Performance parts

71_TA_Javelin

Hi, I am slow as a snails pace building up a modified 70 390. I have an all original 390 that is standard bore and will be installing heavy duty parts for durability. I have found that many are stroking 390's and 401's but I have no information on durability. At this time I have aquired: Custom made 4130 four bolt mains and studs Modified Holley 750 cfm Street Avenger with four corner idle and Truck Avenger mods. Milodon gear drive Torker intake with air gap mod with a two inch ported spacer. Over sized hardend valves that have been nitrided MOPAR Performance Roller hyd lifters Custom oversized bearing 1.7:1 roller rockers Custom ground .625 lift roller cam Note: I am doing away with the stock oiling and cooling system and going to use a dry sump system and electric reverse flow cooling. The engine will have heavy amounts of torque around 3000 RPM and Redline around 7,000. I hope to have about 13:1 compression with mild port job on 70 hi-comp heads. Will need help on the best crank and piston combo At this time I am thinking of using the stock crank and rods and going with KB Hypertek pistons... I hear forged do not work well for daily driven engines in the city. I also hear that stroking the 390 and using forged 360 rods will do too. Any comments? Everyone I talk to says that this is too much for daily driven car but It's my option and would like to do it right the first time.

Mudrat

71_TA_Javelin wrote
The engine will have heavy amounts of torque around 3000 RPM and Redline around 7,000. I hope to have about 13:1 compression with mild port job on 70 hi-comp heads.

Everyone I talk to says that this is too much for daily driven car but It's my option and would like to do it right the first time.

:-| The parts you have and these 2 statements don't fit as any DD I know of :idea: Or at least one driven on most roads around here daily!!! =D>

71_TA_Javelin

What do you mean... I hear of chain stretch, oiling issues, and broken cranks from lack of heavy duty hard parts. I want a dual perpose setup that will put up with variances in driving conditions. Most have either full race or weekender road warior setups. I just would like a bit more information on completing my setup. What would be best to leave the crank alone or stroke it. Is there a good way to run forged pistons on a daily driver that can be thrashed on. I here of heat and sealing issues... am I wrong?

Mudrat

71_TA_Javelin wrote
What do you mean... I hear of chain stretch, oiling issues, and broken cranks from lack of heavy duty hard parts. I want a dual perpose setup that will put up with variances in driving conditions. Most have either full race or weekender road warior setups. I just would like a bit more information on completing my setup.

What would be best to leave the crank alone or stroke it. Is there a good way to run forged pistons on a daily driver that can be thrashed on. I here of heat and sealing issues... am I wrong?

Yo Jav - man, light'n up, didn't mean to pee in your Post Toasties :shock:
The hard parts you have picked up and what you want to do will be great for a full race motor taching out 10K+ and turning in sub 10 times. But it seems way overkill for the street unless you run for pinks on Fri/Sat nights in the Jav - then, hell yeah CrMoly rods and rings, oversized valves, 1.7:1 rollers, billet cranks, forged pistons, and a VERY heafty cam, will support that - and that 10 grand RPM (rollers won't even really come into play untill about 5K or so I'm told - that's why I kept the stock bridged rokers, my cam and intake quit at 5500). I'm just saying that amount of build is over-kill for a mostly DD and weekend wheeler (your nNOT taking the Jav off road are ya? That's a sweet ride and a classic you've got).
I thought I was overkill with a balanced and blue printed 360, .030 over, CrMoly rings on cast slugs, all the oil mods and a double roller chain with the E-brock intake and carb and a nickle timing cover and oil pump assy. that was all. Your parts list is way hotter than mine and will definately give you some HP :t: I just couldn't see spending that $$$ on a DD and weekend wheeler. Just my mods are over 400HP :shock:
As for the last statement - my thoughts have been replace stock with better aftermarket parts to maintain reliability. Anything that changes the basic design decreases reliability. So I would NOT stroke it and change the internal dynamics any more than you are. My shop guy in CA told me once (when I paid big money to really build a 350 4-bolt for a CJ5), 'The higher the performance, the higher the problems.' And between that motor and other HiPro motors, the maintenance DOES goes up exponentially - and so does breakage of transmissions, U-joints and axle parts by the way #-o )

Sorry :smile:

rollen dean montoya

i will add some other things to beef up. axles are the 1st thing to do if they are of the 2 piece type. you better have 1 piece axles back there or have AAA towing. brakes will also need to be upgraded or you might have problems stopping in a hurry. better use heavy duty sway bars front and rear. urethane bushing on all front end components.

jeepsr4ever

With just a couple simple mods to your oiling system and a nice clean area to assemble you can have exactly what you want if you can afford the right parts. The thing about the 70' 390 is that I dont believe anyone makes a std piston anymore. The last one we built had to go .030 over and we used a racing piston for the build. The nice thing about that year is the deck height...you can buy a set of tough pistons from ROSS for around $650.00..check ebay for these. If you have dogleg heads casting #3196291-c or any variation of the first number and -1 or -2 you can buy a set of roller rockers for around $240.00 that will last you a long time. Intake and aspiration are something to look at as well. Edelbrock makes a killer MPEFI that alot of car guys over look. It flows to 1000cfm and you can order it with 36lb injectors. Your not asking too much ...it should be able to be done. Good luck and let us know if you need any tips :t:

fuzz401

I would go with the ross pistons when you get them from them the valve releifs will be big enough compaired to the ones mad dog sells

roller rockers go with either harlyn sharp - crower or crane as far as I know they are about the only ones that make them just for the AMC motor and not used for some thing else
crower 1.6 stainless steel 7/16 stud roller rocker

have the factory rods shot blasted and balanced and made up for full floting pistons good up to 7000 rpm

fuzz401

Torker intake with air gap mod

what they do cut out the heat cross over ? I have been working on one and did the heat cross over + cut the front out too

71_TA_Javelin

Ok... Thanks for the information. I will clarify hard parts... Ford 9 inch /w Daytona pinon support , modified 1200hp th400 from a 78 Jeep (no adapter needed), your rockers are not to beefy compaired to the modified ones I have (barely enough space to mount them on un modified heads), Duel GM front calipers on a ford Mustang Cobra SVT 13.2" rotors, STV 17" x 10" rims, intake already done like yours... I plan on having 13:1 compression and a lot of torque (most manual trannys will break). This is almost ready for the shop but need clarification on best piston setup since it looks like stroking not an option now. I do plan on having the crank and rods double tuffrided and nitrided after all the finishing is done to them. Like I said my engine is stock untouched and has had not been abused (will be a prime canidate for this alone). I have the heads you speak of... I also want to point out that a lot of 401 cranks have been used on 70 390's for replacements or to make it into a 401... but the 390 crank has lighter counter weights. This did not cost much since, it is paying for its self. A rare condition since hard to find NOS OEM parts grab a lot of dough. As for streetablity... low end torque ran through the right gears is better than torque produced by high RPM turning engines. I just could not run the later on the street without getting into trouble. Put it this way... If it breaks its because there is way too much power, not for the lack of good hard parts. Since you question validity... I want to take it to the track every once and a while and drive it not store it. This raises the point on is it better to forget about forged pistons since there is varying degrees on how I run the engine.

71_TA_Javelin

Hi, I came across some killer 4-bolt mains... they are like the one's Indy uses on their 401. I am going to get the front and rear main kit also... After compairing them to old stock 392 Hemi maliable iron and the latest from Milodon... you can't go wrong. If you are interested www.pro-gram.com