vk 308 compression

[bfhoon]

Hi Everyone

Long story short I have a vk with a hq 308 red motor in it. It was an ex turbo blo thru turbo but Ive bought it minus the turbo.

Bit of a background
Red 308 hq motor
red heads pre pollution
750 holley vac secondary
torque power single plane hi rise manifold
straight cut timing gears
gilmer belt driven
Unknown if it has a cam probably
Crane Hi 6 fireball ignition system with lx coil
4 speed m21
4.11 diff gears.

Runs heaps fuelly in my garage it stinks the place out.

I did a compression test and got the below results I did it with the engine warm and all the plugs out

Cylinder
1. 145 psi
2. 125 psi
3. 150 psi
4. 125 psi
5. 115 psi
6. 120 psi
7. 115 psi
8. 125 psi

Ive set te initial timing pretty high about 20 degrees and tuned up the carb the best I can. The best ever vacuum reading I can get is 11-10 hg it bounces around a bit. The motor shakes a tad but nothing heaps serious. Am I wasting my time getting a smaller carb and would my compression results be indicative of a shaly motor. I have a pcv breather catch can and you can see it smoking after the cars been driven and sometimes while idling. I know the compression results arent the best but I didnt think they were all that bad either.

 

[Lacksballs]

If you have access to a gas analyser you could easily check the fuelling as I'm guessing that the carb is still from the blow through set up. Lack of vacuum at idle COULD point to a cam? Compressions aren't the end of the world especially if the previous owner reduced the compression ratio to run more boost safely????? 20 deg initial timing seems a bit on the high side, check the vacuum advance & measure the total timing, you never know that could have been optimised also for the turbo installation.

You really need to do some digging into what you actually have..

 

[bfhoon]

If you have access to a gas analyser you could easily check the fuelling as I'm guessing that the carb is still from the blow through set up. Lack of vacuum at idle COULD point to a cam? Compressions aren't the end of the world especially if the previous owner reduced the compression ratio to run more boost safely????? 20 deg initial timing seems a bit on the high side, check the vacuum advance & measure the total timing, you never know that could have been optimised also for the turbo installation.

You really need to do some digging into what you actually have..

I dont really know as I have no contact with previous owner. I could get my hands on a gas anylyser ie a lpg analyser is this what you mean or do you mean an air fuel ration analyser? I can see a bit of the head gasket it does feel thickish. I had vacuum advance hooked up but that adds even more timing and car seems to run better without it so I disconnected it. ?Unsure of my total timing as I only have the factory timing marks. when revving it the timing mark hardly moves much so its like it doesnt really have much total timing. I did have the initial timing set to about 14 degrees before I only bumped it up to acheive more vacuum even though I onyl gained 1 hg. Would I be better lowering it again back to 14 degress initial ?

 

[Lacksballs]

Ok this is what I'd do if I was in your position.

1: Get the engine running to the best of your ability & drivable.
2: Make sure the cooling system is in good working order, thermostat, water pump, fan, radiator, etc.
3: Ensure you have a good ignition system, plugs, HT leads, correct firing order, timing etc.
4: No external leaks, fuel, oil or coolant, etc.
5: Check for any vacuum leaks, base of carb, inlet manifold, leaking booster, trans modulator, damaged hoses or fittings, etc.

Find a reputable garage/tuner with a rolling road & pay for him to put it through its paces (he should give you an hourly figure for the dyno). Once the test is complete any decent tuner/mechanic will tell you what is wrong and what needs attention. ie re-jet the carb, re-graph the distributor. Normally these guys will have 4 way gas analysers, tune scopes etc to test & record the engines output & systems. They may even make adjustments on the fly.

I'm just a little concerned with the lack of information you have on the engine, you could end up spending a lot of unnecessary extra time & money on it without any result.

Good luck