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Messages - Helmantel

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1965 GT350/R-Model / Re: Another 65 G.T. 350 video recently posted
« on: January 14, 2022, 01:56:40 AM »
Take aways:

The squid he gave a ride to really  enjoyed himself or soiled his pants. I couldn't tell....

Thanks for posting

I doubt he soiled his pants. This is his daily driver:


You can still track your car, they track vintage Ferrari's worth more then twenty times the value of a 65 gt350.

True, but when one of those super valuable F-cars get banged up, does everyone wring their hands and complain that the car no longer has it's "born-with" parts or do they just fix it and move on?


I sometimes get the impression that for super rare cars, originality becomes less important. With rare cars I mean very low total production of the model.

For special versions of high volume cars, originality of the details is (highly) important, because it's the details that makes it rare. To give a Ford related example: A Mustang K-code coupe is (somewhat) rare, but without the original engine, most of what makes it special is gone and it's just another Mustang. A GT40 on the other hand will always be 1/~100, even after 4 crashes and 10 engine swaps.

1965 GT350/R-Model / Re: Holley 715 CFM #3259 float level adjustment
« on: June 18, 2021, 01:40:48 AM »
I have a quick change pot on another carb so I'll probably install that some time and test to find out the best spring. Installing the heavy one was more a matter of let's see what it does.

I agree that the chart is just an approximation with many variables. Or rather, the Holley table is probably accurate for that particular carb on that particular engine and serves as an approximation for other applications.

1965 GT350/R-Model / Re: Holley 715 CFM #3259 float level adjustment
« on: June 16, 2021, 04:28:04 PM »
I didn't check it, but it's a regular 289 fuel pump. I did rev it up to max with the sight plugs off to see if fuel level rose abnormally but it stayed were it was so I called it good.

I had a look at Holley's chart for secondary springs which listed the start of opening and fully open engine speeds for a 350 and a 402 with a 3310 (750 cfm) carburetor. The different values scaled almost perfectly with the difference in displacement between the two, so I recalculated them for a 289, also taking into account that secondaries are a little larger and thus flow a little more. The results are in the chart. For the black spring it actually said that it didn't fully open so I had to make a guess here for the "fully open RPM".

As I wrote yesterday, manifold vacuum was just about to creep up (an inch Hg or so) at 6000 RPM with the black spring installed. The theoretical air consumption of a 289 at 6000 RPM is ~500 cfm, which matches the chart almost perfectly. Maybe dumb luck, because I made several assumptions, but still fun to see.

1965 GT350/R-Model / Re: Holley 715 CFM #3259 float level adjustment
« on: June 16, 2021, 01:00:29 AM »
Mine are now at the equivalent of .0323 but still a little rich, at least for my engine. On an actual GT350 it may be different.

I wonder why they made those idle feed restrictors so large? I understand that they already did that during the 60's?
Do you know if they increased the secondary idle feed as well?

1965 GT350/R-Model / Re: Holley 715 CFM #3259 float level adjustment
« on: June 15, 2021, 05:45:40 PM »
Well, after a long break I finally got back at tuning the Holley. Last year I already installed some bowl sight plugs and had adjusted the float levels a bit below the bottom of the hole (which is the normal rule of thumb setting). But that didn't make any difference.

This time, I took Drew's advice and popped out the idle well plugs. Everything was nice and clean in there, but these carbs have the idle feed restrictors hidden in this well. Measuring their size with a 1 mm drill showed that they were probably ~0.041". I had no idea if that was big or small, but some googling showed that a normal size for a ~750 cfm Holley is in the low .030 range. In combination with my mild roller cam (and thus extra high vacuum), this was probably the reason for the rich transition circuit.

I stuck in some small wires and made some new caps out of aluminum (I didn't have any brass ones). That leaned out the transition circuit somewhat from 10 to 11.5 and thus not nearly enough. At cruising speeds, the AFR creep up somewhat but dropped back to 12 right away due to the power valve. Looking at the vacuum gauge during driving, I concluded that the 8,5" power valve kicked in way too soon. I then installed a 6,5" PV which allowed the AFR creep up to 14, but the power valve still kicked in too soon, especially in fifth gear.

