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Old 01-23-2018, 11:28 AM   #1
SilverMachine
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I feel something is off with my new engine.

Hey guys, I feel like something is holding my new engine back..or something because it's not as powerful as i expected
Engine details
SBC 355
Cam - Howard's cam .223 @ 50...502 lift....108 LSA
Edlebrock aluminum E-street heads. (185, 64cc chambers)
Edlebrock 1406 carb
1.6 roller rockers
I'd say around 9:5:1 compression with the skinnier head gaskets
The engine timing is advanced I believe to around 12 degrees.
Everything else is pretty much new I think but nothing considerable to mention.

The truck has 3.73 gears with positraction....20 in wheels.....700r4 transmission with competition shift kit.

My concern is the acceleration....it cannot do a burnout if I'm sitting still and full floor it. I don't think that should be the case.

If you have any ideas or comments please feel free it would mean alot!
Thanks
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Old 01-23-2018, 12:07 PM   #2
Dead Parrot
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Re: I feel something is off with my new engine.

Not an expert but some questions that might help others better respond.
What RPM range is that cam designed for?
Does it match the stall on the torque converter?
Engine properly broke in?
Tire size?
Is the 12* timing the initial?
Stock type distributor with both vacuum and mechanical advance?
What is the setup on the carb, jets, rods, springs?
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Old 01-23-2018, 12:23 PM   #3
SilverMachine
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Re: I feel something is off with my new engine.

Hey thanks for replying.
Yes the 12 degrees is the initial timing.
the Cams RPM range is from 1700-5700
the torque converter i believe has a 1900 stall.
The engine originally would not accept the initial timing so we had to slowly raise it as it broke in. I would say it has around 1,500 miles on it now total.
The distributor is just a normal stock type one i believe (my dad got it awhile ago so im not sure) but its nothing special like an MSI or something,
and for all of the carb questions i am not particularly sure, i would have to ask my mechanic (he does all my work, i just know the parts hah) but im pretty sure we just slapped the 1406 carb from the old engine onto this one.
Tire size 275 45 20
someone did mention to me awhile ago about having my carb re-jetted,,but im not really sure what he meant.

Last edited by SilverMachine; 01-23-2018 at 12:30 PM.
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Old 01-23-2018, 12:33 PM   #4
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Re: I feel something is off with my new engine.

your mechanic will know what rejetting the carb is....short version is inside the carb there are jets..jets dictate how much gas can travel thru them based on what size hole is in it...the bigger the hole the more gas..
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Old 01-23-2018, 12:35 PM   #5
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Re: I feel something is off with my new engine.

thanks! ill talk to him about it
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Old 01-23-2018, 12:57 PM   #6
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Re: I feel something is off with my new engine.

Stock type distributor? Might be a large part of your issue right there. The stock spring and weight combo was pretty conservative, and the stock HEI module will be limiting you, too. Unless you've had the distributor tuned for the engine, you're probably not getting anywhere near the timing advance that your engine needs, and those HEI modules are really only good for about 4500 RPM or so. Not to mention that if this is a used distributor, it may have enough wear i the shaft to affect the timing. I would recommend looking into a good aftermarket distributor and having your timing curve matched to the engine.
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Old 01-23-2018, 01:23 PM   #7
SilverMachine
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Re: I feel something is off with my new engine.

Yeah it was just one of those chevy HEI distributors for like 75 bucks you can get at pepboys. It was used on my previous engine for a good 4,500 miles or so.
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Old 01-23-2018, 02:43 PM   #8
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Re: I feel something is off with my new engine.

Was that 12* initial timing with the vacuum advance disconnected? (supposed to be.)

If you just have a basic timing light and a tach, you can do a check on your mechanical advance curve.
For testing purposes: Disconnect your vacuum advance and plug the carb hole. Set your initial timing to TC, zero advance. (engine probably won't like it). Watch the tach while you slowly rev the motor. Note the RPM when your timing starts advancing off Zero. Keep speeding the motor up. There will be a point where more speed quits giving more advance. Note this RPM.
You now know when your mechanical starts, ends and how much you get.
Reset your initial timing back to normal.

Discuss your results with your engine builder. He may suggest recurving the mechanical advance. There are low cost kits for that.

