[Stuckinda60s]

Originally Posted by guccieng

both my chebby and poncho give exactly the same amount of vacuum from ported and full manifold. that's with an edelbrock afb clone, a holley street avenger, holley hp street, and a cliff's q-jet. absolutely no difference in vacuum after the throttle is touched.

And you know that how? Do you have a vacuum gauge hooked up to both when you're driving? It can't be exactly the same. Virtually or essentially the same, okay. The throttle blades act as a restriction and cause the pressure to remain higher above them. It's the same thing as a water hose and a spigot. And, there's bound to be a difference in how quickly the vacuum in both areas responds to the throttle being opened.

I don't believe there's anyone out there who hasn't seen a difference in some vehicle when one method is chosen over another, so how do you explain that happening? That's why you try it both ways. Every package is different and no one method is going to be the best in all situations.

I used to tune emissions era engines for friends to make them more drivable and help their mileage, and all of those stock engines worked better when using manifold.

I was not saying that Jake should have used fmv, I was only asking if he had tried it after advancing them cam.

[guccieng]

Originally Posted by Stuckinda60s

And you know that how? Do you have a vacuum gauge hooked up to both when you're driving? It can't be exactly the same. Virtually or essentially the same, okay.

well that's just splitting hairs. whats 1 mile minus 1 inch? the answer is 1 mile (significant digits). on an analog gauge that only reads inches of hg, what's 21 inches minus the tiny restriction caused by the throttle plates? the answer is 21 in/hg. the vac can cannot tell the difference and will act the same is my point.

[Stuckinda60s]

Originally Posted by guccieng

well that's just splitting hairs. whats 1 mile minus 1 inch? the answer is 1 mile (significant digits). on an analog gauge that only reads inches of hg, what's 21 inches minus the tiny restriction caused by the throttle plates? the answer is 21 in/hg. the vac can cannot tell the difference and will act the same is my point.

It may be splitting hairs, but please explain the difference in performance often seen when going from one method to another. Response time of the timing and vacuum is certainly a factor.

[guccieng]

Originally Posted by Stuckinda60s

It may be splitting hairs, but please explain the difference in performance often seen when going from one method to another. Response time of the timing and vacuum is certainly a factor.

as i mentioned earlier, many things could be wrong: a restriction in the line or carb that is slowing flow, a slow moving vac advance mechanism (could be dirty or sticky) or a bad vac can. a properly working vac advance system should see no difference in response time; it's almost instant.

[Stuckinda60s]

Originally Posted by guccieng

as i mentioned earlier, many things could be wrong: a restriction in the line or carb that is slowing flow, a slow moving vac advance mechanism (could be dirty or sticky) or a bad vac can. a properly working vac advance system should see no difference in response time; it's almost instant.

So, explain to me how changing from manifold to ported would make a difference if there was a problem in any of those areas. Also, do you really think there was a problem in each of the cars where a difference was noted?

[guccieng]

Originally Posted by Stuckinda60s

So, explain to me how changing from manifold to ported would make a difference if there was a problem in any of those areas. Also, do you really think there was a problem in each of the cars where a difference was noted?

it would make a difference if the flow of air from the carb to the vac can was slow. the time required to move a vac can with a problem would already have it in postion with the fmv. the problem would only present itself if you noticed it with ported. and yes, there's very likely a problem if there's a difference noted. if the distributer is dirty or rusty under the cap, the advance mechanism could be 'lazy' to return as well, and that would have nothing to do with the vacuum source.

bottom line: if your vac can doesn't move right away, something is wrong and running fmv to try to cover it up is silly, imho.

[jakeshoe]

My experience with FMV vs. ported has been that USUALLY I've been working with an HEI that came from a smogger car.
Those things have too much mechanical advance built into the curve.

Somewhere between 20-24* usually.

That was so they could use ported vacuum, have slow timing 0-8* initial, and still have 30-34'ish at WOT.
The slow timing at idle was purely to clean up HC emissions at idle, and it does work for this.

However it KILLS throttle response. So the ported would bring on some timing when the throttle was cracked open to get some acceleration.

You can use FMV to get more instant throttle response in this scenario. Lighter mech advance springs as well.

The REAL fix is usually to limit the mechanical advance so you have 20*+ at idle, and ~36* total or whatever the engine likes. The you use vacuum advance purely for part throttle cruise to improve mileage and driveability.

Somebody did this distributor correctly. It is also a points type dizzy converted to electronic, so it may not have had that much mechanical built into it.

I've used FMV in many cases and USUALLY it does work better. On this car, it brought in too much timing at idle before we retimed the cam, however after we got the cam in correctly it seemed less sensitive to timing over 20* at idle.

[gtome]

Originally Posted by guccieng

it would make a difference if the flow of air from the carb to the vac can was slow. the time required to move a vac can with a problem would already have it in postion with the fmv. the problem would only present itself if you noticed it with ported. and yes, there's very likely a problem if there's a difference noted. if the distributer is dirty or rusty under the cap, the advance mechanism could be 'lazy' to return as well, and that would have nothing to do with the vacuum source.

bottom line: if your vac can doesn't move right away, something is wrong and running fmv to try to cover it up is silly, imho.

