Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Dreaded nozzle drip 17056200

<< < (6/7) > >>

68rs/ss:
Just to clarify, I did not touch the divider. The two cross overs cut out between the two sides are factory.
So, I guess I would be wise to use a four hole gasket with stainless shield that I had got from u when I got my kit.
This thing is not going to cause me any problems I hope.
Phil

Cliff Ruggles:
You must use the factory gasket arrangement to effectively seal off the "hot slot" in the front of the intake.   If the holes are left open on each end of the "channel" then there will also be hot exhaust gasses traveling across under the carb to heat things up for improved thermal efficiency (allows a leaner mixture to be burned as it's heated a bit).

Good idea in theory but it can be problematic in actual use so many engine builders and owners of vehicles with engines using those intake block them off. 

You'd be AMAZED at how many early Chevy carburetors are sent here with a carbon track across the bottom of them clearing showing that the wrong gaskets were being used and there was a HUGE vacuum/EGR leak into the engine. 

Anyhow, the gasket goes down against the intake and the stainless steel shim gasket directly against the carburetor.  No other gaskets are used or needed with that set-up.......

old cars:
"50 cent piece" This is like a history lesson . Have not seen a 50 cent coin here in Canada for years. Don't even remember the size of it. Anyways I googled 50 cent US coin (1.2" diameter ) so half of that is .6 inch ( moderate ) . I should have specified a dimension.
Looking at the picture of his intake wouldn't it be better to drill/tap/plug the channel , unless you live in a cool/cold climate driving.

Cliff Ruggles:
There are still thousands of early GM engines in use out there that use additional passages in the intake to heat the bottom of the carburetor.  Once in a while we'll get a complaint or tech call to the shop from someone having fuel percolation issues that they believe is being caused directly by too much heat to the carb from that system.

Many times we actually find out that they have other issues instead, but we still do get some legitimate complaints from folks who have those set-ups.  It is ALWAYS in the hottest summer months, never in cool/cold weather.

I don't leave it open here on most builds we've done simply because of the way these cars are used these days.  Most only see use in summer months and it's usually pretty hot out as well.  I've never seen any negatives anyplace from blocking off the holes as the intake eventually gets pretty hot anyhow and transfers a good bit of heat to the carburetor unless the later type thicker gaskets or spacers of some sort are used........

68rs/ss:
Just a update on my carb and new engine build. Engine dyno today. Engine fired right up and performed very well. Carb was very close with modification recommendations by Cliff. A/F ratio was good on primary side and secondary side needed a little richer rod. I had turned down some extra DR rods by by .010 and .020 in case. Used the .010 one in the end. Timing was 34 total with 10 initial. Idle speed at 750. Did find a couple small issues. After full throttle pull, idle went rich. After some investigations, we found secondary side was hanging open a little. Throttle shafts worn, so will be bushing this side as well. I didn't think the secondary side was a issue as for as worn shafts/bushing. Most play was up and down and not front to back. Will watch for this in future.
Top cover leaking, so will need to check float and gasket.
I expect some of my initial issues when I had first posted were poor ignition wires and old distributor. Half dead battery didn't help much either.
440HP and 451tq in my little 396. Happy with this. I expect I may need to do some fine tuning when it is the car.
Will be calling shop soon to get required parts.
Thanks Cliff for your assistance in all this.

Navigation

[0] Message Index

[#] Next page

[*] Previous page