Edelbrock intake fit.

[Fathead Racing]

Did a dry fit on the Edelbrock big port dual quad intake just a while ago on cast 690s. The 881 that I took off had the upper bolt holes or slots cut down at one time to fit low perf heads. I have Moon valve covers on the heads and left them in place when I pulled the 881 intake, the manifold cleared the valve covers. When I put the Edelbrock between the heads the upper bolt holes or slots would not clear the valve covers in this area. Has anyone had this problem? Also the oil splash pan was not fit tight against the mounting surface port area of the intake and I think under the right circumstance it could lock the intake to the heads if you pushed the sheet metal below the head port area. Does anyone see this? I never did get a chance to see if the bolt holes lined up! I got out of the garage before I started to have a bad day. : I'll tackle the intake again tomorrow.

 

[CDNpontiac409guy]

Fat, I don't know about installing the factory GM splash shield under the Edelbrock intake. It's a tricky fit at best.
I'd be inclined to block the ex heat crossover s at the cylinder heads, and fabricate my own "partial shield" for under the rear portion of the manifold.

On my manifold, we've pretty much finalized a design in the pattern/casting that is self-baffling ( which is not such a concept that one should find baffling ), so no shield will be required. Actually, this has been one of the hold-ups in getting the manifold done.

 

[Fathead Racing]

Yeah, I think Edelbrock could have thought the oil separator thing out a little better, Actually, the stock sheet metal shield fits pretty good. I think my problem is this shield got beat around a little from storage. I massaged the shield some and the fit is acceptable. I drilled and tapped the holes in the intake using the stock shield as a pattern. Only one hole was not doable, due to a design change at the pvc bung. I am going to remove the valve covers and see how much material needs to be removed from either the vave covers or the intake to seat the valve covers. Exhaust crossover has been blocked with stainless always. The intake will be finished today.

 

[Skip FIx]

When I put the factory 881 intake on the Edelbrock heads on the flow bench there was a slight issue with the factory splash pan hit the bottom of the head below the intake ports. On the E head the E intake slots were not deep enough to line those holes up. Will need some slotting.

 

[MRHP]

intake concerns

Fatride, also pay attention to the distributor mounting flange. I had to use 2 gaskets or the oil pump shaft would have bottomed out into the oil pump. I believe .060 clearance should be considered the minimum on the shaft to pump clearance. Good luck. I am just using the front breather for now and no pcv. If it is not enough venting, I will add some sort of breather to the back of the covers as to not detract from their good looks.

 

[Fathead Racing]

Just got out of the garage after a 5 hr flog fitting the Edelbrock "bolt on intake" to the 690 heads. A lot of the problem had to do with the upper bolt hole flange interfering with the Moon valve covers. When I put the valve covers on they would bottom out on the intake on the upper bolt flange not allowing the valve cover to be tightened to the gasket. I probably removed over an 1/8" from the intake in this area. The other issue was the angle/depth of the same bolt slots. I found it was more of the angle than a depth problem. The inner slot seemed to clear the bolt hole with a minimum of grinding while the angle needed major massaging. Anyway, it's on the engine now. Looks good and the fit seems to seal very good. All in all I would recommend the intake if the track times compensate for the added time it took to modify for fit. The stock sheet metal oil separator after some massaging seemed to fit ok. I have the MSD distributor and had to double up on the gasket to keep it from bottoming out on the oil pump drive with the 881, I will watch this area.

 

[Brian Thompson]

Ray-

I too had the same problem with the upper holes on the Edelbrock intake with Edelbrock heads! The only problem with valve covers is with the Offy's. They hit the head studs, so I had to grind the lip of the valve covers to make them fit. I probably could have gotten away with just doubling the gaskets to make them fit.

I do agree with you, these should have been "bolt-on" intakes.

 

[b-d409]

Ray,

Sorry I am chiming in so late. The replacement splash pan that ShowCars makes fits the 881 like it was made for it. I also had problems with the upper bolt holes/slots and had to have them deepened to be able to get the bolt to line up. I didn't have any issues with valve cover clearance, but I am using stock covers. As Aubrey suggested to you, I used block off plates on the heat riser crossover when I installed mine. Cooler carbs are always a good idea.

Dan

 

[62impala409]

Doesn't blocking off the crossover passage in the intake manifold change the sound of the exhaust? I blocked off the crossover in my 0540 manifold several years ago and it sounded like a four cyl. car at idle. My pipes exit aft of the rear wheels. I took the plates back out the next day and the motor sound was way different!!!!!

 

[b-d409]

I does seem that my exhaust is much quieter with the crossover blocked off. I couldn't put my finger on the cause at first. Anyone know why a blocked crossover would cause that. My understanding was/is blocked crossover = cooler carbs = more performance. If I am wrong here someone please correct me.

 

[Fathead Racing]

Nope, your right Dan, blocked crossover helps keep the intake cool for a more dense fuel charge, more fuel = more power. Yes the blocked ports will cause the engine to sound a little different. That is because there is a direct path via the intake that links the two heads, exhaust ports together. If you peer down the crossover port in your heads you should be able to see the exhaust valves in one or more cylinders. I would think the link along with valve timing in the connected cylinders would promote hot exhaust gas flow through the intake crossover port. I always likened this link to the same effect as the exhaust crossover pipe you would plumb into your exhaust system under the car. This is the way I understand it.