I need your guys help real bad. I have been real excited building my 300-six, using the knowledge of everyone on these boards. My problem is I am very disappointed in the performance results of the 300 so far. I have followed closely the mods everyone seems to make, have copied most of them and still seem disappointed. I was wondering if you could give me some direction here, I don't really want to spend too much more money on this motor, but just can't live with it the way it is. Here is a list of things I done so far. New Edelbrock 600cfm, Clifford non-water heated intake, EFI manifolds, 2" dual exhaust with turbo mufflers, K&N Filter, Flex-Lite fan, Crane 270-2H cam and lifters, Reconditioned head, valves, and springs. I believe my compression is stock with this head, a compression check was done before I bought the motor and was said to around 125psi ea. cyl- is this where I should advance next, milling the head say .060" and raise it to approx 9:1 ? Will this make any seat of the pants difference? I know this motor will never get V8 Big Block power, and my truck is very heavy but what am I missing here? I looked into the 240 head with SBC vavles, $100 for the head, $300 for the vavles and rebuild- This is way too much for me to spend right now. Help please guys!
P.S. I am posting this on the 'other' board also.

 

125 PSI of compression per cyl is VERY low, my 80 has a stock re-build(not bored) with 2000 miles on it, and, it has 175 across the board, and, the 82 has 200 across the board. It sounds to me like your engine is in need of new rings. The engine I yanked from the 82(ran 1200 miles with the thermostat backwards) had 152,000 miles on it, and, on the 4 cyls that the head wasn't leaking on, it had 130 psi of compression.
Evan MacDonald
1982 F100 SWB
300 HD: Cliffy 290H, 9.1:1 compression, forged everything, ARP'd bottom end/Hedman hedder/dual 2½" exhaust
NP 435/2.75 geared 9"
1985 F150 HD, 300 HD/needs a NP 435/4.10 geared 8.8
70,000 miles
1980 F100 Custom, 300/Np 435/2.75, 58,000 miles

 

Wow, I was told that 125 was normal for this low compression head. It doesn't use any oil or smoke. Maybe I need to do a check of my own. - I can borrow a gauge. Can anyone explain the process in detail for me?
Thanks

 

Ok, gonna quote my Chilton's here, yank all the plugs, disable the ignition(I like to unhook the coil), block the throttle wide open, screw the guage in(if you have that style of guage, they are the better one) crank it over two or three times in short bursts, read the guage at the end of each series of cranks and record the highest of the readings, repeat for the other five cyls. The difference between any 2 cylinders should me no more than 12-14 psi, and, no less than 80% of maximum(the book makes reference to the maximum being listed in the tune up spec chart, but, it isn't listed.) Try running both a dry and wet(~ a tbl spoon of clean engine oil in the cyl) test, and see if there's any difference, if it goes up wet, then the rings are at fault.
Good luck
Evan
1982 F100 SWB
300 HD: Cliffy 290H, 9.1:1 compression, forged everything, ARP'd bottom end/Hedman hedder/dual 2½" exhaust
NP 435/2.75 geared 9"
1985 F150 HD, 300 HD/needs a NP 435/4.10 geared 8.8
70,000 miles
1980 F100 Custom, 300/Np 435/2.75, 58,000 miles

 

Thanks for your help, I'll do this tomorrow. If the rings are at fault, looks like I need to pull the engine and re-ring.

 

[updated:LAST EDITED ON 30-May-02 AT 04:43 PM (EST)]Your problem is the 600 cfm carb, I am sure alot of people will dis agree. I have noticed that alot of people with large carbs are un satisfied with their engines. To find my CFM size I used this equation.

(cubic inches x max rpms) divided by 3456

(300 x 5000 rpm) divided by 3456 = 434 cfm

I have a 500 cfm carb and it bogges so I add the largest k=n filter I could buy and an MSD 6 off road ignition system. The MSD help alot to eat the gas at lower RPM, as i will shoot a double spark under 3000 rpm.I still plan to re jet my carb.

