My Engine Dilemma..need honest answers

[SilverMachine]

So here we go, basically i had my 2 year old 350 crate machined and bored 30 over, new pistons (went with flat tops to keep compression around 9:5:1 for my daily) new crank new everything. New Edelbrock E-Street aluminum heads (185cc intake 64cc chamber) New cam - howards max torque cam: 275 adv duration, 223@50, .501 lift (with new 1.6 roller rockers) 62 seat overlap 108 LSA and 104 ICL. new 2200 stall converter, 3.73 gears w/positraction, 275/45/20 tire. Hedman headers. So basically this feels no better than my stock goodwrench 350....my mechanic cannot get the timing perfect (how he likes it) so the idle is a tad higher than i would like, and the engine is very tight (as expected i guess for a 3 day old engine, when we had the timing like my mechanic likes the engine wouldnt crank back up). when driving down low is a little better than my stock goodwrench but mid range power is nowhere to be seen. when i let off the gas and start to decelerate i actually start go go faster (a little push faster than giving more gas in midrange..makes no sense) so everybody i have talked to have told me that 1, i need to let the engine break in (still i was expecting a difference from the start) and 2, that my carb is too small (what i think the problem is) i have an edelcrock 1406 600cfm carb. the engine does feel like its needing more gas and it will clunk and it feels like its dropping almost when i give it decent gas. full throttling from stop will not even spin the tires....( i didnt want to WOT but felt it was necessary for a test)

do you think changing the carb will have that much of an effect? Thank you.

[geezer#99]

The little power surge when you back off on the throttle is from your vac advance adding more timing. Which tells you you need to fine tune your timing.
More initial with less in the mechanical that's all in quicker (closer to 2800 rpm).
What's your initial timing set at?

[SilverMachine]

Honestly i do not know. we tried to advance/more timing on it and it sounded mean like the idle should with this cam, but it wouldnt crank back up, it just wombwombwomb and wouldnt crank. so we set back the timing and raised the idle rpm. im assuming once the engine breaks in a little more we can get the timing and carb tune just right and it will come to life.

[geezer#99]

Maybe you need an interupter switch. A toggle switch wired into the power supply for the distributor. Leave the switch off, get her spinning over, flip the switch and it fires. You can run way more initial timing that way.
Turning up the idle just gives you other problems like idling on the power circuit.

[Dead Parrot]

Not an expert by any means.

What does Howards say that cam's rpm operating range is? You could be chasing performance in a range that your build isn't going to provide.

Until you open the back barrels on a 4 barrel, you have a 200~300 cfm carb. A larger carb isn't likely to solve your low and mid range issues.

What is your idle vacuum? Might not have enough to kick in the vacuum advance.

Ask your mechanic how many miles it takes before the rings fully seat in. You might not have a good seal yet and lower then expected cylinder pressures. Yep, another vote for let it get broke in a bit more.

[bilfman]

It does sound like timing. There are many variables such as the which vacuum port the vacuum line is on, is there a mechanical timing adjustment on the distributor, weights and springs in the distributor. All these need to be tailored for your engine. Someone with expertise in dizzy magic should be called in. Also , as mentioned earlier, there is the matter of break in.

[SilverMachine]

Ok thanks for the info guys, sounds like ill just let it break in more then try to tackle the timing. and the cam rpm range is 1700-5700 rpm. we will see what happens with time!

[Jake Wade]

600 cfm carb is not the problem. Did he degree the camshaft? Who knows where its installed if he didn't. Engine may be really tight on the clearances.

Your tune could be off. 16 initial minimum with that camshaft, 18-20 mechanical advance in the distributor, all in by 3000 RPM. Limit vacuum advance to 10-12 degrees and I would suggest hooking up to full vacuum port on carb. DUI distributors can build you a HEI distributor that will provide this. Give them a call, money well spent

[TrailerTrash]

The way i understand is you changed the converter when you had the engine done. It is going to feel different going from a stock torque converter to a 2,200 stall. not saying that is the problem because from your post and peoples replies you obviously have some engine issues.

is your guy setting the timing by ear? and did he properly adjust the rockers?

is also sounds like you are out womping on the engine before its even broke in

[SilverMachine]

Hey guys, yeah im pretty sure he advanced the camshaft by 2 degrees when he installed it. and yeah i havent been out dogging the engine. the only time its been close to WOT is when my transmission guy was driving it to adjust the transmission, and he realized something was wrong so he stopped and gave it hard gas to see how it would pull to confirm his suspicion of it not pulling correctly/like it should.
what im thinking was done is that he retarded the timing and raised the idle rpm.

[SilverMachine]

Ok, so after letting the engine break in for awhile we were able to put the initial timing at 8 degrees, it was at 0 before. it feels like a completely different truck now! My mechanic said we will try to get it around 12 degrees initial timing during my next oil change. so the initial timing at 0 was the problem! hopefully it will be even better at 12 degrees initial!

[DieselSJ]

You will also need to spend some quality time with that carb with rejettng and finding the right metering rod/spring combination. I probably spent 20 hours on my last carb'd vehicle to get it right and it was night and day difference between when I started and when I finished. If all you changed on the carb was your idle mixture then you are leaving a lot of performance on the table.

[Pontiac1976]

Just about time for up-date, How Miles on the motor since the build.
So how it now.