Engine Compression very low, options

Trebor · Jul 20, 2021

Hello all. I had picked up a 92 GT Vert in really good condition. GT 40 tubular intake, vortech V1, 24lb injectors, MFU. Ran ok but sluggish, I knew something was wrong. Brought it in for a compression check. I am being told that all the cylinders are in the 80 psi range with oil. Recommending replacing engine with a crate motor. I plan on keeping the car for a long time, but I don't want to drop a ton of money on the engine. I'd honestly be happy with the stock engine, the vortech, 42 injectors and fuel pump to elminate the FMU, and a terminator x. Considering the cost of labor in NJ, what kinda of options do I have?

Mstng93SSP · Jul 21, 2021

For less than 5k shipped my friend got a stroker 347 longblock crate engine from blueprint engines. It has a 3 year warranty, aluminum heads and made over 430 HP. The second option is to take your existing engine out and have it rebuilt. I had an engine built recently for my turbo car. The short block rebuild was around 2k.

manicmechanic007 · Jul 21, 2021

You have tons of options depending on what you want to do with the car. The engine may have just jumped time. the older ones had a phenolic cam gear. Jersey great love visiting the pike. Find someone like me at your local autozone who is willing to come over and tear down the motor a little. Check the valve springs and the cam timing. It takes the big 3 to start and you are missing 1. This is just your first engine. Owned my stang for 43 years and had 3 or four motors and trans in it for fun. Back to a owning a stock boss motor but currently running a Gapp and Roush prepped bogus boss with modified 4v351 heads. All Fun Stuff

manicmechanic007 · Jul 21, 2021

I spent a ton of money on mine back in the day. I am a tech and I know machinists so it is easy for me. I also make a ton of money and that helps. These days I do mechanic work on old classics for fun or for free. You need a balance shaft in your benz thats 10k. Go to az and see who is going behind the counter to buy parts. That will be a commercial guy like me. Ask the counter man if they trust anybody. Find an honest one who will not break your balls. Let me know how it turns out

Trebor · Jul 21, 2021

manicmechanic007 said:
I spent a ton of money on mine back in the day. I am a tech and I know machinists so it is easy for me. I also make a ton of money and that helps. These days I do mechanic work on old classics for fun or for free. You need a balance shaft in your benz thats 10k. Go to az and see who is going behind the counter to buy parts. That will be a commercial guy like me. Ask the counter man if they trust anybody. Find an honest one who will not break your balls. Let me know how it turns out

Thanks for the information. I just don’t like where this seemed to be headed. I got the talk about how once the engine is make the hp it’s going to show problems with the transmission etc.

If I bought a just new block and aluminum heads how much of my current parts can be reused ?

Noobz347 · Jul 21, 2021

Trebor said:
If I bought a just new block and aluminum heads how much of my current parts can be reused ?

Just about everything that is mounted to the engine externally.

Trebor · Jul 21, 2021

Noobz347 said:
Just about everything that is mounted to the engine externally.

I assume that is more cost effective than buying a complete crate engine or is it probably a wash once labor and tracking down the one off problems occurs.
Reliability is my main goal here.

Noobz347 · Jul 21, 2021

Trebor said:
I assume that is more cost effective than buying a complete crate engine or is it probably a wash once labor and tracking down the one off problems occurs.
Reliability is my main goal here.

Even crate engines don't come with alternators, smog pumps, etc..

