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Discussion Starter #1
I’d like to see some engine pics that show how the metal fuel line from the fuel pump to the carb is routed on a ‘65 GTO. Did the original AFB 4 bbl carburators have the fuel inlet on the Right rear like Edelbrock? If so, how is the fuel line routed from the Fuel pump to the carb? The fuel pump is located on the left front of the engine. Pictures are worth a thousand words. Thanks!
 

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Yes, it comes from the back drivers side of the carb. Have you looked in the Ames catalog to see if they have a pic? They're available reproduction.
 

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Discussion Starter #3
Yeah, I want to see one installed on the engine and if the AFB carb inlet is on the left/driver’s side then what I’d really need to see how the fuel is routed for an Edelbrock carb which has the inlet on the right/passenger side.
Thanks!
 

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You can buy a fuel line that goes down/under on the passenger side and then tie it in with your existing steel line - which would have to be cut, modified, and joined together with fuel line hose. Edelbrock Carburetor Single Feed Fuel Line Kits | JEGS

You could get a length of 3/8" steel line and form it to do the same as above, but keep it one piece. Cut the end going into the carb, use the fuel line nut, double flare the steel line, and use the banjo fitting to attach the steel line to it and the banjo fitting to the carb.

You can tap the drivers side inlet and seal the passenger side fuel inlet. edelbrock dual feed fuel line | General car talk
 

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Discussion Starter #5
PontiacJim, Thanks for your input. I prefer to use all metal/aluminum fuel line and wanted to see if anyone had pictures of the fuel line coming up from pump on left (Drivers side) and crossing over intake to connect with Edelbrock fitting on the right side. I have the Edelbrock fuel line kit but didn’t want to get into changing the inlet to the left side. Anyway, the reason being the Qjet I’m running Now can’t seem to keep up with the high Reving 389. I’m have fuel starvation issues, apparently draining the fuel bowl too quickly. I have a 600 cfm Edelbrock 1406 and a 600 cfm singe feed Holley and I thought I’d try one of these to see if they’re any better. The Holley does have a left side feed so it would be an easier installation. In addition to that, my 389, .030 over bore, has ‘69 Ram III heads and I have to add a couple gallons of 112 octane per tank full to eliminate pinging. Is there anyway to tune this out where I can run either 90 octane ethanol or 93 w/10% ethanol. Or... do I just keep adding 112 to the mix?
 

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First, no, you probably will not be able to tune out the need for higher octane with the factory high compression set-up. The RA III #48 heads are listed as 68 cc's, smaller than the typical GTO 72 cc head. Boring .030" increases compression. If you are not using a dished piston and have the typical 6.6 cc valve reliefs, your compression is just over 10.0. Too much for pump gas.

I had been working with a member who has an original 1970 RA III/4-speed/3.55's. His engine had detonation problems on pump gas. I tried everything in my power to come up with a means to allow the engine to run pump gas premium. This included removing the cam that he had put in it and go with a Summit 2802. Helped some, but still pinging. The engine ran hot, so got all the cooling items sorted. Engine ran a little cooler, bit still pinging. Then we went through a series of timing changes to include adding the vacuum advance he had removed. Again, helped a little on the cooling and it was running temps where it should, but still pinging. The timing got way retarded on total still trying to remove the pinging, got as low as 25 BTDC @ 3,500 RPM's. This sacrifices a lot of power at this amount of retard, but this low of a retard also began to cause his engine temps to run higher again. Still had slight pinging, but this was the best out of all timing changes.

The end result? Could not remove the pinging completely. He decided it was time to get a good brand octane booster and add it to his gas. With that, I told him to now re-adjust his timing back up to take advantage of the higher octane and bring online the power he had lost.

That being said, unless you drop the compression closer to 9.0, octane additive or a racing gas blend is what you will have to do or damage the engine. On the PY Forums, I believe Cliff Ruggles has run this high with pump gas, but squish has to be on the money, tune has to be perfect, and a big cam with a lot of duration and 114-116 LSA like the RA IV cam has to be used. With that, you give up some low end power, raise the power band, and want the higher RPM's to take advantage of the cam. A lot of variables when trying to narrow a "good" cam that has to be exacting with your engine/compression combo. I prefer a little leeway on cam selection due to the lower compression which gives me a little fudging room if I don't have a cam that is exactly matched to my build - it'll still works great and I won't know that it doesn't.

Here is a good post on the subject if you read to the end. I got a little confused by some of Cliff's posts as it seems to flip-flop a bit between aluminum head and iron head compression ratio's. My take is that you can go 10 to 1 with iron head with a well set-up engine, but in one of his last posts, he mentions timing/fuel management which in my mind means electronics. So, like most forums and internet searches will turn up, 9.0 and up to 9.5 can use pump gas, but I prefer to recommend 9.0 which may be a bit conservative, but it does not put the engine on the close side of needing octane boosters or mixing race gas - in my opinion.


BUT, if you go bigger lift with the later heads, you will really need to know if the block has been chamfered for valve clearance and as well as the pistons.

Second, your Q-jet should have no issues supporting the needs of your engine. If the carb is going dry and you know this, then I would be looking at other fuel delivery problems. Swapping to a square bore AFB will mean either using an adapter to mate to the Q-jet manifold or another intake (factory or aftermarket) that will accept the square bore carb.

I feel that a 600 CFM will be too small and you will be giving up power and/or higher useable RPM's. The smaller size will make the throttle response snappier which may work for you if you keep RPM's down anyway.
 

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Discussion Starter #7
Thanks for the advice. I’m currently running 18 degrees BTDC at 650 rpm and 36 degrees total, no vac advance With 14-15“ vacuum. I may back it down a couple degrees but I know it won’t help the pinging. I’ve in contact Cliff too And changed the pimary jets/rods and secondary rods and .135 needle & seat. We think maybe using a .140 or .145 seat may help the starvation problem. I like the spreadbore design and see that Demon has a 750 where the secondaries are one big opening. Have you had any experience with these?
 

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Thanks for the advice. I’m currently running 18 degrees BTDC at 650 rpm and 36 degrees total, no vac advance With 14-15“ vacuum. I may back it down a couple degrees but I know it won’t help the pinging. I’ve in contact Cliff too And changed the pimary jets/rods and secondary rods and .135 needle & seat. We think maybe using a .140 or .145 seat may help the starvation problem. I like the spreadbore design and see that Demon has a 750 where the secondaries are one big opening. Have you had any experience with these?
No, no experience with a Demon carb.

Back in my youth, one of the problems mentioned with the Q-jet was that the secondary fuel well could starve out. There are 2 very tiny holes that are fed by the main well. To cure the secondary starvation problem, those 2 small holes got opened up. I am not 100% sure as it was so long ago, but I think I used a 1/64 drill bit. It was nothing big, but it did enlarge the holes to keep the secondary fuel wells from starving. I did this on all my Q-jet rebuilds. You can ask Cliff on this one.
 
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