have just got my engine in the car.
I use a comander 950 pro with a stelth ram intake.

I have used this intake on a ZZ4 enginge before. but changed engine to 350 wihth more power, so I am familiar to the 950 set up.

this is the parts in the new engine:


so when I start to run this I notice that this engine don't run well below 25 degrees BTC.
I need to ste it for about 30 to get a smooth and free from bang in the exhaust.

I feel 30 degrees is much, but is there anyone that can confirm that this is normal with this type off engine?

 

Man that is a HUGE cam. The bigger the cam the more advance you need. I know it would be at least 20 degrees, I woudlnt be surprised if it's 30. But I dont have any experience with stuff that big.

 

jepp
a huge cam, but it works.. for now..
due to this cam I also have redused vacum. but that I can live with..

should I go more than 40 degrees at max? ( I don't think so)
and maybe I should use the alfa-N programming with the comander 950...

 

Have you done a compression test?
I'd be curious to see what your cranking pressure is. If it's low, below 170 psi then that could contribute to the need for all that timing. That came has big duration numbers and without the compression to support it, you may have trouble.
I would assume that you've verified that the timing pointer and tdc marks are all correct.

 

I have done a comp test. but I am not sure if the value is 100% correct on my pressure tester say about 120 psi at max. That is lower than what you say so maybe this give me a issue!
I am not an expert on engine building, so I have to ask. Do my (probably) low comp give ma a problem...


I have checked the TDC and this look good...

 

If your 120 psi measurement is accurate, then you've isolated your problem. A cam of that size will bleed off almost all of the low speed cylinder pressure and the result is very poor engine performance. That you require all that inital timing is a good indicator of that.
For the record, it's generally understood that a MILD performace street engine would have about 180 psi. That would be at the low end of the scale. 200 psi is more like it. A racing engine (with a large cam like yours but with a static compression ratio to match) would like to see 220 psi.
Here's a link to a really good article on the subject. It may interest you.

http://cochise.uia.net/pkelley2/DynamicCR.html

 

hmmmm.. I need to calibrate my my compression meter..
at least check it..
So I also am a little off, when running this engine with my electronic controller, I would be bether with a carburator. cause this will be hard to tune at idle. (maybe over all RPM)

Thank you for helping me out here..

 

If you have a mismatch between your cam and compression (an all too common mistake) then no amount of tuning or change in induction will help. At least not to the point of achieving optimal performace.
Have you done a static compression ratio calculation?

 

eehhh.. no, have not done that.
I even didn't build the engine my self. I did see this one for sale and was thinking this could be something for me.

 

Do you have a part number for the heads or do you know what the combustion chamber volume is? A quick calculation with some raw numbers will tell whether or not you're dealing with a large mismatch.

 

I was told this one have about 10.5-1 comp.
heads 64 cc
stroke 3.48
flat pistons
deck hight, I don't know
gasket I only know it is a ACL performance
bore is also not given to me..

I wish I could get the man that build this engine on my phone now..

 

A 64 cc chamber, flat top piston (with valve reliefs of 5cc), 4.030" bore, stock deck height (.025") and an average gasket of .040" might get you 9.75:1.
A cam that size wants at least 11:1 (and I would think even more for a race application)where it should really perform, at high rpm that is. I would think that peak power would be near 7000 rpm or more. Provided your heads do their job.

 

If the gasket is a thinner one, it could be 10.2:1. Depends.

That said, some of the speed pro 350 pistons have a 1.540 compression height, and some a 1.560. Kind of a crapshoot as to whether or not his pistons are an extra .020 in the hole.


I also found a rule of thumb chart that suggested for durations of 290-300 that a good baseline is 14-18. I would imagine less compression means it needs more cylinder pressure, so you would increase the base timing to do that. Another guy said approaching 300 adv duration needs 18-20 degrees.

But... to the OP, you should get rid of the cam, and put some more mild vale springs and a more mild cam in it. Ifyou're around 10:1 I woudlnt go bigger than a Comp XR276. An LT4 hotcam might work well too. Should make for a pretty snappy engine.

