivers side of the balancer. Then if Im looking at the engine from the front, zero is on the drivers side and it then goes 4 8 12 16 20 towards the passengers side. Is it backwards?

It is a dog off the line pretty much got to floor it to get it to do anything.

And 28 initial timing without vac advance would be another issue. Is it possible the vac advance weights are stuck, permanently advancing the distributor too much all the time?
 

Olds 98

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Jun 20, 2019
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North Dakota
Its not the stock tranny. Its just a 3spd.

What do you mean the zero timing mark should point to the passenger side? The timing marker itself is mounted on the drivers side of the balancer. Then if Im looking at the engine from the front, zero is on the drivers side and it then goes 4 8 12 16 20 towards the passengers side. Is it backwards?

It is a dog off the line pretty much got to floor it to get it to do anything.

And 28 initial timing without vac advance would be another issue. Is it possible the vac advance weights are stuck, permanently advancing the distributor too much all the time?
Well I removed an old inline fuel regulator between the pump and the carb, switched vac sources for the tranny. There was a rear and a front one. Then I adjusted the holley carb so that that the secondaries open at least some. Noticed a big difference pulling out of the driveway. Got up to 75mph at least. Satisfied just to be able to drive 30 minutes to town without getting run off the road. 😏
 

Olds 98

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Jun 20, 2019
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North Dakota
Well I removed an old inline fuel regulator between the pump and the carb, switched vac sources for the tranny. There was a rear and a front one. Then I adjusted the holley carb so that that the secondaries open at least some. Noticed a big difference pulling out of the driveway. Got up to 75mph at least. Satisfied just to be able to drive 30 minutes to town without getting run off the road. 😏
I drove it to town 30 miles just now, it has problems on the hills. It will lose 10mph with it floored. But on the straights it’ll go 75. Air fuel meter reads 10 with it floored, but during straight cruising its 12-14?
 

Intragration

Member
Apr 2, 2019
40
22
8
Chicago
What kind of exhaust do you have on it? A blocked catalytic converter could do something like this. I also suspect the timing, not sure about the timing marker on yours, and what you're seeing versus what's actually going on. I'd try to find actual zero. Among other ways, get it close to TDC on cylinder one, and then using a wooden dowel rod through the spark plug hole, turn the engine over slowly with a breaker bar, and see when the piston gets right to the top. Compare this with zero on your indicator, and you'll see if it's close to accurate.

When setting timing, I prefer to disconnect the vacuum advance rather than pinching it, just to make sure you're not getting any. I think I have mine set to about 16 initial, 26-27 total, and I limited my vacuum to 13. For me, the limitations were, initial can't be too high because then I have problems starting when it's hot (high cr) and vacuum had to be limited, because otherwise I get detonation when tipping in at a high-speed cruise.
 

Olds 98

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Jun 20, 2019
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North Dakota
What kind of exhaust do you have on it? A blocked catalytic converter could do something like this. I also suspect the timing, not sure about the timing marker on yours, and what you're seeing versus what's actually going on. I'd try to find actual zero. Among other ways, get it close to TDC on cylinder one, and then using a wooden dowel rod through the spark plug hole, turn the engine over slowly with a breaker bar, and see when the piston gets right to the top. Compare this with zero on your indicator, and you'll see if it's close to accurate.

When setting timing, I prefer to disconnect the vacuum advance rather than pinching it, just to make sure you're not getting any. I think I have mine set to about 16 initial, 26-27 total, and I limited my vacuum to 13. For me, the limitations were, initial can't be too high because then I have problems starting when it's hot (high cr) and vacuum had to be limited, because otherwise I get detonation when tipping in at a high-speed cruise.
Yes when I ran it years ago it had a hard time starting when hot, like the starter couldn't turn over. Its starting a lot easier now when hot now that I retarded it 8 degrees.

It died in town an hour ago, this engine has always ran hot. I have an old analog/bulb type temp gauge and it reads 210 at idle. Maybe thats due to a blocked exhaust like you suggested earlier. The cat is newer but it’s probably 15 years old. The last engine 307 was an oil burner so I could see that ruining the cat. Had a local mechanic stop by he thinks the ignition module in the hei distributor is about dead. The heat causing the module to intermittently work then sputter out. It’ll start but then die 10 seconds later if not held open 50%. Gonna try and limp it home on the back roads.
 

Olds 98

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Jun 20, 2019
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North Dakota
Yes when I ran it years ago it had a hard time starting when hot, like the starter couldn't turn over. Its starting a lot easier now when hot now that I retarded it 8 degrees.

It died in town an hour ago, this engine has always ran hot. I have an old analog/bulb type temp gauge and it reads 210 at idle. Maybe thats due to a blocked exhaust like you suggested earlier. The cat is newer but it’s probably 15 years old. The last engine 307 was an oil burner so I could see that ruining the cat. Had a local mechanic stop by he thinks the ignition module in the hei distributor is about dead. The heat causing the module to intermittently work then sputter out. It’ll start but then die 10 seconds later if not held open 50%. Gonna try and limp it home on the back roads.
I made it home earlier with one foot on the brake and one on the gas keeping the revs up. I could feel the engine missing on a dead spark occasionally on the flats. Ordered a new module. But when I got home it idled fine in the driveway. Will cut the exhaust tomorrow ahead of the cat and see how it behaves. It just has stock exhaust manifolds.

Anybody used those hi torque starters? Any recommendations?
 

