Hard start & fuel boiling > Some interesting carb insulating data

[firefighter3931]

Just thought i'd throw this info up to illustrate the effectiveness of blocking the cylinder head heat crossover and insulating the base of the carburator. These questions often come up so here's a little data to chew on.  

Background : Recently i helped a buddy fire up a new engine build and break in the cam. When he was assembling the engine i recommended the Felpro 1215 intake gasket which blocks off the heat crossover and a carb spacer or thick base gasket. Denis installed the 1215 valley pan and a 1/2in spacer. During the breakin i measured temps in several locations to make sure there were no issues. The infrared heat gun is an excellent tool to help monitor EGT's as well as other vital points of interest during the breakin.


On to the pertinent data. While breaking in the cam & fresh engine i took several readings of the engine at different locations and at different times during the breakin period. Worth noting are 3 different temp readings from the top end of the engine :

(1) cylinder head surface temp : 231*F
(2) Intake manifold surface temp : 198*F
(3) Carb main body surface temp : 129* F

* This particular build has iron heads and an iron intake manifold


These readings were all taken at the same point in time....literally seconds apart. From the data it looks like the heat crossover block off is worth a 30* reduction. A further reduction of 70* was achieved with the phenolic spacer.  

So, the  two mods together offer a combined reduction of 100* in temperature. Given the poor quality fuel available these days and the fact that this fuel is designed for high pressure (EFI) fuel systems....these are certainly worthwhile modifications.   Cooler fuel makes more power and is less prone to vapor lock/fuel boiling  



Ron

[Steve P.]

Yet another great tip from our resident smart guy....   I think we should sticky this and the motor mount fix... Not to mention about 3000 other great tips...   

[69chargerR/T]

Thats good info Ron I have the 1215 intake gasket I'm going to put on when I do my cam swap. I don't have room for a carb spacer with the rpm intake, but I use a thick carb gasket. Alan



     PS. How come I don't see any of your engines in the proven engine builds. I'd like to see your builds

[Sublime/Sixpack]

I can understand the benifits of blocking off the crossover, but don't you need the crossover open for proper choke operation? Or am I not thinking through this correctly.

[flyinlow]

That's more temperature drop than I would have guessed for the insulator. Definitely great bang for the buck HP. 

What was temperature that day?

Thanks for the info,

Craig

[flyinlow]

Hey Ron,

How much Heat do Firemans coats insulate you from?

[Ghoste]

I can understand the benifits of blocking off the crossover, but don't you need the crossover open for proper choke operation? Or am I not thinking through this correctly.

Not so much for choke operation as choke assist and emmissions.  The idea of the heat crossover was to get heat under the plenum of the intake and reduce fuel puddling and get everything atomizing better.  This sound fine except for a few key points.  First, the quality of modern fuels as Ron mentioned; they boil too quickly and make the crossover contribute mightily to vapor lock.  Second, one of the reasons for crossovers as you noticed was to help with cold weather operation, but it is cold weather operation from a large scale manufacturing compromise point of view.  These cars when new had to operate in Arizona and Alaska.  Drive your car much in the winter?  And I mean real winter.  Most of us, when we take these cars out it is rarely in freezing temps and when we take, it is seldom a jump in and throw it in "Drive" right away to get to work.  We let it warm up in the driveway for out afternoon cruise.  Lastly, the heat crossover robs power and many of us drive these cars for the feeling of power they have available.  Our compromise today has become one of better acceleration over less practical utility driving.

[Just 6T9 CHGR]

Damn and to think I only used that block off valley pan so the paint wont burn off my freshly painted intake manifold

PS---be sure to use the FelPro brand one that solidly blocks off the port....the Mopar Performance version uses the pan that is mfg'd with the hole open & they supply you with 2 hokey strips of metal to lay on top of the open holes

[jerry]

sounds good for some.i wouldn't try spacer blocks on a 69 1/2  6bbl car or a 70 charger six pack unless you plan on driving without hood . for good info Ron. [just kidding around]

[Nacho-RT74]

I do have the phenolic carb insulator because in fact rebuilt kits for TQ already carries them... but THERE IS NO WAY I will block the crossover...is great get the choke propperly working with the crossover help and electric choke control unit assistant. Just 4-6 minutes to get a nice iddle instead 10-12 minutes.

GREAT INFO THOUGH RON!!!

[tan top]

good info Ron    100 degrees thats a lot 

[FLG]

Id be curious to see how the TQ carbs helped to lower temps even more considering their main bodies were a type of plastic 

Granted im not going to be running one in the finished engine (whenever that may be LOL), but i run one on my 400 and shes happy.

[kamkuda]

There is a local guy how was having some performance issues, including intake paint burning off. (the guy with the charger that we met at the Canadian Tire Cruise) This may be a help.
Thanks

[Sublime/Sixpack]

It would be interesting to have a heat measuring gun like Ron is using.  I'm a curious type so I'd probably be checking the temp. of the various engine parts plus the brakes, transmission, u-joints, diff., etc.

[Steve P.]

Try here:  http://www.amazon.com/gp/product/B0017L9Q9C?gclid=CNDL0LDp-pcCFQJvswod1HZYDg



I know discount auto and Auto Zone both sell them as well. 

[John_Kunkel]

I'd like to see comparative numbers with the identical setup only with the crossover open.