General karthief · Jul 21, 2021

Lots of options with stock engine replacement, I've used Jasper engine and trans quite a few times.

manicmechanic007 · Jul 21, 2021

What trans do you have? You should be able to transfer all the internals too if you bought a new block SVO for instance. Is your block toast? Is your crank okay? Are the rods round and straight? A crate motor just means it comes with manifolds waterpump and timing belt if equipped and ignition parts. Oil pan and valve covers. All pretty but added expense. Some come with no core charge so you can keep your motor and see what went wrong, Like a spun lifter or a round cam shrunk piston etc. Most of the Transmissions these days are only good for 300 to 400 ft lbs of torque. I think my early ZF 6 speed is good for 350 and it is noisy. The later ones are good for 320 and are quieter. Most T5's are only good for 300 or so. RUG toploader 4 speeds are tough around 400 maybe. Do not worry about the trans they are cheap. Scattered a few myself fun stuff

manicmechanic007 · Jul 21, 2021

I agree with the General and Noobz that a longblock from just about anywhere is sufficient. They come with 3/36 warranty so until the nitrous hits you are ok

JD1964 · Jul 22, 2021

80psi on all cylinders? That’s kinda odd really. I’d be seeking a second opinion on that report.

There are things that can make cylinders go down to 80psi, but equally across all cylinders is odd. Was it controlling oil ok or was it smoking out the exhaust? What about coolant? Was it holding coolant ok?

JD1964 · Jul 22, 2021

One thing that can cause low compression across all cylinders is severely retarded cam timing. If that’s the problem, it can be fixed without replacing the engine.

Cams with really long duration will also lower cranking compression across the board.

Combine long duration and retarded cam timing and you’re making it even worse.

I would hesitate buying a new engine until you’re sure what the problem is.

manicmechanic007 · Jul 23, 2021

80 psi sounds like the cam is not spinning or jumped a tooth
I would not buy squat until a teardown and inspect
You can have the dealer TDI it for you for around 400 in 1990 dollars
The motor man at the dealer will want to pull both heads and both the intakes at least
Talk them out of inspecting the crank and rods. You should assume that at least some of the momo is ok

Trebor · Jul 23, 2021

Went to the shop yesterday. Hooked up a gauge to a few different cylinders. Plugs were all out. Intake was as shown in pic. Turned the engine over. First reading was 100 psi. Cleared gauge turned over again. 80 psi.

Trebor · Jul 23, 2021

My plan right now is to change the valve cover gaskets, because they were leaking bad, change the plugs, put it back together. Enjoy what it is till I find an affordable option or a friend that will do the work with me.

Trebor · Jul 23, 2021

Trebor said:
My plan right now is to change the valve cover gaskets, because they were leaking bad, change the plugs, put it back together. Enjoy what it is till I find an affordable option or a friend that will do the work with me.

And I forgot. Fuel injector o rings.

General karthief · Jul 23, 2021

Just swapping in new plugs should help a lot, those in the pic are wasted.
and you have a turbo, didn't recall that.

Trebor · Jul 23, 2021

Vortech v1 SC

7991LXnSHO · Jul 23, 2021

Trebor said:
Went to the shop yesterday. Hooked up a gauge to a few different cylinders. Plugs were all out. Intake was as shown in pic. Turned the engine over. First reading was 100 psi. Cleared gauge turned over again. 80 psi.

You have a closed throttle body in the picture. Was it closed during the compression test?

Engine Compression very low, options

Trebor

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Mstng93SSP

You have a nice rear end there Dave.

manicmechanic007

manicmechanic007

Trebor

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Noobz347

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General karthief

wonder how much it would cost to ship you a pair

manicmechanic007

manicmechanic007

JD1964

there is enough sticking out to grab on to

JD1964

there is enough sticking out to grab on to

manicmechanic007

Trebor

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Trebor

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Trebor

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General karthief

wonder how much it would cost to ship you a pair

Trebor

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7991LXnSHO

wanna catch the space herp

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Engine Compression very low, options

New Member

You have a nice rear end there Dave.

New Member

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Stangnet Facilities Maint Tech... Er... Janitor

New Member

Stangnet Facilities Maint Tech... Er... Janitor

wonder how much it would cost to ship you a pair

there is enough sticking out to grab on to

there is enough sticking out to grab on to

New Member

Attachments

New Member

New Member

wonder how much it would cost to ship you a pair

New Member

wanna catch the space herp

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