540 bbc procharged issues

[mikes]

Hello! Having some issues with a newly purchased engine and I cant figure it out. No matter what I do, I cannot get this thing to run right. Wont idle clean, not much power, almost feels like a big vacuum leak. Ive check all the obvious, lash, leak down is good, timing is right on but when I ran a compression test I only come up with 100lbs on all cylinders. Now Im thinking possibly cam timing. Heres whats in this engine. 540 bbc, dart 380 pro 2 cylinder heads, flat top piston(steve morris pistons) Cam is a 285/303 @ .050 on a 115, IO 31.5 IC 73.5 /EO 90.5 EC 32.5. Lift is .782/.775. Looking at the jesel belt the timkng pointer reads -2 degrees. Now I know whithout a degree wheel that doesnt mean much but cam card wants cam on a 111 ICL. If this is 6 degrees retarded, will that give me some of my issues? I might have to pull this apart and look it all over. Maybe even a smaller cam. We are only pushing 15-20lbs boost and turning 7300rpm. Carb is a CSU that we ran for years on previous 555 BBC that made 1400hp with no issues but with a cam running 20 degrees less intake and almost 30 less exhaust duration. Thanks for any input!

[Tom68]

Massive cam, will have a high idle speed even with 540ci.

[mikes]

The procharger is an F2 with 66 bottom and 46 top pulley. Timing was locked out between 25-30 depending on tune on previous engine but this one needs almost 40 degrees and its just is not happy with anything under 1500 rpm idle and then it still has no throttle response. Previous owner was running a 140 crankdriven f3. I might be able to speed up the current procharger with a pulley change but will that even be enough?

[ou812]

"Looking at the jesel belt the timkng pointer reads -2 degrees. Now I know whithout a degree wheel that doesnt mean much but cam card wants cam on a 111 ICL. If this is 6 degrees retarded, will that give me some of my issues?"

Are you saying the cam was NOT degreed in?

[mikes]

Thats a great question. This engine was purchased assembled so we're unsure. It just feels very lazy. If this was built for 30+lbs boost, will our 15lbs cause this to run this bad?

[Orr89rocz]

Cam seems massive but with that head size i guess you want to turn alot of rpm? 100 psi makes sense cranking with flat tops and that much cam.

Either way it sounds like possible fuel tune up at idle, and def needs some timing. Sounds like a good application for port efi

Check cam timing with degree wheel and does it have a wideband o2 sensor for air fuel? What fuel is it on? Id check fueling at idle and low rpm to verify that to get it stable.

[Lloyd klem]

That cam is better suited for 13 to 1 compression and at least 25 lbs boost.

[mikes]

We are running E85. This was purchased for another project build but we needed to use this engine in the meantime. We are definitely struggling with fuel issues that we cannot seem to iron out, we are running a blow through carburetor and this thing seems to like a lot of timing. Going to have to program some sort of timing curve into it or possibly swap to a much smaller Camshaft and see how it responds.

[mt-engines]

If you have a damper with timing marks on it, determine TDC is accurate with a stop.

Is it a turd because of boost leaks?

[mikes]

TDC has been verified. No boost leaks that we see. We are only pullied to turn 56k impeller speed.

[Dave Koehler]

Do you have enough fire power for boost?

[prairiehotrodder]

that 100 psi of cranking pressure would be a big red flag to me. Either the engine is worn out or the timing chain is wrong or the valves are adjusted wrong.

[Tom68]

that 100 psi of cranking pressure would be a big red flag to me. Either the engine is worn out or the timing chain is wrong or the valves are adjusted wrong.

Late inlet closing with the massive cam is creating the 100 psi, that just means there's no power until boost and or high rpm's.

The overlap from the cam is going to make the low speed fueling tough to sort.

[mikes]

[/quote]

Late inlet closing with the massive cam is creating the 100 psi, that just means there's no power until boost and or high rpm's.

The overlap from the cam is going to make the low speed fueling tough to sort.
[/quote]

And that's exactly the trouble we're having. Might install our other cam to get us by for a little bit.