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Discussion Starter #1 (Edited)
It has been awhile since i have been on here....but now im starting to plan our new build for our radial car. As alot of you know we had serious rod failure in our F-2 blow-through alcohol 434 sbc last season....we had thoughts of switching to a 3.500" stroke crank and build a 380" instead of the 434,but i think we have decided to stay with the 434,do to the cost of the sbc cranks with the bbc snouts...we already have the 4.00" stroke with the bbc snout. but instead of going back with the 5.870" rods (1.467 R/S ratio) like we were running in it,we are wanting to run a 6.100" rod for a better rod/stroke ratio of 1.525. Our compression height with the 5.870" rod was a 1.430,but if we go to the 6.100" rod it will need to be a 1.200". Can a good piston and ring package be built for 30 lbs. of boost with a 1.200" C.H.? will the pin be into the oil ring with this C.H.? we will contact Steve for the Pistons/Rings/Pins and Camshaft and Valvesprings,just wanted to get everyones input on it. Here is what im thinking as far as combination....

Dart Iron Eagle block 9.315" deck 350 main
Callies Magnum 4.00" stroke w/bbc snout and dual 1/4" keys
GRP Pro-2000 rods 6.100" 2.10" journal
Custom Steve Morris/Diamond Hard Anodized pistons/rings/pins
right around 11-1 compression
Custom Steve Morris solid roller/Morel HIPPO lifters/.145" 3/8" pushrods
Moroso Billet oil pump/Moroso 21019 oil pan
Trick Flow 18* heads flow around 370cfm intake/250cfm exhaust
GM 18* intake ported to flow with heads
C&S 4150 Blow-Through Alcohol carb w/electronic bowls
MSD 7535 ignition/RCD Crank Trigger and degree ring,plug gap .016"
F-2 Procharger(we will start out conservative,we have the biggest pulley procharger sells on it,i think its a 58 tooth,and 73 tooth crank pulley,it pumped 23 lbs. on it before spinning it 52,000 rpm)
2 1/8" headers,4" collectors,4" Vibrant mufflers
Powerglide with 1.80 gear set and Chance Bolt Together converter
Moser 9" Ford w/3.50 gears 35 spline axles

We ran 5.40's with this same basic setup before with a mild tuneup,(we were only spinning the F2 52,000,and probably not winding the motor over 7200,since it was a new combo,we were just trying to be conservative with it),only this time we would have the longer rods,Steve Morris camshaft,and Steves design of pistons/rings/and pins.

btw,the old Comp cam we had in it when it ran 5.40's was 310/314 adv. duration,279/283 [email protected]" .776"/.776" lift, 112* lobe seperation,108* intake centerline installed at 110*. This cam wasnt ground for this engine,but did come out of a F3 sbc,I dont know how much different Steves cam would be as far as specs,but I believe Steve's cam would be alot better setup for our combo. We bought a cam from him in the past for our old 383,and we were very impressed....

Anyway....what do you'll think? We are open to any suggestions!!

btw...we have to run a carb with alcohol in our class....no alcohol injection allowed....

Thanks!! Brian
 

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For years I have heard dont let the rod ratio effect your piston design. Let the piston and crank dominate the rod length.
 

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I think all the above make valid points . I think Steve will get you the best bang for your buck . By the way welcome back Brian !!
 

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I would have to agree with everybody above- dont sacrifice piston strength, so you can get a certain length rod in there. I'd rather have a strong piston and live with a shorter rod
 

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Discussion Starter #9
First of all.....thanks for all the reply's and thank you Vader..... to answer some questions....we were only turning it around 7200 and the F2 52000 because it was a new combo,we were just starting out conservative with it to see where the TuneUp was at and then start turning up the wick slowly....instead of going balls out right from the get go with a new combination. About the longer rods.....we are staying with aluminum ....as that it what is preferred in most blown/alcohol strip setups ......as they do act as a shock absorber .....therefore a little easier on bearings....and if it does happen to throw a rod .....most of the time they are more forgiving on the block than a steel rod, not to say you can't ruin a block with aluminum rods,because you certainly can. About the rod length...... since we are going to have to by new pistons anyway....we figured we would just go to a 6.100" rod in it......the pistons would still have a 1.200" C.H......in which I figured Steve could still design a good piston for.....and along with the shorter C.H. height is a lighter piston....but would still be plenty strong...... but we are open to suggestions as we haven't ordered anything yet.....

Thanks again... Brian
 

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For years I have heard dont let the rod ratio effect your piston design. Let the piston and crank dominate the rod length.
Have you ran a 1.200 compression height before to say this? I run a 1.075 piston with 38 psi. I use pin buttons so the oil ring is not exposed. You just have to watch aluminum rod to piston clearance on underside but the right company can manipulate this into the design
 

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This is just my opinion on it and I understand about trying to save money. I would go to a smaller stroke crank and make your bottom half a little stronger in my opinion . Your crank should fetch a good price on the market and since you already are comitted to new rods and pistons why make your build difficult in terms of trying to make a strong piston under all types of obstacles . I really dont think the extra cubes are gaining you anything with the forced induction . I can say I have been in your position and had to make a similar choice . My original shortblock had a 5.7 rod and JE pistons . After talking with Steve we came to the conclusion that instead of trying to band aid something together just do it over . I switched to 6" rods and his piston for the sake of strength and stability. I never even ran the engine with the old setup.
Being that alcohol tunes are less forgiving than gas I would want the best piston package that I could fit . Again this is all JMOP. Steve would be able to tell you whats best but you asked so i figured I would give a different perspective . Whatever you decide I hope you have a good year and wish you all success with the combo !!
 

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MFI on CH3OH
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Being that alcohol tunes are less forgiving than gas
:confused: that's the first time ive heard that ?????? Everyone who I no who runs alky have said its so much more forgiving with the tuning.
 

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From what I have seen gas is pretty straight forward and alcohols fuel curve is a little tricky . Usually when you miss the tune with alcohol it ends up with the rods coming out . I am sure when the tune is correct you will make more HP on alcohol as opposed to intercooled gas . But getting the tune correct is a bit more difficult to do. Steve gave some good info on it at his boost seminar .
 
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