I took it apart again, inserted a thicker wire in the idle feed restriction (0.024", reducing the flow area by 1/3th) and at the same time, I also installed #66 jets (instead of the stock #68), a 3.5" power valve and the stiffest (black) spring in the secondary canister (it had the next to lightest yellow one, which I assume is what it came with). Not very scientific perhaps to make so many changes at the same time, but I had grown tired of taking the carb apart all the time.

Anyway, idle AFR remained at ~13, light cruise (on the transfer circuit) increased the AFR to ~13, cruise (on the main jets) to 14.5-15 and WOT to ~13. It smelled much less and drove smoothly without much hesitation. There's still some under some conditions, so a little more tuning of the acceleration circuit required I guess, but overall it drives well. At 6000 RPM, manifold vacuum crept up to maybe 1" Hg (hard to see exactly when trying to look at the tach, the vacuum gauge and of course the road at the same time...), so I guess the stiff secondary spring didn't make the carb very restrictive. The light cruise AFR didn't increase as much as the flow area reduction suggested but I guess that's due to the unchanged secondary idle circuit. Maybe I'll give it one more go and fix that too.

Replicas and Tribute / Re: 65 Mustang steering box
« on: June 15, 2021, 07:14:32 AM »
Late answer, but yes: it's a matched set. It's basically a fancy version of a bolt (shaft) and a nut (block) and just as the thread pitch of a bolt and a nut must match, so do these steering parts.

Replicas and Tribute / Re: 65 Mustang steering box
« on: May 23, 2021, 03:54:15 PM »
The difference between the 16:1 and 19:1 ratio boxes is in the worm gear. It's a matched set of shaft and block as the balls recirculate through the block back to the other end of the shaft and as a consequence the pitch of shaft and block needs to be the same. I never counted the grooves but the quicker ratio must have fewer per inch. I believe 19:1 is a rounded number and that ratio is actually 19+:1, so 8 for the quick box and 10 for the slow one makes sense.


the last magazine i know was

Autovisie 1965
this was from Netherland in dutch language

the car stands on gras, but when you look on the first test, you see that is clearly the same car and test...

I think this article was also posted a few years ago (and got lost when there were forum issues I think). I posted a translation back then (I'm dutch). I'll check if I still have it somewhere.

1965 GT350/R-Model / Re: quick steer
« on: March 08, 2021, 09:04:32 AM »
I can't find it now but at some point I remembered reading that the longer steering arms didn't need to be used by Shelby on later model cars because Ford changed the steering gear ratio in the steering box. Since there are so many comments about headers not clearing the longer steering arms on the early cars (65-66) I'm wondering if the header clearance problem could be solved by using a later steering box. Anybody know?

The later cars have shorter steering arms on the spindles, which quickens the steering the same way longer pitman arms do, although to a lesser extend (about 5% vs ~15%). 

1965 GT350/R-Model / Re: R Model Heads, Cam and Intake
« on: March 08, 2021, 07:58:49 AM »
According to the 1966 Shelby American Performance Equipment parts catalog, the competition  GT350 road racing engine (PN S1CR-6003-3) had the following cam installed:

Valve lift: 0.445 in
Intake Opens: 29 deg BTDC
   "       Closes: 75 "    ABDC
   "        Duration: 284 deg

Exhaust  Opens: 75 deg BBDC
    "        Closes:  29  "   ATDC
    "         Duration:  284 deg

Intake /Exhaust tappet clearance (hot): 0.018 in

Specifications taken at 0.001 in valve lift

That cam has rather wide lobe separation angles at 113/113. The LeMans cam had much narrower angles at 107/109 while the Hipo cam had both narrower (intake) and wider (exhaust) angles at 109/119.

1965 GT350/R-Model / Re: Holley 715 CFM #3259 float level adjustment
« on: November 03, 2020, 02:50:31 AM »
The only other thing that you haven't mentioned that you looked at is the metering block.

The block has emulsion tubes in it for both the idle circuit and the main circuit. I don't think they were ever intended to be serviced after manufacture.

