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1973 gremlin with built 350

  
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1973 gremlin with built 350

 
roy57 roy57
New User | Posts: 5 | Joined: 12/12
Posted: 12/29/12
03:26 PM

I have a 73 gremlin that im putting a 4  bolt main, sbc 350 into in place of the 304...i purchased an eagle forged 4340 crank with a 3.48 inch stroke.. also bought a set of forged h beam rods from eagle as well that are 5.7" length.. i have a 327 that has been bored 0.40 over... it has 10.1 dome top forged pistons in it.. i was wondering if i could use the pistons out of the 327 in the 350 if i have it bored 0.40 over???...i also have a set of 461 double hump heads(i got in trade) that have been fully ported, polished, has screw in studs and have upped the valves to titanium  2.02 intake, 1.60 exhaust valves...these are 64cc hump heads by the way...with the dome pistons combined with the high compression heads, what would be the highest lift cam i could use without causing serious problems like the pistons hitting the valves.. my dad had one back in the 70's and he kept bending valves with his until he put in a set or triple valves springs.. and he had flat tops back then and one hell of a big cam.... so maybe this will shed some light on my worries... im spending alot of money on this 350 and i dont wanna  mess it up.. but i do want to keep the hump heads even tho there are prolly some aftermarket heads that flow better... but these are well improved from what they were stock.. ive seen videos of them fully worked producing 575hp.. which isnt half bad in my opinion for gm iron heads... help please!! lol and thanks! Smile



Roy  

76Skylark 76Skylark
Guru | Posts: 853 | Joined: 12/11
Posted: 12/29/12
03:40 PM

No the 327 has a stroke of 3.25 and the 350 is 3.48 the pistons would stick 1/4 inch out of the Hole not bad heads at all but get them pressure tested because they are old. I recomend you use a flattop piston for a 350.gas today Ain't what daddy used to buy. Shooting for 350-400 HP is a smarter Move for a first engine. tell us about the use for the car, what trans, how much Gear.  

roy57 roy57
New User | Posts: 5 | Joined: 12/12
Posted: 12/29/12
03:55 PM

i bought a new b&m turbo 400 tranny and have a 9 inch ford reAR end that has new 4.11 gears and a new posi unit.. gonna have to buy wheelie bars im sure because the car only weighs 2700 lbs... i plan to take it to the local dragway for street fights... i have had a 350 apart before and am fairly familiar with them just wasnt sure about the pistons... im buying all forged internals because i wanna add a little nitrous as well...i wanna get as much power out of this 350 as i can.. and those hump heads were pressure tested by the machine shop before they worked the heads... they are good to go... so with flat tops i could go as wild as i wantd to with a cam right?? high lift high duration i  mean....thanks for your help bud!  


Edit:  the turbo 400 is b&m's bulletproof series...they gaurantee i wont put enough hp or torque to hurt it...we'll see....lol


ROy  

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 12/29/12
10:35 PM

Roy
  B&M has been around along time. For them to say you won't break their part. They know what they are talking about. TCI also has advertisies a 700-R4 that will take a 1000HP.
  It's not so much the Horse-Power that breaks parts, its the torque,the (Twisting Action) of those engines that break parts.The better bite you get from your car the better chance you gave of breaking a part.
  There is a thin line between how strong they can make parts. Then how much twisting force a part can take.
  Torque has NO MERCY! It shreads even best parts made. Ask guys that have Run Pro/Mod cars, Top Fuel, etc.

Bob  

76Skylark 76Skylark
Guru | Posts: 853 | Joined: 12/11
Posted: 12/30/12
09:12 AM

If it is a track car put in domed pistons Nitrous Likes Compression.  

Dave632 Dave632
Addict | Posts: 2220 | Joined: 07/08
Posted: 12/30/12
09:36 AM

Icon Quotepepsi1:
Roy
  B&M has been around along time. For them to say you won't break their part. They know what they are talking about. TCI also has advertisies a 700-R4 that will take a 1000HP.
  It's not so much the Horse-Power that breaks parts, its the torque,the (Twisting Action) of those engines that break parts.The better bite you get from your car the better chance you gave of breaking a part.
  There is a thin line between how strong they can make parts. Then how much twisting force a part can take.
  Torque has NO MERCY! It shreads even best parts made. Ask guys that have Run Pro/Mod cars, Top Fuel, etc.

Bob


Right Bob, there is nothing made that cannot be broken.

