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4V 351 spec

7K views 19 replies 8 participants last post by  needturbo6 
#1 ·
Hi Guys,

Ive watched and enjoyed your forum for a while, this is my first post.

Im looking for opinion for a motor im currently building:

4V 351 +30, solid cam 575/600 lift, 247/257 @50, 107 lobe sep, shot peened rods with ARP bolts, 4MAB crank, 10.5: 1 comp with 4V closed chamber heads on PULP.
Useage will be street/strip, 6500 rpm limit, looking for 480-500HP.

My dilema is 3 fold:
1) What piston will suit my application without going over board?
2) What is the best inlet manifold to suit? ive got a 4V torker at the moment, will it do? or do i need to go bigger?
3) should i use inlet tounges on these heads?

Any advice would be appreciated

Thanks.
 
#2 ·
Hi 4Vman, welcome to the forums, in my opinion :
1) TRW flatops
2) Torker should be fine
3) Inlet tounges should help, but i don't think you NEED them, my 4v's go fine without them.

What about the rest of your specs , what car, carby, gearing stall ..... ? do you have.
 
#3 ·
Thanks for the info,

Do you use a similar combo?
Are port tounges over rated?

its a spare motor, but will probably end up in my XBGT or XYGT, both are manual, 3.7 gears, 750 HP series Holley etc,
Thanks.
 
#4 ·
My ports are actually ported !, but i have 4:88 gears which helps the 4v's down low.
I have not tried tounges myself, but i hear they are good for windspeed.
My combo is similar, except i have a 850 dp, and a much bigger cam.
 
#6 ·
1) What piston will suit my application without going over board?

TRW 2379F Forged Flat Top 10.5:1 with 63cc heads seems to be choice

2) What is the best inlet manifold to suit? ive got a 4V torker at the moment, will it do? or do i need to go bigger?

Torker is good but have heard the X-Cellerator is more responsive off the line. Smaller ports and longer than the Torker

3) should i use inlet tounges on these heads?

If u want. I have a tongue inlet plate from Active Performance which bogs the bottom off. Haven't tried them yet. Others also sell alloy or epoxy tongues u need to grub screw.

Good luck.

Hopefully with a C4 - 4000 stall and LSD 4.0:1 with 26*8.5*14 MTs u do a 11.99 sec quarter. That's what I'm aiming for with mine !!!
 
#7 ·
Thanks for your help,
what are peoples opinion of ACL pistons? Both the duralite and Racer series.
Forged pistons seem a bit over the top for an engine that will be in a weekend street car? or will the HP figure im looking at make it manditory,
Thanks!
 
#8 ·
Your compression is really borderline for pistons that aren't forged. Most non-forged pistons state a safe compresion ratio as 10:1 but you can get away with 10.5:1. I am sure ACL states this on their website too.

Brenden
 
#9 ·
not an expert but id go the inlet tounges for the low down torque and since its "only" going to be revved to 6500rpm. didnt the xy gtho's rev to 7500rpm down conrod?

also heard the x-cellerator is an excellent manifold, everything ive read to do with it has given it a thumbs up, and would be very suitable for the 6500rpm limit
the torker obviously would work but if u can find an x-cellerator at the right price i would go for it. either way u go port matching would help.

re-reading ur post i noticed your power goal which is very realistic indeed.
 
#10 ·
The torker will be fine for what you want to do. I personally chose the TFC because of it's top end capabilities.

I have installed port toungues, even NASCAR motors that revved to 8000rpm still had their ports filled in. It greatly increases air velocity.

I found that the ACL race series piston to be quite good, but as said earlier there are forgies out there which aren't bad. I would go for a 6" 302 rod on your 351 crank and use a SRP forged alloy piston, they go for approx $800-900 and will give you 357ci at 30 thou with 10.3:1 compression with a 64cc 4V closed chamber head. big HP potential.

You have some good pieces there? (carb etc.) With that crank, maybe a set of 6" forged rods ($600 or so) and maybe consider solid roller, you can aim for 500-550hp.

Best of luck mate, cant wait to see it happen. Mine is almost there and i just cannot wait to hear her for the first time...

shane
 
#11 ·
The ol Larry Perkins ACL Race Series pistons came out with the 351C piston using the 302 rod version. I think they stated 400 hp and 6000 rpm limit but they tested it a 500 hp and ran at 6500 rpm for like 14 hours to simulate a caravan towing round Oz ??? They came with moly rings and weren't to bad in price. Bout the same is they TRW 2379F without rings. Might c if I can find the web page.
 
#14 ·
Hi Guys,
i guess i wanted to keep to some sort of budget, if i got to H Beams i might as well go Forged pistons and might as well go TFC manifold then go to CHI heads etc etc and then rev it to 7500 to get value for money, but ive already got the std shot peened rods with ARP bolts etc and ive already got a set of +30 ACL pistons and ive already got the Torker, it was really going to be an engine to use all my left over stuff if it met my aim of 480+HP @6500 rpm without detonating.
As far as 4V heads goes the motor will go into a Genuine GT so i want to keep with the original style fitted motor, theres also nothing quite like the sound of the hi comp 4V Clevo!. also all my parts are to suit 4V heads,
Thanks again!
 
#16 ·
My 73 XBGT already has a recently built 448HP solid F238 cam 4V motor in it (original motor), ive also got an XY GT with tired wrong motor in it and i was going to throw this motor together for it.
I often hear people say 4V motors are sluggish down low but all i can say is my current motor will absolutely toast the tyres if you stand on it in first and second while driving along with the motor barely reving 2000rpm.
Im hooked, 4V for me!
 
#18 ·
i definitly think u should go the inlet tongues now, what decisions have u made about the motor so far?

i can see where ur coming from now, as ur using a lot of parts u already have. no point buying more stuff when u dont need it hey. it might be a good idea to search the net for some cars using the torker manifold to see the results and if porting gets any improvements.

im curious as to what extractors (and it specs) u will u be using?
 
#19 ·
Ah yes the age old problem, what extractors?
Im using pacemaker 4 into 1 with 1 3/4 primaries on the XB at the moment. They worked well on the engine dyno with that motor so ill probably use the same again.
The only thing that makes me wonder about using tri y's is that all the group C guys used to run them, and the DJR Greens Tuf XE ran a huge cam, 670 lift and 278 @ 50 with the standard duel plane manifold, and tri y's which resulted in about 520HP @ 8000 so its got me stumped!
 
#20 ·
do u know whether or not the djr XE used a carby spacer, so as to make it practically into a single plane, if it wasnt that they mustve been running a big carby?......
very interesing figures there, but if it was that good i would think everyone would be using tri-ys and a dual plane and i also i remember Dicky ran "fully" ported 2v's as he said they flowed better. its prob the only peices of engine info i can remember when i read an article. ill try and dig it up and see what else i can find, could be interesting
i do like that rev figure tho - u cant beat the sound of a high revving clevo

properly designed 4-1 headers would be much better than tri-y's in my opinion, which would be influenced by the amount of cars these days with high horse motors and 4 into 1's

whats the specs on the xb's motor btw?
 
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