Intragration

Member
Apr 2, 2019
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22
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Chicago
Yeah, not sure about "ignition module about dead". The symptoms you describe sound a lot more like the exhaust than the ignition module. I've only had one ignition module fail on me, and it was more of a dead/won't start situation. I suppose anything is possible. Curious to see what you find when you cut the exhaust off tomorrow. I personally am not a fan of the high-torque starters. It might take care of your hard-starting problems, but so might lubing the weights in the distributor. This was my fix for the worst of it. (Weights would stay advanced when I turned the motor off, and would be set somewhere in the 20+ degrees range. Once I lubed them, they would settle back down to 16)
 
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Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
Usually the HEI modules just die outright but are pretty reliable. You may have carb issues. What kind of advance curve is in that distributor? You want about 40 max with the initial and mechanical advance in by 3000 rpm. On a low compression Olds V8 the factory 30 degree vacuum advance works good on manifold vacuum, not ported. And 10" is very rich.
 

Olds 98

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Jun 20, 2019
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North Dakota
Usually the HEI modules just die outright but are pretty reliable. You may have carb issues. What kind of advance curve is in that distributor? You want about 40 max with the initial and mechanical advance in by 3000 rpm. On a low compression Olds V8 the factory 30 degree vacuum advance works good on manifold vacuum, not ported. And 10" is very rich.
Im not sure what kind of curve is in the advance how do I find out? I did notice the secondaries dripping fuel at idle after I removed that selectable fuel regulator, are they supposed to be, or only during a call for wot power? I read online that vac advance liked ported vac better (below the manifold plate)? 10” at wide open throttle (floored) is too much?
 

Intragration

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Apr 2, 2019
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Chicago
The curve just consists of, what's your base timing at idle, and then how quickly does it ramp up and hit full advance. You do this just with the timing light and a tach, to make sure you're getting a good total advance and that it comes in soon enough.

Do you have a mechanical or electric fuel pump? You said you adjusted the secondaries so they "open some". I'm not very familiar with Holleys, but if you have them open too far, you might be getting some airflow through them at idle. Either that, or you have too much fuel pressure. The car should be running pretty fantastic even if it's just running on the primaries. You would be down on top end power, like racing power, but around town and even on the highway at part-throttle, the increased vacuum signal (as a result of reduced airflow capability) should feel healthy and responsive. (e.g. my 455 is massively under-carbed, but it feels like it's fuel injected. It runs GREAT, it's just leaving some extra power on the table at the top end.) It doesn't sound like this is the case for you, which leads me back to the exhaust... Since it's a possibility, it would be good to rule this out.
 

Olds 98

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Jun 20, 2019
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North Dakota
The curve just consists of, what's your base timing at idle, and then how quickly does it ramp up and hit full advance. You do this just with the timing light and a tach, to make sure you're getting a good total advance and that it comes in soon enough.

Do you have a mechanical or electric fuel pump? You said you adjusted the secondaries so they "open some". I'm not very familiar with Holleys, but if you have them open too far, you might be getting some airflow through them at idle. Either that, or you have too much fuel pressure. The car should be running pretty fantastic even if it's just running on the primaries. You would be down on top end power, like racing power, but around town and even on the highway at part-throttle, the increased vacuum signal (as a result of reduced airflow capability) should feel healthy and responsive. (e.g. my 455 is massively under-carbed, but it feels like it's fuel injected. It runs GREAT, it's just leaving some extra power on the table at the top end.) It doesn't sound like this is the case for you, which leads me back to the exhaust... Since it's a possibility, it would be good to rule this out.
Its a mechanical pump mounted next to the water pump. I’ve run into this issue before with getting too much fuel except on the 307. Thats when I installed the summit fuel regulator. 5 different settings.
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
My understanding is the WOT AFR should be 12.5 to 13 to 1. I would think your pressure is still a bit high with dripping.
 

Olds 98

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North Dakota
My understanding is the WOT AFR should be 12.5 to 13 to 1. I would think your pressure is still a bit high with dripping.
I cut the entire exhaust off before the cat. Added the mechanical adjustable fuel regulator back in and its at setting 5 and then it was running rough so I enriched it some more and it smoothed out. Added a second temp gauge downline from the thermostat. It shows about 10 degrees cooler than the other temp guage ahead of the thermostat.

It accelerates better and faster but now have a dead miss only sometimes and the whole car will surge. On acceleration 0-25 is normal then 30-60 it really takes off. This is with the pedal mashed. I am now able to accelerate on a hill from 65 to 80.

I should throw a new cap and rotor in, and may as well do plugs. Then start over. I have a new module just in case.
 

Olds 98

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Jun 20, 2019
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North Dakota
Good news, long story short. I installed a new cap a rotor then had wires switched between 4 & 8. And I couldn’t figure out what was wrong till tonight. Now it runs great. Was able to drive it 60 miles at 70mph. Does good on the long hills on the highway. I feel a hesitation on the highway in my seat when holding power constant kind of intermittent hard to tell what exactly it is. Might be carb or plugs related. I havent done plugs nor wires yet.

I checked timing. Initial is at 19 and then at 3,000 rpm’s its at 31 or so with vac advance disconnected. When I had the distributor apart, the springs and the mechanism look shiny and new.

Without a thermostat temps run 155 to 165 on the highway. Running the fuel regulator currently at its highest setting.
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
I would bump the timing another couple of degrees, probably 2 to 4 more. Go with NGK XR45 plugs and quality wires.
 

Olds 98

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North Dakota
I would bump the timing another couple of degrees, probably 2 to 4 more. Go with NGK XR45 plugs and quality wires.
Will do thanks.

I was looking at headers since i cut the exhaust off. As much as I like the loudness I couldn’t do it all the time. Just a glass pack for now.

Recommendations for headers or stick with stock manifolds?