Drew has a video on his Facebook page that shows you how to service them.
since you are having issues with the idle circuit, you need to consider servicing them.

There are also air bleeds in the main body and need to be cleared out with a numbered drill bit. They are small and clog easily.

It wouldn't be a bad idea to ask Drew to go through that carb for you, set it up and test run it for you? The issue is he's a very busy guy and it might take a while for him to get to it?

For what it's worth, this carburetor is hardly used and everything inside looks brand new and clean, including the air bleeds. I don't know about the emulsion tubes though.

I'm sure Drew could get it right. I do live in Sweden though, so shipping it back and forth would be a bit of a hassle. Also, I had this carb intended for a new engine build I have planned (if I ever get to it....) so if I can't get it right, I might have Drew look at it for that application instead.

You’ll find the difference is negligible....
Specific gravity of .748 vs .756 etc. the range from E0 to E10 is well within the range of gasoline variability.

Fuel pressure variation and needle/seat diameters have a much greater impact.

Yeah, you're right. Density is probably not much affected by the ethanol.

I wondered about the (strong) influence of fuel level on the mixture. Initially I thought that the pressure of an inch (or thereabout) of fuel would be negligible, but when looking into the vacuum created in a booster venturi, I found that the vacuum at cruising speed for a 289 is probably only 1-2" of water or so (~40CFM per venturi at 2000 RPM/half load). Compare that to an inch of fuel (~3/4" of water) and it becomes obvious that the influence of the fuel level will be significant at low airflow levels.

When running on the idle and transfer circuit, the holes are directly exposed to the manfold vacuum (or whatever the vacuum will be right at the tip of the throttle blade) so it is much higher than in the venturi booster. Could there be an effect of the exposure of the different emulsion tube holes, with the holes being under or over the fuel level under different operating conditions? Thereby affecting the amount of air that enters the emulsion?

1965 GT350/R-Model / Re: Holley 715 CFM #3259 float level adjustment
« on: November 02, 2020, 05:21:26 AM »
I had set the float levels set to the (somewhat confusing, see first post) recommendation of 3/8" front and 1/2" rear. Now the fronts are a little lower due to the float interference with the bowl. Since the engine ran much better I thought I was on to something, but it's still running rich. I guess I can give it a try and set the floats lower. All this fiddling with the floats sure makes me long for externally adjustable floats and side plugs :) I'm still considering drilling and tapping my bowls for side plugs: there's a patch on the bowls already.

I wonder if the ethanol fuels require a lower fluid level in the bowl or if  the fluid level should be the same but that the density of the fuel requires a lower float dry setting? Or maybe a combination of both.

The needles in seats are in like new condition and the power valve tested as OK, but will replace it anyway and see what that brings. I will also check for any signs of fuel dripping at idle.

1965 GT350/R-Model / Re: Holley 715 CFM #3259 float level adjustment
« on: November 01, 2020, 06:05:59 AM »
Thanks for the suggestion but that doesn’t seem to be the case. Although Now that I look it it, it does seem possible to bend the tab and the float bracket in such a way that a 3/8” setting can be achieved without the float hitting the bowl.

1965 GT350/R-Model / Re: Holley 715 CFM #3259 float level adjustment
« on: October 31, 2020, 06:31:41 PM »
I lowered the primary floats a little to prevent them from bottoming out, but the engine runs just as rich as before: 12,5 at idle (tuned for best idle setting, ~3/4 turns out, 18" vacuum), ~10 at light cruise, ~11-12 at highway cruise and ~12,5 under acceleration. It idles smoothly and doesn't run bad otherwise but smells fuel and fuel consumption is high.

It seems that something is leaking fuel but I can't figure out what. A leaking power valve could be a possibility but it worked fine when I tested it with a vacuum tester (pulling vacuum on the membrane side) and all gaskets seem fine (the blue non-sticking type on the metering blocks). I didn't have any new ones handy but I guess I'll buy some and see if that helps.

Unless the specific calibration of this carb works ONLY on a GT350 engine and not at all on my 289 (short duration but .533 lift roller cam, Shelby Hirise manifolds, 351W heads with mild porting, headers, 10:1 compression), but that seems unlikely.

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