Vacuum advance is for part throttle driving and economy. Has no impact on full throttle power.

Get your timing working correctly first, then play with the carb. On a non-emission motor, you usually want as much advance as you can get without knocking/pinging.
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Old 01-23-2018, 05:53 PM   #9
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Re: I feel something is off with my new engine.

To add to what deadparrot asked, what’s your idle rpm?
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Old 01-23-2018, 08:37 PM   #10
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Re: I feel something is off with my new engine.

Are you running 92 or 93 octane? or just 87?

I am going to agree with guys above and say that timing could be a major restriction here. And i don't mean just initial timing I mean everything from the weights, coil pack, even the distributor itself.

Then I would say tackle the carb and see whats up with that.

Are you running manifolds and cat(s)? What kind of exhaust setup
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Old 01-23-2018, 10:25 PM   #11
SilverMachine
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Re: I feel something is off with my new engine.

Hey guys thanks for all the replies,
i run 89 non ethanol
my exhaust setup: hedman headers true dual with no cats. mufflers are dynomax mini bullets 3".
my idle rpm is probably anywhere from 650-750.

I may just be stating reality...the engine might just not be quick at all haha. but with the upgrades i did to it i would have thought for it to have a little more punch! it annoys me when i have to give it 70% throttle just to keep up with traffic from a stop light!
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Old 01-23-2018, 11:00 PM   #12
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Re: I feel something is off with my new engine.

You might be limited by your poor flowing heads. Better than stock but not the best. And likely way to much cam for your compression ratio. And your pistons might be quite aways down in the bore creating poor quench and actually only creating sub 9 to 1 compression.
You might not be able to run too much initial.
Have you tried more initial?
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Old 01-24-2018, 11:22 AM   #13
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Re: I feel something is off with my new engine.

Quote:
Originally Posted by SilverMachine View Post
I may just be stating reality...the engine might just not be quick at all haha. but with the upgrades i did to it i would have thought for it to have a little more punch! it annoys me when i have to give it 70% throttle just to keep up with traffic from a stop light!
Nah, I would think it should be considerably quicker that what you describe. My flatbed dually hangs with traffic at 1/8 throttle and pulls away with any more than that. It isn't nearly as built as yours either. Brown box RV cam, Vortec heads, Edelbrock Performer RPM, 1407 carb, long tubes w/duals, built TH350, and a one piece aluminum driveshaft. Granted it has a 4.10 rear end, but that's not a crazy jump from yours. Get your tune dialed in man.
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Old 01-24-2018, 12:14 PM   #14
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Re: I feel something is off with my new engine.

Way too much camshaft ,equals no off idle performance. Any "Street" profile camshaft that's starts at 1700 RPM, too high.

That distributor is killing it, you need to check timing to see what the "Total" advance is should be 36 -40 ALL IN.

You can get an MSD module for a stock HEI distributor which will open the top end up from 4500 rpm.

Lighter springs and weight in the distributor will let thee timing come in faster which will help your combo a lot.
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Old 01-24-2018, 12:43 PM   #15
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Re: I feel something is off with my new engine.

Quote:
Originally Posted by Desert1957 View Post
Way too much camshaft ,equals no off idle performance. Any "Street" profile camshaft that's starts at 1700 RPM, too high.

.
And truth be known that cam likely doesnít start to work until 25-2800 rpm.
Itíll be a dawg on the bottom end.
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Old 01-24-2018, 01:26 PM   #16
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Re: I feel something is off with my new engine.

Quote:
Originally Posted by geezer#99 View Post
And truth be known that cam likely doesnít start to work until 25-2800 rpm.
Itíll be a dawg on the bottom end.
True...
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Old 01-24-2018, 06:30 PM   #17
SilverMachine
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Re: I feel something is off with my new engine.

Alright!
ill check out that MSD module and try to hone in my timing!
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Old 01-24-2018, 07:18 PM   #18
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Re: I feel something is off with my new engine.

You and your mechanic should read this.

http://www.badasscars.com/index.cfm/...d=76/prd76.htm

And this might be helpful too.

http://www.crankshaftcoalition.com/w...EI_distributor
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