Timing frustrations

[Don C]

I think you made a good carburetor choice, and wise decision to move on and get a new carburetor.

 

[Big Red Mach 1]

I think you made a good carburetor choice, and wise decision to move on and get a new carburetor.

Thanks Don! I appreciate it! I might have kept chasing this one, but even if I got it halfway right, it may not have stayed that way for long, and the not having a choke was really never something I would have been happy with long term.

 

[boilermaster]

So fella's,

I went to summits website to check this carb out and read reviews.

Two things caught my eye, primary and secondary power valve ratings.

Summit has the primary power valve at a higher Hg. rating than the rear, this makes no sense.

Then I read review # 28 and I believe the pv ratings are a typo.

Second thing is primary jetting, the summit carb's primary is quite a bit fatter than what should have come in big reds

avenger (this will not hurt big reds idle in any way what so ever.

Both my 351 and 408 wanted the same primary jetting as what came in the avenger #72 and was confirmed by wideband o2 on both engines (not saying this is what big red needs or should have, just my observation).

Way too many variables come into play here to even begin to make a suggestion .

Boilermaster

 

[Big Red Mach 1]

So fella's,

I went to summits website to check this carb out and read reviews.

Two things caught my eye, primary and secondary power valve ratings.

Summit has the primary power valve at a higher Hg. rating than the rear, this makes no sense.

Then I read review # 28 and I believe the pv ratings are a typo.

Second thing is primary jetting, the summit carb's primary is quite a bit fatter than what should have come in big reds

avenger (this will not hurt big reds idle in any way what so ever.

Both my 351 and 408 wanted the same primary jetting as what came in the avenger #72 and was confirmed by wideband o2 on both engines (not saying this is what big red needs or should have, just my observation).

Way too many variables come into play here to even begin to make a suggestion .

Boilermaster

You're definitely right in that some of the specs are "interesting",  and that particular review is truly a bad review. I'll give it a shot based on 101 of 108 reviews being 4 star or higher and most people finding success with it somehow on a plethora of different motors. Again, if it doesn't vastly improve my situation (Shouldn't be hard) back in the box with the return label it goes. Again, I'm new to carbs, but I did like the solid base on it, and I heard that Annular Booster carbs really weren't overkill for any engine at any carb size. Not sure how or why, but I did read that among comments on more expensive Annular Booster type carbs. Thought it was worth a shot. And I definitely did need something to compare my current carb to.

 

[cv_72mustang]

Hi, I've been reading this thread for a while and got me thinking about the Annular carb and found this link very informative.

https://www.hotrod.com/articles/carburetor-showdown/

 

[Big Red Mach 1]

Great Article. Thanks!!

 

[Big Red Mach 1]

Speaking of atomization of the fuel, I should mention that a recent add to the carb was one of these. Although I knew it would not be a cure for what is ultimately wrong with this carb, with this installed, it did idle smoother and start noticeably quicker. I would definitely recommend this to just about anyone. I'm sure that on a good carb, the results would be very pleasing. Read the reviews online. Hard to find a negative from anyone. Be sure to read the reviews on their facebook posts.

https://thompsonperformance.com/collections/all?fbclid=IwAR13NkVEmLuX4S0Hy9CudcrvEdXkCHyKdOkJUemWB4_66CkowOmolCcz9Po

 

[boilermaster]

Cv-72mustang,

The hodrod article Did explain why the annular discharge boosters would like a larger main jet.

If and when my s/a carb takes a crap, I would now really have to consider one of the summit carbs.

Will be waiting on big red's seal of approval.

Boilermaster

 

[Stanglover]

Cv-72mustang,

The hodrod article Did explain why the annular discharge boosters would like a larger main jet.

If and when my s/a carb takes a crap, I would now really have to consider one of the summit carbs.

Will be waiting on big red's seal of approval.

Boilermaster

 Me too!

 I've been hung up on switching to a QF HR735, but now I may have to look at the Summit instead and it's cheaper too, bonus!

 

[Big Red Mach 1]

Not quit there yet, but close. When i order from Summit, I almost always get parts out of Sparks, NV and it's great. Takes literally a day. This time based on one item in my cart, it kicked the entire order to Ohio. Figured no worries, still shows a Saturday delivery. Well, Saturday came and went. It delivered about 2 hours ago.

The carb comes super well boxed. Plenty of padding and protection in just about every way imaginable. You could probably drop the box off the roof and not hurt the carb. I'm assuming most others are the same though. It's pretty. Looks good. The size of the annular boosters are impressive. They look cool, can't wait to see them discharge the fuel.

A couple of things kept me from completing install. I want/need to use a 90* fitting coming off the fuel rail. I really need that so that I don't fight with the coil and have a big wide bend in my fuel line. My fault for not thinking about that.

I also need the transmission kick-down lever parts. The lever itself is on the carb, but it doesn't come with the adjusting screw or clip for the screw. There was conflicting information on this on the site. But for those of you with a C6, you need the additional kit. I'll put a photo below. Summit says it does not come with the kick-down, a review said it did, and you can see the lever in the photos. Why they have the lever, but not include the .25 cent bolt is beyond me. My Holley didn't have it either, so I could not salvage the bolt from the Holley. Maybe that's why it shifted like $h!t.

