'69 u20 w/Mikunis' Heat Shield Question

[Dan_Magliari@Yahoo.com]

Hi - hoping I might solicite some guidance from the group.

I recently bought my first roadster after a couple of good experiences with my earlier '70 240 & '78 280s.

I picked up a nice '69 u20 Roadster with the twin Mikuni 44 Carb set-up. I have been going thru the engine & exhaust - making my first pass at dialing things in.

After pulling the Intake to go thru the Carbs, and sending the Header out for Jet-Hot Coating, I think I'll have my first set of projects pretty much dialed - well that is except for that cracked & dangling heat shield that lives between the Carbs & the Header. ... OK, here's my (hopefully not too lame) question.

- How critical is this heat-shield to proper carb operation? At this point? I am wondering if after I get the header back - with this nice slick ceramic Jet-Hot coating, if this shield will still be something I need (?)

The existing shield looks like it's had a hard life and has been rewelded once or twice in the past & has rattled apart once again. Before I replace it, perhaps I can just forego this reinstallation of this fine piece. oooor if not, ...Any thoughts??

Many thanks for the feedback.

Dan Magliari

[Minh]

I'm don't have the entire answer to this one.

I am assuming someone else on the baord will give a better answer.

However, I have seen a brand new heat sheild on Ebay up for sale every other week. I think it goes for about $30-35.

If you need it sooner than any of the vendors will probably have that part readily available. No idea how much they charge though, sorry...

[spl310]

You really do want the heat shield. You also want to have the heater hoses connected to the manifold properly (not blocked off as suggested in the Bob Sharp manual) for a street car. You can have the heat shield welded and chromed if you want, or to be really slick, trace it and have one made from aluminum - you can polish it! Another thing to consider is to rivet or bond some header wrap to the back side of it. Heat is a bad thing....

[SLOroadster]

It sounds like you have almost the same setup as I have. I made a heat shield out of thin Stainless steel stock. I basicly copied the real thing, traced it out on the stainless stock, and cut it out with a set of metal shears. My heat shield is identical to the real thing except for the ridges that the real thing has. It was easy enough to make. After cutting it out I polished it up with my buffing wheel, It looks really good with the Jet Coated headers. I also painted my intake with 1200 degree stable silver engine paint. It is almost the same color as the headers. Looks sharp.
The ceramic coating on the headers does keep underhood temps down, but you still want the heat shield.
If you have the engine out, install the front carb and heatshield as well as the rear carb insulators (but not the carb itself) That will ensure that the intake and headers are firmly in place (because trying to get your hand on the rear nuts under the headers is nearly impossible in the car.) Once the engine is installed, then install the rear carb onto the insulators ( it won't clear the brake master otherwise) the front nuts on the carb are much easier to get to than the ones under the headers.

Will

[Ldino21]

You can always get a new heat shield from Rallye they have them for around $50.

www.datsunroadster.com

Thats where I got mine!!

Lou Smaldino
66-1600
67-2000

[Dan_Magliari@Yahoo.com]

Very Good feedback from all, thank you.

I thing I will go the route of fabricating a replacement. I don't think it would be a big deal to make. The SST approach would look good.

Also thanks for the input on not to plug-up the cooling hoses running thru the manifold. I was tempted to do that to clear up some clutter, but was being cautious for fear of mucking up the cooling. I'll stay with it the way it is.

While I had everything out, I bead blasted the intake manifold & carbs to clean them up. Looking clean. Slowly but surely it's come together.

Target my first good run to Solvang this April.

Thanks again to all for the feedback.

Dan

[SLOroadster]

Dan,
Where are you. I have a cracked heat shield that I used as a templet. I used a set of sheet metal sheers (hard on the hands) to make mine then I ground the edges smooth.

Will

[Dan_Magliari@Yahoo.com]

Will,

Thank you for the offer.

I am still toggling along at this moment.

I still have the old one & just had it welded up at a local exhaust shop, but..... of course then I get ta thinking.... how long will that weld actually hold ??? I am toying with the idea of hogging one out of sheet metal or SST. (good opportunity to torment myself further).

I am in San Jose. Thank you for the offer for your template, but I think I should be able to use mine as a baseline should I go that route.

Thanks again.

Dan

[spl310]

If you are going to make one that is custom, I have a suggestion. Heat is the enemy so to speak. The production unit - while good - is a compromise for ease of production. Take a look at it and see if you can improve things. You can make it bigger, more custom fitted, or just different. Take a look at this page:

http://home.att.net/~jason510/weber.htm

Jason made a custom heat shield that is MUCH more effective at shielding the carbs from heat. You could almost encapsulate them in a heat shield - sort of like the "turkey pan" from the 427 Cobra. Just a thought.