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I have a chevy 305 V8 in my '76 nova. i recently bought a holley 600 cfm carb to step up from a 2 to a 4 barrell carb. i will be purchasing an intake manifold shortly, as well as an inline fuel filter, which my mechanic said i would need.

but what threw me for a loop was that he also said ill need to purchase a different distributor advance kit for the car, because with the new parts on it, the engine is going to advance differently.

now ive been looking on summit, but i dont know the difference between different types of distributor advance kits, like the springs, or curves or whatever. also, the product descriptions say they are to make it stock again. why would i want a stock one? my mechanic said ill need a diferent one.

im just lost because i didnt think i needed anything besides the carb mani fuel filter and air filter.

2007-08-05 15:22:14 · 4 answers · asked by dude 2 in Cars & Transportation Car Makes Chevrolet

for an advance curve kit, heres one from summit i looked at.
http://store.summitracing.com/partdetail.asp?part=SUM%2DG5212&autoview=sku
is that what i would need?

2007-08-05 16:28:57 · update #1

And yes, i already did a bit of exhaust work. i got the summit racing headers, and dual exhaust minus cats with turbo mufflers all the way back. i even extended them a little bit because they came pretty short.
i was almost thinking of getting an intake manifold/valvetrain combo from holley
http://store.summitracing.com/partdetail.asp?part=HLY%2D300%2D502&autoview=sku
its not too expensive, but i dont know if it would be worth it to dumb money into my 305 instead of just putting in a 350 or selling the car.

2007-08-06 12:24:13 · update #2

4 answers

what he is talking about is recurving the advance on your HEI distributor. Its comon practice to do this, just ask for an HEI recurve kit, like 20 bucks or something...... oh and exhaust, dont forget about the exhaust

2007-08-05 15:29:12 · answer #1 · answered by Christian 7 · 0 0

Yes but no. Yes good chance you will have a ping if you just throw it together without touching distributor but you can adjust that I believe. Anyways I had the same problem on my 302 Ford. I built the motor all up with new cam, intake, carb, headers and had a slight ping in the 3000rpm range because my advance was off. I first disconnected the vacuum advance and that dam near fixed it but still had slight ping on hot days so I just bent the stop tabs slightly on the mechanical advance so it won't advance as much. Also on the Ford distributor on the mechanical advance stop plate you have I believe 18 degrees of advance on the on side and only 13 on the other side, all you have to do is take it out and turn it over but i didn't even need to resort to that in my case. I buy all my parts on summit as well. Don't forget to throw some headers on there as well, exhaust is just as important as intake for making power. Also I believe the heads for a 350 will bolt onto a 305 so you should check out the aluminium performance heads on summit, they are for a 350 but they should work and they are cheap! Hope I gave good advice because I'm going by Ford parts because I don't have much GM experiance.

2007-08-05 19:17:07 · answer #2 · answered by 81Mustang 4 · 0 0

From the sound of it, the man doing your work knows what he's talking about and trying to get you alittle more power..

Has NOTHING to do with detonation as others on here said. The mods your doing will not need timing retarded more.. Detonation comes from cyl pressure, cyl pressure comes from higher compression ratios, smaller cam, boost, etc.

Here's a quick course on what the timing curve is..

You have 2 major timing setting.. Timing at idle.. Put dist in and turn it
mech. advance.. The shaft, weights, springs inside dist.

As you drive, higher the RPM goes, the more the weights swing outwards and the more total timing advance.

GM set the timing poor from the factory.. Most HEI dist gives 19* to 21* mech advance.. The OEM timing specs at idle is like 8* ... Well add 8 to 20 and you get 28* total.. That's about 8* too low for most power (36*)

Next is the rate of advance.. You want all of your timing to come in where you drive at.. GM set up the HEI to be fully advanced at 4500-5000 rpm.. How many times do we drive at that RPM?

So by changing weights and springs in dist, you can get the full advance to come in sooner (about 3,000 rpm)

By setting total timing to 36* (16* at idle) you gain better throttle responce, better idle, more power..

Then by bringing the advance in sooner you gain more torque where you drive the car at.

2007-08-05 19:12:38 · answer #3 · answered by chevyraceman_383 7 · 1 0

this set up will be fine the only thing you would have to do diffrent is set the timming a little retarded than stock because of the increase in airflow try to set the timming to factory specs and see if it is pinging under load if so back if off just a little to correct this problem chevy engines love to run a little lean a very slight ping wont hurt but to mutch will detonate cylinders

2007-08-05 16:11:51 · answer #4 · answered by tylthorpe 1 · 0 0

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