2.7 decision time

otto_kretschmer · 03-12-2018, 09:03 PM

I havn't posted anything new on my car in a long time. I want to retire in two years so all my spare money is going into that effort. $10k to $20k engine builds will have to wait until I get to my final destination and I have a shop to work in.

Over the Christmas break I got the engine running. It's sat for maybe 7 years. It ran poorly so I knew there was something wrong. Eventually it would run for a bit and then wouldn't restart. This weekend I pumped out the old gas, replaced the plugs and did a leak down. The cylinders ran 100/96 100/95 100/75 100/80 100/95 100/88

The oil pressure is on the low side but not enough for the idiot light to flicker when idling.

When I get back to Arizona and I'm not working, and driving, I want to take the car down to the tub and bring it back to life, sorta what Magnus Walker does. The car will be a blank canvas and I can do whatever I want. The car is a 76 so I won't feel bad not making it original.

But... right now I'd like to drive it again. A good friend says I should drive it for a couple hundred miles and redo the leak down. If I can get the car to pass smog, I'll do that.

If the car won't pass smog and I got to go into the engine, then I need to decide how much of a band-aid I want to do.

so my choices seem to be

re-ring the pistons

send the cylinders to be replated if they need it and get new pistons

buy a new set of OEM piston/cylinders

buy a new set of AA iron cylinders/piston kit

split the case, align bore, new oversize main bearings and new OEM jugs/pistons

in every case, I will replace the rod bearings and have new guides installed in the heads and replace as necessary the valves, and a valve job

Eventually when I get back home, I'd like to build a 3.2 with an aluminum block and maybe run PMO carbs. I may just let the car sit for a few more years. I have plenty of other toys to play with.

otto

Matt Monson · 03-13-2018, 04:52 AM

Your friend gives sage advice. After sitting like that your car needs an Italian tuneup before you trust those numbers.

otto_kretschmer · 03-13-2018, 04:07 PM

Are 2.7 mag engines worth rebuilding?

If the oversize bearings have become unobtanium then splitting the case is not an option.

Matt Monson · 03-13-2018, 04:35 PM

A lot has changed while you slept. Middies are desireable and numbers matching now matters. If you want a crazy hot rod then you will do some 3.2-3.6 swap and efi. But thats $25-30k done cheaply. $40-50k is more common. You can do your 2.7 to rs spec for $12-15k. Or buy a used SC engine for $7-10k and take your chances. Its a different world now.

PS, bruce anderson poisoned thinking about 2.7s. He was a smart man and RIP, but on the 2.7 he unfairly trashed it.

rwest · rwest's Garage

Did you do the leakdown warm? Those numbers are not super terrible and could improve. You should also be able to figure out where the air is going to determine what minimal amount of work you could get by on.

I’m no expert, but I don’t think the leakdown numbers are causing the running issue. Maybe make sure your fuel pressures are good and ignition is healthy. Vacuum leaks are also a big source of grief on the CIS cars.

otto_kretschmer · 05:07 PM

thanks Matt,

I'm never going to sell this car so resale is moot. This car will give me a life time of tinkering. When I retire and move back to Arizona, I still will have most of my friends in California so I'll be using this car to visit them. A perfectly running stock engine is probably what I'll end up with. If the car doesn't pass smog, I'll have to drop the motor and investigate. I suspect a previous owner has rebuilt the engine once but I'm not sure. The last time I had the car registered, it passed smog so there is hope.

otto_kretschmer · 03-13-2018, 05:15 PM

I did the leak down cold. The plugs were soaked and dirty. The gap was a little on the open side except for one that i probably dropped and didn't see how tight it was. Since I was replacing the plugs, I did a leak down while I was there. The numbers should get a little better once all the crud has burned off. I did the leak down Sunday and didn't get to put new gas and see if she fires up. I expect it to run when I get home this weekend. Dave Radmacher told me to start with the tank. The fuel pump is noisy so I'm going to replace it and maybe have the tank cleaned. The fuel lines under the tank should be replaced so I'll do that when I put the new pump in.

if someone wants to read my last thread about this car, you can go here

skinny-fat-skinny

Matt Monson · 03-13-2018, 05:23 PM

Given how long it sat, it's likely you will need to go through the CIS fuel distributor. But you're taking it in the right order. Get the tank clean and chase everything back from there.

Trackrash · Trackrash's Garage

Agree. Get the CIS in order and drive it a while.

If it doesn't smoke or use excess oil, continue to enjoy driving it.

If it doesn't have backdated exhaust, it would be a worthwhile upgrade, as long as smog checks are not a concern.

mikedsilva · 03-13-2018, 10:36 PM

Great thread... I like the thinking and sensibility and will follow with interest.

otto_kretschmer · 03-15-2018, 08:05 PM

Does anyone know when these cars came with the thermal reactors? My car is a 76 and didn't have them when I bought it, maybe 2004. A previous owner installed one of those collars on one of the chain tensioners but not both.

Flat6pac · 03-16-2018, 04:47 AM

The thermal reactors were California in 76 and across the board in 77 USA
You can spot the thermal cars because the exhaust studs were unusual in that they were 8mm but necked down to about 6 mm in the center of the length.
The thermal reactors inserted into the heads like the late SC s, are thick flanged like the same.
Bruce