Also found some more home-brew crap. The previous owner took a hammer to the old linkage, banged it flat and tapped himself a couple new holes for the throttle cable. Why, I have no idea. I also can't believe my blind eyes didn't notice it. But it wasn't super noticeable, and I had nothing to reference it against. Speaking of which, can you guys please confirm the hole I should be using in the photo below.

Getting there guys. I'm a 90 degree fitting and a kick-down screw away. : )









If you guys ever end up getting this carb, I'd suggest the parts below.



free image hosting website

 

[Stanglover]

I'm not sure about the throttle link pin on that one, so can't offer a definite yay or nay.

Personally, I like that this comes with  a solid fuel connection between bowls, but I would suggest you do this later. Rubber hose is ok for now and to get you going, but this is what I did to make a solid 3/8" steel fuel line from the pump. You may have seen this before.





I put a short rubber connector at the pump to take up any vibration.

 

[Big Red Mach 1]

Nice job on the fuel line!

It does look like your throttle cable is hooked up where I'm expecting to hook mine up at. But that compresses the cable quite a bit.

 

[Big Red Mach 1]

I see now. Looks like many people have had issues with different carbs and their throttle cables not jiving and not allowing the carb to open up all the way. I'll probably look to replace my cable and also modify my bracket or fab one up somehow.

 

[boilermaster]

Ok Big RedMach 1,

I see that in your picture of your carb install that you are running a throttle cable return spring.

This is just an observation at this point but consider these facts.

71-73 mustangs throttle cable assembly's come with a return spring.

Your carb has a built in return spring.

If running an automatic transmission, your kickdown linkage has a return spring (only comes into play @ or near WOT.

If you want to run an additional return spring, that's your call.

This carb. you are installing is an ALL aluminum carb.

I have not seen very many Holley carb's with worn out throttle shafts, but I have seen plenty of all aluminum carbs with warn out throttle shafts.

If you choose to keep the return spring, I am suggesting that you at least take these steps (after start up)

With engine off and all return springs disconnected (including throttle cable) see how freely the carb returns to closed,

Then again with the throttle cable clipped on and lastly with the aftermarket return spring installed.

If you feel that this is too much return pressure, you can always run a lighter return spring.

Just my opinion

Boilermaster

 

[Stanglover]

Nice job on the fuel line!

It does look like your throttle cable is hooked up where I'm expecting to hook mine up at. But that compresses the cable quite a bit.

Yes it does. Boilmaster's reply is interesting. I take from that, that the throttle shafts themselves are aluminum. I find that surprising and a point to keep in mind.

In my case with a 4 speed, I actually run double return springs as well as the throttle cable. It seems to need this just to make sure it snaps shut when I let off on the loud pedal! Works for me anyhow.

I think the basic size of all these carbs is pretty much the same overall, even the Edelbrock, so the typical location of the components would be about the same, therefore the throttle cable should be relatively in the same place on the Summit as on the Holley. Does that make sense?

 

[boilermaster]

Geoff,

I don't specifically know that the actual throttle shafts are aluminum (hope not) but the carb body sure is, and I don't

think there any bushings.

Given that and where the pivot points are on the throttle shafts, all the pressure from the various springs is going to ride in a 90 degree arc to the rear of the throttle side and to the front of the non throttle side.

Why prematurely wear this new carb out with too much spring tension.

Boilermaster

 

[Big Red Mach 1]

Outstanding info at always Boilermaster! I will definitely see how she acts with and without the spring, especially if it may cause premature wear.

 

[Stanglover]

Geoff,

I don't specifically know that the actual throttle shafts are aluminum (hope not) but the carb body sure is, and I don't

think there any bushings.

Given that and where the pivot points are on the throttle shafts, all the pressure from the various springs is going to ride in a 90 degree arc to the rear of the throttle side and to the front of the non throttle side.

Why prematurely wear this new carb out with too much spring tension.

Boilermaster

 Thanks for your response. I too would be very surprised if the shafts were aluminum. That makes no sense at all and probably the way I read the post. No bushings, that makes no sense either except for cutting cost. For sure all the wear would be as you describe and I agree too much spring tension will almost certainly cause premature wear. But aren't all carbs bodies aluminum, die cast or machined alloys? You bring up very good points and definitely something to verify before I'd buy one of the Summit carbs for use on my car.

Interesting indeed.

 

[Big Red Mach 1]

The shafts are definitely steel. My old S/A carb sure looks and feels like aluminum. Not polished like this one, but almost certainly aluminum. It's certainly not magnetic at all, and doesn't weigh a whole lot. I also don't see any more visual signs of bushings on the Holley than I see on the Summit. Metal to metal with no bushings doesn't even seem logical.

 

[boilermaster]

Big RED & Geoff.

I figured that all of the shafts are and were always steel.

There are bushings (plastic) both older and present carbs, but the older Holley's were Zinc .

Now most all are aluminum and that will wear faster than zinc period...

I am not an engineer but I can drive a train ! (sorry I just wanted to say that on the internet.)

Yes I really can drive a train.

Boilermaster