Edelbrock Streetmaster vs Blue Thunder

[jholmes217]

Trying to decide if I want to use a Streetmaster or Blue Thunder intake manifold on my 428 Cobra Jet.  I have 2 questions that the answers may help in that decision.  I already have both manifolds.

1.  Will the rocker drainback tins work with both manifolds if the Precision Oil Pumps roller rocker arm and end stand system is used?

2.  My car will be used in some parades in the winter time, and it has been 17 degrees here in Western Washington during the Christmas Parade in the past.  Should I block off the exhaust heat riser or leave it open?

The car and engine is a 1969 Q code Mach 1 4 speed with a 3.50 traction lock rear end.  Engine is a 428 Cobra Jet with the original iron heads and a Oregon Cams version of the Comp 280H Magnum.

[Joe-JDC]

The BT mimics the PI in looks, and flows more than the Streetmaster stock.  The Streetmaster is shorter in overall height.  If the manifolds are simply gasket matched, the BT still would be my preferance for street duty and looks.  Ported, they reach parity, and it simply becomes which "look" do you prefer.  Joe-JDC.

[jayb]

You have to modify the tins to make them work with the Precision Oil Pumps stands, but its not a big deal.  Both manifolds will surely work with the short tins, but I'm not sure about the long tins.  My guess is that they would both work.

I always block the heat crossovers, and just figure on a little extra warm-up time on cold days.  Once the engine is warmed up, I don't think you'll notice if the crossover is blocked.

The manifolds are really close in performance, especially on a 400-450 HP engine.  I think either one would be fine - Jay

[cammerfe]

I'm a strong believer in blocking heat passages. In warm weather you are contributing to performance degradation with open passages and the exhaust does NOT do good things to your manifold. In cold weather you can put a water-warmed spacer under your carburetor if you feel the need.

KS

[Qikbbstang]

The Streetmaster will need the simple to find and do plenum modification. If by any chance you have both intakes it might well be worth the hassle to swap them and see which performs better to your liking.

[jholmes217]

Well, after more than an hour port matching one port on the Streetmaster, I said heck with this and put the Blue Thunder on!  Seems like it would take forever without air tools to port match the Streetmaster to low riser/Cobra Jet ports, then do the plenum mods.  I'll continue to work on the Streetmaster as time and patience allows, but get the car back on the road with the Blue Thunder.

[My427stang]

Well, after more than an hour port matching one port on the Streetmaster, I said heck with this and put the Blue Thunder on!  Seems like it would take forever without air tools to port match the Streetmaster to low riser/Cobra Jet ports, then do the plenum mods.  I'll continue to work on the Streetmaster as time and patience allows, but get the car back on the road with the Blue Thunder.

LOL God bless the porters, I don't have the patience either, but the good ones do great things!

[cammerfe]

The first time I port-matched an intake manifold I was working on an 'XE'-marked sidewinder. It was surely cast at the experimental foundry at the Rouge and had had such things as a fore-'n'-aft plenum divider welded in and material welded in to the bottom of the runners so it would work with low-riser heads for the '27 I was putting together for my almost-new '67 XR-7 GT.

It was altogether hand labor and I did it using a wood-rasp and a shoe rasp. The very aggressive teeth on the rasps made fairly short work of the aluminum. I had it all done within a couple of hours. 

KS

[JamesonRacing]

While it doesn't hurt to block the heat riser passages, they don't really see much heat from the exhaust if you don't have a functioning heat riser valve one of the manifolds.  If you have long tube headers, then all the less issue, as the possible heat source is only from one of the cylinders rather than the four with a factory manifold.  The idea is to block the exhaust from going down the pipe and redirect it through the intake manifold to the other side.  If you do have a functioning valve, definitely do NOT block the passages.

[Joe-JDC]

First, I would not gasket match the Streetmaster to the LR/CJ port size, period.  Nothing to be gained on that manifold by lowering the floor port entry, and velocity to be lost.  The Streetmaster that I sent Jay for his dyno comparison was only MR port size, and it made 633hp/603lbft torque on his stroker.  JMO, but I would only blend the sides and top on that unless you are going all out in the engine build.  Joe-JDC 

[jholmes217]

Too late on that one port Joe-JDC.  Is there a way to fill the bottom back in?

[Joe-JDC]

Welding would be the preferable repair, but JB Weld works well if mixed properly, and the area is clean and has a rough texture to cling to.   Joe-JDC

[jholmes217]

Would aluminum solder work?

[Joe-JDC]

I don't think you could get the manifold hot enough to let the solder wick into the port and hold sufficiently to be safe.  One port will not matter much if you want to just leave it and drive it the way it is.  We are not talking a lot of cfm difference, probably less than 10cfm max.  I was just trying to save you a lot of work.  Make the other 7 ports the MR size on the sides and top, and leave the bottom alone.  It will work well on the street.  Joe-JDC

[TorinoBP88]

Edelbrock factory instructions basically say not to port the streetmaster  intake floor.