WTB - Plenum insulator plates
 

All,
I need to source a set of phenolic plenum spacers. Wish I'd bought Lee's last year for a good price.


Anyway, I'm hoping to use these to correct a slight misalignment I'm having with the ports on my personal engine. Would rather grind on the phenolic to make a smooth transition between plenum & IH.

Re: WTB - Plenum insulator plates
 

Todd,

I've been running a set for years - I purchased 1/4" phenolic sheet from NORVA Plastics when I lived close to them (they sell excess job material on eBay), and made my own using the gasket as a template. The material is very easy to work with and cut/shape/sand as needed. They are currently selling 1/4" sheets on eBay (G10).

Good Luck!

Regards,
Mark

Re: WTB - Plenum insulator plates
 

G10 is not the same as phenolic. Phenolic is cotton, linen, or paper. G10 is fiberglass. It is more dense, and much harder on tooling. Just an FYI. I was a manufacturing engineer in a job shop where we sold and machined a lot of both.

Re: WTB - Plenum insulator plates
 

Not to Hijack a thread but what is the advantage or disadvantage to these spacers. I've never really got a straight answer from anyone. I have a set on my car that a previous owner had put on and I thought about removing them when I do my first plenum pull if they are not helping the performance of the car.


Steve,

Re: WTB - Plenum insulator plates
 

Principal Advantage: Thermal insulator for plenum, to impede heat soak from the engine
Other Advantage: Marginal increase in air circulation under plenum, aids in cooling of plenum & DIS Module.

Disadvantage: 1/4" spacers frequently result in intake contact with underside of hood.
Disadvantage: Requires some bending of vacuum line to PCV top connector.
Disadvantage: requires 2 sets of plenum gaskets. & longer bolts

Re: WTB - Plenum insulator plates
 

I know Todd needs them for another purpose, but the spacers introduce one more place for a vacuum leak.

Re: WTB - Plenum insulator plates
 

^^^ what he said. I'm not doing this for any performance impact, and I doubt the claimed benefits of plenum insulation are even measureable!


I just need the spacers to improve the transition interface between the housings and plenum. What happens, in my case, is a slight decking of the block, combined with skim cut on the cyl head deck, and a thinner MLS gasket = the heads sit fractionally lower. The plenum ports no longer line up perfectly with the housings, so I need to fix that. We're talking millimeters here.


One added consequence, the extra 1/4" or so should move the natural tuned length of the intake slightly lower (perhaps 100 rpm). Peak torque on Build 1 was 5800 rpm, which is more or less where the factory HP peak was, and where the stock runner length is tuned.

Re: WTB - Plenum insulator plates
 

Todd, I have a used set of 1/4" on an engine I acquired last year.

Re: WTB - Plenum insulator plates
 

Todd,

If you don't get the set from Jerry, I have a new set that I bought from Lee earlier this year. It sounds like you need it more than me.

Aloha,
Craig