Need some 351W advice for towing

[Dave Flanders]

I have a later model 351W truck (roller cam) motor in my tow vehicle and am looking to pump up the low end torque and the gas mileage. Not looking to spend much money as my racing career is not what it was so spending a couple thousand to gain 2 mpg won't pay. Here are the parts I have and the parts to choose from:

Low mileage (60k) motor (changed to "P" heads)
Stock 2 bbl intake
Stock 2 bbl carb
Edelbrock Streetmaster intake (single plane, teeny runners)
Edelbrock Performer intake
5.0 GT roller cam
OE Holley 4 bbl for a later Windsor truck

I'm limited to a carb due to the vehicle being a 74 Galaxie so no room for the EFI intake. I had an engine builder friend tell me the GT cam advanced about 4 degrees looked best. I've got a multi index timing set coming and was originally thinking of a lot of cam advance like the old 460 trick but he didn't think excessive advance would work real well. Both cams apparently have 115 LSA and are set at a 115 (or 117) ICL. Does this thinking on the cam sound reasonable? I know neither are optimum for a carb'd motor but it's what I have.

Vehicle weight is probably 4200+ lbs, 18 ft. open trailer and car probably another 4500+ lbs. I've tried driving in 2nd gear and at 27-3000 rpm mileage doesn't suffer but there's no power gain either over towing at 22-2500 rpm. Car also has 2.47 gears, I have a 9" for it with 2.79's.

Should the Streetmaster help or would it be better off with the Performer?

Is 4 degrees advance sufficient or try more?

The OE Holley should be a better match for the whole thing than the stock 2 bbl's, I do have an LM1 I can rig up in it to fine tune with.

What would a Windsor with P heads like for timing? I need to quicken and limit the mechanical advance, it must have 30 degrees in the dist. Can anyone recommend a basic timing curve for this setup on pump regular? If absolutely necessary I can run better gas but would prefer the cheap stuff.

Thanks for any input.

[travis]

The stock truck truck roller cam is tiny but is stronger under 3k rpms.

Personally, I wouldn’t change a thing until you put some real gears in that thing. A set of 3.50-3.55’s will make WAY more difference than any engine mods will. Even a stock 2bbl 351w will pull that weight just fine if it has some leverage.

[bobalattie]

P heads like 32* total timing, what ever cam will give you the most lift, stock mustang cam with 1.72 rockers advanced 4*, and use the performer intake. Try to get the compression ratio 9.5:1

If it’s in the budget, crane has a 208/216 .530 lift cam that works really well for what you wanna do

A good valve job will wake those heads up...

I ran a set on a 351w turning it 6500 in a circle track application..

[Walter R. Malik]

I have a later model 351W truck (roller cam) motor in my tow vehicle and am looking to pump up the low end torque and the gas mileage. Not looking to spend much money as my racing career is not what it was so spending a couple thousand to gain 2 mpg won't pay. Here are the parts I have and the parts to choose from:

Low mileage (60k) motor (changed to "P" heads)
Stock 2 bbl intake
Stock 2 bbl carb
Edelbrock Streetmaster intake (single plane, teeny runners)
Edelbrock Performer intake
5.0 GT roller cam
OE Holley 4 bbl for a later Windsor truck

I'm limited to a carb due to the vehicle being a 74 Galaxie so no room for the EFI intake. I had an engine builder friend tell me the GT cam advanced about 4 degrees looked best. I've got a multi index timing set coming and was originally thinking of a lot of cam advance like the old 460 trick but he didn't think excessive advance would work real well. Both cams apparently have 115 LSA and are set at a 115 (or 117) ICL. Does this thinking on the cam sound reasonable? I know neither are optimum for a carb'd motor but it's what I have.

Vehicle weight is probably 4200+ lbs, 18 ft. open trailer and car probably another 4500+ lbs. I've tried driving in 2nd gear and at 27-3000 rpm mileage doesn't suffer but there's no power gain either over towing at 22-2500 rpm. Car also has 2.47 gears, I have a 9" for it with 2.79's.

Should the Streetmaster help or would it be better off with the Performer?

Is 4 degrees advance sufficient or try more?

The OE Holley should be a better match for the whole thing than the stock 2 bbl's, I do have an LM1 I can rig up in it to fine tune with.

What would a Windsor with P heads like for timing? I need to quicken and limit the mechanical advance, it must have 30 degrees in the dist. Can anyone recommend a basic timing curve for this setup on pump regular? If absolutely necessary I can run better gas but would prefer the cheap stuff.

Thanks for any input.

Been there many times for the same reasons.

Use the performer intake manifold with an 80's O.E.M. Holley 4180 carb. The truck carb is almost the same as the H.O.

There are two different H.O roller cam designs but, they are very close to the same; they DO have the same exhaust lobe profile,
The 85/87 cam, E5ZE-6250-AA, is the cam to use with 4 to 6 degrees advance from the as ground @115 lobe separation and intake center-line.
The revised O.E.M. camshaft, E8ZE-6250-AA, has a slightly different intake lobe, not as aggressive near the seat. It has 10 degrees more S.A.E. valve timing with the same duration @.050" to quiet down the valve train.
It is ground on a 115.5 separation with a 116 intake center-line. All later revisions of the cam have these specs.
The early one is the better one to use for this but, the revised cam will be within an eyelash of the performance.

Put 10, (distributor), degrees in the distributor and initial time it at 15 BTDC at idle; (no vacuum); 35 degrees total mechanical at the damper. Don't make the mechanical advance in the distributor too quick, (all in at 3,200 is fast enough), and definitely tune a good vacuum advance unit for this package.

[cjperformance]

^^^ Spot on Walter

[Dave Flanders]

Not sure if the cam is the early or late one but if they're close then that's close enough for me. Looks like I'll try 4 advanced on the GT cam and the Performer intake. I'll keep an eye out for some rockers.

That's the exact type of info I was looking for on the ign. timing.

I might consider buying some gears, it's just that currently more rpm's just seem to make more noise without any more power. If I can get this thing to feel like it has a sweet spot somewhere I can gear it accordingly.

Many thanks for all the input, it's amazing how much I don't know/have forgotten about V8's in the last 40 yrs. I've spent the last 30 yrs. playing with turbo'd 4 cylinders and actually my first inclination was to cobble up a low boost blow through deal with a couple T3's. Might give me the power I need but probably wouldn't help the mileage any.

[Carnut1]

viewtopic.php?f=1&t=43928 One of my better threads, may give you a few ideas. Love your signature, funny. Thanks, Charlie