Thread: tuning

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hello guys, my name is joe. i just got my first 69 camaro, and rreally dont know alot about engine tunning yet. it has a 4 bolt main 468 bb. with edelbrock victor jr. intake man. a older berry grant 750 carb and edelbrock valve covers, got a 9 inch rear, 4.10's. this is all i know. the guy i bought it from says is set up good, but its not at its best, needing some tunning.its got 9 lbs. of fuel press.(according to meter) and i need some ideas on how to maxiize it? do i need to ceck ignition timing? how? also he says the carb may need adjusting...i messed with one of the screws on the primary, can adjust the idle, but one it goes to like 1200 it will die...it is fast ight now, but for it to idle without me giving it gas it it will die unless i drive it for like 2o min. anyway, i just dont know what to look for to improve it, higher fuel press,carb adjusting, ignition timing? it burns a lot gas, (just cause its a bb?) any elp with my inexperience will be great. cant trust any mechanics around here! thanks friends!

First, Welcome to the forum! Now, trying to help you do this without being there is going to be difficult. I suggest that you go to the library or book store and look for books on tuning high performance vehicles and study a bit to give yourself a foundation of knowledge. Also find a local speed shop and ask about car clubs in your area. If you can get into a car club there will be people there, just like this "On-Line car Club" that can assist and help you learn. That same speed shop may be able to point you to a reliable mechanic. The ones that can be trusted are generally known to the local speed freaks and may even be one of them. And how about the seller as a resource? Or was he selling it because he did not know how to maintain it?

The car sounds like it is nicely set up and should be a real screamer. With a big block like that and 4.10 gears it will probably never see better than 10-12 mpg if that.

I'm not trying to put you off, but trouble shooting and making recommendations without specific information or being able to see, hear and smell is not something easily done.

Good luck and enjoy your project. Learning is all part of the fun

Pat

one thing i forgot to mention, one of the reasons i put this post out there was cuz it backfires sometimes, is this a timing issue?

Is it a HEI or points distributor ?
More of a carb problem than timing I would say.
A few things would help, plugs and a good set of plug wires.
I never had any luck with accell as they get shot very fast.
I have had better luck with mallory.
Is this a mechanical or vacuum carb ?
On the backfire I presume its thru the carb, that's caused by a lean spot. Plus not knowing if it has a choke on it, if not it will have to get on the warm side before you can drive it as the choke makes it more rich and stop's the backfire.
IM running two 650s on a cross ram intake and have to get to 100 degrees before I can drive it without the lean backfire.
I removed the choke housings on them, plus some other work.You can see them on my home page.
Instead of writing a very long guide on tuning a Holley type of carb here is their site, it has a free trouble shooters guide and manual that can be downloaded.
http://www.holley.com/HiOctn/TechSer...o/FMCTech.html
Berry Grant has a site also, but is the same carb type as Holley. To get started with put the screws at 3/4 turns out.
After you adjust the floats then you should use a vacuum gage to adjust the screws on the metering plates.
On the lower side where the throttle is, a screw for the idle.
This is all described on Holleys site.
After driving it for awhile it would be good to read the plugs so you can change the heat range if needed.
If you need any other info please give me a PM or respond to your posting.

Your correct Denny, I missed that one.
Only the newer type of needle seat assembly's will take up to 9 psi.
It should be put down to 6 psi. the carb still should be tuned in for the best drivability.

im really going to sound stupid, but i dont know the differance between points or hei.... also dont know anything about a carb, if its electric or manual, i guess it would be manual if theres no wires going to it? cuz mine ait got no wires, dont know if its ot a choke, or do any adjustments.... guess i dont even know enough to ask for help! i sure am learnin alot from all of you, ps how do i lower my fuel press. down to 6 psi? thanks again pros.

hey preciate the link on the carbs, am reading it right now.. he guys said he set the fuel pressure that high so i emagine i can just lower it down with the trun of a screw somewhere right?

69chevyman, for the st. you dont wont but 5- 6 lbs. of pressuer at the carb. driving down the road, so at WOT its gonna drop some, so get the right size lines on the car, strighter the fuel lines the better, and if it stays around 4 lbs. at WOT that will work fine. the least amount of fuel pressure (at idle that you can live with) the better off you are.

Originally posted by 69chevyman
im really going to sound stupid, but i dont know the differance between points or hei....

alrighty this is really simple to figure out, pull off the distributor cap... inside is there a diod of some sort, or is there a little metal part that looks kinda V shaped, with a piece that rubs against the cam on the base of the rotor... that will tell you a lot, as far as you know you might even have a dual point distributor

It's been my understanding that when the idle rpm is as high as your's is you are probably bypassing the carb idle fuel circuit.In other words any idle mixture screw adjustments made at that rpm would be ineffective.I would try to get the rpm below 1000 and or consult Barry Grant.Good luck!

thats interseting you say that because he said there was aproblem with the idle screw, but i can make it go up, but if i try to go lower than 1200 it will die... any ideas?

after fixing the fuel pressure problem, you might have to have the carb rebuilt, since you probably dont know much about fixing one... the high pressure could have caused many of problems inside the carb and because of one reason or another, its not able to give the proper amount of fuel or air to keep a low idle...

I notice two sizes of spring on that mechanical adv on the hei. Or are my eyes deceiving me?

hey appreciate the pics, i will go see what kind i got! so you think the carb may be the culprit on my idle prob. ok. i was thinking about ifi was worth it to get it rebuilt or just get a new one? also i will go see about the fuel regulator, since i got a guage inside, can i just get it idling, adjust it to like 5 or 6 and then rev it up to make sure it dont go above 6?then i can try to work the idle prob,
i will post my finding in a lttle bit! thanks again!

sounds like the right line of action, once you get that fuel pressure set right, see if your car will idle at lower RPMs, and check your timing, that can cause this as well.... once you have got both set right and it still wont idle right, then i'd say check the float level in the carb before you go out and have yours rebuilt, replaced... having a carb rebuilt will cost you probably $150 as a new carb will cost you somewhere between $350 and $900 depending on what you get.... i wouldn't suggest something in the $900 range though, thats a little too high bred for you, and you'd just run into problems tuning it and such