I’m switching my AV8 over from gravity feed to a fuel pump. I am using one of the early style fuel pumps on my 8BA for additional clearance at the firewall. I bought the 7 7/8” and 8 7/8” push rods to make sure I had my bases covered with the Edelbrock Super Dual intake. Turns out the 8BA use a unique larger diameter push rod than the earlier engines. Anyone know the diameter? Can I make one out of 7/16” drill rod? Whatever I wind up doing, it is going to be a custom length as I am using an early pump stand with oil filler, and I’ll have to neck the 8BA rod down to the diameter of an early rod to fit the fuel pump.
I think you can shove an early bushing into the late directly. Cannot swear to that from personal experience, and right now I can't find my spare bushing to check. If you wind up fabricating, I would just go to MSC and buy a bushing with slightly excess OD, turnit down leaving a slight shoulder, and drop in stock early rod. Oddball reliability parts can bite you later when you have to fabricate a new one with allthread and a Chinese hacksaw in the Home depot parking lot in the dark...
The 59a block uses a steel can or tube that fits in between the block and the intake manifold, and connects to the breather/fuel pump stand. This keeps the push rod centered to the cam, and prevents all the oil in the tappet valley running back into the rear of the pan. The 8Ba block has a much smaller hole that guides the push rod, and doesn't require this spacer under the intake manifold. That's why, when you go to an electric fuel pump with a 59a or earlier you should block this fuel pump hole. Have fun.
Thanks for the tip on the bushing, Bruce. I hadn't thought of skinning the cat that way. I have to order another intake manifold gasket, so I'll pick up a couple of 59A and 8BA bushings to check the fit. Nothing else, I can use them as a template to make a custom bushing/reducer. I'll update the tread about the fit as soon as the parts get here. Bluardun, appreciate the info on the 59A centering tube. It's the subtle diffrences that get you every time.
i just pulled my fuel pump / pushrod off (8cm). if you still need the pushrod diameter i'll check it later today.
10" long, and the bottom and top is 7/16 diameter. not 100% positive it'll be 10 inches long because the car was running an electric fuel pump, and the guy i bought it from originally said the pushrod was taken out...it was still there so i'm not sure if he cut it short. however the wear marks look like it wasn't cut just worn out. hope that helps. fyi: 2 13/32 from the bottom it steps up a hair then 13/32 from the top the diameter drops back down to 7/16. off subject but would you happen to know if i block off the rear fuel pump, put a pcv in the block off plate, left the oil fill/breather in stock location, is it okay to leave the road draft tube or should i make something to plug it?
Something you might want to check before you get too far along is to see if the lobe is still on the cam for the fuel pump. Years ago I had one with a reground cam and the lobe was machined off.
Thanks for the info 50merc808. I'm running my 8BA decked out like an early engine so I'm not 100% on how to do the PCV for an 8BA. I mounted mine to the bottom of the intake. IIRC, the filler and road draft tube are near the front of the engine. As long as you are usng the 8BA style fuel pump stand, I'd think you'll be fine. What you want to avoid is having the valve too close to an inlet air source or it won't pull crankcase fumes. I know some clever ways to set up PVC on an 8BA have been covered in the archives. I thought I had the link but can't find it. Good tip, Andamo. It's anew Isky Max 1 so I'm OK.
In the past I have removed the upper (fuel pump end) which is pressed into a 7/16"dia tube. Then cut the tube as required to give you the length you need after the end is reinserted into the tube. Do not use solid rod as the lower (camshaft end is hardened)
Thanks for the tip about the hardened camshaft end, 51 MERC-CT. Does the 8BA pump end insert (Upper End in your picture) also fit the earlier pumps? Is it the same 7/16" diameter of the 8BA rod? I may run into a problem if it is too large to fit my early pump.
thought i read once, that even if you are using an electric fuel pump, you have to have the push rod in place . or you will have a massive oil pressure leak where it's supposed to be, inside that bushing.
There is no pressure leak there (except for a pinhole to oil pushrod that exists on a few late engines), but oil does get tossed up there. Anything like this or missing vent stacks and baffles in valley can cause oil burning via the guides. Leave all tinware in place, and I would simply leave a stock pushrod or portion of one in the hole. You can cut ti off and secure it so it doesn't ride cam.
sorry not trying to hi jack here but this is exactly what i was trying to find out . i have an 8ba that has had an inop. stock fuel pump left on the motor (previous owner runnnign 6v electric pump). recently pulled out the fuel pump and push rod and covered it with a block off. reading your post maybe it'll do more harm then good? any other tips, trying to set up my fuel system so i can get on the road.
No hi jack, it'as all good fuel pump info for the thread I just cut a long shank 7/16" bolt so it wouldnt quite touch the cam lobe and used it to plug the hole when I was gravity feeding my 8BA. Seemed to work pretty well.
Thanks 51 MERC-CT. I already ordered the parts to try Bruce's idea about using the early bushing as a spacer. If that doesn't work out, I'll pick up and 8BA pump rod and give it a shot.
Bruce, you were right on the mark on both counts. The early fuel pump bushing slipped inside the 8BA's like it was made to go there AND the shorter 7 7/8” was the one to use with the Edelbrock super dual. Other than the hassle of pulling it all apart, making some new plumbing and the tight fit, it was a pretty straightforward installation. The early pump is the way to go in a Model A. I didn't even have to dimple the firewall. The best part is the way she runs. I must have been starving the carbs with the gravity feed tank on the interstate all along. The hotrod runs like I added a couple extra cylinders!
I'm glad to find out the bushing fit is correct...heard it but never tried it myself, so good factoid to have on file when early engines get scarce!
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