[Rbtama101]

Howdy all. I'm having some issues with my 302 in my '67 coupe.

Here's the low down - '74 302 block .40 over; dished pistons (not sure how deep) Comp Cam 280 (.230@50) .512 lift; Comp Cam full roller 1.6; Trick Flow heads; Eldelbrock Torker II; Holley 600 4160 vac. sec.; .31 squirter; 6.5 PV; Blue pump cam on #2; 69 jets; pump lever adjusted; secondaries are working and adjusted with stock spring; vacuum at idle is 11-12 and 15-16 at cruise; MSD 6AL; MSD Distributor all mech. adv.; red stop bushing with 2 heavy springs; '68 4 speed; 3.25 gears; Tri Y long tube; 2 inch exhaust; base timing 14.

I am having an off-idle hesitation until about 2-2400. If you WOT from idle it falls on its face then bucks and kicks until you back off throttle and ease back in it until about 2-2400 then you can WOT no problem. Engine screams and pulls hard until 6500.

I have tried a .37 squirter and that fixed the off idle hesitation but gave me a bog instead (currently getting a .35 quirter). I tried timing all in at 3000 with light springs and blue stop, and the car had no power at all up to 6500.

The car is mainly a street, cruiser. No interest in track. I would like to get rid of the low end hesitation if possible. Any thoughts would be great. Thanks!

 

[sanch052]

So you tried the blue bushing and the light springs with the 37 squirter and had no power? Or did you try the blue bushing and light springs with 31 squirters?

Normally sbf like 36-38 degrees total and they like it early. So the fact that your motor is liking 42 degrees late is throwing me.

Your vacuum at idle seems low, but that could be your cam. Have you played with the power valve since your vacuum increases at cruise? Maybe a bigger size

What do your plugs look like?

.35 squirter might solve your hesitation problem.

 

[Rbtama101]

I tried the .37 squirter with the heavy springs and red stop and had a bog.

Then I went back to the .31 squirter and changed the springs to light and the stop to blue and had a big loss of power overall.

I have a 8.5 power valve I am gong to try and see if that helps. Kind of thinking that might be it along with the .35 squirter.

The plugs do look a little leanish I suppose.

 

[Woodchuck]

" vacuum at idle is 11-12 and 15-16 at cruise;"

Your HIGHEST vacuum should be at idle when the throttle plates are closed. Light throttle cruise should be a couple inches LESS. It sounds to me like you have the throttle plates open too far at idle and pulling fuel out the transfer slots so when you go to WOT you suddenly go lean. Do you have a vacuum leak somewhere?

 

[sanch052]

" vacuum at idle is 11-12 and 15-16 at cruise;"

Your HIGHEST vacuum should be at idle when the throttle plates are closed. Light throttle cruise should be a couple inches LESS. It sounds to me like you have the throttle plates open too far at idle and pulling fuel out the transfer slots so when you go to WOT you suddenly go lean. Do you have a vacuum leak somewhere?

Yeah that's something I have never experienced before. Bartl's theory sounds good.

 

[Rbtama101]

I just did a head gasket up reseal. I also reset the carb to base settings according to the book and went from there. When I get a chance I'll recheck the curb idle stop screw.

I can close the mixtures screws and kill the engine, so my idle circuit should be working correctly?

 

[fastlaneinnovationsllc]

I'm wondering if your secondaries are opening too soon, which would fit with the hesitation going away when you back off. You could lock out the secondaries by disconnecting the linkage from the diaphragm or clamping something on the bar that sticks down from the diaphragm so it can't open them.

Also, is there any vacuum on the ported vacuum fitting at idle? If so, that would definitely mean that your primaries are too far open at idle and exposing too much of the transfer slots.

 

[Rbtama101]

I will check the vacuum port a idle for sure. I disconnected the secondaries and lost a ton of power overall and the hesitation was still there.

Thank you all for the help. As soon as I can get back to it I will check the throttle opening at idle and then then vacuum port. Will post results soon.

 

[fastlaneinnovationsllc]

What's your initial timing set at? I'm also confused that just bringing your timing in early lost power across the whole range. That's very odd, since the timing above 3000 shouldn't have changed. Does the advance plate in the distributor slide smoothly? Are you sure the springs were lighter? Maybe something happened and you weren't getting the advance.