tuning a 4.3 V8

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tuning a 4.3 V8

Postby gunner » Wed Oct 02, 2013 11:42 pm

How can I tune a stock 4.3 V8 to get more hp out of it. Can I close the gap on the spark plugs or advance the timing. Remove the smog pump. Upgrade the coil.. I did install a high flow cat. would a 4 barrel carb with stock heads do any good. I just want to keep it simple.
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Re: tuning a 4.3 V8

Postby marco_1978_spyder » Thu Oct 03, 2013 7:50 am

I'll take a shot here..

I think there are some things you can do to help how the motor feels, and how sporty it run's. You might not see a huge drop in 1/4 mile times without a compression cam and head change, (thats when you just drop a 350 motor in) (and many people consider that easier than micro-tuning).

For you I think the right 4bbl (500cfm) or 390 holley) is going to give the greatest amount of change. It will give you a better top end than the 2 barrel.

Instead of a smaller plug gap, go with an accell or similar drop in distributor with the HP coil inside. Then open the gap up a bit, say .045 for a nice thick spark to each cyl.

You could add an electric fan in place of the engine one. Also removing the smog pump like you suggested would be a benefit.

Keeping the airfuel mixture tuned crisply as well as finding the timing curve the engine likes will be important and may take a lot of tinkering.
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Re: tuning a 4.3 V8

Postby gerbsinmd » Thu Oct 03, 2013 8:13 am

I did some pretty amazing stuff with this engine in an 80 Malibu. This was all done on the drag strip, my friends rented the strip for a day so I got lots of runs in and was able to make one change at a time. Now it wasn't a rocket by any means but the change was nothing short of amazing.

I did 2 basic things to this engine over the course of about 30 runs. More air, more timing.

The car started out just as it was driven in Stock timing, stock everything. First run was 19.xx and 67 mph. I kept adding timing and adding timing till it slowed down. I have no idea where the timing was at the end of the day, I didn't have a dial back light, it was WAY advanced. I did have premium gas in it for the whole thing, I ran it down prior to going to the strip and filled it completely.

When it stopped going faster, I took the air cleaner lid off which was a typical sbc lid and did the old flip it over. this gave me .25 in the quarter and a mph or 2. then I found someone that had an extra 4 in filter and a flat air cleaner lid and put those on and it gave me another .1, then I uncorked the exhaust before the converter and found another .2

At the end of the day I was running low 17.0 at around 79 mph, if I remember right, not sure on the speed anymore that was almost 20 years ago, not a rocket at all but it was good enough to get me to 4th place in a double elimination field of 50+ cars.
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Re: tuning a 4.3 V8

Postby cjbiagi » Thu Oct 03, 2013 8:40 am

I don't think there is anything wrong with a HEI distributor so I would just upgrade that over buying a new one. You can get a performance module for it as well as a good cap with brass contacts and this along with a good set of spark plug wires and plugs will give you all the ignition you need. A upgraded dual plane intake along with a small 4 barrel carb around 500cfm will handle the intake duties. As mentioned, timing is very important so you can adjust that and see some benefits. You may also want to try switching the vacuum advance to a full time vacuum source and see how the engine responds. Headers would also help but can be expensive because you are also talking custom exhaust at that point. I had the 262 V8 in my car when I bought it and it performed pretty darn well for such a small V8.
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Re: tuning a 4.3 V8

Postby Fastmax32168 » Fri Oct 04, 2013 8:00 am

Here would be my low budget plan to make that little motor feel a lot stronger. Small 4 barrel carb on a dual plane aluminum intake my choice would be a performer air gap. Small tube headers through small dual exhaust with a crossover or a single 3" exhaust. Boost the HEI with a better coil and install an adjustable vacum advance that allows you to bring the advance in sooner. Then since you are not a pro at this, take it to a knowledgeable shop, put it on a dyno, and tune the AFR and advance curve. This last step will probably net you more power and driveability than everything else on its own. It should go without saying that all of this needs to be done with new plugs and wires cap and rotor.
It will be an animal compared to what you have now and with smart shopping you will have barely spent $1000.
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Re: tuning a 4.3 V8

Postby cosvega76 » Fri Oct 04, 2013 8:03 am

I'd suggest an advance curve kit for the distributor, too. Get the centrifugal advance all in by 3000 RPM.

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Re: tuning a 4.3 V8

Postby Fastmax32168 » Fri Oct 04, 2013 8:16 am

LOL I was just thinking about how I forgot to include that and was coming back to this post to put it in when i saw yours. You are a step ahead of me. :)
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Re: tuning a 4.3 V8

Postby gunner » Sun Oct 06, 2013 5:41 pm

If I install the performer intake and the edelbrock 500 cfm with an after market air cleaner will I have enough clearance under the hood.
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Re: tuning a 4.3 V8

Postby monzabug350 » Sat Oct 12, 2013 4:42 pm

If you do all the tune up work and carb/intake change how about a cam change? Check out the cam co's on the internet and see what they have for your eng. One co. Kenny Bell,has a line of v6 parts including cams from mild to wild, and also intakes and carbs. I had a friend who had me install one of Bells "daily driver" cams in his v6 a few years ago and he told me it felt like he had 2 more cylinders,and he had a 3mpg increase in gas mileage. Just a thought.
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Re: tuning a 4.3 V8

Postby Monza Harry » Sat Oct 12, 2013 8:33 pm

I am surprised nobody suggested to pick up some swap meet 1.6:1 rockers and try them on exhaust only first then both intake and exhaust, cheap to try this way out, and you can replace them if that works out for you with some new ones if your afraid of the used ones (fear isn't always a bad thing) Harry
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