Your suggestions please, I am jonesing to build.

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HemiEd

HemiEd

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I have built a lot of motors but things have changed tremendously with all the newer options, and I would appreciate your input.

Currently, my 68 has a motor that is wearing me out, even though it is very fresh, less than 300 miles. It has about 210 lbs. of compression cranking on the starter, and requires race fuel.

It is a 340, with a .200 stroker, to make it 3.5100 and Wiseco flat tops and Scat H-Beam rods. I pocket ported and gasket matched a set of J heads myself. I have a hydraulic Comp Thumpr 486/473 227/241@50 with Harland Sharp roller rockers.

I am tired of it, and want to build something a lot more streetable, that runs on pump gas. $$$ is an object, a serious one right now.

I hate to break up the 340, as it is balanced, and makes gobs of power. I am planning on just putting it on an engine stand, so it can be on "call."
Currently, I have a standard bore 360 that I want to work with, but have never used an external balanced motor.

Some of my thoughts are to build a 4 inch stroker motor, with low compression dished pistons. (anyone done this?)

However, the 3:58 stock crank is a very nice piece also, it appears to only need polishing. It would also save a lot of $$. I have had it all apart now for a while, so Saturday I am running it to the machine shop so they can hot tank it, and tell me if it needs bored or not.

I am also thinking about using off the shelf RHS heads, or Eddys, not sure which. I have an LD 340 that will be used as the intake.

What would you build?
 
Do you race?

If you do, then keep your current motor.

If you dont, quit pissing around with all of the high dollar, high HP parts. Just build yourself a stock motor with cheap, easy to obtain parts, and run it that way. It'll be dependable, economical, and still fun to drive. Stock Mopar motors put out plenty of HP.

I just dont understand the guys that build a balls out, high hp motor, then all they do is take it to cruise-in or run a couple laps around town. I think they just like to brag about how much useless horsepower they have. I have a friend that has a hemi pushing over 1000 hp. He never takes it anywhere but shows, and constantly complains how expensive it is to operate. All of my cars have stock, or close to stock motors, and they're more than enough to have fun with, and I can afford to drive them.
 
Thanks for the post, great point. NO, I do not race anymore, in fact this is a convertible and I don't want to put a bar in it.

I am very guilty of what you said, guilty as charged. But, on the other hand, it is a toy.
 
jeryst said:
I just dont understand the guys that build a balls out, high hp motor, then all they do is take it to cruise-in or run a couple laps around town. I think they just like to brag about how much useless horsepower they have.
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I am that guy, don't race, mostly just joy rides, its just a toy. I like the feeling of massive gobs of torque, the thrill of driving a car with a lot of power. Is it practical? Absolutely not! But I get a smile on my face every time I take my car for a drive and to me that is what it is all about.
 
hemied said:
I have built a lot of motors but things have changed tremendously with all the newer options, and I would appreciate your input.

Currently, my 68 has a motor that is wearing me out, even though it is very fresh, less than 300 miles. It has about 210 lbs. of compression cranking on the starter, and requires race fuel.

It is a 340, with a .200 stroker, to make it 3.5100 and Wiseco flat tops and Scat H-Beam rods. I pocket ported and gasket matched a set of J heads myself. I have a hydraulic Comp Thumpr 486/473 227/241@50 with Harland Sharp roller rockers.

I am tired of it, and want to build something a lot more streetable, that runs on pump gas. $$$ is an object, a serious one right now.

I hate to break up the 340, as it is balanced, and makes gobs of power. I am planning on just putting it on an engine stand, so it can be on "call."
Currently, I have a standard bore 360 that I want to work with, but have never used an external balanced motor.

Some of my thoughts are to build a 4 inch stroker motor, with low compression dished pistons. (anyone done this?)

However, the 3:58 stock crank is a very nice piece also, it appears to only need polishing. It would also save a lot of $$. I have had it all apart now for a while, so Saturday I am running it to the machine shop so they can hot tank it, and tell me if it needs bored or not.

