81 Vette performance

[81vettelover]

Anyone ever run accross this? Installed Edelbrock RPM intake, 650 Edelbrock carb and new distributor. Seems like I lost the burst when I kick it down. The factory parts would set you back in the seat and these are kind of dogish. Anyone know or had this happen to them? Is the carb big enough? Any help would be great. Thanks Randy

 

[wishuwerehere82]

Oh yes,

A long time ago, I installed a Holley street dominator manifold and 650 double pumper on my Pontiac 350.
I was looking for some HP increase with a new street cam in it. It didn't have nearly the perfomance of the stock manifold and carb.
Proper jetting is the probably the answer, but I never found it. I decided to trade in the car a little while later. So I put the stock manifold back on an sold the performance stuff to a freind. The car ran so good on the way to the dealer to trade it in, I wondered what I had done wrong.
Trading it in was probably the first thing. Not re-jetting the Holley 650 to get the proper fuel/air mixture was was probably the worst mistake I ever made.

 

[MoeJr]

Most likely your lack of low end grunt is caused by that RPM manifold. You would be better served with the stock one or a plain Performer intake.

 

[Bob Chadwick]

Check out the advance curve on your distributor as well. If the old one had been recurved to bring the advance in earlier and this one is set up with the stock advance you'll see a difference there as well.

MoeJr makes a good observation on that RPM manifold as well. It makes its power higher up than the stock or performer manifold.

 

[81vettelover]

Hey thanks, I wondered when I put that on what it was going to do (not much) The main reason I did it was it ran real rich with the stock Q jet. It was there first year with that. What do you think about going back to the stock manifold and running a 650 Edelbrock. Someone mentioned about the distributor maybe not set at the right curve. How important is that going to be? It should still kick the 4 barrells in hard shouldnt it??? Thanks a lot for your input Randy

 

[MoeJr]

Definitely go back to the stock intake. Also what distirbutor did you buy for the car. Does it have a vacuum advance? The 600 Edelbrock will be plenty of carb for you though I personally like the QJet. We'll get ya back to running the way ya want.

 

[81vettelover]

Definitely go back to the stock intake. Also what distirbutor did you buy for the car. Does it have a vacuum advance? The 600 Edelbrock will be plenty of carb for you though I personally like the QJet. We'll get ya back to running the way ya want.

Not sure what distributor I bought I will have to look, Got it off e bay. Yes it is vacuum

 

[81vettelover]

Its called a procomp distributor.

 

[AKRAY4PLAY]

Randy,

are you lacking power in the mid-rpm band?? by not setting you back, are you cruising down the road and go full throttle and the tranny down shifts, rpm go up to 3500ish and you have no power?? if this is the case, your intake is fine. the carb would be my focus. you need to remember that you pulled a spread-bore carb off and replaced it with a square-bore. these two carbs behave at two different ends of the spectrum. a square-bore it good for drag racing and some situations that require smooth linear throttle responce. spread-bores are more "slap you in the face" when the secondaries are opened. your stock Q-jet is rated for around 800 cfm, quite a bit more than the Edel. your motor will only take around 550 cfm to operate unles you have other mods. the size of the carb is alright for what you are running, but i would bet the mid range and top end jetting are lean. set your distributor to be full advance by 2500-2800 rpm. these are easy and quick changes to try before pulling the intake. Brian

 

[81vettelover]

Man Im glad they have something like this, you guys are right on with it. This is how it all started. When the car was all stock and I was at idle it was really running rich. So I was told that I should do away with the computer controled carb. Besides running rich it would set you back in the seat when you came down on it. So here is what has been done and how it runs now. Edel. carb 600, edel performer rpm intake, procomp distributor. Now when I bought the carb the guy mentioned the springs had been changed to lean it out??? One step Im thinking.
Now for the real help I will take the intake off go back to stock. Can I replace the stock carb with a non computer Q jet? And this distributor I dont know anything about it but all I can see is that it has a electronic senor for the spark.
Thanks you guys so much, maybe after all this I will get my vette back.

 

[AKRAY4PLAY]

Randy,
you can put any carb on that you want, i would recommend that you go with an electric choke Q-jet without the computer control. it is a very common practice to run an older style carb. try getting one for a '78 Chevy pick-up. it seems every time you go to the parts store for some thing and tell them it is for a Vette, bam, instant 100% mark-up in price. any Q-jet or even the new Edelbrock Q-jet copy will work fine. or you can go with a tuning kit for the Edelbrock you already have. Edels are very easy to tune, try running the orange springs if you go that route. the tuning manual that comes with the kit is great for those who need a little extra help in understanding the carb. but the spread bore design carbs give you more "hit" you are looking for. it is up to you, we can help either way you want to go. tuning the idle circuit is real easy once the motor is warm. every carb will need to be set-up for every individual motor for best results.

your distributor sounds like it is an HEI style. stock motors don't really benefit from high dollar race distributors, so you can probably keep the one you have. Moroso (and others) make advance kits for HEI distributors, usually around $20. they will come with new weights and several springs. the springs change the rpm range that the mechanical advance comes in at. the lighter the spring, the low rpm the advance comes in at. shoot for 2500-2800 for full advance. other than that, you should be sitting pretty. keep us posted on the progress. Brian