Big Block Advice Needed

-
d55dave

d55dave

Well-Known Member
Joined
May 20, 2010
Messages
2,585
Reaction score
1,137
Location
Kelowna, British Columbia
OK guys, not an A body but I want to make my 49 Plymouth gasser a little quicker, on a budget LOL. Think cam and intake change. I would like to pick up a half second in the 1/4 if I could.

I built this car, a rat rod / gasser through covid and had it on the road for the first time this summer. The car has proven to be real consistent, but I would like to be a little quicker while staying consistent.

Here are the current build details, dont slam me for the mis matched combo, I didn't build the engine. It is a good runner, probably has 10000 miles on a proper rebuild and was previously run on propane. It uses no oil, has no blowby and has 125 to 130 PSI compression on all cylinders. It is a mid 70s 440 with a large comp flat tappet hydraulic cam (I am not sure of the specs but believe it to be the largest flat tappet hydraulic cam that comp offers). It has closed chamber iron heads with light porting, is guestimated to be around 9:1, has a performer rpm intake, 1” spacer, a holley 850 dp and a body hooker super comp fenderwell headers. Trans is a 727 with a&a internals including a brake, converter is a 5000 rpm and is good, rear is a dana 60 mounted on leafs with ladder bars, housing floaters, 4:10s and a spool.

Launching off the two step at 4200 and shifting between 5800 and 6000 the car runs 7.95 at 85 in the 1/8, 60 foots are 1.77, the car with me weighs 3200 pounds. The car ran 12.7 in the quarter with an ignition miss.

On my shelf I have another set of closed chamber iron heads that are ported with big exhaust valves, a set of crane ductile iron adjustable rockers, an old school offy tunnel ram with single dominator top, and a dominator 1050.

What I am thinking is swapping to a mechanical flat tappet cam (in the 540 to 570 lift range), adding the tunnel ram and dominator, or possibly an M1 if I can find an affordable one and putting the ported heads on it.

Will this get me what I want? Any ideas or suggestions?

BE11F012-CA41-433A-B0EC-D76CD8160F25.jpeg


5F402E33-6FD2-472B-B343-99AB4C3091FC.jpeg


AC19E662-B3F3-4326-B2DE-D861A6A6BB32.jpeg


E06A4AB5-DBA8-443F-87B3-DCCF3BB0D248.jpeg


E59E9AA1-BA24-4F21-86E9-8C22AE0E8C9F.jpeg


2392C74B-BFC2-4E02-8CF7-AA19908F2190.jpeg
 
Last edited:
I can't answer your question if the dominator and tunnel ram will lower your et a half second.
Maybe add a solid flat tappet cam, it might help
But I can say that is one cool car !
 
MOPARMAGA said:
I can't answer your question if the dominator and tunnel ram will lower your et a half second.
Maybe add a solid flat tappet cam, it might help
But I can say that is one cool car !
Click to expand...
Thanks! Had some fun with it this summer, first event was the Langley Loafers old time drags at Mission Raceway where I won nostalgia gas class, second event (and my completion date and goal) my son and I ran in the Canadian drag week, Miles of Mayhem where we placed third in bracket class. Good times!
 
d55dave said:
Thanks! Had some fun with it this summer, first event was the Langley Loafers old time drags at Mission Raceway where I won nostalgia gas class, second event (and my completion date and goal) my son and I ran in the Canadian drag week, Miles of Mayhem where we placed third in bracket class. Good times!
Click to expand...
That sounds like a **** load of fun.
My buddy Ken loves going up to mission, he didn't go this year because he's building a drag only 68 dart and retired his blue 68 gts. I'd like to check it out but the last time I went to Canada I was told I'm not allowed in lol. That was 15 years ago or so.
 
Is the 360 intake a split plenum tunnel ram like the 360 low single plane ?
 
d55dave said:
Yes, the plenum has a divider running front to back that does not go all the way to the bottom
Click to expand...
Interesting, I have one of the short version.
What ratio are the rockers ?
If you're looking for a mechanical flat tappet my best advice would be Howard's cam or Hughes engines. Howard's grinds Hughes but Hughes list details on there website to help guide people in the right direction.
 
MOPARMAGA said:
Interesting, I have one of the short version.
What ratio are the rockers ?
If you're looking for a mechanical flat tappet my best advice would be Howard's cam or Hughes engines. Howard's grinds Hughes but Hughes list details on there website to help guide people in the right direction.
Click to expand...
Awesome, thank you. The rockers are 1.5
 
By the way my wife is from Kelowna, but just as a little kid
 
Half a second quicker is going be a big ask with 9:1 CR.
I would at least check or measure the current cam so that you have a starting point.
You say it has the largest FT cam that Comp has. The engine should have a very rough idle & a high idle speed. The largest HFT cam in my Comp catalog is 320* adv, 268 @ 050. Could not imagine that would be very streetable & going bigger might produce diminishing returns.

Here is a warning in the Erson cams catalog. It only appears in the Mopar 440 section, no other brands. Hmm:
'...beware of too much duration [ with TF transmission ]. Although the longer duration cam will make more HP, the loss of tq at low rpm will more than offset the gain at the top end & the ET will suffer.'

This is because of the high rod/stroke ratio of the 440.
 
I t hink a bigger solid flat tappet cam, and the ported heads could get you where you want to be IF (a big if) the compression ratio is what you think it is. Pull a head and see how far down the hole the piston is. Those motor home engines were about 7 1/2 to one. I would recommend finding out what the cr really is, before selecting a cam.
And then after the cam and head swap, at least try the dominator tunnel ram. It's way too cool to sit on the shelf.
 
