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Author Topic:   rpm+hei+module
Whitelightning
Member
posted March 31, 2003 11:36 AM
Ok I know you have probly seen my pevious post but I am wondering if it really is my gearing or something else, First off I am running a 350,block is 30 over, flattop pistons with coated skirts(hypers),336 heads which are 76 cc but mine are shaved to 70cc, some port work done, howards cam 410/410 lift to meet rules, advertised duration is 298, @ 50 it 240. lobe sep 106,rpm is 2600 to 6000,and I run a qaudrajet 4 barrel, turb 350 second gear with a 3.42 gear on half mile track. The engine really seems strong but when it hits 4800 rpm thats where it seems to wanna stay at, I think it should turn more with that gear, I am running staock hei, also I run power brakes but seem to not have enough vacum that i cant hardley mash the brakes at idol or going in the corners cause the pedal is so hard,but i figured this cam should pull enough vacum, what could be wrong or should I try lower gears like I was thinking before


rico 08
Member
posted March 31, 2003 11:52 AM
A stock HEI is really weak above 4500 rpm,i'd try a good module/coil,what kind of timing are you running?that will make a lot of difference on vacuum,also you're cam with 106 lc won't pull much vacuum but you should have plenty when you let off going into corner so you may have another problem.


dirtrace54
Member
posted March 31, 2003 11:58 AM
I have always taken the power brake master cylinder off and put a manual one on. The way i do this is using an 85 S10 manual master cylinder and gutting the original brake booster to use for a spacer. It kinda fools everyone when their lookin at it too.LOL


Whitelightning
Member
posted March 31, 2003 12:49 PM
running 36 degrees timming


teamstertom
Member
posted March 31, 2003 06:09 PM
Two places where I would put my money,gears 1st...HEI 2nd.

How do your plugs look? Do you have that nice coloring at the tip,or are they wet?

dirtrace 54 is right,get rid of that power booster.

66jj
Member
posted March 31, 2003 07:13 PM
IVE RUN STOCK HEIS TO 7000, IN A 14-1 LATE MODEL MOTOR.

I LIKE MSD MODULES THEY DO HAVE A HOTTER SPARK BY FAR.

ACCELL MODULES ARE JUST STOCK. NO BETTER.

JEFF

doubletrouble
Member
posted March 31, 2003 11:05 PM
Something doesnt sound right here.We run a pure stock Olds with stock gears(high gear)on a 1/4 mile track.....in first gear we hit 5200 RPM's down the back straight


Whitelightning
Member
posted April 01, 2003 07:59 AM
what should plug gap be , i set it on .045, also what gear would yall try a 3.73


dirtrace54
Member
posted April 01, 2003 01:46 PM
I would try the 3.73. On a 1/2 mile we like a 5.88 or 6.00 final, but the 1/2 miles are a lil small around here. On the gap we run what the plug calls for. We dont mess with it much


racer3397
Member
posted April 01, 2003 02:21 PM
i would look at my carb also.... we run a 3.73 on our 3/8 mile track. a 3.42 should be enough. also check for ur valve springs,my car done the same thing and it was the valve springs to weak.

[This message has been edited by racer3397 (edited April 01, 2003).]

Whitelightning
Member
posted April 01, 2003 03:06 PM
If it will turn good rpms above that 4800 in first gear then would it be safe to rule out the carb, valve springs, and hei and guess its gear thing. Also I have to run the gm 7.5 to meet rules so its impossible to run high gear, but would there be a big difference in running first gear with a numerically lower number rear gear, such has say 2.41 in first would be like a final of 6.07, instead of running second gear with a 3.42 or 373, Does it matter as long as the final gear is right. The reason I ask is I have to more stock rears but have to pull covers to see what they are and I know If I go to 3.73 I have to buy the gears and then pay to have them installes cause I hear it can be expensive mistake if the gears are off a bit.


racer3397
Member
posted April 01, 2003 03:25 PM
the final gear is all that maters,go for the 3.73 after thinking about it,a 3.73 should make it turn harder!!


teamstertom
Member
posted April 01, 2003 06:08 PM
You will not go wrong by buying new gears and having them done correctly. I know the investment into the rearend seems pricy,but it will be well worth it. 10 bolts are known for bearing failures big time on the right side where a banked track is raced on.

