The car in question is a 1970 lesabre 455 2.73 rear end stock converter stock rebuild 30 over stock rebuilt 7040240 q jet only modifications are hei distributor from ta ta112 cam and some blind first attempt port and polish work on the heads runs pretty strong drove from Arkansas to Virginia and averaged 13 mpg with the car loaded down ok so to get to the point I've asked on here a few times about some pinging issues I've been having do to what the guys on here think is too high compression. After changing octanes and dialing back the timing to 24-28 total no pingingn but I feel like there is more power to be had thus in thinking maybe the stock jets are too lean for the cam and port work one of the guys told me the jet sizes it came with stock what do you guys think/recommend. Thanks ahead of time guys
Do you know what jets are in it? Originals had 67 jets and 41 rods according to my notes. You could go to 68 or 69's. if you are having idle issues with the 212 cam you will need to enlarge the idle tubes. I have new and used jets available, and idle tubes and all other parts on my website store.
I like 71 jets and 45 pri rods with that combo. Should allow you to restore timing to 28-30. Make sure you have 180 tstat......
Thanks guys and yeah the jets/rods etc. are all stock and it idles like a champ and has tons of vacuum. Drivability is not really the issue I just feel like there is a little more to be squeezed out of her. The pinging usually only occurs at highway speeds just mashing the gas and going around somebody and from a stop if you gun it it just loads up and sometimes depending upon how aggressively you slap it to the floor it will try to cut out. It'd be a lot easier to troubleshoot if I knew the stock distributors built in mechanical advance and vacuum advance and also the stock SF code cam lift duration and all that. If I did I could just set my new hei up exactly like the factory distro and then by comparing the cams I could see if my engine is really breathing better thus needs richer jetting or not.........or I could just by a wide band o2 sensor in just bein cheap lol what do you guys think. Oh and just to make sure it's the ta112 not the 212
As thanks as well BQuick all I'll probably order a kit that comes with jets in and around those sizes and see what works but as for the thermostat I've heard a lot of contradictory stuff about lower temp thermostats actually making the engine run cooler so idk.
No secret about the stock distributor mechanical advance, right there in the 1970 Buick Chassis manual. The stock 1970 455 distributor was part number 1111984. Initial timing was specified as 6* BTDC. Mechanical advance started at 1000-1200 RPM, at 1800 RPM, the mechanical advance was 19-23*, and 30-34* at 4600 RPM. Stock vacuum advance started at 6-8" of vacuum. At 16" of vacuum it was 14-18*. Now that the engine is no longer stock, I would not think that the stock distributor specs were the way to go. Look at the stock specs, a maximum of 30-34* of mechanical advance with initial advance of 6*. That means at WOT, your timing could potentially be 36-40* Certainly too much in my opinion. With a 2.73 gear, 60 MPH would probably be around 2100 RPM. With an initial timing of 6*, and mechanical advance of 19-23* and a vacuum advance of 14-18*, highway timing would be around 40-45*, about right for best fuel economy. So you have an HEI. Have you put a timing light on the engine and mapped the timing curve? If it is pinging, the first thing to do is look at the timing at various RPM. Easy to do. Try disconnecting the vacuum advance and see if the pinging on the highway stops. Have a look at my Power Timing thread, http://www.v8buick.com/showthread.php?63475-Power-Timing-your-Buick-V8
I think the idle tubes and idle channels are a couple of the best mods you can do to wake up a near stock qjet. of course slightly larger jets and rods help too.
