Technical SBC gurus I need some opinions.

I like a stock pump rod and usually have a few of them around too. Chances are that you got a big block pump rod unless it is the one that came in the motor and no one has changed it. It would stand to reason that a big block rod would be longer. I have never compared them.

 

if the pushrod were too long, it would not try to pull the pin out of the pump housing, eh? odds are good it's just a case of Carter making some pumps not quite right.

We'll probably never know, because you'll change everything at once, and one of the 5 things you did will fix the problem, the other things will get the credit.

 

The rod in it now measures 5.770 (.020 longer than spec). From what I can find the big block rod spec is the same length as the small block push rod @5.750 Comp , Moroso and GM PP parts and others list them as the same number. The one I had installed was a Chromy one from GM PP Parts. Here is the one I have ordered from Comp to try now.
http://m.summitracing.com/parts/cca-4616?seid=srese1&gclid=CK7Avun3k80CFQqoaQodUdkJOQ

 

Have you considered running an in line electric pump between the tank and the mechanical pump on a toggle switch? I do this just as a way to pump up the pressure before trying to start a car after it's sat awhile, but it might be a good way to back up the mechanical pump when racing. You shouldn't have to, but it's a thought.

 

You're using a stock pump , that was never intended for hi-perf & probably was designed to not see over 4K rpm, in a hi-perf application. Then you wonder why it fails ???? Get a hi-perf. pump , if you break that , then you've got a bitch ...Sorry , had to say it...LOL
dave

 

Mike ,are you getting oil to the pump? I found a casting flaw with no hole to the pump chamber. The guy had to replace the pump about every 6 months.

 

Its actually marketed as a Carter Muscle car pump. its rated 10GPH higher and is supposed to have heavier springs for anti float but still its a cheap pump. I dont disagree a racing pump would be better but this pump should be able to handle this. I've flogged many a SBC with stock type pumps higher RPM's than this one and never had this failure.

 

Thats interesting Jim, this is a newer Vortec block some don't even have the push rod hole machined into them. There wasn't much oil in the pump chamber but there was some oil. I just checked and ran a zip tie several inches into the drain back hole to make sure it wasnt blocked or not drilled all the way through. Man for a minute I thought you might have had it but as far as I can tell it seems to be correct.

 

Also by measuring the wear marks on the push rod the cam lobe appears to be about .350 lift

 

Put the Holley pump in, I doubt if it will make claimed pressure..Just had a bout with them [about not making advertised pressure] but Holley also has a problem with the valves getting loose..IMO think its more do to pump quality just not up to it...

 

I had a Holley mechanical on a 480 HP street BBC from RHS. I installed a gauge because we sprayed it and damn if it didn't make near 7 PSI at idle and 5.5 PSI in the traps at WFO. All steel O/T muscle car, 468, ran 11;70 on the juice with no bottle pressure in high gear, eventually ran 11-teens, like .16-.18, about 121 MPH. Fun car that ran faster on the street. Go figure...? The point being the pump kept up and supported what we did but that was in 95. Ya know, I still have that pump but it won't fit a SBC according to the number tag.

 

Read through this thread and I have a different problem.We had to make a road side repair this past weekend.we replaced the fuel pump on a buddies SBC.One guy had a fuel pump but no gasket so we made one out of gorilla tape between the pump and plate.Now the pump knocks when running.could the gasket be to thick and leaving a gap at the push rod.Or could the pump arm be bottoming out?Are all SBC mech.fuel pumps the same.Thanks The gasket will be replaced with the right one.

 

Big block Chevy mechanical fuel pumps look the same but the arm on them is a hair longer. You might want to check the numbers to verify what pump you have.

 

How much tape? A gasket is maybe .060 (?) so three layers would get you close. As said, BBC and SBC are different. You may well be bottoming out.

 

Mo rust and theHIGHLANDER,thanks for the replys.we will check that pump and replace with the correct one.