I am also thinking about using off the shelf RHS heads, or Eddys, not sure which. I have an LD 340 that will be used as the intake.

What would you build?
Click to expand...

Honestly, I would fix the 340 for a lot less money. You can fix this in one of 3 ways. 1 Buy custom dished pistons for your assy and have it re ballanced. 2 Put a stock 340 crank in it with lower compression pistons or 3 Buy a rotating assy stroker or otherwise to install in the engine. Low machine work costs due to the fact of leaving everything the same and just cleaning the 340 up and having it puff honed. It's hands down the cheapest way to go and still get what you want. IMO.:toothy10:
 
340sFastback said:
I am that guy, don't race, mostly just joy rides, its just a toy. I like the feeling of massive gobs of torque, the thrill of driving a car with a lot of power. Is it practical? Absolutely not! But I get a smile on my face every time I take my car for a drive and to me that is what it is all about.
Click to expand...
i agree. would never build a race gas motor however. when i finally get to it, i will have a 572 or so Hemi in my Dart, but it will not be a race gas motor. Roller cam and EFI yes, but no race gas stuff. I kind of feel that if it something you want, why not? You only live once......
 
340sFastback said:
Here is a thread about RHS heads:

http://www.forabodiesonly.com/mopar/showthread.php?t=88220

If you can afford a 4" stroke crank they make great torque and are ideal for street cars. It will give you the feeling of a big block but without the weight.
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I have been following that head thread, and would love to have them. But for my application, I think the stock ones may make more sense.

OH Yeah, that 4 inch crank has been calling me since they released it. I have a buddy that is running mid 9s with one


340sFastback said:
I am that guy, don't race, mostly just joy rides, its just a toy. I like the feeling of massive gobs of torque, the thrill of driving a car with a lot of power. Is it practical? Absolutely not! But I get a smile on my face every time I take my car for a drive and to me that is what it is all about.
Click to expand...
X2, it is amazing how that .200 changed the manners of the 340. I have had a lot of 340s, but this one is really different, it is a lot torquier but still kind of winds like a 340.



hemijoejr said:
Honestly, I would fix the 340 for a lot less money. You can fix this in one of 3 ways. 1 Buy custom dished pistons for your assy and have it re ballanced. 2 Put a stock 340 crank in it with lower compression pistons or 3 Buy a rotating assy stroker or otherwise to install in the engine. Low machine work costs due to the fact of leaving everything the same and just cleaning the 340 up and having it puff honed. It's hands down the cheapest way to go and still get what you want. IMO.:toothy10:
Click to expand...

I have thought about that option, a lot, thank you. Already have the nice block, and rods, so the crank, pistons and heads would be the only big ticket items.
The current pistons are badass, and just plain pretty to look at. Maybe they could be sold at a swap meet, but with the odd pin height, nobody is stopping at .200 stroking so they would probably just become paper weights. I hate the thought of that.
 
You have to cut the compression down and go with a milder cam at minimum. Otherwise I don't see why it wouldn't be streetable unless the heads are seriously ported. Stock heads or Eddys would be fine. An Eddy RPM intake would be a good addition or any 2 plane. The LD is old but should work fine.
 
Start drawing that line between how serious your finances are and how fast you want this thing.....that'll pretty much determine if you use that 3.58 stroke crank or go 4". I'd go 408 if possible, with RHS heads.....and pay close attention to your cam selection and machine work, and get your block decked for the proper quench. That should still scare ya a bit......
 
jeryst said:
Do you race?

If you do, then keep your current motor.

If you dont, quit pissing around with all of the high dollar, high HP parts. Just build yourself a stock motor with cheap, easy to obtain parts, and run it that way. It'll be dependable, economical, and still fun to drive. Stock Mopar motors put out plenty of HP.