This may all be a posibility?? All i can say is with my set up.
With my old HEI dist, changing from manifold to ported vac made absolutely no difference anywhere....even at idle. Put I knew it was problematic.
So I bought a new dist (HEI...thanks PDude!) and the ported vs man vac makes a big difference.
On the new dist, I put a hose to the vac can and sucked on it and I could hear it pull and snap back without a whole lot of effort. That is the extent of my testing.

I guess what i am saying is that I am making 14 hg of vac, on a brand new dist and can, and I do see a slight hesitation, with ported advance, before the advance comes in (but I dont know that it is vac advace...could be mechanical is coming in??). With manifold vac, it is very smooth and no noticeable transition. Is there a problem here??? Doesnt seem to be...but i couldnt say for sure.

By the way I am making 16* at idle with 36* in by 3000 rpm

[guccieng]

Originally Posted by gtome

This may all be a posibility?? All i can say is with my set up.
With my old HEI dist, changing from manifold to ported vac made absolutely no difference anywhere....even at idle. Put I knew it was problematic.
So I bought a new dist (HEI...thanks PDude!) and the ported vs man vac makes a big difference.
On the new dist, I put a hose to the vac can and sucked on it and I could hear it pull and snap back without a whole lot of effort. That is the extent of my testing.

I guess what i am saying is that I am making 14 hg of vac, on a brand new dist and can, and I do see a slight hesitation, with ported advance, before the advance comes in (but I dont know that it is vac advace...could be mechanical is coming in??). With manifold vac, it is very smooth and no noticeable transition. Is there a problem here??? Doesnt seem to be...but i couldnt say for sure.

By the way I am making 16* at idle with 36* in by 3000 rpm

i would check for ease of movement of the vac advance with the cap off. if it pulls and releases easily, then it's good. also, if you have a can that pull alot of advance, it may take a little longer to get there, but not enough to notice. another thing to think about; vac advance is good for lean conditions. if you see a difference coming on the throttle between ported to manifold (after the can has checked good), you may just need more accelerator pump shot. so, a performance difference in manifold and ported may be an indicator of a needed carb adjustment. just another possibility. but i still believe covering up a vac can/pump shot problem by having to use fmv is not right. once everything is correct, then choose what works best. i'm not a 'only ported' guy, either. i run one of each!

[Stuckinda60s]

"There could be a problem...It would make a difference if"... There's nothing concrete here, it's all speculation. Jake's right on the money. As I said, before, fmv is a band-aid, just the same as throwing more fuel in at idle.

A quick story. A buddy of mine had a '69 Le Mans, 250" Chevy six/powerglide. I recurved the distributor, changed it from ported to manifold and played with the carb a little. He was tickled with it, the power improved and he picked up over 2 mpg. The really impressive thing was the time he nailed it from an idle and almost ran over another friend. The tires broke loose and the car leapt off the line! He hadn't expected that and just missed his friend. He ran in the house, all excited, to call me and tell me about it.

There were 3 vehicles I played with that didn't pick up mileage, although they did run better. One was a 400 Chrysler, one a 360 Ford pickup (although a 351 pickup did improve) and one a 400 Ford wagon.

[gtome]

Originally Posted by guccieng

i would check for ease of movement of the vac advance with the cap off. if it pulls and releases easily, then it's good. also, if you have a can that pull alot of advance, it may take a little longer to get there, but not enough to notice. another thing to think about; vac advance is good for lean conditions. if you see a difference coming on the throttle between ported to manifold (after the can has checked good), you may just need more accelerator pump shot. so, a performance difference in manifold and ported may be an indicator of a needed carb adjustment. just another possibility. but i still believe covering up a vac can/pump shot problem by having to use fmv is not right. once everything is correct, then choose what works best. i'm not a 'only ported' guy, either. i run one of each!

I know the can is working well, and I just went from a #31 pump shot to #35 nozzle on my Holley 3310. I cant imagine that it could need more than that. Maybe I will play with the pump cams a little a see what it does.
The car is really running well how it is.... but I just want to do it to see how it affects things.

[Kyflier]

Well Jake, how does it run now? Any improvement with degreeing the cam?

[madtexan]

Originally Posted by Kyflier

Well Jake, how does it run now? Any improvement with degreeing the cam?

Jake did post a few updates about how it ran so far.

Originally Posted by jakeshoe

I was a bit disappointed today because it didn't seem to want to break the tires loose like it did on my last test drive. It does run much better IMO but it should be more responsive off idle IMO.

We learned it is very sensitive to timing and not what you typically expect. You could advance it some and it seemed to lose bottom end but still not have any detonation issues.

I'm really starting to think a converter swap might be the best thing to wake it up. A quality ~2500'ish converter.
It is just soft from a standing start. Once it pulls in the secondaries, it seems to run like it should. Fairly strong on the secondaries and I would guess it is shifting near or at 5000 rpm WOT.

