1970 300 Hurst motor.

[commando1]

Just curious, what does the "H" pipe actually do for performance over straight dual exhaust?

So little on a C-body that when you need to drop the driveshaft, you'll wish you hadn't done it.

 

[rush]

I have a big comp cam in mine and it does not like to have the air on at an idle. I do have a stick in it so I can get away with it but if I was you I'd stick with a stock 375hp cam better vacuum =brakes. I'd look for a good set of used aluminum heads as they dissipate heat better and you can run a little more compression .TTI makes very good headers but as all headers go they can be pita when you need to work on it.
H-PIPE like this.

 

[BIGBARNEYCARS]

Samplingman, The H-pipe allows the exhaust gas preasure to balance out before it exits the exhaust pipes. Only issue I know of is that if both pipes are not built with flanges and a removal cross over piece you MUST drop the whole exhaust system off the engine to do anything under there! And for what? Ah few more horses that are too few to measure?

 

[Wollfen]

I have a big comp cam in mine and it does not like to have the air on at an idle. I do have a stick in it so I can get away with it but if I was you I'd stick with a stock 375hp cam better vacuum =brakes. I'd look for a good set of used aluminum heads as they dissipate heat better and you can run a little more compression .TTI makes very good headers but as all headers go they can be pita when you need to work on it.
H-PIPE like this.

Hey Rush, nice how you manage to turn your car over to work on it, more workshops should be able to do this

 

[rush]

The exhaust is pretty. The shop I take it to really likes to work around it actually I've haven't had to do anything under the car except for changing the starter out and I still have the stock manifolds on it so no problems .

 

[Samplingman]

Great info, thanks. Seems like this "H" pipe thing is a modern development, I don't remember ever seeing one back in the day.

 

[70bigblockdodge]

I believe Chrysler was the first to use it on the hp models back in the day, the X is a more recent development.

 

[bluefury361]

The H-pipe allows the exhaust gas preasure to balance out before it exits the exhaust pipes. QUOTE]

What Jer says ........ The H pipe will balance the exhaust "pulse" from bank to bank and enhanse both HP and Torque. Also, as a bonus, creates a much more mellow exhaust note. Part of the unique "Mopar" big block sound.

We used to determine the optinum position of the "H" on custom exhaust applications by painting the exhaust pipes behind the engine and before the muffler .... Run the engine to hot and located the "H" where the paint no longer burned off.

 

[Fratzog]

This is some of what went into the 440 in the Monaco a few years back...makes for a lively street motor.
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=706&sb=0
http://www.summitracing.com/int/parts/cca-1322-16/overview/
http://www.ebay.com/bhp/edelbrock-2191
http://www.ttiexhaust.com/PDF/C_MNM6573.pdf

 

[BIGBARNEYCARS]

Samplingman. My 1st memory of the H-pipe on one of Motherz production car waz the '66 Hemi Charger. And once the two center pipes that made the H were clamped together you were screwed. Sawz-all or fire wrench time for removal, Jer

 

[Mopar001]

yep, it is a Hurst with a AVS. I pulled the intake off today. was going to pull the heads off and get them rebuilt but, that cam looks warn down really bad, so, plans have changed to total rebuild of the motor. Hope to have her running this spring.

 

[Mopar001]

Ok, Now. When I get the heads redone, can I just get them ground and reseated and use a Lead additive? Or put all new valves and seats and burn unleaded? This car will be a once or twice a month cruiser. HELP!!!

 

[70NPORT]

Although it doesn't sound like the car will be driven much, If the heads are coming off I'd have hardened seats put in then you can burn unleaded without any cares.

 

[commando1]

Buying pints of lead additve and adding them every fillup is a PITA. Go for the hardened seats.

 

[BIGBARNEYCARS]

BTW Mopar001. That's 8 seats not 16. The exhaust side are the critical ones for hardened seats unless you're going way oversize on both sidez. And DO NOT BYPASS having the heads and deck flattened, It's cheap insurance. Those are 906 heads on that 440 and they are known to warp over time. The last 440 I had rebuilt the builder straight edged the deck and missed a low spot between #3 and #5 and another low spot in front of the forward mounting pin. I got 13 hours out of ah complete rebuild and lost the engine, and we won't talk about what the builder said when I came back on him!