I just dont understand the guys that build a balls out, high hp motor, then all they do is take it to cruise-in or run a couple laps around town. I think they just like to brag about how much useless horsepower they have. I have a friend that has a hemi pushing over 1000 hp. He never takes it anywhere but shows, and constantly complains how expensive it is to operate. All of my cars have stock, or close to stock motors, and they're more than enough to have fun with, and I can afford to drive them.
Click to expand...


Man,you hit the nail on the head...i love seeing these guys at cruise-ins and show with these high dollar cars and engines.."ya it makes 800 h.p."..do you ever race it??.. no its just for show..WHAT A WASTE!!!..whats even more amusing is when they take these cars to the track thinking they're going to lay down some impressive number and the thing run a 13,always good for a laugh:toothy10::toothy10::toothy10::toothy10:
 
Hey Hemied! What are the dimentions of then pistons you have? (pin size, bore size, and pin height) I have several 3.480 stroke, 340 journal cranks that I bought when IROC closed it's doors. Your set of pistons might work with those cranks. Let me know if you want to get rid of the pistons if you decide to fix the 340.
 
hemijoejr said:
Hey Hemied! What are the dimentions of then pistons you have? (pin size, bore size, and pin height) I have several 3.480 stroke, 340 journal cranks that I bought when IROC closed it's doors. Your set of pistons might work with those cranks. Let me know if you want to get rid of the pistons if you decide to fix the 340.
Click to expand...

I think these may have come from that same close out deal. There was a lot of it on ebay just a few years ago.
The pistons and crank were Mopar Performance.
I would have to do some digging to find the specs on the pistons at home, because my memory is getting bad. But they are 4.06 bore and carried a MP part number for a 3.45 stroke crank.
I bought them thinking I might have to cut some off of the top, as they might end up as much as .030 out of the hole, but didn't have to, they ended up @ 0 deck height. They are standard pin size.

Been stewing on this hard this afternoon, with some great input here. I don't really want to break that motor down past the short block, it is just too nice. I will definately keep you in mind if I go that way.
 
do a search in these forums.. lotsa smart people building decent engines..

thats what i'm doing right now, hence i havn't been here much latey..

450+cube '308' headed pumpgas smallblock..

yah i love life.. later.
 
A-BOMB360 said:
do a search in these forums.. lotsa smart people building decent engines..

thats what i'm doing right now, hence i havn't been here much latey..

450+cube '308' headed pumpgas smallblock..

yah i love life.. later.
Click to expand...

Good advice, thanks a lot. I have been spending a lot of time reading some of these, great stuff. There are so many options now with all of this aftermarket stuff, the choices are almost endless.

When I was drag racing a BB, the best affordable option was a set of 906 heads, since nobody could afford Max Wedge heads. I milled them .130 and totally eliminated the quench area, they worked great.
 
Have you tried calculating your compression ratio? Can you put larger chambered heads on it? What about a thicker head gasket? Have you thought about backing off your timing so that it can run on pump gas? I would think those would be much cheaper and easily reversible if you want to get your performance back later.
 
juvat said:
Have you tried calculating your compression ratio? Can you put larger chambered heads on it? What about a thicker head gasket? Have you thought about backing off your timing so that it can run on pump gas? I would think those would be much cheaper and easily reversible if you want to get your performance back later.
Click to expand...
juvat, he's allready running J heads, a open chambered head @ approx. 72cc. Theres no bigger. He didn't mention that he milled it.
I was also tinking of a thicker gasket. Like a custom Cometic @ .060 though I don't know how thick his gaskets are now. Timing could be an issue as well like you mentioned, but it kills performance off alot!

What head gaket are you running now?

You said 210 cranking pressure, what does that convert to on a static ratio?
 
rumblefish360 said:
juvat, he's allready running J heads, a open chambered head @ approx. 72cc. Theres no bigger. He didn't mention that he milled it.
I was also tinking of a thicker gasket. Like a custom Cometic @ .060 though I don't know how thick his gaskets are now. Timing could be an issue as well like you mentioned, but it kills performance off alot!

What head gaket are you running now?

You said 210 cranking pressure, what does that convert to on a static ratio?
Click to expand...