I would do a compression test on all cylinders and just make sure they're all close, if so it's still a 350, wouldn't take much to tame it down to something more streetable and still pretty quick.

 

I am learning allot her guys!
I actually found the man that build my engine on "face book" maybe he reply back, and tell me what bore there is and what piston number it have.

but I see no reason why he fouling me on the comp ratio... at least I hope not..

 

Depending on quench distances and gaskets used etc, it could be close to 10.5. Just depends on a lot of small fudge factors that can shift it as much 1 total point total. The main thing is that cam needs a lot of compression, and 10.5 may not really be enough to be ideal for it, but it just depends.

 

oki. but if I can get the engine running with 25-30 degrees at idle. there should be ok to run with this. or do I get some problems when coming up into higher RPM's?

I have done comp test for all cylinders and there is all the same value.

that LT4 hot cam is that the same as the '400 hp' upgrade for ZZ4 motor. I did that once some yers ago. so I have the original ZZ4 cam.

 

You may have to just lock it out at 32 degrees or whatever. You dont want to exceed 32-36 degrees normally at high RPM under load. It's a good idea to start at 32 and tweak it up as you verify the engine is running without detonation. You can approach 40 even, but 32-36 is the most common range. Just be careful not to get into detonation and blow it up by advancing it too far.

The main disadvantage of locking it out is harder starts, small drivability issues. Just having a lot of base timing wont damage anything as long as the total timing is kept in the right range.

LT4 hotcam is usually good for 350-375hp in a Vortec 350. You should be in the 300-400 range with it depending on various other factors. Much better street cam than what you have, but wont make as much peak power. Also not really the greatest cam, but it's a great, affordable, common cam that is a proven combination with LT1's and Vortec heads.

 

I understand.
well I dont think 300-400 is enough for me. I want to be over 400.
the ZZ4 with hot cam kit was to little.

have i mind I am not driving this car evry day.
i have 350 trans with manual shift and rew-lock up and a ford 9" in the rear.

I have ordered a new powermaster starter high torque to handle 11-1 comp, so hope this can tun the motor, even with this ign-setting..

spending some new oil and filter today and see if I can run this...

 

just a question.
I have the GM performance 10185071 cam, in my garage. almost not used. this I have with new complete set of valve springs.

but can I run this with my solid lifters?

 

You can't mix hydraulic and solid parts together. Hydraulic lifters and solid lifters need different accomodations in the design of the cam lobe so it's best to not mix and match.

The Hotcam is a bigger cam than that one, though.

 

Any luck with the engine builder and details on the build?

 

oki..
I was asking cause I have this cam in my storage.. so it would be easy to try it....
I understand that the hot cam is bigger.....

"skinny z" I have no luck with contacting the engine builder.. so if anyone know mr. Shawn Hughes in Tennessee I would be happy to get in contact with you!!!! (like I am that lucky).....

 

The problem as I see it is the very (very) low compression pressure you see through your test. No amount of cam swapping is going to make up for that. Without that, the torque you need to make isn't going to happen and your power output will be greatly reduced.
Here's a link to a compression ratio vs cranking pressure calculator. I've plugged in some numbers and at 120 psi cranking pressure you're at less the 8:1 cr.
http://www.not2fast.com/turbo/compre...pressure.shtml

 

As I told you the pressure meter is not calibrated. I did try to test this against my compressor and found that it is way out. there is more pressure than I told you before..

 

That is certainly encouraging.
Be sure to keep us posted regarding your progress.

 

yea.. I am going to test on the strip this weekend..
I can now after some tuning run closed loop at idle with no problem.. starting is also no problem.. and the car feels fast.. but wether is not so good, rain and some snow. so I hope it will be bether this weekend...

 

so.
went out driving today.
worked fine for a while, but I noticed som noice from enginge . But couldn'n define where or what it was....
in the evening i did get som oil leak from front sealing on my crank.... bad bad bad..
so I opend my oil pan ti inspect off my front bearing.. this is what I found..





but what is this middle shims very thin, on this picture:



ned a new crank and allot off work...