I believe you will also see a gain in useable RPMs....

NYhick
Member
posted April 01, 2003 08:31 PM
I switched my stock 2.73 gears to a 3.42 and picked up some serious rpms. I went with 3.42 over 3.73 to start because I didnt have a very good motor in at the time and didnt want to blow er up. Once I got a good motor I switched to the 3.73 and I couldnt believe the difference. I now run about 5,800 rpms on a half mile which is good for me because i dont have the money to rebuild motors. You definitely need the gear though or you will never be able to keep up.......


backwoodsracer
Member
posted April 02, 2003 06:03 PM
backwoods, my tires are like 84 inches, and my trans in second come out to be like a 5.20. I talked with a guy that owns several top 5 cars and owns a salvage yard about some 3.73 gears and he had a set but said that every car he builds for my track that does not have ford rear end leaves with a 3.42 gear and thats what I have. Like I said the cam specs are listed above and it says 2600-6000, howards also recomended advancing cam 4 degrees, which I did, also would that affect the rpms because I think I should be able to hit 6000 rpms either way. I went down the old farm rd started in first on the floor it finally hit 6000 rpm but it took a long time between 5000-6000. Could this be module or coil problems. Could it be carb problems but the carb runs smooth and very responsive so Im confused, very confused..


backwoodsracer
Member
posted April 06, 2003 07:21 PM
how do you have your transmission done? If you have the right gear and your motor is strong, you should be getting more RPM's than that I would think. Does it feel like you can stand on the gas coming out of the corner without smoking the tires? Make sure the tranny is actually in 2nd, I had the same problem during a practice night and it turned out the transmission was in 3rd somehow.


limitedmod45d
Member
posted April 08, 2003 09:21 PM
are your cuvres tight because at our track we run around 600 gears but we turn around 6300-6400
but we run the same gear at our 1/4 track and still turn 5800. what does the car weigh weight can make a huge difference.Your valve springs being too weak would cause it to bang at high rpm. sounds like gear we run a 241 in low in our pure stock that has to have stock rearend and thats 607 and it works perfect. A stock motor wont blow at 6000 or a little more we ran my last motor 3 years doin 6500 and it wasnt balanced or anything even had dished pistons. Running low rpm will cause the motor to bog and that puts it in a bind and it will over heat so i would deffinately change the gear but go the cheapest way.GM also makes a 228 for 7.5 that would come out to be 574 in low with 350 turbo that what we run in our limited modified with no problems


Whitelightning
Member
posted April 09, 2003 09:23 PM
well I advanced the cam with the timmming gears, I just got advance timming light and found out that my 36 degrees of timming is not comming in to about 4000 rpm. Its about 30 degrees around 3000-4000 so I have ordered a lock out kit from jegs now I hope it will crank with the 36 degrees all the time.Do you think that will help any? I have a rear end with 2.41 gears but I am scared if I run it in first it will turn to much. What do yall think about going from a 5.20 to a 6.07 final. Also I know it under no load but when timming engine we ran it up to 5000 rpm had plenty of pedal left you could hold it at 5000 and burp the trottle and it would respond buy climbing on up but I was scared to let go anymore! hehe


kong
Member
posted April 10, 2003 10:05 AM
ran my last 350 turbo 3 years never did anything to it except put more fluid in every week


towmandan
Member
posted April 11, 2003 12:03 AM
quote:
Originally posted by limitedmod45d:
ran my last 350 turbo 3 years never did anything to it except put more fluid in every week

what about valve lash...maybe a little on the tight side , might help vacume also . As far as rear gear if it will turn the rpm in 1st or 2nd sounds like your tune is close and you need more gear.



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