All excellent questions, and well received, thanks!. You guys are getting into some stuff that I have never probably paid proper attention to.

You are right, that is the reason I thought I could get by with this, the open chambered J heads. They were only cleaned up in the milling, about .010 to square them. Same with the block, as we knew it was potentially going to be an issue.

I am running the cheap builder Fel Pro head gaskets, almost embarrassed to admit it. To my surprise, I have not blown them with all of the cyl pressure this thing is creating. I have purchased two new sets of Mopar Performance head gaskets, they measure .030.

I used to fight blowing head gaskets on my drag car motor, until I went to those Fel Pros with the stainless ring, but didn't ever bother to measure them.

I do not understand the difference in compression formulas, but I did plug the numbers into a link, someone had posted in another thread. It was around .488 or something like that, my short term memory is fried. :-D

I just know that 210 lbs. with almost no cyl to cyl variation is the highest I have ever measured with any motor, even my 426 Hemi. My 383 race motor, with .130 milled heads was right in that range, but that was 22 years ago.

Do you really think a different head gasket could lower it that much? I guess that makes a lot of sense, it would be like dropping the piston .030 in the hole. Do you have more information on locating those thick gaskets?

**edit** found this article, very interesting. http://www.hotrod.com/techarticles/engine/hrdp_0603_cometic_cylinder_head_gaskets/photo_04.html

Timing is extremely sensitive on this motor, it wants 38 total, real bad. I run a MP race distributor with no vacuum advance, and the chrome box. In fact, it starts falling flat on its face and won't idle below 30.
 
You can Cometic gaskets from Don at 4secondsflat.com or direct from Cometic. PM sent
 
I would take the top end apart on the 340 and get the measurements,cc the heads,pistons,check deck height ect.Once you know these things you can make some decisions.I would ditch that cam and go with something in the 230 range @.050 with a 110 lobe seperation.You can add a few ccs to the heads by properly removing small amounts of material and polishing the combustion chambers and not mess with quench.With those small changes you could loose the 25-30 psi you need to be fine with a good tune.
 
hemied said:
Do you really think a different head gasket could lower it that much? I guess that makes a lot of sense, it would be like dropping the piston .030 in the hole. Do you have more information on locating those thick gaskets?
Click to expand...


Yes, a thicker gasket is very similar to droping a piston down in the hole the like amount of the increase in gasket thickness. If your head gaskets are .040 and you increase the thickness an additional .020, it's very much so like dropping the piston down the hole .020. While this amount may or may not be enuff, it's the direction I found to be cheapest and very effective in lowering compresion.

If you have a domed piston or rely on a quenched area for the set up, it will take away the effect of the set up/quenched area and the engine would probably run poorer if additinal steps aren't taken. Like reduced timing, which at this point, probably won't hurt the performancve as much as it does now, though, it may. It gets very particular in this area. Engines can be a cranky ting from time to time and this is one of them.


MoPar used to sell (And may still do) a shim designed to be used with the older high compresion piston engines. It was / is .060 thick and can be combined with a head gasket or used alone with Holymar to seal it.

In the past, I needed such a thing and combined it with a .039 Fel-Pro to get a pump gas ratio. At a total of .099 thick minus any additinal thickness from the Holymar sealer, it's quite thick and the intake gaskets may also need to be addressed at this thickness. Multiply intake gaskets may be needed.
 
I would try backing your mechanical timing off to 34* and plugging the vacuum advance and seeing if it would run on 93 octane first. That would be a fast and cheap test. You might be down on power, but these other options of lowering compression or building a lower performance engine are doing the same thing. If you can get away with just moving the timing you can have the best of both worlds, streetable but able to be quickly tuned to a race engine if you go to the strip.
 
The standard Felpro head gaskets are .054" thick. The performance Felpro head gaskets are .039" thick. If you are running the standard gaskets, with that stroke, zero deck pistons, and those heads, your cranking pressure should not be that high. I am wondering if the intake valve closing timing is causing the high pressure? Was the cam degreed in?

