Engine Tune help - Team Camaro Tech
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post #1 of 21 (permalink) Old Apr 6th, 11, 02:29 PM Thread Starter
Justin
 
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Engine Tune help

Good evening gentleman,
Ok to begin, short and sweet, Im on here on behalf of my good friend mike. We live approx 30 miles apart and he doesn't currently have internet where he's at. He's the camaro muscle car guy, im the project turbo miata guy (hopefully i dont get flamed for that comment..lol).
I told him I would jump on here with my first post and see if we could summon the power of the car gods for some tuning help as he has always had issues he could never resolve and Ill throw out some questions just for my own personal know how. So let me start by listing what his setup is....


He has an '81 camaro and about 9 years ago He received an engine from an old high school buddy of ours as a wedding gift.
Its an L65 350ci. from a 1969 camaro (T0827hc) made in new york August 27th 1969 250hp..yadda yadda.

It currently is running an edlebrock 1405 600 cfm non egr carb,
Holly street dominator intake, .030 over bore, 2.02 heads, headman headers, accel ignition complete (wires,coil,plugs,cap,rotor) crane roller rockers, 9:1 comp,summit cam (194. 204 duration and 398. 420 lift) he runs accel u groove plugs and the coil is accell super hot coil (45000 volt)

Now, what he mentioned is that he has always had to fight with it to get it even remotely tuned and obviously can not figure out what is wrong. He knows the engine has more in it that it shows. When asked the characteristics of how it runs he said usually it starts fine but occasionally will give him trouble on start but also the idle is uneven, goes goes up and down, wants to stall when you come to a stop!

Thats about all I have at the moment, I am well aware and not expecting an answer over night. I also mentioned that you guys will most likely need us to check compression and timing amongst other things and I will be seeing him this saturday so will have more info at that time. In the meantime if you need any thing else, he is only a call or text away.

My own personal info is based on what i mentioned, the engine stock had roughly 250hp, do you think conservativly this engine if well tuned would put out 300? ok guys thanks a million in advance for any and all help provided.

kind regards,
Justin
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post #2 of 21 (permalink) Old Apr 6th, 11, 02:44 PM
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Re: Engine Tune help

Quote:
He knows the engine has more in it that it shows....... usually it starts fine but occasionally will give him trouble on start but also the idle is uneven, goes goes up and down, wants to stall when you come to a stop!
Classic symptoms of sec butterflys not set, and the dizzy timing not even in the ball park...and most proberly even the VA if it has one is way out of requirement.
A forum search with the button above will give you/him all the info needed and how to, and explain what u are doing and why.

My Spelling is not incorrect...it is creative

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post #3 of 21 (permalink) Old Apr 6th, 11, 02:54 PM
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Steve
 
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Re: Engine Tune help

For starters go through a basic tune-up....check the timing...should be anywhere between 10 and 14 deg advanced with vacuum plugged....adjust idle screws on carb for best vacuum or highest RPM at idle...ballpark 3/4 to 1 1/2 turn out on each. Go from there.

69 SS, 350/300 h.p., M-20, 12 bolt, matching numbers.


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post #4 of 21 (permalink) Old Apr 6th, 11, 03:31 PM Thread Starter
Justin
 
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Re: Engine Tune help

ok, fantastic with the quick responses. Ill definitly do some searching on here before we get ahead of ourselves, one quick question as I dont know near as much about v8's and even less about carbs..... when you mention
Quote:
and most probably even the VA if it has one is way out of requirement
VA stands for? lol bear with me

....you wouldnt' be talking about Vacuum Assist would you?
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post #5 of 21 (permalink) Old Apr 6th, 11, 03:33 PM
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Re: Engine Tune help

Vacuum Advance...

...Dennis

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post #6 of 21 (permalink) Old Apr 6th, 11, 03:41 PM Thread Starter
Justin
 
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Re: Engine Tune help

Thanks, Im on the phone right now with him..
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post #7 of 21 (permalink) Old Apr 6th, 11, 03:54 PM
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Re: Engine Tune help

I can think of a dozen issues to cause the problems you are describing. Let's start with the basic's...

1 - What condition are the plugs, plug wires, dist cap, rotor and overall engine bay wiring in?

2 - What's the timing set at? initial, total & vacuum advance?

3 - Is there Vacuum Advance and what vacuum port is feeding it?

4 - How old / what condition is the carb in? How much tuning (just turning screws) has been done to the carb? Any parts replaced or has the carb been rebuilt recently?

5 - What's the mileage on this 9 year old gift? How much of it has been put on in the last 9 years? Was it rebuilt 9 years ago or long before that?

Answer as much as you can and it will greatly help everyone get you the best info and help...

As for HP, an SBC 350 is a 350 as far as bore and stroke go; cam, compression, heads and the sum of all the parts are what makes one 250hp and another 400hp.

Keep in mind an '81 Camaro weighs in around 3500 lbs compared to your Miata it's a barge so don't expect the same results from HP numbers... Also without knowing what transmission and rear gearing that '81 has it's going to be hard to estimate if their is more in the engine than it's currently putting out...

...Dennis

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post #8 of 21 (permalink) Old Apr 6th, 11, 05:11 PM
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Alan
 
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Re: Engine Tune help

We are not there yet, but at some point, we need to find out when the vac advance is coming in as that can cause the idle to hunt as well as the mechanical advance springs being too loose.

alan

P.s. who gift wrapped the engine and brought it to the wedding?
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post #9 of 21 (permalink) Old Apr 6th, 11, 05:23 PM
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One super- basic thing to add, check the float level on the holley carb before attempting any other carb adjustments.