If you want a 1/2 second in the 1/4 mile. Switch to a solid or better yet a roller cam, bump the compression a full point, and leave that Performer RPM intake on there. That intake is honestly probably the single best piece of hardware you have on that engine. They really are that good of an intake.

Tom
 
Thanks for all the advice. To clarify, I am not talking about going to a bigger solid cam, I am talking about a similar sized solid cam for a few reasons. Added stability at high rpm, between my 4200 launch and 6000 shift, where hydraulic cams suffer, solids with a similar advertised duration actually have a shorter duration due to valve lash, and going solid will require me to use my crane rockers which have a true 1.5 ratio versus the factory rockers currently on the engine which in reality are more like 1.4 or less.

I agree that the performer rpm is a great intake…… for a heavy street car with a tighter converter. Again, I am reasonably light and am looking for gains above 4200 where a good single plane or tunnel ram should come out ahead.

Yes, roller cams are miles ahead…… but not currently in my budget, LOL.

I am looking for some real world and experienced advice from someone who has run a flat tappet and tunnel ram.

Thanks all!
 
It’s pretty hard to make any power from a combo that only has 125-130 cranking pressure.
One or more of these scenarios is probably in play-
-CR is less that 9:1
-cam is rather large
-cam is installed retarded

Imo, a head needs to come off and things measured to determine true CR.
Cam specs need to be verified..... by measuring or by part number.

Imo, the TR/1050 won’t help with your goals.
 
PRH said:
It’s pretty hard to make any power from a combo that only has 125-130 cranking pressure.
One or more of these scenarios is probably in play-
-CR is less that 9:1
-cam is rather large
-cam is installed retarded

Imo, a head needs to come off and things measured to determine true CR.
Cam specs need to be verified..... by measuring or by part number.

Imo, the TR/1050 won’t help with your goals.
Click to expand...
Or all three, LOL.My first step, in a few weeks, will be to pull the intake and heads to measure actual CR. I do know for a fact that when my buddy put the cam and heads on this engine he just stabbed the cam in and didn’t degree it.
 
I would pull a head and measure to figure out compression, take a look a the head and see what kind of work has been done. I would consider the other heads if they seem nice.
The RPM intake is probably fine for 4000-6000 rpm.
I would put a solid cam in it with the rocker arms you have.

Here is a smallish solid Lunati cam that shows to be in stock.

Voodoo Solid Flat Tappet Cam - Chrysler 361-440 272/280
 
If you look at a lot of dyno test you'll find a single plane Victor intake on even a 600-700 HP will make 30HP over a Performer RPM intake, but not until around 6000 rpms. However that same engine will make 60 ft lbs. less torque with the Victor than the RPM intake. The Victor will only start surpassing the RPM in HP at the very top end of the RPM range right around your given rpm limit. In your application the RPM still wins hands down over a single plane everytime. Torque moves the car, not horsepower.

Tom
 
PROSTOCKTOM said:
If you look at a lot of dyno test you'll find a single plane Victor intake on even a 600-700 HP will make 30HP over a Performer RPM intake, but not until around 6000 rpms. However that same engine will make 60 ft lbs. less torque with the Victor than the RPM intake. The Victor will only start surpassing the RPM in HP at the very top end of the RPM range right around your given rpm limit. In your application the RPM still wins hands down over a single plane everytime. Torque moves the car, not horsepower.

Tom
Click to expand...
I agree that the RPM is a terrific manifold, and better than the Victor for the o.p's present combination. The tunnel ram can make good low speed torque too, and if o.p. goes to better heads, and a solid cam, he might end up with 500 to 700 more usable rpm range, and the TR should help that. He HAS the TR, and dominator. After the cam/head swap (and assuming the cr isn't in the low eights) why not try it?
 
I think the tunnel ram would be a great intake, if it had a two carb top. I am not sure that it would be of much advantage with a single 1250 on it since the fuel distribution will not be ideal compared to 2x4's. Good thing is he has two different intakes to play with.

Tom
 
5000 stall converter? low comp? almost 1.8 60ft?
Yeah, using the tunnel ram with a single Dom on it would be the last thing I'd do.
 
If it where me I would use a m1 single plane. Along with your closed chamber heads you already have set up and a .590 mechanical purple shaft installed 4 degrees advanced to get some bottom grunt back. There is probably better cams but that cam just flat out works
Click to expand...
 
When I bought my 68 Barracuda this is what was in it, 446 with 2266F pistons .074 in the hole,.020 steel head gaskets, 509 cam, Team G intake, 850dp, 906 heads cleaned up gasket matched [91cc] measured. Less than optimal for performance. Turbo Action 3800 converter, 391 gears. Weight about the same as yours. It ran 11.91 @ 111. I upped the CR to 12.5 and put .557 sft in and it went 11.41 @ 117. Changed the the cam to the .590 it went 11.27 @ 119. With Indy SEZ heads, Torker II intake an ATI in 5200 converter 10.82 @126 @ Cecil Cty. With a Thumper dommie and Super Victor 10.66 @ 125 @ Mason Dixon b/4 it finally took a crap. Pull your heads to see what pistons are in it, put the best heads you have or some aluminum [if you have the funds] on and sft or roller in it. 440s make power it doesn't have to be perfectly optimal. Just have fun. What M1 are you looking for 4150? For what it's worth I found no difference between an M1 and a TorkerII.
 
Last edited:
You must log in or register to reply here.
-

Back
Top