Ctfuzzy,

That is 'cut and paste' from the Edelbrock website.

 

I do most of my playing at 6000 feet not 600. maybe it is a typo but at higher alt's I need to go leaner right. So if i stay with stock primary and go to a leaner secondary I should see the difference. I read the edlebrock web too thanks. I have to ask the shop if they used a factory timing set. Thanks for all the help guys

 

Sorry that should be:

For 6000 feet you should have in the primary:

24 1427 (.098) 1456 (073 x 047) Rod

The secondaries should be:

JET #1425(.092)

 

I own a fith wheel camper and when I'm pulling it over the passes is when I notice it the most. Thanks again for the help

 

You don't know how to check the timing set without takeing it apart do you

 

Gentlemen,

pardon me for interrupting again, but I think we may be overlooking some basic math here.

If the recommended maximum material removal from the deck surface of the heads is .025 and you cut .040 off of it, and it does not stick a valve into a piston (or vise versa), what is the next most likely problem?

? The intake not sealing well to the heads because it is being held off of them by the front and rear cylinder block contact ?

? Unless the intake to head bolts are WELL below the centerline of the actual intake ports, would this not tend to allow the top edges of the intake to seal "ok" as the intake flexes but the bottom edges of the ports to *very potentially* not seal well, thus causing it to suck in crankcase vapor?

. . .just thinking out loud. Nothing more.

 

The easiest way to check if you have a zero degree timing set is to ask the people who installed it.

 

ordy,

danlee is using specs for a 1405, which is not tuned the same as a 1406. For your altitude, use #7 on the Edelbrock chart http://www.edelbrock.com/automotive/eps_1406.html I would also check the initial and total timing. Usually when towing, the timing needs to be retarded to prevent detonation. I would leave everything as-is and take the truck to a reputable smog/repair shop and let them adjust the carb to max efficiency and timing to specs. If this doesn't correct the problem, contact Edelbrock Tech Support http://edelbrock.com/tech/index.html .

Where is the vacuum advance connected on the carb...ported or full? Is the PCV connected to the carb? Is the tranny auto or manual? It may be prudent to check vacuum to the tranny. Also check the plug wires.

Good luck,

Chris

 

I want to be on the sidelines watching when that happens. That would be entertaining. Saskatoon is colder than a witch's tit in February.

I'm stuck on the idea that there's a vacuum leak somewhere and that's what's throwing the carb off. Maybe you should measure the manifold pressure at idle, that might reveal something.

I've found two leaking power brake boosters on vehicles that I've owned. Fixing them changed the whole personality of their engines.

WRT checking valve timing, the tricky part would be finding TDC. I bet you could thread a rod through the spark plug hole that would contact the top of the piston. Rotate the engine one way until the piston contacts this patented spark-plug-hole-piston-stop device. Mark that position on the damper. Rotate the engine the other way and repeat the process. Split the difference. Vwah lah! - TDC. Make a nice mark on the damper that shows where TDC actually is. This is necessary because we're trying to be as accurate as we can be; we're trying to measure a difference of 4 degrees.

Now you'll have to measure the cam lobe off the top of the hydraulic lifter. You'd have to remove the number one intake rocker and assume that the internal spring in the lifter is holding the lifter in its fully extended position. I've heard that this can be unreliable but I don't see why you can't get a pretty good idea of whether or not the cam is retarded 4 degrees.

Of course, it might just be easier to try a 4 degree advanced timing gear and see if that helps. It's brute force but there's something to be said for emperical data. Considering that you live and tow at higher altitudes, the advanced cam might make sense anyway.

On the subject of the distributor and a removed EGR valve. It occurs to me that the way to recurve a distributor when the EGR is gone is to modify the vacuum advance part of the distributor only. The mechanical advance shouldn't have to be modified. That means you have to change the vacuum advance pot thingie and the little plate with the slot that connects to the vacuum advance rod. On some distributors that plate is the points plate. Or you could weld the slot in the plate to shorten it. Or jam a screw in it. The screw idea has the advantage of being something you could tune, move it back and forth it until the part throttle knock goes away.

The later 400 vacuum advance pots will have a lot of advance to compensate for the slower buring air/fuel mixture when exhaust gas is in the mix. The earlier 400 vacuum advance pot would have less movement. Get parts from a 1970-71 400 or 351C. I'll bet that's all you'd need to do. If you did that, you could set the timing to 10 or 12 degrees and recover a lot of lost power and economy. As a temporary crutch you could really limit the vacuum advance, cut the length of the slot in half for example, and then set the initial timing to 12 degrees. This would work with the existing advance pot.

 

[QUOTE]Originally posted by pcmenten
I want to be on the sidelines watching when that happens. That would be entertaining. Saskatoon is colder than a witch's tit in February.[quote]

It is my opinion this is the last direction the Yankees will expect us from. As strange as it may sound, it was a . .

Saskatoonite (giggle),

that though of it; Waxy. Well, it was he that informed me of the change in plans anyway. I thought it was going to be Long Island.

Sucking crankcase gas would *certainly* constitute a vacuum leak !!

I think you just found the way to prove, or disprove, the theory pretty conclusively, too.