If you know all the specs of the engine and the intake valve timing you can use this tool to compute compression:

http://www.kb-silvolite.com/calc.php?action=comp
 
jefflock said:
You can Cometic gaskets from Don at 4secondsflat.com or direct from Cometic. PM sent
Click to expand...
Thanks for the information, and I appreciate the PM. Once I figure out exactly what I am going to do, that may be the best option. Thanks again.

lead69 said:
I would take the top end apart on the 340 and get the measurements,cc the heads,pistons,check deck height ect.Once you know these things you can make some decisions.I would ditch that cam and go with something in the 230 range @.050 with a 110 lobe seperation.You can add a few ccs to the heads by properly removing small amounts of material and polishing the combustion chambers and not mess with quench.With those small changes you could loose the 25-30 psi you need to be fine with a good tune.
Click to expand...

Hmm, the deck height is 0, and CCing the heads might be a good idea as they could have been milled extensively prior to my ownership. I am on my 3rd cam, this is by far the most radical. I had a real small, almost stock 340 Clay Smith solid, then a 467 Comp solid, I still have it but can't remember the duration, now this one. (Yeah I know, I have a sickness and love playing with these things)



rumblefish360 said:
Yes, a thicker gasket is very similar to droping a piston down in the hole the like amount of the increase in gasket thickness. If your head gaskets are .040 and you increase the thickness an additional .020, it's very much so like dropping the piston down the hole .020. While this amount may or may not be enuff, it's the direction I found to be cheapest and very effective in lowering compresion.

If you have a domed piston or rely on a quenched area for the set up, it will take away the effect of the set up/quenched area and the engine would probably run poorer if additinal steps aren't taken. Like reduced timing, which at this point, probably won't hurt the performancve as much as it does now, though, it may. It gets very particular in this area. Engines can be a cranky ting from time to time and this is one of them.


MoPar used to sell (And may still do) a shim designed to be used with the older high compresion piston engines. It was / is .060 thick and can be combined with a head gasket or used alone with Holymar to seal it.

In the past, I needed such a thing and combined it with a .039 Fel-Pro to get a pump gas ratio. At a total of .099 thick minus any additinal thickness from the Holymar sealer, it's quite thick and the intake gaskets may also need to be addressed at this thickness. Multiply intake gaskets may be needed.
Click to expand...
I really like the shim idea, will check with Mancini tomorrow, if anyone should have it, they should.



juvat said:
I would try backing your mechanical timing off to 34* and plugging the vacuum advance and seeing if it would run on 93 octane first. That would be a fast and cheap test. You might be down on power, but these other options of lowering compression or building a lower performance engine are doing the same thing. If you can get away with just moving the timing you can have the best of both worlds, streetable but able to be quickly tuned to a race engine if you go to the strip.
Click to expand...

I have one of those old MP race distributors, no vacuum advance.

340sFastback said:
The standard Felpro head gaskets are .054" thick. The performance Felpro head gaskets are .039" thick. If you are running the standard gaskets, with that stroke, zero deck pistons, and those heads, your cranking pressure should not be that high. I am wondering if the intake valve closing timing is causing the high pressure? Was the cam degreed in?

If you know all the specs of the engine and the intake valve timing you can use this tool to compute compression:

http://www.kb-silvolite.com/calc.php?action=comp
Click to expand...

Great information, thanks. Yes, I have degreed in all three cams, that I have had in this motor. I believe this one is ground on 107, I think the others were 110 and 112 but I would need to check the cards to verify.

I just assumed it was the .200 more stroke, that was allowing it to take in more volume to compress, the reason for the high pressure. That is actually .400 more travel from TDC to BDC, correct?

But as one poster mentioned, these heads may not still have all the CCs they were born with. We did not check that, we just cleaned them up.
 
Change the cam to bleed off the comp.Shoot for 175 and you should bee good.You can also mess with the head gasket but you dont want to get too thick.
 
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