Baja Rooster

iTrader: (1)

Have you checked the tanks vents? That's a fairly common issue for fuel supply problems.

89Force235

Yeah I should have mentioned that... Vent is clear and working; well enough to blow fuel on my feet when I top it off with fuel any way...

89Force235

In case anybody is wondering here's the specs of the Summit cam i put in the motor. Cost a whopping $109.99. I've got my idle set around 600 rpm and I've idled all over the place with this cam and havent noticed any reversion. So far seems to run well but like I said earlier, havent had a chance to really open it up.

Summit Racing Part Number:SUM-K1303
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 3,000-6,500
Intake Duration at 050 inch Lift: 238
Exhaust Duration at 050 inch Lift: 248
Duration at 050 inch Lift: 238 int./248 exh.
Advertised Intake Duration: 304
Advertised Exhaust Duration: 316
Advertised Duration: 304 int./316 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.540 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.540 in.
Valve Lift with Factory Rocker Arm Ratio: 0.540 int./0.540 exh.
Lobe Separation (degrees): 114

89Force235

Here's what the factory fuel pick up looked like.





Here's the proposed solution;

Drilled out shoulder in 90 fitting with the hose nipple already installed. (threads of the hose nipple half covered the opening in the bottom of the 90) I also drilled the hose nipple a 1/32 larger in inside diameter. The anti siphon check ball was removed long ago...


Miter cut on the pick up tube and ditched the screen in favor of an inline filter.

89Force235

Well, That didn't work... I didn't see any improvement what so ever from the mods I made to the pick-up.... Fuel pressure starts dropping at 3000 rpm and is down to 4psi by 3500...

Here's the pump I'm running;
https://www.holley.com/products/fuel...arts/12-454-20

Are there others running this pump on 525sc or similar engines?

Maybe it's floating out and I need a light weight fuel pump pushrod?

Budman II

iTrader: (1)

Talk to Eddie Young about your fuel system. He makes up custom 1/2" tank pickups to your specs - they have a nipple fitting that will accept a sweeping AN fitting to promote better flow. He posts on here a lot - just do a search on the tech discussion forum for his name. Great guy, and he knows what he is doing.

Don't know on the pump, but probably best to run a non self-regulating pump that has higher flow rating and a bypass regulator with a return line to the tank if you are feeding a supercharged application.

MILD THUNDER

iTrader: (3)

Heres my setup. 800hp supercharged.

-10 from tank to filter head. Filter is a wix 33405, and filter head, has 1/2 NPT ports. From filter, -10 line to mechanical, 6 valve block mounted pump with 1/2" NPT inlet/outlet. -10 from pump to a fuel block. Then, -6 to each carb bowl from fuel block.

Carbs need volume, not pressure . Pumps dont pull fuel, nearly as well as they push it. The basic mechanical pumps I have, were used on merc 800 and 900sc engines. They have been proven to support 1000 plus hp blown. But , if the fittings, lines, adapters, filter, etc arent right, they are not going to.

Budman II

iTrader: (1)

MT makes a good point - the stock filter adapter can also present a restriction. I think I posted a thread on a good, cheap aftermarket filter adapter that has 1/2 pipe thread fitting in and out. It has dual fittings which could also be used for your return if your tank doesn't have provisions, and you elect to go with the bypass regulator.

Budman II

iTrader: (1)

Look at these threads for more info on fuel system setups and the 6-valve pumps like MT mentioned:

http://www.offshoreonly.com/forums/g...available.html

http://www.offshoreonly.com/forums/g...mech-pump.html

http://www.offshoreonly.com/forums/g...na-575-hp.html

Happy reading, and good luck!

Budman II

iTrader: (1)

Oh yeah, info about tank pickup:

http://www.offshoreonly.com/forums/g...er-pickup.html