[Sublime/Sixpack]

 

[Sublime/Sixpack]

Try here:  http://www.amazon.com/gp/product/B0017L9Q9C?gclid=CNDL0LDp-pcCFQJvswod1HZYDg



I know discount auto and Auto Zone both sell them as well. 

Thanks Steve, I was expecting them to be more costly. Think I'll use some of my Christmas money for one.

[firefighter3931]

PS. How come I don't see any of your engines in the proven engine builds. I'd like to see your builds

Alan, i had a 4 page writeup on the 446 on the old D-C.com but it vanished when that board folded up. I should repost it sometime. 

I can understand the benifits of blocking off the crossover, but don't you need the crossover open for proper choke operation? Or am I not thinking through this correctly.

The choke will still work....it will just take longer to close. Honestly, this engine didn't take any effort to fire...and it reached operating temp quickly even in the unheated garage with a blizzard raging outside. 

What was temperature that day?

Craig

Craig, it was cold out that day.....15in of snow fell while we were working on that car. I almost didn't make it home, lol ! Had to make an emergency pit-stop at Home Depot for some sandbags to help with some "high-tech" traction control on the 2wd 1/2 ton Ram. 

Hey Ron,

How much Heat do Firemans coats insulate you from?

The bunker suits work extremely good....they are flashover rated to 3500*F (NFPA rating) and i have been in live training with interior burnhouse temps exceeding 600*F. Trust me....600* is plenty ! 

Not so much for choke operation as choke assist and emmissions.  The idea of the heat crossover was to get heat under the plenum of the intake and reduce fuel puddling and get everything atomizing better.  This sound fine except for a few key points.  First, the quality of modern fuels as Ron mentioned; they boil too quickly and make the crossover contribute mightily to vapor lock.  Second, one of the reasons for crossovers as you noticed was to help with cold weather operation, but it is cold weather operation from a large scale manufacturing compromise point of view.  These cars when new had to operate in Arizona and Alaska.  Drive your car much in the winter?  And I mean real winter.  Most of us, when we take these cars out it is rarely in freezing temps and when we take, it is seldom a jump in and throw it in "Drive" right away to get to work.  We let it warm up in the driveway for out afternoon cruise.  Lastly, the heat crossover robs power and many of us drive these cars for the feeling of power they have available.  Our compromise today has become one of better acceleration over less practical utility driving.

That pretty much sums it up...well said Ghoste ! 

Damn and to think I only used that block off valley pan so the paint wont burn off my freshly painted intake manifold

It sure doesn't appear that blocking off the crossover hurt the looks (manifold paint) or performance (low 13's on street tires) of your car Chris. 

There is a local guy how was having some performance issues, including intake paint burning off. (the guy with the charger that we met at the Canadian Tire Cruise) This may be a help.
Thanks

I remember that sweet looking Charger ! Pass this info along to him Rob....it will help for sure ! 

It would be interesting to have a heat measuring gun like Ron is using.  I'm a curious type so I'd probably be checking the temp. of the various engine parts plus the brakes, transmission, u-joints, diff., etc.

Yes the heat gun is an excellent tuning tool. I like to look at temps at different locations on the block which could indicate a potential issue with the cooling system. Hot spots might indicate an air pocket in the cooling system. I also like to keep an eye on the header/ex manifold temps for signs of lean carb or timing issues. Radiator efficiency can also be guaged by comparing temps at the inlet & outlet to see how well things are working.

I'd like to see comparative numbers with the identical setup only with the crossover open.

I'll have to check that sometime John....most guys i know run the 1215 valley pan or aluminum heads that have no crossover provision.



Ron

[Sublime/Sixpack]

The taking longer for the choke to open is what concerned me. The choke pull off works but still . . . .

[Nacho-RT74]

if your choke coil is wired you can mount an electrick choke asistant to help, they float on ebay quite often... BUT IMHO still in that way

this is single stage control... sending just one voltage stage. they are theorically for SBs
http://cgi.ebay.com/ebaymotors/1973-1974-Choke-NOS-MoPar-Runner-Cuda-Challenger-Dart_W0QQitemZ140270538372QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item140270538372&_trksid=p4506.c0.m245&_trkparms=72%3A727|65%3A12|39%3A1|240%3A1318

double stages are supposelly for BBs and send two diff voltages depending of engine bay temp variation. Is the same piece but with a ballast on it.

[Chryco Psycho]

Ron do you have comparative #s with an Alum intake ?

[Silver R/T]

Good info, thanks for posting

[ACUDANUT]

What, no pic's of these ?

[bakerhillpins]

About to order the parts for the crossover block off and the insulating spacer and have a few questions. I have a 69 RT, auto with AC, OEM intake and 4640sa carb.

Of the 3 Edelbrock Heat Insulator Gaskets (9265/9266/9267) that I see at Summit I wonder which is more appropriate for a stock 69 iron intake?
I see that the 9267 is for the dual quads but I figured I could just use one or both under the Carter AVS for my application?  

I recall reading in the myriad of thread hits I got in searches that getting a 4 hole gasket (67) would give faster throttle response (and more manifold vacuum?) and the open center (65) would help on top end?  Do I have that correct as I can't seem to find that thread again.  

With regard to the Fel-Pro Q1215 block off gasket I understand that it isn't necessary to use the supplied gaskets with the stock parts unless they have been surfaced? And that each pathway should rather be sealed with a copper based RTV?


If I remember I can probably borrow the IR temp meter from the office and get before/after temps.