I have a 69 with 350, Edelbrock Perormer intake and Rochester Quadrajet carb and HEI distributor. When I remove the vacuum line going to distributor and plug it,set timing (12 deg) .When I reconnect vacuum line timing remains the same.The vacuum line is connected to the port that is front pass side of carb. Other is another vacuum port on right side of carb and when I put vac gauge on it it slowly builds vac at idle. There is a third port in middle of carb higher up that has vacuum at idle.I connected distributor to this port and at idle vac advanced to approx 30 set. What port should i be connected to. Thanks
It was originally suppose to be connect to the ported vacuum source which has no vacuum when the throttle blades are closed. The vacuum single will begin when the throttle blades begin to open. Sitting the timing, you want to disconnect the advance vacuum line in case the idle is higher causing the the timing to advance.
Some people choose to use a manifold vacuum source. That is the port that has vacuum single all the time at idle and when throttle blades are open. Used mostly on none stock engines. That will give you more advance at idle, often helping the idle quality and aid in a little higher idle speed and enhanced cooling at idle.
I have dual Edelbrock's, so my tranny line vac is hooked to my rear carb.. But, front one looks like this.. Middle hose is always off when I set timing. (Note to all who have helped on this before--Yes, the Harmonic Balancer was worn out, new one is on!)
Last edited by Lit3; 07/26/1611:34 AM.
1957 Thunderbird 289 1967 Firebird Base 461 1968 C-20 327
I have dual Edelbrock's, so my tranny line vac is hooked to my rear carb.. But, front one looks like this.. Middle hose is always off when I set timing. (Note to all who have helped on this before--Yes, the Harmonic Balancer was worn out, new one is on!)
Why would you remove your PVC hose when you set your timing? Only your vac hose to your vac advance on dizzy needs to be off and plugged when setting timing.
Turns out that my intake is an Edelbrock Performer RPM. I have heard that the original cast iron Pontiac intake is better. Anyone with any knowledge of this please let me know
Here's what I've heard over the years. The performer is essentially the same as the stock 4 bbl but much lighter. The RPM is better performing but less street manners. Take that with a grain of salt.
I have dual Edelbrock's, so my tranny line vac is hooked to my rear carb.. But, front one looks like this.. Middle hose is always off when I set timing. (Note to all who have helped on this before--Yes, the Harmonic Balancer was worn out, new one is on!)
Why would you remove your PVC hose when you set your timing? Only your vac hose to your vac advance on dizzy needs to be off and plugged when setting timing.
Correct, disconnect and plug distributor vacuum line for intial timing. Leave pcv operating.
From experience with many cyl hd/cams/intake combo's over the yrs, the RPM is to large for stock heads other then the RAIV/SD 455 port size with RAIV and larger size cams. Its lazy under 2500 rpm and doesnt make much more power till about 4500/5000 rpm depending on combo.
The Performer is much lighter, but the upper runners are alttle different shape and lenght which loses some power in the upper rpm vs a stock intake. Been over 20 yrs since used one so dont remember rpm range vs stock intake. Probly not much.
Thanks for the help. I had heard from others that the RPM intake was not ideally suited for the 350. I previous owner believed that it was an HO car as it had a period correct 4bbl carburetor and intake. I believe these were probably installed by the dealer in 69 at buyers request. My understanding is that only HO cars were built with 4bbl carbs so when people look under hood and see a 4bbl and factory intake they assume HO and do not confirm block code or head numbers. I have yet to decide if I will go back to original cast iron intake which I have or purchase a Performer intake.