Crate engine swap advise please?

[68post]

LOL I hear ya. When they're up to snuff they're great and super reliable but when you start to have little nit picky issues they can sometimes be hard to track down and makes it frustrating.

They're as much fun as a really nice new two barrel carb.

 

[Old77]

 

[Georgeb]

See, my engine needs to be replaced in the future due to a crack in the block. Uses coolant but not real fast. While contenplating an engine I need to choose if I will stay with the TBI or scrap it and go carborated.

 

[Georgeb]

They're as much fun as a really nice new two barrel carb.

I had a 2bbl 307 in a truck that would walk all over this tbi 350 all day long!

 

[foamypirate]

I'm ditching my TBI 350 (which is running like poop again. One day of excellence among weeks of poopiness), and going with a 6.0L and a 4L80E.

 

[Old77]

I'm ditching my TBI 350 (which is running like poop again. One day of excellence among weeks of poopiness), and going with a 6.0L and a 4L80E.

That's cuz you the man and gonna make all of GMSB jelly of that 3+3

 

[foamypirate]

That's cuz you the man and gonna make all of GMSB jelly of that 3+3

Yum....jelly...

 

[73 C10]

OK, couple things.

18" of vacuum means you should be running the 8" step-up springs in the Edelbrock. I stretched mine so they rested at 1/4" longer than they came at, to get closer to 9". The rule of thumb is the springs should be 1/2 of your idle vacuum, so that's why I say switch to the 8", and maybe even stretch them. As it is now, you are in the cruise circuit all the time, and with those needles, it means you are running lean as hell. That's why it is doggy right now. You need the more powerful springs to force the step-up pistons up and get into the thin part of the needle when you get on the throttle.

That's your biggest problem right now.

I would still try the needles I suggested above, as well.

Those advance numbers sound like camshaft degrees, which is the way distributors are traditionally specced. Normally you figure 20* of mechanical, and 15* to 25* of vacuum advance. Those are crankshaft degrees. But 10*-11* mechanical and 10* vacuum advance sound like camshaft degrees, which are half as much. Does it say in the instructions which degrees they are talking about? You can check this by noting the timing, then plugging in the vacuum and noting the timing again. You should be able to see whether the timing with the VA hooked up moves 10* or 20*.

My own recommendation is 20 crankshaft degrees mechanical (10* on the cam) and 16 to 24 camshaft degrees vacuum advance (8* to 12* on the cam). That's the range of most GM applications with the HEI. If those numbers you quoted are camshaft numbers, which I strongly suspect they are, you are right on the money.

12* base is OK. With 20* mechanical, that's 32* total advance with the throttle open at rpm, and 52* at cruise, which is about as high as you want to go, and also gives your best mileage. You could try for 16* base later, to get 36* base + mechanical, which is the maximum horsepower/torque point at rpm with the throttle open for GM V8s, but then you need to back the vacuum advance down a bit to keep base+mechanical+vacuum (cruise) at 52. That is, as you increase base timing for more advance during acceleration, you need to bake off vacuum advance to keep cruise timing the same. Make sense?

OK. This morning I popped in the stretched 8" springs. You can see them here sticking out because of the stretch.

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I also popped in rod 6557. This is as close as I could get with what I had.

First off, it wouldn't start. It was not getting enough choke. It was about 65* F this morning. I turned the choke by hand and it fired up.

I just drove it to work. I think it is running pretty good. Just no balls. Maybe the distributor was part of the problem.

 

[73 C10]

I've been looking at this chart. Do I need to throw it in the trash? It looks like we have gone off the reservation with this rod and jet.

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[rich weyand]

Yeah, I am way off the chart on mine as well, but the AFR meter says I am spot on. I would never have gotten there using the chart without the meter.

65/57 should be real close. Maybe a little rich in cruise, but not bad. I'd leave it for now unless you are going to buy a meter.

You need to adjust the choke. It's really simple. Don't worry about all the stuff on page 8 for now, just do the paragraph on the top of page 9 in the manual.
http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf

The other thing you could do is dial the vacuum advance back to 8 camshaft degrees (16 crankshaft degrees), then up the base timing to 16* BTDC. This will leave your idle timing the same (16+16 instead of 12+20), and your cruise timing the same (16+20+16 instead of 12+20+20), but will give you more advance at full throttle and at RPM (16+20 instead of 12+20). That 36* for base + mechanical is the sweet spot.

 

[rich weyand]

Rich....I just want to say I really enjoy reading your posts. You are a wealth of good information, sir

Thanks, but there's also a lot of stuff I'm dumb as a post on. Haven't ever done it, or it's been a long time, whatever. I just read what other people say and try to learn, from MO and others.

Whenever I do something on the truck, I research it pretty heavily before I do anything, and sometimes pull boner moves, then I fix it and move on. Hopefully I save somebody else from having to work through the same mistakes. I'm lucky in that I am not hard up for cash to fix my mistakes.

Anyway I try to limit my comments to stuff I actually know. Engine timing, that I got.

BTW, here's the best thing I have found on the net about engine timing. Other competent sources bear out this information. Read the first three posts.

http://www.hotrodders.com/forum/distributor-tuning-theory-part-1-a-59033.html

 

[73 C10]

65/57 should be real close. Maybe a little rich in cruise, but not bad. I'd leave it for now unless you are going to buy a meter.

Is there any benefit to having the ability to put the afr meter in both pipes. If I get one should I have a boss welded on both sides while we're under there?

 

[rich weyand]

Is there any benefit to having the ability to put the afr meter in both pipes. If I get one should I have a boss welded on both sides while we're under there?

Sure, why not. The bungs are cheap.

They go on the exhaust pipe, right after (about 6" is good) the header flange.

 

[73 C10]

Guys, I think it's running smooth. Nice. Thanks.

Now, let's give it some balls. I like the 4 step program. The:

#1 Cam to go with the,
#2 Heads to go with the,
#3 Carb. to go with the,
#4 Roller short block, idea.

if I got that in the right order. Can it be done without buying the cam twice? Probably not, because of the roller parts? I'm assuming I will deal with less then perfect output 'till the small block stage when the pistons match the heads.

But first help me tune what I've got. it ain't winning any races the way it is.

 

[MadOgre]

Yeah, I am way off the chart on mine as well, but the AFR meter says I am spot on. I would never have gotten there using the chart without the meter.

65/57 should be real close. Maybe a little rich in cruise, but not bad. I'd leave it for now unless you are going to buy a meter.

You need to adjust the choke. It's really simple. Don't worry about all the stuff on page 8 for now, just do the paragraph on the top of page 9 in the manual.
http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf

The other thing you could do is dial the vacuum advance back to 8 camshaft degrees (16 crankshaft degrees), then up the base timing to 16* BTDC. This will leave your idle timing the same (16+16 instead of 12+20), and your cruise timing the same (16+20+16 instead of 12+20+20), but will give you more advance at full throttle and at RPM (16+20 instead of 12+20). That 36* for base + mechanical is the sweet spot.

Ya thanks Rich! Everybody should have something valuable to chime in about. I try to keep it to what I know and so do you and most others on here as well! That's what I like about you and most other guys on here! Sometimes we learn something and even by a healthy argument every now and then. But at the end of the day we don't pull **** out of our ass just so we can look smart!