johnyIROC

So I just pulled out all of the old fuel line...

I have an 11.5:1 383.. should be in the 450HP range...


Here is my fuel system:

-Stock tank/sending unit from 87 MPFI V6 with the in tank pump removed and replaced with hardline
-3/8" Aluminum fuel line from the tank to the pump
-Holley 110GPH Mechanical pump
-6AN Braided stainless to the fuel log
-Earl's 6AN fuel log to carb
-Holley 650DP


I've heard for anything over 400HP... you need to go to 1/2 inch fuel lines... but the in tank sending unit has integrated 3/8" hardline... so I don't really see a way around this bottleneck.

Asside from that.... everything I've read says to match -6AN with 3/8 hardline... but when I visually look into the red fittings, I can see that the diameter is much smaller than that of a 3/8 hardline... am I actually restricting my system by using the stainless braided with AN fittings?


I have a holley blue pump... but I was saving that for a standalone nitrous setup in the future.


I really don't see any way to get the true benefit of a 1/2" line without running a fuel cell... because of the 3/8 hardline in the sending unit... and a fuel cell is not in the budget... this is a street car.


Do you think I will be okay with my system? I don't want to lean this thing out.

Chickenman35

If you are looking at adapter fittings, such as AN -6 to pipe thread, then yes, the inside diameter will be slightly smaller. Has to be that way to give enough strength to the fitting. Same with brass fittings.

Some fittings are better than others. Russel is junk. Earls and Aeroquip very good quality. Specialty makers such as Barry Grant make low restriction adapters with larger inside diameters. Be aware that they are also more prone to cracking if you tighten them up too much.

Use as much hardline as you can...it's cheaper and lighter than SS braided. Stay away from 90 deg adapters. If you have to make a 90 deg turn, it is better to use a 90deg hose tube rather than an adapter. Much less restriction.

Use a big enough fuel filter and you should be fine. I'm running a similiar setup on my Hillclimb car and it's never had a problem supplying enough fuel. Make sure that you take the sintered filters out of the carb inlet. They are a big restriction.

88IROC350TPI

Its not very hard to modify the stock fuel tank for 1/2" line ...I think its silly NOT to upgrade to 1/2" line if you have a high performance motor even if it only makes 450HP now, bigger is better when it comes to fuel line regardless of what your motor needs. You will always have room to grow.

CamaroMike

I think that modifying the stock sending unit for 1/2" line would be a biatch. These cars were never made for real perfomance. Small exhaust, long tubes headers destroy ground clearance, weak rear ends, trannys that blow up or don't shift, and worst of all a fuel system that does nothing but gather heat and is almost impossible to plumb without going near a heat source. Everything on our cars costs a ton to build right. Hell a good fuel system with modified sender, electric pump, fuel filter, regulator, braided hose and AN fittings is like a grand!

I just stuck with 3/8'' aluminum line, a Holley Blue pump, K&N billet fuel filter, and Holley regulator. Routing it away from heat is almost impossible. I went up the drivers side to the front of the tranny and mounted the regulator on the torque box. From the regulator I went up the tranny tunnel past the distributor and on to the carb with 3/8'' hose. This is the best setup I have been able to come up with that is heat tollerant, short, and efficient. Man, I don't mean to rant and rave but I have fought fuel percolation problems for the better part of six years with carb setup. Lucky INJECTION b@stards! 50PSI works wonders for vapor lock issues!