MS wrote:

That carb is a good carb. Sounds like power valve is blown, but you say it runs great…

 
It does run good.   Any thoughts on engine noise video?

Steve69 wrote:

MS wrote:

That carb is a good carb. Sounds like power valve is blown, but you say it runs great…

 
It does run good. Any thoughts on engine noise video?

I always use my mechanic's stethoscope. Can get one from Amazon for around $6.00.

Last edited by KeithP (7/12/2024 11:08 AM)

6sally6 wrote:

How about vacuum leak ?! (EZ stuff first)
That will REALLY make'um suck fuel while still running pretty good.
Put some more timing in it. That tends to lean them a little while picking up power.
Please tell us you re-curved your distributor's timing curve !!!
Re jet the carb leaner a few steps see if that makes any difference...
6s6

Thanks for the info Mike!

Steve69
 

boss347convertible wrote:

My 347 specifications are probably similar to yours, except that I am using a Victor Junior intake. On my engine, Ford produced maximum horsepower with a 750 cfm Holley and open headers. I am using a modified Autolite 4100 and had to re-jet the carburetor. What is the cfm rating of your carburetor?  600 CFM

For the rich condition, using Holley's jetting chart might be a good way to set a baseline and then adjust jetting from that point. I am not familiar with the Summitt carburetor, but understand that it is similar to a Holley,  If my understanding is incorrect, ignore the foregoing.  I would also check your fuel pressure and float level. Black smoke on acceleration could also be indicative of an accelerator pump circuit that is excessively large or not properly tuned to provide the correct amount of fuel at the correct time upon actuation.

My engine is set at 36 degrees advance total timing. Your piston crown, valve placement and cylinder head design might be different than mine, so I can't say whether retarding or advancing the timing would be advantageous to you. What does Blueprint recommend for your engine?  Between 32 and 36 degrees total timing 

Regarding the ticking, I have found that noise can migrate throughout the engine/transmission and that a stethoscope can be very handy in pinpointing the noise. You can put the stethoscope on each header tube to narrow down the noise source by listening for a different sound from one or two header tubes. After listening to the header tubes, continue working around the engine and you should eventually locate the source of the noise. What break in procedure did you use to seat the rings?  Use there break in oil and change oil in 500 miles.  It has a roller camshaft.   
Good luck.

   Thanks for the info!
 

I don't think that sound is anything to be concerned about.  It doesn't sound like a header leak to me.  It sounds like fairly normal valvetrain noise.  What kind of cam/lifters and rockers does it have?

If the exhaust is burning your eyes and mileage is way down I'd say its definitely running rich.  5MPG is insane.  I had a big block truck that got better mileage than that.  An AFR gauge is definitely handy, but might check MS's suggestion about the power valve first.  After that I would check and set the idle and then make jet adjustments from there.  Have you looked at the plugs?

Did the engine ship with a balancer/timing pointer or did you provide those? 
 

Lord I am still stuck on its getting under 5 mpg.

I think an AFR gauge will tell you what you already know, you’re running very rich.
While idling, look into the carb and see if any gas is dripping into the venturis from the primary and secondary sides.  This will give a ‘hint’ of what the problem may be.
As others have suggested, do all the carb normal checks, float levels, power valve, etc., and post the findings.
Consider the following:
How far open are the idle air screws?  Is this what should be expected?
What is your idle RPM?  Is this what should be expected?
What is the idle vacuum?  Is this what should be expected?
 
Regarding the tapping, I modified my Cobra valve cover oil baffles to eliminate the roller rockers from hitting the baffle.  My link to ImgBB isn’t working right now so I can’t post at this time, I can send pictures in an email if you send me your address.

Easy enough to check the valve covers.  Pull them and see if there are marks on anything from contact.  Granted, its hard to tell for sure what a sound is on a video on the internet, but I don't hear anything high pitched enough for me to think its a lifter tick, failing rocker, or anything in imminent danger of failing.  Its more of a dull sound, so a rocker hitting a baffle would make sense AND it would make sense it gets worse as the engine warms up.  I used SVE valve covers on my 331 and the stock baffle in no way cleared the polylocks on the roller rockers, so I built a new baffle that cleared.  Seems it a pretty common issue with stock height valve covers.

Witness mark from interference can be very tiny shiny spot, so look carefully.
I had a customer once where I built a 302 for him.  He installed shiny new 289 chrome valve covers.  The engine had a noise like yours, but only heard upon harder acceleration.   I made the same suggestions.  He pulled valve covers and found nothing.
So, I had him pull the engine and bring it back to me for repair.
When I pulled the valve cover, I found a tiny shiny spot where a rocker was rubbing the valve cover baffle.  One small dent was placed on the baffle and problem was fixed.
Not saying for sure that is what your noise is, but check carefully to avoid a lot of extra work!

Nos681 wrote:

https://documents.holley.com/techlibrary_power_valves.pdf

My understanding of Summit’s carb is that is a hybrid of Holley and Carter.

Try the troubleshooting for power valve.

As for the ticking, I have used a length of tubing as my stethoscope.
Removing belts may help locate noise.
I would remove valve covers and check for witness marks of of any sorts.

Do the heads have guide plates?
I would check to see if a rocker arm has rolled/shifted off tip of valve.
This would increase valve lash and cause tapping/clatter as well.

I have found that a 3 ft length of old garden hose works great for pinpointing noises. Just hold one end up to your ear and move the other end around to locate the noise.

I am also with MS on the rockers maybe hitting the oil baffle plates on the valve covers. I had that happen when I installed roller tipped rockers. I modified the baffles to clear and no more noises. I also installed 1/2" cork gaskets to make sure.
 

Steve69 wrote:

Ron68 wrote:

Nos681 wrote:

https://documents.holley.com/techlibrary_power_valves.pdf

My understanding of Summit’s carb is that is a hybrid of Holley and Carter.

Try the troubleshooting for power valve.

As for the ticking, I have used a length of tubing as my stethoscope.
Removing belts may help locate noise.
I would remove valve covers and check for witness marks of of any sorts.

Do the heads have guide plates?
I would check to see if a rocker arm has rolled/shifted off tip of valve.
This would increase valve lash and cause tapping/clatter as well.

I have found that a 3 ft length of old garden hose works great for pinpointing noises. Just hold one end up to your ear and move the other end around to locate the noise.

I am also with MS on the rockers maybe hitting the oil baffle plates on the valve covers. I had that happen when I installed roller tipped rockers. I modified the baffles to clear and no more noises. I also installed 1/2" cork gaskets to make sure.
 

   Thanks for the info Ron!   Didn't know you could get valve cover gaskets that thick.  
 

Steve - they may not be 1/2", but they were twice the thickness of a regular cork gasket. I don't have the car here at home to check.....