Engine:
- 300 6 cyl. 9.5:1 compression bored
- bored .030, high comp pistons
- .030 shaved head .030 shaved block
- fully balanced
- 360 deg. Dual port offy intake
- k+n air filter
- edlebrock 500 cfm carb
- 268 deg. Comp cam
- pace setter header, single 3" exhaust
- MSD 6 off road, Msd off road rev limiter
- MSD high vibration coil
- Triple core race rad.

Suspension and Tires:
- 6” rancho lift rancho leafs
- rancho RS 9000 w/ in cab controller
- 16”x10” chrome rock crawler rims
- 315/75r16 goodyear Wrangler MT/R’s

Drive train:
 dana 60 front end warn premium hubs
 dana 60 full floating rear end
 4.11 gears
- T-18 trans
 NP 205 trnasfer case
 Brute force universals
 Custom cromoly balanced drive shafts
 *Arb loacker front and rear

Sorry it's so long I will short it later.

 

Hey wolfface,
Looks like we have almost the same gearing. I think you might be right about the carb size. I think it actually runs lean sometimes due to the fact that being oversized the air velocity is low and the venturi effect suffers and dosen't suck enough fuel. I was contemplating going to a smaller carb if I can find one real cheap, I mean real cheap. So tell me how yours runs.

 

Just my thoughts I know the 600 works fine on my engine Ive used a holley and the edelbrock both work great. Heres my question is this clifford intake a dual or single{open} plane. If its an open with a 600 or smaller and stock gears it will kill the low end big time. Another thought is i beleive this cam is 270 duration rihgt well the comp cam I use is 268 relitively close and you still lose low end with it although I gained tons of upper end. That is a lot of duration in a heavy truck with stock gears even worse with big tires. My last thought is 125 isnt great compresion but it should still run decent as long as thee cylinders are within 15% of each other. Let us know how you make out on the compresion. I always take my readings on the 1st and 5th crank you never really gain anything after the 5th. Thats the way I was taught in trade school. I work on vehicles every day in a {yuck} toyota dealership and have found iy to be accurate.

Good Luck Andy

 

It runs amazing, I couldn't have asked for more. I still have some fine tuning to do ie. spark plug gap, timimg, and jetting of the carb.

I did lose alot of low end grunt until I added the MSD 6 offroad which added a double spark under 3000 rpm.

The full balancing was very worth the money hitting 5000 rpm is almost unnoticable. I am looking forward to seeing where it going after couple thousand Kms. after my rebuild (I have heard I will notice a difference) and after my fine tuning.

 

How did you go about with the balancing. Was each component balalnced / matched or did you balance the hole assembly? I assume you had a shop do it..

 

Yes I had my local speed shop completly rebuild my engine. For an extra few hundred I had them completly balanced the engine, the piston were all matched and all the larger moving parts were balanced.

 

Grey:

What jets do you have in your 600? There are a bunch of people who have the 600 and are having troubles. What intake are you running? Which cam in particular are you running? Whats your compression?


-=Whittey=-

 

The carb is stock out of the box with stiffer step-up springs (2 rates higher) than stock to help rid a small bog. The intake is an ebay single plane clifford non water heated. It has a homemade steel 1" adapter that I made using AutoCAD DXF and burn table, another 1" alum. Mr. Gasget spacer to seal under the carb (since I felt the profile of the homemade adapter might leak under the base of the carb, didn't quite cover the base of the carb) Believe it or not, I am thinking of even adding another 1" carb heat plate on top of all this for a total of 3" before the intake. The cam is a Crane BlueRacer 270-2H (They only list this and the 282 I believe for the engine)

 

Actually the 600cfm with a cam that big isn't all that bad. The bad part is that the Edelbrock is a mechanical secondary carb. Same with the 500. If you can find a vacuum secondary carb of the same size (Holley has a few) the truck shouldn't bog down.
BTW, has anyone tried the Holley 450 cfm mech. secondary chockless carb? It's only $170 and with intake, exhaust, and a cam, I think it might just be enough.

 

The 500cfm Edelbrock is vacuum secondary. As for the chokeless carb, I can't try it due to weather (it doesn't get really cold around here, but 10F normal winter mornings are enough to make me want a choke).


-=Whittey=-