I think I broke every drivetrain part that you can name. On the good side you learn what lives and what does not. My last car was breakage free but it had limited trips down the strip and less power than some of my other cars. It was pretty traction limited with those 10.5W tires.
The Beretta had 17 inch tires on it and it could've used more especially at the tracks I was running at.
Sounds like this guy is heading in the right direction, he has picked up some good drivetrain parts and is going with forged internals.
I would surely test the setup out running motor only at first and gradually add nitrous to the mix. With the short wheelbase that this car has who will surely need some wheelie bars as mentioned.
I would be glad to help with the nitrous as some of my cars had two or three stages on them. Unfortunately I could never get all the power I could make to the track.
Start easy and work your way up until you reach all the power you can put to the chassis you're working with. Believe me you will find the limit if you keep at it.
If you are making 350 to 400 hp motor only you should be able to double that with nitrous. A plate kit is easier, cheaper to install and adjust but the initial hit is harder than a fogger kit. Fogger kits can give you a bigger shot than a plate system but they take 16 pills versus 2 for the plate.
By the way flattop pistons alone will not guarantee that the valves will not hit the piston. Make sure the pistons you buy have a good fly cut in them. Then check the piston to valve clearance with clay.
You do not have to run flat top pistons with nitrous, I ran as high as 15 to 1 on some of my motors with nitrous. Now if you are planning to run pump gas Flaptops may be a good idea but you must switch to racing gas when running juice.
I also suggest a full roller set up as you do want to run some good spring pressure.
There are many other suggestions I have so if you're serious keep posting and we will help you as much as we can.  
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roy57 roy57
New User | Posts: 5 | Joined: 12/12
Posted: 12/30/12
12:08 PM

i appreciate the time each of you have spent to reply to my thread... i want this to be a street/strip car.. i want to drive it around town and also load it up and haul it 50 miles to the nearest drag strip and run it at street fights... flat tops are the way for me i believe... and yes i want a full roller assembly... i wont know exactly what the motor makes but i am gonna have it dynoed so i will know what it makes to the wheels... the guy at the machine shop said it should easily make 500+ hp at the flywheel if i have the right cam/intake combo and thats all he would say.. he just smiled...so theres obviously some potiental with those heads even tho they are old..   what would be a good cam choice?  i know i have to buy an intake to match the rpm range of the cam but am not sure which cam would be best.. i wana get as much hp i can with these heads... i also have a holley double pumper 870 cfm carb... is that suitable?  i can put a motor together but i dont know how to get all i can get out of it...thanks for everything!


Roy  

Dave632 Dave632
Addict | Posts: 2220 | Joined: 07/08
Posted: 12/30/12
05:04 PM

Roy it is great that you are on this site and asking for advice. Many come on acting like they know it all when they know nothing. Asking questions shows intelligence realizing that no one knows it all. I always enjoy talking to someone about drag racing as that is what I did for many many years. My fastest car was a Chevy Beretta. The only thing stock on that car was the headlights, taillights, grill and door handles. It had a 1.07 60 foot and ran mid fours 150+ in the 1/8th mile.
There are quite a few on this site that have a lot of knowledge about engine building and they can get you where you want to be.
Personally I would think the 870 would be fine for your combination I always ran tunnel rams but that was me. I have not built a small block in about 15 years so I think some of the others would be a better choice for cam selection as things surely have changed since then. I would also mention to your cam manufacturer that you're going to use nitrous. I would think 500 hp is not out of the question if done right.
Remember when it is time to order your converter you must consider the fact that you're going to run nitrous. There is no all-purpose converter.
What might work great with your motor only will not work well on nitrous as the extra power will blow right through the converter losing ET and mile-per-hour.
As an example my Beretta was running 144 mph in the eighth and switching to a tighter converter picked up the mph to 153. The bad side of this is that performance on motor will suffer as the bottom end will be sluggish without the juice.
Here is a picture of the motor in the Beretta before all the juice stages were added:
MVC 026S  
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skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 12/30/12
09:21 PM

Hi there,
Your motor will last much longer without the laughing Gas..


That is what is was made for in the days of Samuel Colt who
owned a manufacturing outfit of it..It paid for the manufacture
of the guns..Fact is stranger than fiction....Happy New Year....  
skyeking

BuzzLOL BuzzLOL
Enthusiast | Posts: 380 | Joined: 12/10
Posted: 12/30/12
11:34 PM

.. The 327 pistons wouldn't stick out a 1/4", but 1/8" with a 350 crank...

