General Category > Quadrajet Carb Talk and Tips
help with 17082224
Cliff Ruggles:
It was one of my first experiences with high compression on pump gas and that engine ran flawlessly for well over 100,000 miles before I sold the vehicle.
I did a second high compression pump gas engine shortly after, to power my 1967 Impala SS. It was the original 327 using flat top pistons .015" in the holes at TDC, .020" steel shim head gaskets, 350/300hp cam and the stock 291 casting 327 heads. Just like the previous 406 build it ended up at zero degrees initial timing, short timing curve and 10 degrees from the VA (ported source).
I backed the little 327 with a 4L60 overdrive trans and 3.31 rear gears. It also made enough power to ROAST the rear tires right off the rims, idled dead smooth with 18" vacuum, and excellent street manners. It also delivered 18mpg's city and mid 20's highway.
So come on here and tell me that these engine MUST have all this advance in them, and that you need to run the timing clear off the scale at idle speed, bring ALL the mechanical advance in by 1500rpm's, and put another 20-30 degrees timing in from the VA via manifold vacuum and it's absolutely got to be that way or you are missing out on something someplace......I'm all ears folks....
Cliff Ruggles:
Before I forget I'll add in here that both of the engines mentioned above, the 406 and 327 never even thought about running hot, overheating or pinging anyplace, and managed currently available pump fuel w/o any issues anyplace. So there is a lot to be said for tight quench, high compression, well chosen camshafts and turning the heat produced into making power vs putting a butt-load of quench and a lot of overlap into the equation, then dumping all the heat into the cooling system.....FWIW.....
bruno:
that’s why i wanted to hear!! thanks very much cliff. you have been an amazing help with getting this car running. i will leave the timing where is for now, and see how it goes down the road. just waiting for tires to show up.
I wish i had the time to obtain all your experience, but sadly, very few people around here are into cars, let alone race them. most don’t even run carbs anymore. i love working on them, just don’t have enough experience. but i have learned a ton from you and your book. and even just reading your responses to other questions has answered questions i didn’t even know i had. !!
Cliff Ruggles:
Thanks.
One thing is for certain there are a LOT of opinions when it comes to tuning, much like anything else. I really don't have an "opinion", just facts based on decades of actually doing this for living, running the gauntlet, winning some battles, loosing others and improving my knowledge and skill sets the entire time.
I was actually asked to write another book a few years ago on custom tuning these engines, but sadly I had to decline. Just don't have enough time or energy for it.......
Jeff K:
Back in the early seventies, I picked up a 64 Pontiac Grand Prix. It had a factory 421 4 bbl (real Carter AFB) with a Roto Hydromatic (Slim Jim).
The Slim Jim transmission had no stator / torque converter. L was a vertiable ratio 3.03:1 range. Then when it shifted into S (1.58 ratio), it would couple hard with allmost zero slippage. D range was 1:1 and also coupled hard with all most zero slippage.
The transmission worked well when it felt like it, looking back I think it was tempature sensitive. One time I stayed side by side with a brand new Kawasaki Crazy KZ motor cycle. Don't get my wrong, he beat me but he couldn't loose me..
The only car I can remember from the sixties, that used Ported Spark advance, was was Roto Hydramatic (Slim Jim) equiped 61 to 64 B body Pontiacs with the Trophy Series 389 and 421 engines. If you look at the front, bottom, left corner of the Carter AFB equiped Trophy motors, they had a vacuum outlet for the vacuum advance.
I don't remember if the Tri Power versions came with this feature.
I know the 1958 to 64, four speed Super Hydramatic equiped Bonnevilles and Star Chiefs came with regular manifold vacuum advances. Note that the 4 speed Super Hydramatic transmissions were light years stronger and better performers than the Roto Hydramatics...
Navigation
[0] Message Index
[*] Previous page
Go to full version