airframewizard

Good evening everyone,
Hopefully I can provide enough information here, if not ask away and I will do my best to provide an answer.

I recently acquired a 52' Chev Styleline from a family friend. From what I have been told and through sleepless nights trying to order correct parts it is an 87' Delta 88 chassis paired with the Olds 307 & TH200R4 transmission. The car has been a joy to drive but I have recently come across a transmission issue, which I cannot find a similar issue on any other threads. I'll include a video link to youtube at the bottom as my description may not do it justice, but under load at RPM's over 2700 (only happens in 3rd & 4th gear) the car lurches a significant amount. The RPM's seem to drop then bounce back up and the car experiences a complete loss of acceleration. The previous owner babied the car and did their best to ensure regular maintenance (including trans filter & flush every couple thousands miles).

So far, I've ensured the transmission level is indeed correct, and from what I've seen the shift points seem correct. However I haven't yet checked the line pressures. The original builder put an aux trans cooler likely to help with possible high temps during the summer here in Canada. When this issue first occurred I though it may be a fuel issue, so I replaced the fuel filter, lines & fuel pump to no avail.

I do not have a lot of experience with older cars, however I am an Aircraft Mechanic (AME) so I do know my way around turning bolts & have a fair bit of experience when it comes to carbs. I may be in over my head here, but I called two local transmission shops and was told likely a minimum of $3000 with no guarantee on pricing, and a hint of doubt as to whether or not they would even be able to tear it apart.

Any help, suggestions or hints anyone can provide would be greatly appreciated!!

4R5

From what you're describing it sounds to me as if the engine is stumbling under load. I can't see this being a trans problem seeing as the RPMs drop like you stated.

airframewizard

Never thought of that, but I think you're on to something. I'll grab my timing light from work tomorrow and make sure its timed correctly, maybe throw on a new distributor cap while I'm there. Might not be a bad time to take apart the Qjet and inspect it as well.

airframewizard

I'm not sure if it makes a difference, but under full load in first it doesn't have the stumbling issue. it carries over 4000 without any stumbling.

ART T

It might be searching for lockup.

olds 307 and 403

First check the TV cable setting. Open the throttle by hand, push the button on the TV cable. It could be set too tight. It could be an acting up lock up solenoid. Unhook the connector at the trans and see if it goes away.

cherokeepeople

i'll also jump on the lockup bandwagon.

airframewizard

Thank you everyone for the replies. Had some snowy weather the last few days so I wasn’t able to take the car down the street.

However, today I checked the TV cable setting (didn’t appear to be tight) but still adjusted it as stated above. No dice, problem still persists.

Brought it back into the garage, disconnected the plug at the lockup solenoid, problem still persists.

One thing I want to note, during both test drives the engine stalled out from the RPM fluctuations as shown in the video. Haven’t had this happen before, could barely drive the car as the RPM bog started happening even early (2500 rpm) under minimal engine load.

4R5

From your initial description, this was an 87 Delta 88 chassis underneath the 52 Styleline, correct? Is the engine still on the computer? "on the computer" involves the distrubuter, carb, and other emissions equipment, in addition to the trans OD engagement, all dictated by the computer. If this is still all intact, that's OK, but if not there are a plethora of potential problems.
Going back to my previous post, I'm suspecting this is an ignition problem, either bad plug wires or bad distributer cap/rotor.

airframewizard

Yes 87 Delta 88 chassis underneath the 53 Styleline. I've ordered a new Cap from my local performance shop, I was hoping it would show up today but I don't think I'm that lucky. I'll let you know as soon as it comes in and I'm able to install it and retime it. As per plug wires, I replaced them all last summer with NGK wires & plugs and the car ran fine fore a couple of months before this issue started.

The engine is not on the computer. The distributor has a vacuum line going to it from the carb, I replaced the vacuum line for fear of cracks/pinholes when the issue first started. The OD engagement was wired directly to a switch on the dash. Also all emissions equipment was removed. Sounds like I'm about to go down a rabbit hole haha.