.. Rods from a 400 would make them work, but don't think you will find them aftermarket forged...

.. As Pepsi mentioned above, whether flat top or domed pistons, you have to determine whether the valve reliefs/eyebrows cut into the top of the pistons will clear the pistons at max cam lift and planned degreeing... assemble engine with one rod and (oiled) piston and use clay on piston while slowly turning engine over by hand...

.. You'll need a steel billet roller cam and Scorpion solid roller lifters if using triple valve springs... Comp Cams would prolly recommend about 234/244 - 255/260 duration range cam... maybe use 1.7 ratio LSx rocker arms...

.. Wish you were putting an AMC 343" or 401" in that Gremlin...  

Dave632 Dave632
Addict | Posts: 2220 | Joined: 07/08
Posted: 12/31/12
01:12 AM

Many are scared to use nitrous and with good reason.
If you do not know what you are doing and everything fuel related is not working properly you are going to melt things.
I have seen many blow holes in their pistons with juice. They all screwed up. It was almost always human error of some kind. The other times it was loss of fuel pressure to the nitrous without a hobbs switch.
I never burned a piston with nitrous and I ran it a lot. You will pound the bearings with high HP settings unless you run aluminum rods but you have to pay some price for all that power. I also had some cap walk on a 2 bolt big block but never on my 4 or 6 bolt blocks.
I sold my aluminum 632 to my friend who made about 3 passes down the 1/8th with it.
He sold it to some other racers who had no clue and they melted the like new pistons I had sold him in one nitrous pass. I had about a 100 passes on those pistons, most with nitrous, and when I pulled the heads off before I sold it to him they looked like new.  
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roy57 roy57
New User | Posts: 5 | Joined: 12/12
Posted: 12/31/12
06:21 AM

Keep the info coming .. Im like a sponge, soaking it all in.. Lol.  Would also  like to ask, since the shop "trued" up the mating surfaces of the block and heads, what kinda head gasket shud i use with these 461's? I honestly appreciate everyones willingness to help me and for you kindness and patience with me...the more i talk with you guys, the more comfy i get about the parts i choose...i cant wait to run this thing down the 1/4....  

Dave632 Dave632
Addict | Posts: 2220 | Joined: 07/08
Posted: 12/31/12
03:32 PM

I have not been down the track in about 4 years now. I miss it but financially I cannot do it anymore.
I retired a few years ago and the income is not there anymore.
I used to spend a 1000 a month just to race one meet and one test and tune a month. That did not include the cost of the car, just the cost of entry fees, fuel and maintenance.
If you plan to pull the heads frequently I would go with copper, they are expensive but you can use them over and over. They were 100-125 a set back when I was running.
They handle the nitrous well too. Some cheaper gaskets will blow right out when you hit the juice.  
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76Skylark 76Skylark
Guru | Posts: 853 | Joined: 12/11
Posted: 01/01/13
12:53 PM

Icon QuoteBuzzLOL:
.. The 327 pistons wouldn't stick out a 1/4", but 1/8" with a 350 crank...

.. Rods from a 400 would make them work, but don't think you will find them aftermarket forged...

.. As Pepsi mentioned above, whether flat top or domed pistons, you have to determine whether the valve reliefs/eyebrows cut into the top of the pistons will clear the pistons at max cam lift and planned degreeing... assemble engine with one rod and (oiled) piston and use clay on piston while slowly turning engine over by hand...

.. You'll need a steel billet roller cam and Scorpion solid roller lifters if using triple valve springs... Comp Cams would prolly recommend about 234/244 - 255/260 duration range cam... maybe use 1.7 ratio LSx rocker arms...

.. Wish you were putting an AMC 343" or 401" in that Gremlin...


My Bad buzz, there is a 401  on Atl. CL today 950.00 as rare as they are now that is a good price.  

roy57 roy57
New User | Posts: 5 | Joined: 12/12
Posted: 01/06/13
08:12 PM

i appreciate your reply...its extremely helpful buddy... and the 304 i pulled had been rebuilt by prior owner and it runs really well actually..i just wanted more cubes and power....and sbc's are cheap and make good reliable power..not saying the amc motors arent good, i just like chevy motors and the look of the gremlin....lolol anybody lookin for a freshly rebuilt 304 for an amc or jeep just give me a yell cause i dont want or need it anymore...it has alot of aftermarket goodies.. like a mild cam(unsure of the specs), edelbrock high rise intake, holley 4 barrel carb and aftermarket hei distrbutor...it really is a solid motor...  

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