I degreed the cam on the recommended 106 ICL. It has 4* adv ground into it, so the timing set is "straight up" or dot-dot but the cam is at the recommended ICL.

Originally Posted by jakeshoe

I'll have to check the idle vacuum. I haven't put the vacuum gauge back on the car. I think we achieved our goal. I'll have to install it though because I'm curious now that you mention it.

The valve adjustment would also have effected the vacuum.

I think the combined effect of several factors was the reason it felt so weak.
The air valve felt "OK" if you tipped them open, but I felt they were a bit tighter than I usually set them up. However I haven't really been doing a bunch of Q-jet tuning since I was playing with the one on my Chevelle a few years back.

The valve adjustment made the engine sound as if it was a solid roller. We lashed them down to 1/2 turn past no lash. It's still noisy (roller rockers always are IMO) but better.
Maybe it was losing some effective duration?

I could spend another full day just tweaking small things, but Tony has mentioned wanting to possibly change intakes and other combo changes, so there is no reason for me to spend his money perfecting the tune on this setup.

I notice a slight "burble" in the part throttle steady rpm cruise that I would want to work on.

I do feel like there is better throttle response at cruise rpm, when you slightly accelerate.

I'l let Tony drive it and get his thoughts, I have pretty limited drive time behind the wheel so he'll be more likely to notice the minor things.

I think we got it all sorted out.

It seems to have been a combination of things. It will definitely break the tires loose now, seems to pull well going down the road.

The issues we found and addressed:
Cam timing 3* retarded, set for straight up.
Valve adjustment sounded loose, re-adjusted valves.
Air valve on carb was too stiff. We took some tension out and that really seemed to help the off the line response after all the other changes.
Modified trans governor for higher RPM WOT shifts.


It feels like a different car now. I think Tony will like it

I agree,
some gears and free flowing exhaust would make a profound improvement again.

[tr709]

Update!

Monday I had Jake install the long branch manifolds wifey got me for christmas and today a new 2 1/2 exhaust with dynamax super turbos was installed (thanks you Tom Hand for your research!)

She is really pulling harder, we are headed in the right direction

[1967Tempest]

Originally Posted by tr709

Update!

Monday I had Jake install the long branch manifolds wifey got me for christmas and today a new 2 1/2 exhaust with dynamax super turbos was installed (thanks you Tom Hand for your research!)

She is really pulling harder, we are headed in the right direction

How is the direction now??? Updates??

[jakeshoe]

Originally Posted by 1967Tempest

How is the direction now??? Updates??

I don't think Tony gets on everyday.

I know we installed a helper fuel pump awhile back. He felt that since the mods the car runs better but seemed to fall off in the upper rpms before the 2-3 shift.
Sounded like a classic case of fuel starvation.

I haven't gotten any feedback on whether that improved it or not.

[tr709]

Hey all!

Jake the helper pump did solve the problem. Car is still a little soft off the line, which I think is converter related. After that it pulls real hard, last time out at WOT right before the 1-2 shift the tires broke loose and that got my attention I think there still more potential to be had and I think the performer manifold may be choking things a bit. I bartered for a factory 68 intake that I may send to SD for the CNC Cliff's port special. But there hasn't been much talk/reviews of it on the forum, so I'm not sure. Other than that and the converter, I'm hesitant to make any other major changes as I don't want to mess things up, the car is an awesome cruiser and a blast to drive on the backroads with the top down.

[Cliff R]

"Combo
72 400 block w/428 rotating assembly from PPR
D-port 96 heads rebuilt and ported by butler
comp cams hyd roller XE276HR (yes the same cam that has been the subject of much discussion here) - 276 I - 282 E 224 I - 230 E .502 I - .510 E
q-jet - rebuilt by Cliff
performer intake"


We back to back tested the prototype ported iron intake on a 428 engine. We used a 1967 428 block, stock Arma Steel crank, Oliver rods and Ross pistons. The engine was topped with unported KRE aluminum "D" port heads with 74cc chambers. We used a custom ground HR cam from Comp Cams, 236/242/110.

Aside from a tad more compression and a bit more camshaft, the combo's aren't that far off each other. Our KRE heads were stock, not ported. We did clean up the runners a bit and the seats down into the bowls, and port match them exactly to a stock Felpro blue intake gasket.

We tested three intakes back to back with the following results:

Ported HO aluminum intake (reproduction), 487HP
Stock Edelbrock RPM (port matched), 491HP
Ported factory iron intake, 497HP

I ran that same intake to mid-11's in my old 455 engine. My new engine is using a 1971 HO intake ported to the same specifications, as the iron intake didn't have quite enough material for a good port match to the larger runners in the new 290cfm KRE heads from SD Performance.

I only dyno tested a Performer intake once, and it was down some on power for the combination of parts. I attempted to street/strip test the same Performer intake, but my engine ran poorly with it in place, and we decided not to continue the testing.......Cliff