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post #10 of 21 (permalink) Old Apr 6th, 11, 05:42 PM
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Re: Engine Tune help

Compression? Might as well check that and get a good baseline.

What smog and ignition systems did these engines have or has this one been stripped of all that?

alan
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post #11 of 21 (permalink) Old Apr 6th, 11, 11:36 PM
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Re: Engine Tune help

Quote:
for some tuning help as he has always had issues he could never resolve
From this it would be safe to assume carb butterfly bushes, HT leads, Spark plugs and other 'maintance stuff is all good
IF it is NOT...put new plugs in , oil change BEFORE doing any tuning.

The other week I was stuffing around, did a tune O2 logger etc....running sweet...But out of interest the plugs where pretty worn, done around 25K over several yrs.
Then changed the plugs, see what would happen....picked up approx 0.5 on road test...re tuned and picked up another 0.25 ....

My Spelling is not incorrect...it is creative

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post #12 of 21 (permalink) Old Apr 6th, 11, 11:56 PM
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Re: Engine Tune help

I had an L65 spec engine with just a 0.030" overbore, mild cam (peak torque at around 3000 RPM), original 441 heads, Performer RPM intake, Holley 670 carb, 1-5/8" headers, and Flowmaster 2.5" exhaust. It made 263hp at the wheels so it was at least 300hp on the engine.

I would guess that the engine now has a GM HEI in it. IF that's the case and the vacuum can is hooked up to full manifold vac it will cause all kinds of issues. An old HEI can has a whole lot of advance in it and needs about 20" of vacuum to pull in. My engine made about 12" at idle and ran good with a factory HEI can hooked to ported vacuum and 12" initial advance.

Easy enough to pull off the vacuum advance line and plug it. Edelbrock carbs can also be hard to tune.

'69 Camaro
Dart 400-AFR 195-224/224 HR-Powerjection III TB with F.A.S.T. Sportsman XFI
TKO 600-Moser 3.42-Detroit Truetrac
500hp/538lbft

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'69 Camaro Beater-SFT 327-M20-Moser 4.10-sold
'02 Z/28 vert-stock-sold and totaled
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post #13 of 21 (permalink) Old Apr 7th, 11, 01:32 PM Thread Starter
Justin
 
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Re: Engine Tune help

Wow, this is great! you guys are throwing out tons of good info, Ill try to keep up
The engine has roughly about 25k miles since rebuild. 20000 of which were with our buddy ron (doner) and the other 5k with mike (current owner) he doesn't drive it much well between constant tinkering,Michigan winters and cost to keep liscenced and insured along with his many other cars. I didn't get a chance to mention that he did buy a vaccum advance kit a while go so it does have that and not too long ago he found out the distributer was wore out and was never keeping timing. He recently rebuilt it and installed it today.
He wanted me to mention that he has replaced all vaccum lines with new and set initial timing to 10. Said It still is having a problem with idle but other wise seems fine. He wanted me to ask where to set the initial settings on the carb.
I will also mention to him about the HEI can.....
I tried to mention it over the phone at work but am about to call him and read off the post in more detail. he was initially a little confused but then realized that yes he does have HEI on the vehicle but it didnt look like a can...Lol...tomato-tomatoe.

Ill keep everyone up to date as the info comes in!

---UPDATE--
I just got off the phone with mike, He mentioned he always had the option to run egr or not and had opted to not run it, anyways upon inspection noticed the EGR blockoff plate gasket was nasty/dryrotted and is in the process of replacing it as we speak!

Last edited by detroitmuscle; Apr 7th, 11 at 03:07 PM.
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post #14 of 21 (permalink) Old Apr 7th, 11, 03:15 PM
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Re: Engine Tune help

Quote:
An old HEI can has a whole lot of advance in it and needs about 20" of vacuum to pull in. My engine made about 12" at idle and ran good with a factory HEI can hooked to ported vacuum and 12" initial advance
Not all GM HEIs are the same...there are 100s of varariations of the early 4 pim module specs....BUT most are for post 72/74 pollution addons... ported VA...and the Cent totals often different to......Pre this where pionts with manifold vac
Thats the bad news..no plug and play...but hey when it comes to ANY dizzy..there is no plug and play...its like buying a rifle, add a scope and expect to drop a deer at 300 yrd without dialing in.

Now the good news.....it is not hard to customise , mod the HEI cent or the VA to earlier specs...
simple stiuff like if need more cent, take ,5 to 1/2mm off the tail of the counter weights, rounding them off
If want to reduce,,,in the top plate where the rotor screws on, there is a hole, tap it and put a screw with a head filed into a cam...limits cent and adjustable.
The VA...can file the gap that the actualtor arm sits in to give more or start earlier...
Or put stops made of scrape metal top and bottom attached the the VA mounting screws

Basically one now has a full adjustanle HEI that can be customised for anything.

These same methods also apply to customising the pionts dizzy.

My Spelling is not incorrect...it is creative

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post #15 of 21 (permalink) Old Apr 7th, 11, 09:34 PM
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Alan
 
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Re: Engine Tune help

Hmmm, there are lots of vac advance cans, each one with different specs. Remember the list from JohnZ's article, a whole bunch of different va cans.

alan
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