Ok, I bought a 78 2 wheel drive f250 just to get the 460 for my 79 f350 4x4. I loved how the bone stock motor ran in the 2wheel drive truck before I removed it. I decided before installing it in the 4by to freshin it up. So I bought this cam COMP Cams CL34-227-4 - COMP Cams High Energy Cam and Lifter Kits - summitracing.com & matching springs.Straight up timing set.
Eldelbrock performer, Holley 750, oil fuel and water pump, main bearings and seals. Got it all done and Im not impressed really. Its kinda doggy in 1st and 3rd. Feels good in 2nd. I had a new eldelbrock 600 on a jeep of mine so I put that on the 460 and its better. Gobs more power in 1st. 2nd still feels good but 3rd is not as good as the 750 was. Im thinking of just buying a 650 and settle with that but now Im wondering if I bought the wrong cam. It pulled hard in every gear when it was stock in the 2wheel drive truck and would just love for it to be like that now. I kinda wish I had left it alone.
Would appreciate any advise as to where I should go from here. I was so excited to get this motor in my truck and just kinda bummed out now.

 

Well one thing you haven't mentioned was the gear ratio and tire size differences between the truck (when you mention it being gear specific instead of rpm specific makes me rule out cam and think truck instead)
That cam isn't really radical so should make a lot of difference, I might have put a different intake with it but otherwise it's ok.
As to the carb, did you do any tuning on it like jet sizes? They are setup for a generic engine which is actually usually smaller then a 460 so tuning comes into play. Also did you use the same ignition parts that were on and with the engine originally? any other external parts that are different from original like exhaust etc.

 

I have 4:88 gears and my tires are 36 inches tall. (I know the 2 wheel truck had much smaller tires) Im not saying I wish it was as fast its just it dont really seem to be a big difference from the 400 I replaced. Im using the stock ignition parts that were on the 400 only cause they were pretty new. New stock manifolds with 2.5 inch duels into series 40 flowmasters. I have not changed anything on either of the brand new carbs. I dont know if this makes sense but the auto trans seems to shift much better with the smaller carb.
Oh and I havent mentioned rpm's cause I dont have a tach yet.

 

Vacuum secondaries or mechanical on the Holley?

 

check your vacuum too, borrow a vac gauge if you have to. Want to make sure you don't have any vac leaks or other issues.

 

Vaccum secondaries on both carbs Ive used. I will put a gauge on it tonight and check the vacuum. How much am I looking for? I do believe there might be a small leak under the dash with the a/c stuff only cause I can hear it leak down when I shut the truck off. I did run the truck with all the vacuum acc's unhooked and the ports plugged up except for the modulator and it ran the same.

 

Comp list that cam as 218*/218* & 494/494 lift, wonder if their listing is with 1.70 rockers.
Cam I used from Summit, it was listed 204*/214* & 479/504 lift but checking it out they had it with 1.70 rockers. When I checked it had 484/509 lift with the 1.73s.
Even though my engines in a motorhome, it has 4.63 gear & 19.5 wheel with tire measuring out 36" & I'm well pleased with how it runs. Got the ol Ford 600 carb on it as well.
Neil

 

After looking at comps site Ive found a note that says "may require longer push rods".
I ordered my stuff from summit and never saw this till now. Plus when I ordered my parts I also ordered stock replacement push rods made by comp. When I replaced them I noticed they were a little bit shorter than the stock ones. I didnt really know what to do so I went ahead and replaced them. Now Im wondering if this might be my lack of performance. Dont get me wrong, the motor runs really good. I just feel I would have been better off hopping up the 400 at this point.

 

I dont know about that 400, might be better off getting things sorted out with the 460 you got, rather than trying dig & scratch trying to find something to build up the 400.
All I've read the 400 is kinda by itself, hard to find stuff, might be wrong about that though.
I know when I found out you could built 700 HP on top of that stock Ford cast 460 crankshaft, wasnt nothing else big enough for me.

I got a good friend has a built up 351M/400 in a big 4X4, & its in such bad shape it will tear a dollar out your hand if you hold it in front of the tail pipe.
Neil

 

Yeah, Im not really into the 400 Im just frustrated. I know the 460 is a much better motor I just want to get it running right. I honestly believe I would have been happier right now had I left it alone and not changed all these parts. I just need to figure out where to go from here. To make matters worse I just got spanked by a mini van at lunch time today.

 

You just got a combination of things need checking to get the 460 right then you'll be more pleased with it & could be something simple you just not put your finger on yet.
A new carb right out of the box needs setting up for the engine its going on. Summit says they are ready to go, but dont beleave that, get a good carb man to set it up right.
Neil

 

Well I ran some quick CFM calcs for you based on the cam/engine specs:

Based on a max rpm of 5500 I calc out 659 cfm based on 90% volumetric efficiancy (which is a little high for a street vehicle), with the 750 that puts it at about 12% too much carb. Reduce the primary fuel jets by 1/2 (ie 6%) and that should put you within 1-2 jet sizes of being on the mark (example if the carb has #70 jets, 4.2 is about 6%, so start with a #66 jet).

There's no need to buy another carb when this one can easily be tuned to work. Also IMHO, the cam is a fairly meek cam, even for torque in the low rpm ranges so my suggestion is to stay as close to oem specs for carb, etc for the best performance.

 

Want to do some more 460 figuring beechkid .
Say the cam has .484 intake .509 exhaust lift & set at 4* advance with a set of ported D3 heads, but stock intake & exhaust manifolds, could you figure a carb for that or you would need flow numbers from the heads to figure it right.
Close will be ok by me.
Thanks, Neil

 

Thanks for looking that up for me beech !! Its somewhere to start. Does anyone one have any thoughts on my push rods being too short?