intermittent Miss at cruise rpm

[markm]

If you think you can get "high teens" on the highway (70-75 MPH) with a 454, dual 600 Holleys, tunnel ram, 3.54 rear (which OD ratio?), standard distributor, and the radical cam you talk about, I should be able to hit mid 20's with my 502, EFI, 410 rear, .50 overdrive, and relatively mild cam.

125 miles isn't enough distance to determine mileage very accurately. I'm not buying it.

Your pompous and arrogance is really showing through here. Please show ne where I stated that I had a radical cam and a 454 in my 55. I have always freely stated its a 1965 Impala 396 with a 425hp 427 solid cam. The only racial cam equipped 454 I own is in a Camaro and is not capable of a 125 mile road trip. The 8 gallon fuel cell would be empty before I got to the county line. Your final drive ratio is about the same as mine so why don't you quit pontificating and get to work and prove something.

[55 Rescue Dog]

It really doesn't matter whatever engine/gear/car/truck you have. 9 MPG or less is where the fun happens!!! Until you have to refuel, or repair/replace something.

[markm]

It really doesn't matter whatever engine/gear/car/truck you have. 9 MPG or less is where the fun happens!!! Until you have to refuel, or repair/replace something.

Actually that is about were I was at with a BW Super T10. Actually launches better with 5 speed due to lower 1st gear, No other changes so I kinda got the best o both worlds.

[chevynut]

Actually that is about were I was at with a BW Super T10.....No other changes so I kinda got the best o both worlds.

So you were at 9 MPG and made no other changes other than the TKO600? If that's the case your .64 overdrive got you to 14 MPG. That's more believable. Certainly not "high teens".

[chevynut]

Please show ne where I stated that I had a radical cam and a 454 in my 55. I have always freely stated its a 1965 Impala 396 with a 425hp 427 solid cam. The only racial cam equipped 454 I own is in a Camaro and is not capable of a 125 mile road trip. The 8 gallon fuel cell would be empty before I got to the county line. Your final drive ratio is about the same as mine so why don't you quit pontificating and get to work and prove something.

Well since you talk so much about your 454 and your big cam, one would assume it's in a tri5 since that's what this forum is about. I didn't know you had such a small big block in it . But nobody really knows what your car is because you have never posted any pics of it. In fact, you've never proven to anyone here that you even own one.

And since you're apparently a little math challenged, 0.5 isn't nearly "the same" as 0.64....it's a 28% difference. In other words, if I'm cruising at 75 MPH at 1800 RPM, you would be at 2304 RPM...that's quite a difference.

[markm]

You only hear what you want to hear. I have posted pictures and U-Tube links to ne a drags, since you are so smart find them. Most guys with running cars have a 4.10 with a 6 speed. Therefore I figure 3.54 x .68 about the same result.

[Eds56]

You can go too far on timing without having audible pinging, but with most small blocks it's pretty rare.

On initial timing, 16 may be a bit much. But if it's not pinging or kicking back against the starter when the engine is warm, it's probably OK. Your mechanical advance setup is pretty good (again provided there's no pinging).

When you install the vacuum advance distributor, don't change anything and monitor for pinging. I don't recall if the MSD distributor has adjustable vacuum advance or not? May want to limit how much.

I installed the MSD 8361 dist. this weekend, as listed below, i do NOT think this vacuum can is adjustable. Now have more questions--
I set the total timing @ 34/35 & all in by 3k rpm. initial 16 degree + 18 mech. (using the same spring / bushing combo) with vacuum hose disconnected and plugged. Then hooked up vacuum line to manifold vacuum. I then had to back DOWN my curb idle. Rechecked @ idle with vacuum connected and the timing is now at 36. I increased the RPM's to 3k+ and it seems to max out around 52 degrees. Does this sound correct?
I still do NOT hear any pinging, rattling, etc... I only drove it 4 or 5 miles, but it still started right back up, without any starter drag. Had plenty of power & Actually seemed to run a bit cooler. Before this, at idle my temp would always creep up a tad above stat level when just sitting at idle.....But it didn't yesterday and it was mid 90's outside like usual.

I hope to put a few more miles on her this weekend to better judge the results. It just doesn't seem right to see that much advance. I'm sure there is a big difference between 3 or 4k RPM in neutral VS. under load. I suspect that under load that number will drop.

[Rick_L]

It all sounds good, normal, and what's expected. The cooler running is something that wasn't discussed that I recall, but it's also expected.

[markm]

Sounds like you won all the way around.

[55 Rescue Dog]

Seems like a lot of advance at idle with that much initial advance. With that much initial, you could see how it runs with ported vacuum. Or, put in the
25 degree bushing and back the initial down to 11,or so, which would give you 36 total, and idle vacuum timing would drop 7 degrees too. Just need to experiment a little, to see if you can improve it, one thing at a time. It would also be good to adjust your idle mixture screws too. Or, if it runs the way you want, don't mess with it.