Re: Headers to 2.5" Ramhorns
 

Thanks for digging that info up, Pete. I picked up a set of flat spark plug heat shields from ebay that, while not original, come with bolts (attached) that can get me by until I get correct bolts. I posted a picture of the tented heat shield you shared with me and I purchased two of so folks have a visual reference.

The last two photos are used stove and heat shield sets designed to work with the ram horn manifolds we have been referencing. There are slight differences in these sets (two tented shields vs one) and stoves with no holes vs two holes. I've seen plenty with one hole but from what information I gathered the stove with two holes was specific to CA trucks subject to CA emission standards. I could be wrong so please correct me if I am misleading folks here.

Re: Headers to 2.5" Ramhorns
 

Are the spark plug wires routed around the sides and under the manifolds? My plug wire retainers are gone so I could use some direction on where these wires should be routed and what retainers should be used to work with ram horn manifolds. The attached photo seems to show two small spark plug retainers.

Where would these go? I presume these go somewhere halfway on each side since they hold only two wires each.

Re: Headers to 2.5" Ramhorns
 

If I'm reading the parts manual correctly, there are three examples each w a different part numbers for 71-72 small blocks: 3919807 left front, 3917664 right rear, and 3817657 left rear and right front. I'll edit this post later w photos that illustrate each.

I've not been able to locate a p/n for the heat stove. Definitely, the CA emission trucks used the two-hole version. It seem though that there are more two-hole versions floating around fwiw. I suspect the two-hole design was also used on at least some non-CA emission motors. I'll look through my base line photos of the 350 that's now in my K20 to see what it had. This engine came totally complete from a running survivor K20 Suburban w ~50k miles on it. Also, I'm wondering how well the repro vette pieces will fit since I believe these are designed for 2.5" outputs rather than the 2" for K trucks.

EDIT: Engine photos here. Not best angle but stove appears to lack the holes http://67-72chevytrucks.com/vboard/s...7&postcount=20

Mine are off in winter storage. I need a separate garage.

Plug wire routing is a great topic that I need to know more about. I'm thinking there may be existing threads on the specific topic we can dig up and bring to life.

Re: Headers to 2.5" Ramhorns
 

Great info and the photo is a really nice reference to see what else is missing and where it should go, thank you.

The repo ram horn exhaust manifold a I picked up are 2.5” straight dumps (probably cast from trimmed Corvette manifolds). I'm curious how they will fit too.

Re: Headers to 2.5" Ramhorns
 

Here's a pic of how I mounted mine, I used a stud for ease of mounting the 2 pieces of shield and spark plug wire mount, but the mount for wires will only fit 7 mm wires, plus being bare metal leaves a lot to be desired, you could plastic dip them

https://live.staticflickr.com/8141/2...f31b92ea_c.jpgWIN_20160921_10_03_04_Pro by [url=https://www.flickr.com/photos/97391199@N06

Went through all my pics, and this is the only one I have of that area, the wires come straight down from the spark plugs to the clips you have shown, then to the clips on the oil pan clips, and then up to the brackets on the block by the distributor

I'm pretty sure the corvette wires are 7 mm,IIRC

Re: Headers to 2.5" Ramhorns
 

Thanks for providing a photo and explaining. This might be an obvious answer but what are U shaped washers(?) behind the manifold bolts designed for? I don't have them. Are they necessary?

Re: Headers to 2.5" Ramhorns
 

Imho, they are the best way of preventing the exhaust manifold mounting bolts from getting loose( OEM )

Usually, you would run 2 or 3 heat cycles, then bend the small tabs over, locking the bolts in place

Re: Headers to 2.5" Ramhorns
 

Ahhh... I see the tabs now. Makes sense. Thanks!

Re: Headers to 2.5" Ramhorns
 

Corvette parts suppliers like Zip carry those French locks for the manifolds.

Re: Headers to 2.5" Ramhorns
 

Found them, thanks Pete.

https://www.zip-corvette.com/66-80-3...stainless.html

Good you sent me there- I noticed something about the exhaust manifolds when comparing them to the set I purchased.

Zip-Corvette shows exhaust manifolds that have the correct raised flat fins on top while the set I purchased from Assault Racing do not. The set from Assault appears to have had a lot of material removed from the outside and have been smoothed. Not sure what effect this will have long term (cracking) or if the stove assembly will fit properly on the Assault manifold.

Re: Headers to 2.5" Ramhorns
 

There are so many choices... which are the right ones for our trucks?

https://www.zip-corvette.com/68-82-c...manifolds.html

Re: Headers to 2.5" Ramhorns
 

You bet. The Corvette suppliers carry a lot of overlapping parts and I wish I had gone to these sources years sooner.

To me, the image depicts a combo of repro and GM manifolds. The example in the upper left corner looks correct for both sides for a non-AIR engine. I believe pickups had a 2" outlet. A quick search should turn up the correct p/n's for the manifolds.

Re: Headers to 2.5" Ramhorns
 

Old thread but good info nonetheless.

I just replaced the wire heat shields on my 1970 Blazer 350, and it used two 3919807 "tented" shields with the hole for clearance of the temp switch/sensor. One of those is the RH rear position and the hole is for the TCS high temp switch, and the other is LH front for the temp switch/sensor for the temp light or gauge depending on optional equipment. This is contrary to all of the GM parts books which state that the 3919807 shield is solely for the LH front position. Both front shield positions have the separate small steel two wire looms 3744408 for proper spark plug wire retention. The other two "flat" shields used on my application are 3817657 or 3917663, which fit the LH rear and RH front.

3817657/3917663:

https://i.ebayimg.com/images/g/fQgAA...RA/s-l1600.jpg

3919807:

https://i.ebayimg.com/images/g/bWAAA...Ld/s-l1600.jpg

3744408:

https://i.ebayimg.com/images/g/xCUAA...u1/s-l1600.jpg